Discussion
132
Using pattern recognition of hyperbolic shape as a key to discoveries in exploratory data analysis, 133
we started research for traveller's Thrombosis and COVID-19, and as a result, our concept of the geometrical 134
viewpoint allowed us to discover many unrecognised patterns. Therefore, approaching data from geometry 135
and exploring data focusing on hyperbolic patterns can be a practical option for researchers. 136
In traveller's thrombosis, we obtained consistent results from two analyses (7.1 hours and 11.8 hours 137
vs 9.2 hours and 12.1 hours) (Fig. 2, b, Extended Data Fig. 3). The discrepancy between the value of 7.1 138
hours and 8.5 hours seems to be explained by the miscalculation found in the data review process (see 139
Methods). Although many researchers have led controversial discussions based on a single curve, our results 140
implied two S-curves. We hypothesised two high-risk periods and two types of high-risk groups, which may 141
have to be considered with the "factor V Leiden paradox"42 (Supplementary discussion 3: two high-risk 142
periods and two types of high-risk groups?). 143
Another noteworthy point is the cyclic patterns (wave) (Fig. 2, c, d) and the raw-risk period just 144
before 90 days in Kelman et al.27 (Extended Data Fig. 5). In Cannegieter et al.24, the cyclic pattern 145
disappeared around 90 days, consistent with that the high-risk period in oral contraceptive (OC) use was the 146
first three months (90 days)42. Also, the above raw-risk period explains extended-use type OC, which has a 147
planned drug withdrawal, such as 84 active days and seven placebo days43-45. In addition, the uptrend in the 148
data by Kelman et al.27 could be explained by depot agent type OC administrated 90 days cycle46. So, our 149
findings imply that the 28 days cycle OC is attributable to the cyclic pattern, and both cycle type and 150
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extended-use type OC use is triggered by travel. An opposition may arise considering that both of relative risk 151
reported by Martinelli et al.22 and Cannegieter et al.24 were low (Fig. 2, b), but it seems to be explained by 152
bias derived from using their partner as control (Supplementary discussion 4: OC users and bias by their 153
partner). 154
A halfway cycle (17.9 days) in Kelman et al.28 was explained by a mixture of the 28 days OC cycle 155
and a type of HRT cycle (sequential type; daily estrogen dosing and 10–14 days progestogen)46. Also, another 156
problem is that the wave in Cannegieter et al. was clear (thrombosis onset: March 1999-March 2000)25. 157
However, the wave in Kelman et al. (1981-1999)28 was not clear despite the exposures in Cannegieter et al. 158
(air travel, train, bus, and 48.5% car trip)25 was more complex than Kelman et al. (only air travel)28, was 159
answered by the history of HRT. In Kelman et al.28, there might be both young women taking OC and 160
menopausal women receiving HRT, but only OC users might remain after the HERS study reported risk of 161
HRT (1998)31, which was assisted by the growth of thrombosis onset slowed at the HERS study31 (Extended 162
Data Fig. 6). Also, the above cars might be honeymoon cars. Although it was not decreasing, the result might 163
be caused by some woman's desire for joyful travel to Paris with HRT. 164
Our thought on pharmacoepidemiology in the real world, starting OC or HRT was triggered by 165
travel and decision making of HRT connected to travel, which means that well-planned usage based on risk 166
diversification may allow more safe use of OC and HRT. 167
In appreciation of our ideas to COVID-19, the dataset grouping by Matsushita et al.32 matched the 168
grouping by data cut-off dates (Extended Data Fig. 7), and age structure diverged from middle age to mature 169
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and elderly, which was consistent with the hypothesis that COVID-19 spread from the seafood market. 170
Middle-aged people might go into the workforce for manual labour treating fish containers, mature people 171
might want to select IT jobs, and elderly people might stay in the house. 172
Interestingly, our analysis of the data by Guo et al.34 showed three clusters of subgroups, and one of 173
those formed the tilted parabola. Also, the patterns matched the other studies (Fig. 4 a, b, Extended Data Fig. 174
8 & Extended Data Fig. 9)36-41. Considering the study by Budnik et al.36, those subgroups may have different 175
biological mechanisms. 176
Additionally, we found patterns on the side surface of this parabolic cylinder (Fig. 4, c, d, & 177
Extended Data Fig. 10). A paradoxical result on troponin was obtained just before the pandemic48, and 178
Meisel et al. mentioned that the CRP to troponin ratio (CRP/troponin) could serve to differentiate between 179
myopericarditis and acute myocardial ischemia (AMI), although not the study on COVID-19 patients. In 180
COVID-19, Caro-Codón et al. reported interesting behaviour of CRP35. Also, a meta-analysis by Lagunas-181
Rangel reported that the lymphocyte‐to‐C‐reactive protein ratio (LCR) level, which was not a simple 182
measurement value but a ratio, might be related to an inflammatory process47. 183
The above studies might imply complex data structures in 2-dimensional and 3-dimensional scatter 184
plots consisting of biomarker values, and our findings may serve cardiac biomarkers' research field. 185
Supplementary, we explain the misuse of linear regression analysis in the study by Guo et al.35 186
(Supplementary discussion 5: misuse of linear regression analysis). 187
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Although many studies on visualization of meta-analysis have been conducted48, our simple idea 188
(hyperbolic pattern) has not been proposed. As named “error”, researchers usually view an error bar 189
negatively. Also, in the wheel's history, an invention of carriages, which was achieved by arranging the 190
wheels in parallel, appeared in ancient times, but the idea of the bicycle, which was innovatively arranging 191
wheels vertically, had not been conceived before the 19th century49,50. Those mental blocks might have made 192
it hard to imagine that vertical error bars provided information on a horizontal axis. 193
Evaluating our ideas, we discovered many oversights which were entirely beyond the initial scope. 194
Appearing overlapped hyperbolic patterns may show poor data review and analysis. Currently, pattern 195
recognition based on Artificial Intelligence (AI) detects cancer sites from images. Considering our discoveries 196
by an analogy that Newton's theory enabled the prediction of a planet's orbit, implementing our idea (a kind of 197
mathematical model or theory) in an AI system might assist another discovery of clinical issues. 198
199
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200
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326
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327
Methods
328
1. Numerical experiment 329
Unavoidably, this study conducted a numerical experiment to determine what curve approximates an 330
edge of a confidence limit (Fig. 1, c). 331
Generally, a dose-response relationship often indicates an S-curve. Considering the distribution of a 332
population at thrombosis risk and the cumulative thrombosis onset, each of those is monomodal distribution 333
and the S-shaped curve, respectively. So, we decided to use the sigmoid function, which is generally used in 334
curve fitting to dose-response data, as the formula for the S-curve fitting. 335
Contrastively, the curve expressing the end of a confidence interval (confidence limit) is a sum of 336
the S-shaped curve and U-shaped curve because the width of the confidence interval narrows near the centre 337
of distribution due to many cases around the points. Similarly, the confidence interval widens at the 338
distribution edge due to the small number of cases (see Fig. 1, d). 339
Based on the above consideration, we selected the parabola as a candidate for the U-shaped curve 340
because this curve was mathematically easy to handle (just junior high school level mathematics). So, we 341
examined the validity of using parabola. However, mathematical proof of our conjecture was difficult because 342
normal distribution was continuous probability distribution. So, we used a kind of discrete probability 343
distribution, binomial distribution, to prove our conjecture experimentally because normal distribution could 344
be approximated by binominal distribution. This idea was thinking in reverse of the usual statistical technique. 345
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To generate binomial distribution data, we used the "BINOM.DIST" function, which is a function 346
for calculating the probability of binomial distribution in a kind of spreadsheet software, Microsoft Excel○R 347
(Microsoft Corporation, Redmond, Washington, US). 348
349
2. Equations for regression analysis 350
The equations for the S-shaped curve, the upper end of the confidence limit, and the lower end of the 351
confidence limit, those equations are the following (1), (2), and (3), respectively. Note that in the below 352
equations, the coefficient L is generally set as 1. So we used this equation under the condition as L=1 unless 353
there is some reason. 354
355
𝑦 = {
𝐾1
1+e𝐿(𝑥−𝑀) + 𝐾2} (1) 356
𝑦 = {
𝐾1
1+e𝐿(𝑥−𝑀) + 𝐾2} + (𝑎𝑥2 + 𝑏𝑥+ 𝑐) (2) 357
𝑦 = {
𝐾1
1+e𝐿(𝑥−𝑀) + 𝐾2} − (𝑎𝑥2 + 𝑏𝑥+ 𝑐) (3) 358
359
Also, a complete square of the quadratic function that represents the parabola is the following equation (4). 360
361
𝑎𝑥2 + 𝑏𝑥+ 𝑐 = 𝑎 (𝑥 +
𝑏
2𝑎)
2
−
𝑏2−4𝑎𝑐
4𝑎 (4) 362
363
Besides, the point P is the apex of the parabola is the following (5). 364
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365
P (−
𝑏
2𝑎 , −
𝑏2−4𝑎𝑐
4𝑎 ) (5) 366
367
The following equations are the formula that expresses the outline of the distribution obtained by differential 368
calculation on the S-shaped curve (6). 369
370
𝑑𝑦
𝑑𝑥 = −
𝐾1𝐿𝑒𝐿(𝑥−𝑀)
{𝑒𝐿(𝑥−𝑀)+1}
2 (6) 371
372
3. Analysis tools in this study 373
Reading values from the published figures were performed using the public domain software ImageJ 374
in the public domain (https://imagej.net/Welcome). Regression analysis was performed using Python (Python 375
Software Foundation, Delaware, USA https://www.python.org/psf/records/incorporation/). At this time, 376
Python's functional modules NumPy (NumFOCUS sponsored open-source project, https://numpy.org/), 377
Pandas (NumFOCUS sponsored open-source project, https://pandas.pydata.org/), SciPy (NumFOCUS 378
sponsored open-source project, https://www.scipy.org/) and Matplotlib (NumFOCUS sponsored open-source 379
project, https://matplotlib.org/) were also used. Additionally, a function as "Chart option" of Microsoft 380
Excel○R , which was shown in the "Trendline Options" section contained in "Format Trendline," was used. In 381
the case of symbolic formula manipulation was required, formula manipulation software wxMaxima (Project 382
Maxima maintained by 27 volunteers, https://maxima.sourceforge.io/) was used. 383
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p. 22 of all 74
384
4. Analysis 1A (dataset: Chandra et al.)7 385
1) Data review to validate eligibility for regression analysis 386
a. The process of data review in this analysis 387
As the first step, we performed data mapping. In the figure of meta-regression analysis reported by 388
Chandra et al.7, it was not described what the data points correspond to the four original papers (Martinelli et 389
al., 2003; Parkin et al., 2006; Cannegieter et al., 2006 and Kuipers et al., 2007)23-26. So, we measured the 390
positions of each point and compared them with the original descriptions in the papers. In the second step, we 391
performed a data review, which was an examination of the accuracy of cited values, and appropriately from 392
the viewpoint of biomedicine. Our re-calculation confirmed the odds ratio (OR), confidence interval of the 393
OR, and adjusted OR. In examining the values, we did not confirm Chandra et al.7 and the four authors23-26 394
because Chandra et al. described that each author did not respond to inquiry7. As a final step, we performed 395
regression analysis using the eligible data for using regression analysis. 396
397
b. Data review 398
The data review showed some problems in the research reported by Cannegieter et al. and Martinelli 399
et al.23,25, and we excluded those data in the regression analysis. Also, there was a point to notice in the data 400
reported by Parkin et al.24 (see Extended Data Fig. 1). 401
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p. 23 of all 74
In confirming the accuracy of the values, there were no problems with the two studies (Kuipers et al. 402
and Cannegieter et al.)25,26, but there were problems in the other two studies (Martinelli et al. and Parkin et 403
al.)23,24. 404
In Martinelli et al.23, the problem was gender imbalance and unadjusted OR. In addition, although 405
there were no explanations for the odds ratio described in the text cited by Chandra et al7, the above OR was 406
presumed to be an unadjusted value, judging from the context. Comprehensively, judging from both 407
calculation results and the original article, the odds ratio cited by Chandra et al.7 was strongly suspected of 408
being an unadjusted value. 409
In Parkin et al.24, there was a discrepancy between the OR and the described OR calculated by us. 410
Also, it was suspected that cells in the cross table were mistaken (e.g., in the table of Fig. 1a, the cell for 411
control and the cell for total were mistaken). However, the error bar's length was relatively small since the 412
total number of cases was notably smaller than other studies. So, qualitatively, it could only be used to group 413
data to find hyperbolic patterns. 414
In confirming from the viewpoint of the biomedicine side, there were no problems with two studies 415
(Kuipers et al. and Parkin et al.)24,26, but there were problems in the other two studies (Martinelli et al. and 416
Cannegieter et al.)23,25. In Martinelli et al.23, judging from the subtitle, "interaction with thrombophilia and 417
oral contraceptives," oral contraceptive (OC) bias was suspected. Initially, the study aimed to evaluate the 418
interaction between OC use and travel. Considering the above, the OR had to be considered a value that 419
contained a strong bias (see also Supplementary discussion 4: OC users and bias by their partner). In 420
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Cannegieter et al.25, the data contained car travel, and the other studies contained only air travel. So exposure 421
factors were different, and there was a problem from the viewpoint of comparability (e.g., air pressure, 422
dehydration, and time difference). Also, Chandra et al.7 showed two types of analysis results, including 423
Cannegieter et al.25 and not. Besides, the cyclic pattern could be explained by OC use was observed (see Fig. 424
2, c & d). Also, Cannegieter et al.25 did not adjust the OR by sex and OC use. So, it was strongly suspected 425
that there was a strong bias derived from the different types of exposure factors and OC. 426
Judging from the above two types of data reviews, we excluded the data reported by two studies 427
(Martinelli et al. and Parkin et al.)23,24. In the data reported by Kuipers et al.26, there was no problem. The 428
data reported by Parkin et al.24 seemed to be used only for the purpose described above. 429
Interestingly, in four studies used in meta-regression analysis by Chandra et al.7, all the first authors' 430
names seem to be women's names ("Suzanne" Cannegieter25, "Saskia" Kuipers26, "Ida" Martinelli23, "Lianne" 431
Parkin24). 432
433
2) Regression Analysis 434
For the data judged as eligible, hyperbolic patterns were visually searched, and each data point was 435
grouped into two groups. Then, a non-linear regression analysis using the formulas above was performed. In 436
the fitting of the U-shaped curve, since there were many unknown coefficients for the number of data (there 437
are seven unknowns, K1, K2, M, a, b, and c. in the equations (2) and (3)), the S-curve was fitted first, and the 438
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p. 25 of all 74
remaining unknown coefficients (a, b, c) were fitted to the residuals of the S-curve fitting (see equation (2) 439
and (3)). 440
441
3) Additional analysis 442
As described above, the cyclic pattern in the data reported by Cannegieter et al.25 was observed, and 443
we performed additional analysis. To conduct an appropriate non-linear regression analysis, we made an 444
equation by combining two types of equations. The exponential decay equation was usually used to express 445
radioactive decay in physics and clearance in medicine. The other was a trigonometric function (sine function) 446
to express waveforms. The equation is shown in as below equation (7). Also, this scientific model (model 447
formula) was used to estimate the ratio of patients by integral calculation. 448
449
𝑦 = 𝑁1𝑒−𝜆1(𝑡−𝑏) + 𝑁2𝑒−𝜆2(𝑡−𝑏) Asin{𝐵(𝑡 − 𝑏)} (7) 450
451
The data reported as a bar graph was weekly data (see Fig. 2, c and Extended Data Fig. 2). So, the 452
week was converted into the number of days before the analysis, such as; the day getting off the vehicle was 453
set as days 0, the first week was set as days 4, the second week was set as days 4 + 7, and the third week was 454
set as days 4 + 7 × two, and the Nth week was set as days 4 + 7 × N. 455
Supplementary, according to the original description by Cannegieter et al.25, 68 patients developed 456
thrombosis in the first week, and "233" patients developed thrombosis within eight weeks after travelling. 457
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However, there was a slight discrepancy in the values read from the bar graph. The value in our measurement 458
within eight weeks after travelling was "234", but the effect of only one patient was allowed to be regarded as 459
small (the description of 68 patients was the same.). 460
Cannegieter et al. described the number of patients who travelled with their partners to evaluate the 461
effect of OC (Cannegieter et al., PLoS Med. 2006 Aug;3(8):e307., Table 2)25. We found some mismatches for 462
the number of patients in the table, and the overall discrepancy was only one person by offset, and 463
Cannegieter et al. described that there were derived from missing value25. The mismatch between our 464
measurement and description might be related to the described explanation. 465
466
5. Analysis 1B (dataset: Philbrick et al.)4 467
1) Dataset search and data review 468
a. Dataset search 469
To validate the result of analysis 1A, we searched another dataset from meta-analysis or systematic 470
review on the traveller's thrombosis. To conduct this search, we used PubMed® setting the following search 471
Keywords
"economy class syndrome [Title] " OR "traveler's [Title] AND thrombosis [Title]" OR "traveler's 472
[Title] AND thromboembolism [Title]" OR "flight [Title] AND thrombosis [Title]" OR "flight [Title] AND 473
thromboembolism [Title]" OR "flight-related [Title] AND thrombosis [Title]" OR "flight-related [Title] AND 474
thromboembolism [Title]" OR "travel [Title] AND thrombosis [Title]" OR "travel [Title] AND 475
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p. 27 of all 74
thromboembolism [Title]" OR "travel-related [Title] AND thrombosis [Title]" OR "travel-related [Title] AND 476
thromboembolism [Title]" (Filters: Meta-Analysis, Systematic Review). 477
As a result, we obtained the eight articles (da Silva LF et al. J Vasc Bras. 2021 10;20:e20200164; 478
Benhaberou-Brun Perspect Infirm. 2010 7(3):16-7; Chandra et al. Ann Intern Med. 2009 151(3):180-90; 479
Kuipers et al. J Intern Med. 2007 262(6):615-34; Philbrick et al. J Gen Intern Med. 2007 22(1):107-14; Hsieh 480
et al. J Adv Nurs. 2005 51(1):83-98; Ansari et al. J Travel Med. 2005;12(3):142-54; Adi et al. BMC 481
Cardiovasc Disord. 2004 19;4:7). 482
Subsequently, we selected articles containing available abstracts on PubMed® online, confirming the 483
contents. As a candidate for our analysis, we selected a systematic review reported by Philbrick et al.4. The 484
study was taken up by the ACP Journal Club of the American College of Physicians5 and another journal 485
club10. So, it seemed to be a highly reputed study. Therefore, we regarded that the dataset contained in the 486
research was suitable for validation. 487
Also, the research contained two lists of tables, one of which was a cohort studies dataset, and the 488
other was the case-control studies. However, the case-control studies had many different exposure factors. So, 489
we decided to use only the cohort studies dataset. 490
491
b. Data review 492
In the data review process, we reviewed the table containing ten cohort studies27,28,51-58 and found 493
seven eligible cohort studies27,51,54-58 for regression analysis. In Gajic et al. and Kelman et al., the only 494
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p. 28 of all 74
distances were described28,52, and Hughes et al. reported duration data for not per one flight (e.g., mean 39.4 495
h)53, so time data for regression analysis was unavailable. 496
Additionally, although Philbrick et al. described that incidence per million was 0.5 in table 2 of their 497
article4, the number was incorrect because it was based on only 1998. In the original description, Clérel & 498
Caillard mentioned that "According to the number of the passengers landing in the Aeroports de Paris, the 499
incidence during 1998 is 0.5 per million passengers"27. 500
501
2) Regression Analysis 502
For the seven studies, data stratified by Pulmonary Embolism (PE) and Deep Vein Thrombosis 503
(DVT), regression analysis was performed using an S-shaped curve formula (see equation (1)). In the case of 504
curve-fitting on DVT data, we cancelled the setting of coefficient L=1 to increase the degree of freedom of the 505
S-curve (Extended Data Fig. 3, b). To show the error bar in the figure (Extended Data Fig. 3), we did not 506
use the values of confidence limits described in the report by Philbrick et al.4, but values were re-calculated 507
from the number of cases using Wilson's method because data review result described above showed the error 508
of values at the citation. 509
In the seven studies, not OR or relative risk (RR), only the data indicating the incidence rate of 510
thrombosis was available. So, the hyperbolic pattern did not appear in the figure theoretically, and we 511
performed only the S-shaped curve fitting. This mechanism is explanted from the following calculation on a 512
confidence interval of a ratio. 513
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The formula for a 95% confidence limit of a ratio using binomial approximation is expressed by the 514
following formula: P is a ratio, and N is the number of trials. 515
516
𝑃 − 1.96 √𝑃(1−𝑃)
√𝑁 ≤ 𝑃 ≤ 𝑃 + 1.96 √𝑃(1−𝑃)
√𝑁 (8) 517
518
In the above equation, the fraction's numerator is not a constant value and does not depend on only the N, 519
which is associated with a data point's position in a population (see Fig. 1). 520
In this regression analysis, converting time categories to time points was necessary, so we performed 521
this in three directions. The first one was taking the midpoint if the category was not the end of a category 522
sequence (e.g., 10-15 h could be converted to 12.5 h). The second one was taking the midpoint between the 523
time point of 0 and the lower limit of the category if the category was the lower end of a category sequence 524
(e.g., <3 h could be converted to 1.5 h). The third one was taking the sum of the value of the upper limit and 525
the value of the midpoint between the time point of 0 and the lower limit of the category sequence if the 526
category was the upper side of a category sequence (e.g., > 12 h could be converted to 12 h + 1.5 h =13.5 h). 527
Details of conversions are shown below (the original time category is shown in brackets). 528
Belcaro et al. [10-15 h]: 12.5 h (Belcaro, G. et al., Angiology. 2001;52(6):369-74.)51; Clérel et al. 529
[12.7 h]: 12.7 h (Clérel, M., & Caillard, G., Bull Acad Natl Med. 1999;183(5):985-97.)27; Jacobson et al. [11 530
h]: 11 h; Lapostolle et al. [ 12 h]: 1.5 h, 4.5 h, 7.5 h, 10.5 h, 13.5 h (12 + 1.5 = 13.5 531
h) (Jacobson, B.F. et al., S Afr Med J. 2003;93(7):522-8.)54; Pérez-Rodríguez et al. [ 8 h]: 3 h, 7 532
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h, 11 h (8 + 3 = 11 h) (Pérez-Rodríguez, E. et al., Arch Intern Med. 2003;163(22):2766-70.)56; Schwarz et al. 533
2002 [> 8 h]: 12 h (midpoint of 0-8 h is 4 h and 8 + 4 = 12 hours) (Schwarz, T. et al., Blood Coagul 534
Fibrinolysis. 2002;13(8):755-7.)57; Schwarz et al. 2003 [> 8 h]: 12 h (midpoint of 0-8 h is 4 h and 8 + 4 = 12 535
hours) (Schwarz, T. et al., Arch Intern Med. 2003 2003;163(22):2759-64.)58. 536
537
3) Additional analysis 538
a. Regression analysis (data: Kelman et al.28) 539
In the review process, a cyclic pattern was observed. So, we worked on regression analysis. 540
Considering that onset of thrombosis tends to increase again, an equation upward-sloping curve was added to 541
equation (7). The equation is the following (9). 542
543
𝑦 = 𝑁1𝑒−𝜆1(𝑡−𝑏) + 𝑁2𝑒−𝜆2(𝑡−𝑏) Asin{𝐵(𝑡 − 𝑏)} + (𝑎𝑥2 + 𝑏𝑥+ 𝑐) (9) 544
545
b. Analysis by using correlogram (data: Clérel & Caillard27) 546
We considered using the "correlogram" in this study because it was more practical than observing 547
the original data's fluctuation. Periodic fluctuation patterns may be unclear when looking at the original data 548
alone, but potential patterns can be obtained using a correlogram, a data visualization method for analyzing 549
time-series data. Also, as the correlation coefficient plotted on the correlogram, we decided to use Spearman's 550
rank correlation coefficient instead of Pearson's product-moment correlation coefficient, which is easily 551
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affected by outliers. Also, we performed a non-linear regression analysis using a mathematical formula (10) 552
that includes two sine functions. 553
554
𝑦 = 𝑛1 sin{𝑎1(𝑥 − 𝑏1)} + 𝑛2 sin{𝑎2(𝑥 − 𝑏2)} (10) 555
556
In correlogram creation, firstly, a combination of data (data X1, data X1) was created by arranging 557
the original time series data (data X1) and a new combination (data X1, data X1') was created by shifting one 558
of them. Secondary, the correlation coefficient (also called the auto-correlation coefficient) between the 559
original time-series data (data X1) and the sifted time-series data (data X1'), except at the ends of two types of 560
time-series data where some correspondence could not be formed. By repeating shifting the time string data 561
and calculating the correlation coefficient, the locus of the correlation coefficient becomes the shape of waves. 562
Firstly (original waves of time strings are overlapped), the correlation coefficient is 1, and the value of the 563
correlation coefficient gradually decreases as the distance of the overlap increases. Finally (the wave is 564
inverted), the correlation coefficient is -1. 565
In this study, since the risk of developing thrombosis is expected to increase as travel time increases 566
by cumulative exposure to environmental risk factors, it was necessary to investigate whether the fluctuations 567
in the number of patients really reflect the periodicity by confirming the fluctuation of the percentage of onset 568
patients to the total number of passengers to examine whether the fluctuation reflects the increase or decrease 569
in the number of passengers. However, this confirmation could not be made because data on the total number 570
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of passengers was not available. So, we focused on a method that suppressed the influence of the height of the 571
wave and evaluated only curved shapes. Therefore, we decided to draw a correlogram that reduced wave 572
height by the property of the correlation coefficient, which fluctuates only between -1 and 1. 573
However, Pearson's product-moment correlation coefficient has a weakness: it is easily affected by 574
outliers. Also, as the progress of shifting the one side of the data string against the original data, their 575
correspondence decreases. In other words, the number of data that can be used to calculate the correlation 576
coefficient gradually decreases. This problem may cause considerable variation between the calculated 577
correlation coefficients. Also, the thrombosis onset was recorded in 1-hour increments, and the length of the 578
data was limited to 24 hours (24 data points). Therefore, instead of Pearson's product-moment correlation 579
coefficient, we decided to create a correlogram using Spearman's rank correlation coefficient. 580
581
6. Analysis 2 (dataset: COVID-19)33 582
1) Dataset search and data review 583
c. Dataset search 584
To apply our idea to COVID-19 problems, one of the authors (KK) searched hyperbolic patterns 585
using a search service Google (https://www.google.com/) provided by Google Inc., which allows displaying 586
search results as "images." The search keyword was "COVID-19 AND Meta-analysis". In the case of 587
displaying bubble charts instead of the error bars, the size of the bubble chart (inversely proportional to the 588
length of the error bars) was converted in mind. Consequently, we selected a suspicious study reported by 589
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Matsushita et al. (Matsushita, K. et al., Glob Heart. 2020;15(1):64.)33 that included eight research papers in 590
Figure 559-66. 591
592
d. Data review 593
As in the case of Analysis 1, we reviewed to evaluate numerical accuracy and appropriateness from 594
the viewpoints of biomedicine. Since Matsushita et al.33 originally made web Figure 5 and excluded 17 595
studies35,67-82 from avoiding duplication of studies in Wuhan city in the making of Figure 5, we inspected both 596
of studies in Figure 5 (8 studies) and only in web Figure 5 (17 studies). 597
Based on the results shown below, considering the issue of comparability, we excluded the data 598
reported by Yuan et al.65 and Wang L. et al63. Also, we re-calculated age difference using data reported by 599
Guan et al. 61 (see Extended Data Fig. 1). 600
As a side note, the numbers assigned to each point in figure 3 were the same numbers described in 601
the original figure by Matsushita et al.33, and the correspondence relationship is the following (Fig. 3): No.2: 602
Cao et al. (Cao, J. et al., Intensive Care Med. 2020;46(5):851-853.)59, No.7: Deng et al. (Deng, Y. et al., Chin 603
Med J (Engl). 2020;133(11):1261-1267.)60, No.8: Guan et al. (Guan, W.J. et al., N Engl J Med. 604
2020;382(18):1708-1720.)61, No.19: Wang D. et al. (Wang, D. et al., JAMA. 2020;323(11):1061-1069.)62, 605
No.20: Wang L. et al. (Wang, L. et al., J Infect. 2020;80(6):639-645.)63, No.21: Wu et al. (Wu, C. et al., JAMA 606
Intern Med. 2020;180(7):934-943.)64, No.23: Yuan et al. (Yuan, M. et al., PLoS One. 2020;15(3):e0230548)65, 607
No.25: Zhou et al. (Zhou, F. et al., Lancet. 2020;395(10229):1054-1062.)66. 608
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p. 34 of all 74
609
(i) No.8 Guan et al. (Guan, W.J. et al., N Engl J Med. 2020;382(18):1708-1720.)61 610
We found a matter of consideration in the data reported by Guan et al61. Initially, features of that 611
data differed from the other studies, which contained only cases reported from Wuhan city. In contrast, the 612
data reported by Guan et al.61 contained cases outside of Wuhan city. Also, regarding the situation of the early 613
pandemic, there were concerns about the presence of patients who could not take appropriate medication, 614
especially in non-urban areas. Also, Matsushita et al.33 did not use the data divided into the severe and non-615
severe groups by Guan et al.61 but used the data divided into yes and no by Guan et al.61 using "Presence of 616
Primary Composite End Point", which means entry to the intensive care unit (ICU), use of mechanical 617
ventilation, or death. 618
Since Cao et al. (Wuhan University Zhongnan Hospital in Wuhan; affiliation of Dr Jianlei Cao: 619
Department of Cardiology)59 and Wang et al. (Zhongnan Hospital of Wuhan University in Wuhan; affiliation 620
of Dawei Wang, MD: Department of Critical Care Medicine)62 also used ICU admission as a criterion for 621
severe or non-severe, we examined the rate of severely ill patients and resulted in 21.4% (18/84) and 35.3% 622
(36/102), respectively. However, in the case of using the "Presence of Primary Composite End Point", the 623
percentage was only 6.5% (67/1032). Whereas, in the original categorisation by Guan et al.61, the percentage 624
was 18.7% (173/926). Therefore, we prioritised the original classification of severe or non-severe by Guan et 625
al61. 626
627
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(ii) No. 9 Guo et al. (Guo et al. JAMA Cardiol. 2020;5(7):811- 818)35 (only in eFigure5) 628
We read this paper carefully, a report from Wuhan city published in March 2020. Although this 629
document may significantly influence the studies on COVID-19 (according to the JAMA Cardiology website, 630
the article was cited more than 1,500 as of 20th September 2021), we found that misuse of linear regression 631
analysis in Guo et al. on a figure (see Extended Data Fig. 8 & Supplementary discussion 5: misuse of linear 632
regression analysis)35. 633
Additionally, three subgroup patterns appeared in a figure reported by Guo et al., although they did 634
not mention it. Precautionary, we considered whether the subgroups in the Guo et al.35 affected the meta-635
analysis on the web Figure 5. The data in other studies allowed to be expected to have the same subgroups 636
because the patient data described by Guo et al.71 and other studies were reported from China (most of them 637
were in Wuhan City). 638
639
(iii) No. 20 Wang L. et al. (Wang, D. et al., JAMA. 2020;323(11):1061-1069.)63 640
In confirming from the viewpoint of the biomedicine side, it was found that a significant matter of 641
consideration on eligibility, patient population reported by Wang L. et al. was limited to over age 6063. The 642
title was "Coronavirus disease 2019 in elderly patients: Characteristics and prognostic factors based on 4-643
week follow-up", and Matsushita et al. 33 had to pay attention to the word "elderly". 644
645
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(iv) No.23 Yuan M. et al. (Yuan M. et al., PLoS One. 2020;15(3):e0230548.)65 646
In confirming the accuracy of values, we found a mixture of values derived from different 647
calculation types in Figure 5: Odds Ratio (OR), hazard ratio, and a value derived from the imputation of 0.5 648
for the zero cells in the cross table. The zero cells appeared in the study reported by Yuan et al65. Yuan M. et 649
al. studied 27 patients who confirmed novel coronavirus infected pneumonia (NCIP) during the early phase of 650
the pandemic to evaluate radiologic characteristics65. In other words, the difficulty of patient enrollment might 651
cause a small sample size, which seemed to be a concern from the viewpoint of comparability (c.f., Guan W. 652
et al., n=109961; Zhou F. et al., n=19166; Wang D. et al., n=13862; Wu C. et al. n=20164; Cao J. et al., n=10259; 653
Deng Y. et al., n=22560). 654
655
(v) The term "Cardiovascular disease (CVD)." 656
There was an inconsistency in the studies on "Cardiovascular disease (CVD)." For example, vascular 657
diseases such as arrhythmia and arteriosclerosis are also classified as CVD, but in the studies reported by 658
Guan et al.61 and Zhou et al.66, the term "Coronary heart disease" was used. Also, "Cardiac disease" was used 659
by Yuan et al.65, "Heart disease" was used by Deng et al.60, and "Cardiovascular disease" was used by Wang L 660
et al63. 661
662
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2) Regression analysis 663
Considering the problem of comparability, we re-calculated OR and visually grouped it into two 664
hyperbolic patterns. In the case of S-shaped curve fitting, since there were many unknown coefficients for the 665
number of data (3 unknown coefficients of K1, K2, and M), the regression analysis was performed after setting 666
the zero point value. In the fitting of upper and lower curves, since there were many unknown coefficients 667
(K1, K2, M, a, b, c), we firstly obtained the coefficient of M (see equation (1)) by the curve fitting of the S-668
shaped curve, and then performed curve fitting of parabolas. After substituting M for x value of apex in 669
equation (4) (see equations (4) & (5)), regression analysis was performed on the data in the middle row of 670
Figure 3 (Fig. 3, d-f). Finally, the S-shaped curve and the parabola were merged (Fig. 3, g-i). 671
672
3) Calculation of weighted average 673
In earlier days group, the median age and the number of cases are tabulated by severe and non-674
severe cases as follows. Guan W. et al. (severe n=173 [age: 52] vs non-severe n=926 [age: 45])61, Zhou F. et 675
al. (non-survival n=54 [age: 69] vs survival n=137 [age: 52])66, Wang D. et al. (ICU n=36 [age: 66] vs non-676
ICU n=102 [age: 51])62, Wu C. et al. (ARDS n=84 [age: 58.5] vs non-ARDS n=117 [age: 48])64, and whole of 677
earlier days group (severe n = 347 vs non-severe n = 1282). 678
The weighted average of severe and non-severe in the earlier days group was calculated from these 679
values by the following formulas. In the earlier days group, the weighted average of severe and non-severe 680
were 57.7 and 46.5, respectively. 681
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p. 38 of all 74
682
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑝𝑎𝑡𝑖𝑒𝑛𝑡𝑠 𝑖𝑛 𝑒𝑎𝑟𝑙𝑖𝑒𝑟 𝑑𝑎𝑦𝑠 𝑔𝑟𝑜𝑢𝑝 (𝑠𝑒𝑣𝑒𝑟𝑒) = 173 + 54 + 36 + 84 = 𝟑𝟒𝟕 683
𝑊𝑒𝑖𝑔ℎ𝑡𝑒𝑑 𝑚𝑒𝑎𝑛 𝑜𝑓 𝑒𝑎𝑟𝑙𝑖𝑒𝑟 𝑑𝑎𝑦𝑠 𝑔𝑟𝑜𝑢𝑝 (𝑠𝑒𝑣𝑒𝑟𝑒) = 173
𝟑𝟒𝟕 × 52 + 54
𝟑𝟒𝟕 × 69 + 36
𝟑𝟒𝟕 × 66 + 84
𝟑𝟒𝟕 × 58.5684
≅ 57.7 685
686
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑝𝑎𝑡𝑖𝑒𝑛𝑡𝑠 𝑖𝑛 𝑒𝑎𝑟𝑙𝑖𝑒𝑟 𝑑𝑎𝑦𝑠 𝑔𝑟𝑜𝑢𝑝(𝑛𝑜𝑛 − 𝑠𝑒𝑣𝑒𝑟𝑒) = 926 + 137 + 102 + 117 = 𝟏𝟐𝟖𝟐 687
𝑊𝑒𝑖𝑔ℎ𝑡𝑒𝑑 𝑚𝑒𝑎𝑛 𝑜𝑓 𝑒𝑎𝑟𝑙𝑖𝑒𝑟 𝑑𝑎𝑦𝑠 𝑔𝑟𝑜𝑢𝑝 (𝑛𝑜𝑛 − 𝑠𝑒𝑣𝑒𝑟𝑒)688
= 926
𝟏𝟐𝟖𝟐 × 45 + 137
𝟏𝟐𝟖𝟐 × 52 + 102
𝟏𝟐𝟖𝟐 × 51 + 117
𝟏𝟐𝟖𝟐 × 48 ≅ 46.5 689
690
In later days group, the median age and the number of cases are tabulated by severe and non-severe 691
cases as follows. Cao J. et al. (ICU n=18 [age: 66] vs non-ICU n=84 [age: 31])59, Deng Y. et al. (Death n=109 692
[age: 69] vs survival n=116 [age: 48])60, and whole of later days group (severe n = 127 vs non-severe n = 693
200). 694
The weighted average of severe and non-severe in the late date group was calculated from these 695
values by the following formulas. In the late date group, the weighted average of severe and non-severe were 696
68.6 years and 40.9, respectively. 697
698
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑝𝑎𝑡𝑖𝑒𝑛𝑡𝑠 𝑖𝑛 𝑙𝑎𝑡𝑒 𝑑𝑎𝑡𝑒 𝑔𝑟𝑜𝑢𝑝 (𝑠𝑒𝑣𝑒𝑟𝑒) = 18 + 109 = 𝟏𝟐𝟕 699
𝑊𝑒𝑖𝑔ℎ𝑡𝑒𝑑 𝑚𝑒𝑎𝑛 𝑜𝑓 𝑙𝑎𝑡𝑒 𝑑𝑎𝑡𝑒 𝑔𝑟𝑜𝑢𝑝 (𝑠𝑒𝑣𝑒𝑟𝑒) = 18
𝟏𝟐𝟕 × 66 + 109
𝟏𝟐𝟕 × 69 ≅ 68.6 700
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p. 39 of all 74
𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑝𝑎𝑡𝑖𝑒𝑛𝑡𝑠 𝑖𝑛 𝑙𝑎𝑡𝑒 𝑑𝑎𝑡𝑒 𝑔𝑟𝑜𝑢𝑝 (𝑛𝑜𝑛 − 𝑠𝑒𝑣𝑒𝑟𝑒) = 84 + 116 = 𝟐𝟎𝟎 701
𝑊𝑒𝑖𝑔ℎ𝑡𝑒𝑑 𝑚𝑒𝑎𝑛 𝑜𝑓 𝑙𝑎𝑡𝑒 𝑑𝑎𝑡𝑒 𝑔𝑟𝑜𝑢𝑝 (𝑛𝑜𝑛 − 𝑠𝑒𝑣𝑒𝑟𝑒) = 84
𝟐𝟎𝟎 × 31 + 116
𝟐𝟎𝟎 × 48 ≅ 40.9 702
703
4) Additional analysis: Regression analysis on the parabolic cylinder 704
One of the authors (KK) found a way to fit an appropriate curve to the data reported by Guo et al., 705
performing trial and error with his mathematical intuition (Fig. 4). Firstly, he calculated the centre of gravity 706
of the data by each subgroup cluster (centre of gravity: the average of the values on the horizontal axis x and 707
the average of the values on the vertical axis y). Second, he obtained equations of three straight lines passing 708
through the origin and centres of gravity. Thirdly, he obtained the equation of a straight line passing through 709
each centre of gravity and intersecting the straight lines obtained above. Fourthly, he re-set new origin as each 710
centre of gravity and regarded the above two crossed lines as a small cartesian coordinate system. Finally, he 711
applied parabola fitting with Excel○R in each new cartesian coordinate system. In this curve fitting, he used the 712
data of distance between each data point and the straight line obtained secondary, and the data of distance 713
between each data point and the straight line obtained firstly (see "distance from a point to a line" in a high 714
school textbook). 715
716
5) Making example data 717
To explain the misuse of linear regression analysis in Guo et al.35, we made the following data to 718
show the example. It allows being used in R by copying and pasting the following. 719
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p. 40 of all 74
720
Value_X<-721
c(0.04 ,0.08 ,0.12 ,0.16 ,0.2 ,0.24 ,0.28 ,0.32 ,0.36 ,0.4 ,0.44 ,0.48 ,0.52 ,0.56 ,0.6 ,0.64 ,0.68 ,0.72 ,0.76 ,0.8 ,0722
.84 ,0.88 ,0.92 ,0.96 ,1 ,1.04 ,1.08 ,1.12 ,1.16 ,1.2 ,1.24 ,1.28 ,1.32 ,1.36 ,1.4 ,1.44 ,1.48 ,1.52 ,1.56 ,1.6 ,1.64 ,723
1.68 ,1.72 ,1.76 ,1.8 ,1.84 ,1.88 ,1.92 ,1.96 ,2 ,2.04 ,2.08 ,2.12 ,2.16 ,2.2 ,2.24 ,2.28 ,2.32 ,2.36 ,2.4 ,2.44 ,2.48 724
,2.52 ,2.56 ,2.6 ,2.64 ,2.68 ,2.72 ,2.76 ,2.8 ,2.84 ,2.88 ,2.92 ,2.96 ,3 ,3.04 ,3.08 ,3.12 ,3.16 ,3.2 ,3.24 ,3.28 ,3.32 725
,3.36 ,3.4 ,3.44 ,3.48 ,3.52 ,3.56 ,3.6 ,3.64 ,3.68 ,3.72 ,3.76 ,3.8 ,3.84 ,3.88 ,3.92 ,3.96 ,4) 726
727
Value_Y<-728
c(2.01742 ,2.02749 ,2.04454 ,2.02009 ,2.03445 ,2.04749 ,2.03641 ,1.99047 ,1.98671 ,2.06711 ,2.09772 ,2.005729
39 ,1.86985 ,2.01679 ,2.12183 ,1.94453 ,1.86497 ,1.87444 ,2.09483 ,1.91073 ,1.69244 ,1.70968 ,1.81376 ,2.0730
4219 ,1.69059 ,1.75939 ,1.95321 ,1.8417 ,1.58169 ,1.75585 ,1.73497 ,1.47847 ,1.9115 ,1.44962 ,1.85063 ,1.3731
2298 ,1.28437 ,1.74621 ,1.27232 ,1.32763 ,1.575 ,1.56609 ,1.5933 ,1.76707 ,1.11264 ,1.06188 ,1.40139 ,0.94732
084 ,1.0756 ,1.38507 ,1.33408 ,1.54375 ,1.60257 ,1.02029 ,0.98612 ,1.79094 ,0.97916 ,0.81212 ,1.1484 ,1.51733
68 ,1.70236 ,1.38945 ,1.69072 ,1.75042 ,1.67571 ,1.38623 ,1.81503 ,1.80665 ,1.41073 ,2.3175 ,2.24852 ,1.75734
95 ,2.81818 ,1.93654 ,2.36998 ,2.0987 ,2.19539 ,2.44747 ,2.57255 ,3.24637 ,2.78881 ,3.51638 ,2.68107 ,2.87735
259 ,4.3749 ,3.13393 ,3.92099 ,4.1223 ,3.78584 ,4.9666 ,5.4888 ,5.70712 ,4.84752 ,5.1409 ,6.31637 ,5.53198 736
,6.89257 ,7.86387 ,7.98237 ,8.64705) 737
738
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p. 41 of all 74
7. Statement of our intention for data review results 739
To clarify our stance, we mention this statement of intention for results. In this article, we pointed 740
out many overlooking and errors. However, we have no intention to attack previous works because our 741
analysis results owing to their original works, including original research articles, reported valuable data and 742
articles of meta-analysis synthesised valuable datasets. Since just a scientist had better reconfirm the previous 743
studies with no preconception with being grateful to the researchers of those studies, we carefully reviewed 744
the data reported by previous studies. We highly respect previous works, which have the intention to solve 745
medical issues, although some articles contained technical errors. 746
747
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p. 42 of all 74
748
Methods
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with a Combination Assay of B-type Natriuretic Peptide and High Sensitive Troponin I. J Med 839
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p. 47 of all 74
841
Acknowledgements
842
One of the authors, Keiichiro Kimoto, appreciates the kindful encouragement of Hideo Yoshioka, 843
MEcon., who is in charge of the Data Strategy Research Institute representative. 844
845
Competing interest declaration 846
Keiichiro Kimoto has been in charge of external advisor for Data Strategy Research Institute but 847
reserved no financial support for this study. Except for this, the authors have no conflicts of interest and have 848
no financial disclosures that should be disclosed. 849
850
Author contributions 851
Keiichiro Kimoto takes responsibility for this research, making study concepts, data analysis, 852
interpretation of analysis results, and drafting the manuscript. Dr. Yamakuchi contributed to interpreting 853
analysis results, manuscript drafting, supervision and administrative role. Dr. Takenouchi contributed to the 854
supervision. Dr. Hashiguchi contributed to the study concept, interpretation of analysis results, manuscript 855
drafting, supervision, and administrative role. 856
857
Additional information 858
This article has supplementary information that contains supplementary discussions. 859
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is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)
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p. 48 of all 74
860
Data availability statement 861
We analyzed clinical data published by other studies (third parties). Used data is identified by 862
indicated information of citation (reference numbers and list of references). The corresponding author 863
responds to inquiries in the case of measured values from published figures requested by reviewers or readers. 864
865
Code availability statement 866
Correspondence author (KK) can respond to inquiries for the corresponding author's email address 867
on offering the Python source code and spreadsheet software files for statistical analysis. 868
869
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p. 49 of all 74
870
Figures & figure legends 871
Fig. 1 872
873
Fig. 1 | A hyperbolic shape formed by confidence limits. a, A two-way cross-tabulation (contingency table) 874
for calculating an odds ratio (OR). b, Calculation of OR and its 95% confidence interval. c, Histogram of the 875
data following a binomial distribution and a plot of the inverse values of the square roots. d, The mathematical 876
formulas for the hyperbolic shape. Note that the OR is not logarithmic, and only the length of the error bar is 877
logarithmic (see the upper left position of panel d). 878
879
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p. 50 of all 74
880
Fig. 2 881
882
Fig. 2 | Re-analysis based on the proposed ideas. a, Data review and meta-regression analysis using the 883
same method as Chandra et al. Ann Intern Med. 2009; 151(3):180-190. Figure 37. We added information from 884
original studies and our hypothesis to the previously published form, such as latent distribution. The original 885
figure has been shown on the American College of Physicians website, which links to PubMed○R 886
(https://pubmed.ncbi.nlm.nih.gov/19581633/). From Chandra D, Parisini E, Mozaffarian D. Meta-analysis: 887
travel and risk for venous thromboembolism. Ann Intern Med. 2009 Aug 4;151(3):180-90. doi: 10.7326/0003-888
4819-151-3-200908040-00129. Epub 2009 Jul 6. © 2009 American College of Physicians. Adapted with 889
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p. 51 of all 74
permission. b, grouping the data and hyperbolic shape fitting. c, Onsets of thrombosis after travel reported by 890
Cannegieter et al25. This figure was re-used and re-drawn from Cannegieter et al. Travel-related venous 891
thrombosis: results from a large population-based case-control study (MEGA study). PLoS Med. 2006; 892
3(8):e307. Figure 1. https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC1551914/figure/pmed-0030307-893
g001/ Copyright © 2006 Cannegieter et al. Creative Commons Attribution License. In 2006, the Creative 894
Commons Attribution 2.0 Generic, License was available. https://creativecommons.org/licenses/by/2.0/ d, 895
Applying the damped wave function to the data shown in panel c. We decided that the data from Martinelli et 896
al.23 and Cannegieter et al.25 should be excluded, and the odds ratio from Parkin et al.24 may decrease (see 897
Methods). At 2 hours point, Chandra et al.7 did not use available data (panel a). On the original regression 898
line, Chandra et al.7 might conduct a meta-regression analysis reversing the front head and the front side of the 899
cross-tabulation. Compering panels c and d helps us understand that using a three-dimensional graph disrupts 900
our recognition. 901
902
903
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p. 52 of all 74
904
Fig. 3 905
906
Fig. 3 | Hyperbolic shapes found in the figure reported by Matsushita et al33. a, A figure shows the 907
relationship between the severe and non-severe groups reported by Matsushita et al.33, which shows age 908
difference on the horizontal axis and odds ratio (OR) or hazard ratio of hypertension on the vertical axis. To 909
evaluate potential confounding for relative risk by age, Matsushita et al. conducted meta-regression analyses 910
based on the assumption that there was the possibility of confounding by age in the case that the study with a 911
larger age difference has a higher relative risk33. b, Diabetes. c, Cardiovascular disease (CVD). d-f, 912
Comparisons of error bars, which show 95% confidence interval (C.I.) s. It corresponds to the upper figure. g-913
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p. 53 of all 74
i, Hyperbolic patterns were fitted to the OR and the 95% confidence limit of the OR. In the panel i, a 914
hyperbolic shape could not be fitted due to the considerable data variation, likely due to the inconsistency of 915
the term "CVD" (see Methods). The numbers marked to each point are the same as the numbers shown in the 916
original figure. The sources of each data are shown in Methods. This figure was re-used from Matsushita et al. 917
Glob Heart. 2020; 15(1):64. Figure 5. 918
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC7546112/figure/F5/ 919
Copyright © 2020 The Authors. Creative Commons Attribution 4.0 International License (CC-BY 4.0) 920
https://creativecommons.org/licenses/by/4.0/ 921
922
923
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p. 54 of all 74
924
Fig. 4 925
926
Fig. 4 | Parabola shape patterns in the figure by Guo et al35. a, Relationship between high sensitive C-927
reactive protein (hsCRP) and cardiac troponin T (TnT) in COVID-19 patients (left) and relationship between 928
cardiac troponin T (TnT) and N-terminal pro-brain natriuretic peptide (NT-proBNP) (right). b, Data points 929
from the right side of the panel a and fitting parabola. c, Three-dimensional data visualisation was constructed 930
by mounting the value of hsCRP onto panel b. d, Linear regression analysis on the side surface of the 931
parabolic cylinder in panel c. The points were replaced with their average if the values could not be 932
determined due to overlapping (the points indicated by the left-pointing arrow and the error bar, which are the 933
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p. 55 of all 74
average and the range of values, respectively). Panel a was re-used from Guo T et al. JAMA Cardiol. 2020; 934
5(7):811-818. Figure 1 https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC7101506/figure/hoi200026f1/ 935
Copyright © 2020 Guo T et al. JAMA Cardiology. Creative Commons Attribution License (CC-BY). 936
https://creativecommons.org/licenses/by/4.0/ 937
938
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p. 56 of all 74
939
Extended data figures & figure legends 940
Extended Data Fig. 1 941
942
943
Extended Data Fig. 1 | Overall framework of this study. We applied our concept to traveller's thrombosis 944
and COVID-19. These were similar in research history (see Supplementary discussion 1: history of traveller's 945
thrombosis & Supplementary discussion 2: research situations of COVID-19 related thrombosis). In the case 946
of traveller's thrombosis, we analysed a dataset collected by Chandra et al. and Philbrick et al4,7. In the case of 947
COVID-19, we analysed a dataset collected by Matsushita et al7. Flow charts show data accept or reject flows. 948
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p. 57 of all 74
Since duplicating data, Matsushita et al. selected only eight studies data (25 studies included in initial web Figure 949
5)33. 950
951
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p. 58 of all 74
952
Extended Data Fig. 2 953
954
Extended Data Fig. 2 | Unrecognised cyclic pattern of thrombosis onset after travel25. a, A bar graph 955
showing the relationship between weeks after travel and the number of thrombosis onset in a figure reported 956
by Cannegieter et al25. b, Re-expressing as a two-dimensional bar graph avoiding the three-dimensional 957
representation. c, Applying a damped wave by non-linear regression analysis. d, Extraction of damped wave 958
part by subtracting the monotonic decrease function. e, Dividing into 2 sub-group areas by the envelopes of 959
the damped wave that touch the lower parts of the wave. f, Enlarged and added explanation of the ratio of the 960
area. Cannegieter et al.25 used the data up to week eight, and the ratio of subgroup 2 to the total number of 961
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p. 59 of all 74
patients (ratio of S2 to the area of S1 + S2) was 30.0%. In the integration for the infinite interval, it was 30.8%. 962
Peak shifts of the wave (peak position of the wave shifted from the original to the other) appeared when 963
comparing panels d and f due to putting by regression curve located in the centre. Panel a was re-used from 964
Cannegieter et al. PLoS Med. 2006; 3(8):e307. Figure 1. 965
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC1551914/figure/pmed-0030307-g001/ 966
Copyright © 2006 Cannegieter et al. Creative Commons Attribution License. In 2006, the Creative Commons 967
Attribution 2.0 Generic, License (CC BY 2.0) was available. https://creativecommons.org/licenses/by/2.0/ 968
969
970
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p. 60 of all 74
971
Extended Data Fig. 3 972
973
Extended Data Fig. 3 | Curve fitting to the dataset reported by Philbrick et al4. a, data stratification by 974
Pulmonary Embolism (PE) and Deep Vein Thrombosis (DVT). b, Application of S-shaped curve by 975
regression analysis to the stratified data. The value in the bracket (panel b) is the point of time converted from 976
the time category (see Methods). Philbrick et al.4 reported the result of a systematic review with a table (list). 977
In contrast, this visualising allows us to extract latent information. 978
979
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p. 61 of all 74
980
Extended Data Fig. 4 981
982
Extended Data Fig. 4 | Re-analysis of the data in Table 1 by Clérel & Caillard27. a, A figure made by 983
Clérel & Caillard27 showed a relationship between travel time and the thrombosis onset in the case of 984
stratification by medical history of thrombosis. b, The relationship between time and thrombosis (prepared 985
from Table 1 reported by Clérel & Caillard27). c, Correlogram (prepared from Table 1 reported by Clérel & 986
Caillard27). d, Age distribution by sex (made from Table 1 reported by Clérel & Caillard27). As shown in panel 987
a, Clérel & Caillard27 summarised all the data for 12 hours or more, but there were two peaks (see panel b). 988
Judging from the age distribution (panel d), the number of women patients was more significant than that of 989
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p. 62 of all 74
men, but there was no difference between the age ranges. In panel c, there was a periodic pattern. Panel a 990
reproduced from Clérel & Caillard. Syndrome thrombo-embolique de la station assise prolongée et vols de 991
longue durée: l'expérience du Service Médical d'Urgence d'Aéroports De Paris. Bull Acad Natl Med. 1999; 992
183(5):985-997. discussion 997-1001. Figure 3. 993
Copyright © 1999 Elsevier Masson SAS. All rights reserved. Académie Nationale de Médecine. 994
995
996
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p. 63 of all 74
997
Extended Data Fig. 5 998
999
Extended Data Fig. 5 | Cyclic pattern of thrombosis onset appeared in a figure by Kelman et al28. a, A 1000
thrombosis onset distribution reported by Kelman et al28. b, The regression curve is located in the centre of all 1001
average points (the points express the average of thrombosis onset during seven days). c, Curve fitting to the 1002
residual data of the regression curve in panel b. d, Application of damped wave function and adding 1003
interpretation of the results assuming some women started taking oral contraceptives (OC) in the timing of 1004
travel. The observed cyclic pattern was relatively unclear than Cannegieter et al.25 (see Fig. 2). Noteworthy, 1005
the thrombosis onset downed in the days before 90 days, and it seems to be the scheduled withdrawal period 1006
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p. 64 of all 74
of OC use. This figure was re-used and re-drawn from Kelman et al. BMJ. 2003; 327(7423):1072. Figure 1 1007
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC261739/figure/fig1/ 1008
Copyright © 2003 BMJ Publishing Group Ltd. All rights reserved. The BMJ permission team thankfully 1009
confirm this figure adaptation. Also, we obtained permission to re-use. 1010
1011
1012
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p. 65 of all 74
1013
Extended Data Fig. 6 1014
1015
Extended Data Fig. 6 | Thrombosis reported by Clérel & Caillard27 & our novel annotations. a, Clérel & 1016
Caillard mentioned that "their incidence increases during the last years, corresponding to the growth of air 1017
traffic and mainly to the increase of long duration without stop flight."27 c, Chronology of various guidelines 1018
on HRT. In the newly figure (panel b), the increase in thrombosis was associated with the issuance time of 1019
guidelines for HRT. HRT was recommended for menopausal women in the 1990s, but its effectiveness was 1020
questioned in the HERS trial (1998)31. Also, the risk was discovered in the WHI trial at the interim analysis 1021
(2002)32. It might be the effect of the publication on the HERS study (1998)31 that the increase of thromboses 1022
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p. 66 of all 74
was relatively small in 1998 despite the publication of two documents recommended in 1997. Panel a was 1023
reproduced from Clérel & Caillard. Syndrome thrombo-embolique de la station assise prolongée et vols de 1024
longue durée: l'expérience du Service Médical d'Urgence d'Aéroports De Paris. Bull Acad Natl Med. 1999; 1025
183(5):985-997. discussion 997-1001. Figure 1. 1026
Copyright © 1999 Elsevier Masson SAS. All rights reserved. Académie Nationale de Médecine. 1027
1028
1029
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The copyright holder for this preprint this version posted June 7, 2022. ; https://doi.org/10.1101/2022.06.06.22275944doi: medRxiv preprint
p. 67 of all 74
1030
Extended Data Fig. 7 1031
1032
Extended Data Fig. 7 | Data cut-off dates in each study cited by Matsushita et al33. The data acquisition 1033
period in each study was displayed in Gantt chart format. The date display format is year-month-day. The 1034
correspondence between numbers and authors is as follows: No.2: Cao et al. (Cao, J. et al., Intensive Care 1035
Med. 2020;46(5):851-853.)59, No.7: Deng et al. (Deng, Y. et al., Chin Med J (Engl). 2020;133(11):1261-1036
1267.)60, No.8: Guan et al. (Guan, W.J. et al., N Engl J Med. 2020;382(18):1708-1720.)61, No.19: Wang D. et 1037
al. (Wang, D. et al., JAMA. 2020;323(11):1061-1069.)62, No.20: Wang L. et al. (Wang, L. et al., J Infect. 1038
2020;80(6):639-645.)63, No.21: Wu et al. (Wu, C. et al., JAMA Intern Med. 2020;180(7):934-943.)64, No.25: 1039
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p. 68 of all 74
Zhou et al. (Zhou, F. et al., Lancet. 2020;395(10229):1054-1062.)66. Abbreviations: ARDS (Acute Respiratory 1040
Distress Syndrome), ICU (Intensive Care Unit). The number in parentheses means median age. The number in 1041
the bracket means standard deviation or interquartile range. 1042
1043
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p. 69 of all 74
Extended Data Fig. 8 1044
1045
Extended Data Fig. 8 | Bimodal distributions & tiled parabola in COVID-19 patients. a, Guo et al. JAMA 1046
Cardiol. 2020; 5(7):811-818. Figure 1B 1047
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC7101506/figure/hoi200026f1/ 1048
Copyright © 2020 Guo T et al. JAMA Cardiology. Creative Commons Attribution License (CC-BY). b, 1049
Marginal distribution of the scatter plot data. c, Wang et al. Front Cardiovasc Med. 2020; (7): 147. Figure 1 1050
(upper, x-axis: troponin I, pg/mL; y-axis: BNP, pg/mL; lower, x-axis: troponin I, pg/mL; y-axis: 1051
lymphocyte, %)37. https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC7477309/figure/F1/ 1052
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p. 70 of all 74
Copyright © 2020 Wang, Zheng, Tong, Wang, Lv, Xi and Liu. CC BY License. d, Caro-Codón et al. Eur J 1053
Heart Fail. 2021; 23(3):456-464. Figure 1B (x-axis, LN (troponin I))40. 1054
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC8013330/figure/ejhf2095-fig-0001/ 1055
Copyright © 2021 European Society of Cardiology. All rights reserved. This Figure can be used for 1056
unrestricted research re-use and analysis in any form or by any means with acknowledgement of the original 1057
source as part of the COVID-19 public health emergency, for the duration of the emergency. e, Demir et al. 1058
Am J Cardiol. 2021; 147:129-136. Figure 2 (upper: admission; lower: peak measurements; x-axis: troponin T, 1059
ng/L)41. https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC7895690/figure/fig0002/ 1060
Copyright © 2021 Elsevier Inc. All rights reserved. This figure is granted for unrestricted research re-use and 1061
analyses in any form or by any means with acknowledgement of the original source by Elsevier for as long as 1062
the COVID-19 resource centre remains active. f, Virtual example on regression analysis (see Supplementary 1063
Discussion
5: misuse of linear regression analysis). In panel b (also c, d, and e), the histogram was bimodal 1064
(marked "A" and "B"). The crescent-shape pattern closely resembled the ST-segment elevation myocardial 1065
infarction group pattern that appeared in the study by Budnik et al36. 1066
1067
1068
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p. 71 of all 74
1069
Extended Data Fig. 9 1070
1071
Extended Data Fig. 9 | Three subgroup patterns appeared in a figure reported by Guo et al35. a, A 1072
scatter plot showing the relationship between cardiac troponin T (TnT) and N-terminal pro-brain natriuretic 1073
peptide (NT-proBNP) in a patient with COVID-1935. b, Scatter plot to investigate the relationship between 1074
brain natriuretic peptide (BNP) and cardiac troponin I (cTnl) in healthy subjects reported by Sugawa et al38. c, 1075
The visible points that exceeded the value of 26.2 pg/mL (red line in panel b) were re-plotted with parabola 1076
(not accurate regression analysis). d, Visible points in the figure reported by Guo et al.35 with parabolas. e, 1077
Transposed panel d for easy comparison. f, Group 1 in the small coordinate system (centre of gravity as the 1078
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p. 72 of all 74
origin of the coordinate system). g, Group 2 in the small coordinate system. h, Group 3 in the small coordinate 1079
system. In panel f-h, the upper curve is expressed by a quadratic function, in which a coefficient of the 1080
quadratic term is equal to a value of the coefficient of the quadratic term for the solid curve multiplied by 3/2. 1081
In the lower curve, a coefficient of the quadratic term of the solid curve multiplied by 2/3. Most data points 1082
located inside the crescent-shaped region enclosed by the parabolas, but the reason was unclear. Panel a was 1083
re-used from Guo T et al. JAMA Cardiol. 2020; 5(7):811-818. Figure 1B 1084
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC7101506/figure/hoi200026f1/ Copyright © 2020 Guo T 1085
et al. JAMA Cardiology. Creative Commons Attribution License (CC-BY). 1086
https://creativecommons.org/licenses/by/4.0/ Panel b was re-used from Sugawa et al. Sci Rep. 2018; 1087
8(1):5120. Figure 1. https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC5865159/figure/Fig1/ Copyright © 1088
2018 The Authors. CC-BY 4.0 License 1089
1090
1091
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p. 73 of all 74
1092
Extended Data Fig. 10 1093
1094
Extended Data Fig. 10 | A three-dimensional plot reconstructed from the data reported by Guo et al35. 1095
a, Scatter plot showing the relationship between high sensitive C-reactive protein (hsCRP) and troponin T 1096
(TnT) 35. b, Re-drawn scatter plot with a vertical line around hsCRP = 200 mg/mL = 2.0 × 102 mg/mL. c, 1097
Enlarged subgroup 3 in the panel d of Extended Data Fig. 9 (data exceeding hsCRP = 200 mg/mL are 1098
indicated by red, data not exceeding hsCRP = 200 mg/mL are indicated by blue). d, Enlarged subgroup 3 of 1099
the panel d in Extended Fig. 9 with the foot of the perpendicular from each data point to the parabola. e, The 1100
hsCRP value of each patient placed on panel d (shown as a three-dimensional plot). f, The side surface of the 1101
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p. 74 of all 74
parabolic cylinder. The point of TnT = 1.31 observed in panel b is not included in panel c, and the point of 1102
TnT = 1.71 in panel c is not included in panel b (inconsistent). In panel e, the projection of the data points 1103
onto the parabola was used as new points. In panels, e and f, some points of CRP value could not be 1104
determined because of overlapping, so those points were replaced with the average value (the points indicated 1105
by the left-pointing arrows and the error bar, which are the average values and the range of values, 1106
respectively). Panel a was re-used from Guo et al. JAMA Cardiol. 2020; 5(7):811-818. Figure 1. 1107
https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC7101506/figure/hoi200026f1/ Copyright © 2020 Guo T 1108
et al. JAMA Cardiology. Creative Commons Attribution License (CC-BY). 1109
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