This study was evaluated and approved for the purchase of the National Health Insurance Research Database (NHIRD) by the Human Studies Committee of China Medical University Hospital, Taichung, Taiwan. No informed consent was required because the data were analyzed anonymously. The cell line rat aortic smooth muscle cell line A10 cells (BCRC number:60127; used in Fig 3A and 3B ) were purchased from Food Industry Research and Development Institute in Taiwan ( https://catalog.bcrc.firdi.org.tw/BSAS_cart/controller?event=SEARCH&bcrc_no=60127&type_id=4&keyword=smooth;;muscle;;cells ). These cells were derived from the thoracic aorta of rats and served as a commonly used model of vascular smooth muscle cells [ 35 ] and were approved by the Animal Care and Use Committee (IACUC) of China Medical University, Taichung, Taiwan.
The national health insurance (NHI) program in Taiwan was started in 1995 to make health care available for all residents of Taiwan. As of 2010, over 99% of residents were enrolled in the program [ 68 ]. The NHI program provides the National Health Insurance Research Database (NHIRD) resource ( http://nhird.nhri.org.tw/en/index.htm ) for scientists in Taiwan and only for research purposes. Data for this study were retrieved from the “Longitudinal Health Insurance Database (LHID2000)”, which includes all the original claim data and registration files for 1,000,000 beneficiaries, randomly sampled from the year 2000 Registry for Beneficiaries (n = 23.72 million) under the NHI program. This database contains information on patient demographics, diagnoses, prescriptions, records of clinical visits and hospitalizations, inpatient orders, ambulatory care, and socio-demographic factors. Disease diagnoses are coded using the International Classification of Disease, 9 th Revision, Clinical Modification (ICD-9-CM). This database also include traditional Chinese medicine services (Chinese herbal medicine (CHM), acupuncture, and manipulative therapies; http://www.nhi.gov.tw/English/webdata/webdata.aspx?menu=11&menu_id=592&WD_ID=592&webdata_id=3161 ). The data are from the National Health Insurance Research Database, Taiwan (NHIRD) http://nhird.nhri.org.tw/en/index.html . Contact
[email protected] for details and data access.
This study was designed as a population-based retrospective cohort study. In this study, a cohort of one million individuals randomized selected from NHI (Taiwan) was used. The sampled population was representative of all NHI beneficiaries. The study subjects were selected from this cohort and were shown in Fig 1A . There were 84,032 individuals with diabetes (ICD-9-CM: 250) between 1998 and 2010. The hypertension ICD-9-CM used in this study was from 401–405. Individuals under the age of 20 were excluded. Individuals without hypertension (ICD-9-CM: 401–405), who had hypertension before diabetes, who had hypertension within 1 year after diabetes, and who had hypertension after 2009 were also excluded. In addition, at least one of the following enrollment criteria had to med for identifying patients with hypertension in the study: (1) one or more inpatient admissions with diagnosis of hypertension, or (2) three or more outpatients visits within one-year period, each with a diagnosis of hypertension. The first date which satisfied the above (1) or (2) criteria was defined as the date of diagnosis of hypertension. After all of these criteria were applied, 10,664 study subjects were included in the study cohort.
Study subjects with a record of cumulative CHM drug days more than 28 within first year after hypertension were defined as CHM users (N = 984, Fig 1B ). Study subjects with no recorded of CHM usage were defined as non-CHM users (N = 2,434). The date of satisfying the criterion of cumulative 28 drug days of CHM prescription was designated as the index date ( Fig 1B ). The one-to-one match method was used to match CHM users and non-CHM users. After matching these two groups for age, gender and date of diagnosis of hypertension, CHM and non-CHM users were selected ( Fig 1B and Table 1 right side). A total of 980 subjects for each group were selected. The study endpoint was as the following: date of death, date of withdrawal from the NHI program, or date of follow-up termination (31 Dec. 2010). This study was designed as a population-based retrospective cohort study and to explore the effect of Chinese Herbal Medicine treatment on the overall survival rate of individuals with hypertension among type 2 diabetes patients.
All drug codes for CHM (herbal formulas and single herbs) were collected and grouped according to their name. The frequencies of prescriptions, cumulative drug doses, average durations of per prescription, and follow-up person years were calculated from hypertension to the study end for the CHM users. Herbal formulas usually constituted a combination of 2 to 17 herbs (Table A in S1 File ), created by experienced TCM doctors; these formulas have been used for thousands of years. Single herbs were obtained from plant, animal, or mineral material and can be mixed with other herbs to create a formula. The herbal formulas and single herbs in the NHIRD database were all produced by Good Manufacturing Practice (GMP) certified traditional Chinese medicine manufacturers based in Taiwan. These manufacturers included Sun Ten Pharmaceutical Co. Ltd., Shang Chang Pharmaceutical Co. Ltd., Chuang Song Zong Pharmaceutical Co. Ltd., KO DA Pharmaceutical Co. Ltd., and Kaiser Pharmaceutical Co. Ltd.
We collected demographic data such as age, gender, income and urbanization levels. Urbanization levels in Taiwan are divided into five strata according to the Taiwan National Health Research Institute publications, with level 1 referring to the most urbanized communities and level 5 referring to the least urbanized communities. We identified the diagnoses of comorbidities which defined by following diagnoses recorded before the diagnosis date of hypertension: cardiovascular disease (ICD-9-CM: 430–437), ischaemic heart disease (ICD-9-CM: 410–414), chronic kidney disease (ICD-9-CM: 582–583) and hyperlipidaemia (ICD-9-CM: 272) ( Table 1 ). The diagnosis criteria for each comorbidity were similar to those for hypertension.
We also applied the conditional multivariable logistic regression adjusted for all variables in the Table 1 to assess the effect of CHM on the occurrence of blood pressure related disease such as acute myocardial infarction, ischemic stroke, hemorrhagic stroke, amputation, and nephropathy (the results were shown in Tables B–F in S1 File ). The covariates included CHM user, age, income, duration from diabetes to hypertension, and comorbidities before hypertension including cardiovascular disease (ICD-9-CM: 430–437), ischaemic heart disease (ICD-9-CM: 410–414), chronic kidney disease (ICD-9-CM: 582–583) and hyperlipidaemia (ICD-9-CM: 272).
Rat aortic smooth muscle cells (A10 cell line) were cultured in Dulbecco's Modified Eagle's Medium (DMEM) supplemented with 10% fetal bovine serum (FBS), 100 U/mL penicillin, 100 U/mL streptomycin, and 2 mM L-glutamine (Gibco). Y27632, and calyculin A were purchased from Sigma (St. Louis, MO, USA). A10 cells were treated with Y27632 (10 μM), and calyculin A (50 μg/ml) for 10 min. The treated cells were lysed in RIPA buffer (Thermo Scientific ™ ) and then were applied to Western blot analysis and staining with anti-phospho-myosin light chain (MLC) (1:1,000 dilution), anti-total-MLC (1:1,000 dilution), and anti-beta actin (1:1,000 dilution) antibodies ( Fig 3 ; S3 Fig ). The monoclonal anti-phospho-MLC (phospho-myosin light chain 2 [Ser19] mouse mAb; catalog number: 3675) and polyclonal anti-total-MLC (myosin light chain 2 antibody; catalog number: 3672) rabbit antibodies were from Cell Signaling Technology, Inc. The anti-beta actin (actin antibody [mAbGEa]; catalog number: NB100-74340) mouse monoclonal antibody was obtained from Novus Biologicals. The experimental protocol used for Western blotting has been described previously [ 69 , 70 ]. Briefly, cells were harvested, washed, and lysed in lysis buffer (50 mM Tris-HCl [pH 7.5], 150 mM NaCl, 5 mM EDTA, 1% Triton X-100, 0.1% SDS) supplemented with protease inhibitor cocktail (Roche). The lysates were resolved by 12% SDS-PAGE and transferred to polyvinylidene fluoride membranes (Millipore). The membranes were incubated with primary antibodies overnight at 4°C and then incubated with alkaline phosphatase-conjugated secondary antibodies (Goat anti-Mouse IgG (H+L) Polyclonal Secondary Antibody, HRP conjugate; 1:5000 dilutions; catalog number: A16072; Thermo Fisher Scientific). Signals were visualized using a SuperSignal West Femto Maximum Sensitivity Substrate Detection Kit; catalog number: 34096; Thermo Fisher Scientific) in accordance with the manufacturer's instructions.
We presented demographic data such as age, gender, duration from diabetes to hypertension, comorbidities (cardiovascular disease, ischaemic heart disease, chronic kidney disease, and hyperlipidaemia), income, and urbanization level for both groups (CHM and non-CHM users) using count and percentage for categorical variables, and used chi-squared tests to assess their differences ( Table 1 ). We sorted the cumulative person-years for each herbal formula and single herb and listed the top 12 most common herbal formulas and single herbs ( Table 2 ). We employed Kaplan-Meier method to estimate the cumulative survival probabilities and used the log-rank test to explore the effect of Chinese Herbal Medicine treatment on the overall survival rate of individuals with hypertension among type 2 diabetes patients (CHM and non-CHM users; Fig 2 ). We also used conditional logistic analysis to explore the effect of CHM therapy as well as these most commonly used herbs on the reduction of macrovascular and microvascular diseases, and death as the endpoints during follow up (Tables B–G in S1 File ). All p -values less than 0.05 were considered significant. All data management and statistical analyses were performed using Statistical Analysis System (SAS) software (version 9.3; SAS Institute, Cary, NC, USA).