{"paper_id":"4f846550-3e32-4156-b8e8-7eb288417d8e","body_text":"RESEARCH Open Access\n© The Author(s) 2024, corrected publication 2024. Open Access  This article is licensed under a Creative Commons Attribution 4.0 International \nLicense, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit \nto the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other \nthird party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. \nIf material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the \npermitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.\norg/licenses/by/4.0/. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to \nthe data made available in this article, unless otherwise stated in a credit line to the data.\nMirghafourvand et al. BMC Women's Health          (2024) 24:135 \nhttps://doi.org/10.1186/s12905-024-02975-7\nBMC Women's Health\n*Correspondence:\nSanaz Mollazadeh\nsanaz.mollazadeh@gmail.com\n1Social Determinants of Health Research Center, Tabriz University of \nMedical Sciences, Tabriz, Iran\n2Department of Biostatistics, School of Health, Social Determinants \nof Health Research Center, Mashhad University of Medical sciences, \nMashhad, Iran\n3Department Of General Practice, School Of Public Health and Preventive \nMedicine, Faculty Of Medicine, Nursing and Health Science, Monash \nUniversity, Melbourne, Australia\n4Nursing and Midwifery Care Research Center, Mashhad University of \nMedical Sciences, Mashhad, Iran\n5Department of Midwifery, Research Student Committee, Mashhad \nUniversity of Medical Sciences, Mashhad, Iran\nAbstract\nBackground Endometriosis is a benign and chronic gynecological estrogen-dependent disease. Considering the \nprevalence and the importance of measuring the long-term effects of endometriosis in affected women’s lives t the \nEIQ scale was designed and psychometrically analyzed in English in Australia, in three recall periods (last 12 months, 1 \nto 5 years ago and more than 5 years ago). It has never been used in Iran and its validity and reliability have not been \nassessed either. Therefore, the present study aimed to translate and investigate the psychometric properties of the \nEIQ.\nMethods In this study, 200 women were selected through random sampling in 2022. After forward and backward \ntranslation, the face validity, content validity, and construct validity of EIQ (through Corrected Item-Total Correlation) \nwere examined. To assess the reliability of the scale, both internal consistency (Cronbach’s alpha) and test-retest \nstability methods were employed.\nResults Impact Score with a score above 1.5 was approved. CVI and CVR values of the EIQ tool were 0.97 and \n0.94, respectively. The Item to total Correlation confirmed the construct validity of all seven dimensions of the tool, \nmore than the cut-off (0.3) except lifestyle. Cronbach’s alpha coefficient and Intra Correlation Coefficient (ICC) were \nacceptable for all dimensions.\nConclusion The Persian version of EIQ is a valid and reliable scale. This tool is valid and reliable for investigating the \nlong-term impact of endometriosis in Iranian society.\nKeywords Translation, Psychometrics, Validity, Reliability, Endometriosis impact questionnaire, Endometriosis\nPsychometric evaluation of the endometriosis \nimpact questionnaire (EIQ) in an Iranian \npopulation\nMojgan Mirghafourvand1, Vahid Ghavami2, Maryam Moradi3, Khadijeh Mirzaii Najmabadi4 and Sanaz Mollazadeh5*\n\nPage 2 of 10\nMirghafourvand et al. BMC Women's Health          (2024) 24:135 \nIntroduction\nEndometriosis is a prolonged, benign, and progressive \ninflammatory gynecological estrogen-dependent dis -\nease. It is defined as the existence of endometrial glands \nand stroma in a place other than the endometrial cavity \nof the uterus, causing a chronic inflammatory reaction \nin the pelvis [ 1]. The most common replacement sites in \nthe pelvic cavity include the ovary, uterosacral ligament \nand dead end of Douglas, cervix, sigmoid colon, and pel -\nvic peritoneum [ 2– 4]. It is estimated that endometriosis \naffects one out of ten women during their reproductive \nyears (15 to 49 years old) [ 5]. Endometriosis affects \nbetween 2 and 10% (190 million) of women and girls of \nreproductive age worldwide, but its prevalence in infer -\ntile women can even be up to 33% [ 6]. Women suffering \nfrom this disease suffer from related symptoms such as \ninfertility, periodic and non-periodic abdominal pain, \npainful menstruation, bloating, diarrhea or constipation, \npainful intercourse, and painful urination, painful defeca-\ntion [7, 8]. The etiology of endometriosis is complex and \nmultifactorial [6]. The exact cause of endometriosis is still \nunclear, but backward menstruation is widely accepted as \nan effective factor in this disease [ 9, 10]. Unfortunately, \neven though life with endometriosis is very difficult for \nmany patients, the problems of these patients have not \nbeen given much attention, and affected women suffer \nfrom the harmful effects of this disease for a long time \n[2].\nThe EIQ questionnaire was designed and psychometri -\ncally analyzed in English by Moradi et al. (2019) in Aus -\ntralia, and it has been shown that the EIQ is a valid and \nreliable tool for measuring the impact of endometriosis \non women’s lives with a long-term perspective [ 11]. The \npurpose of this tool is to measure the long-term effects \nof chronic endometriosis on various aspects of the life of \nwomen with endometriosis. This questionnaire contains \n63 items that measure the impact of the disease on vari -\nous aspects of the affected women’s lives in 8 dimensions, \nincluding the impact of the disease on physical, social, \npsychological, marital intimacy and sexual relations, fer -\ntility, occupational, and economic, education, lifestyle \naspects and it examines the impacts of endometriosis in \nthree time periods (last 12 months, 1 to 5 years ago and \nmore than 5 years ago) [ 11]. To design this tool, a quali -\ntative study with a thematic analysis approach was con -\nducted in phase 1, and then a cross-sectional study was \nconducted in Phase 2.\nOther standard instruments such as EHP-30 1 (2001) or \nEHRQ2 (2021) examine the quality of life in these patients \nduring the last four weeks. This questionnaire with 30 \nitems includes five scales of pain, control and disability, \n1  Endometriosis health profile.\n2  Endometriosis reproductive health questionnaire.\nemotional well-being, social support, and self-image. Six \ncentral section’s consisting of 23 questions measure sex -\nual intercourse, work, relationship with children, feelings \nabout the medical profession, treatment, and infertility \n[12].\nAlso, Endometriosis Reproductive Health Question -\nnaire (ERHQ) was conducted in Iran in 2021, has 35 items \nand 4 dimensions, physical problems (9 items, questions \n1–9), mental-psychological problems (12 items, ques -\ntions 10–21), instability in married life (8 items, ques -\ntions 22–29) coping strategies (6 items, questions 30–35) \n[13]. But due to the chronic and recurring nature of this \ndisease, some of the effects of the disease can be ignored \nwith a short-term perspective. EIQ is the first question -\nnaire that measures multidimensional effects with a long-\nterm perspective. Validation of a tool includes collecting \nempirical evidence about its use. Compared to EHP-30, \nEIQ has two new subscales of education and lifestyle, \nwhile EHP-30 has subscales of communication with chil -\ndren, medical professionals, and therapy [11].\nStudies have recommended the need to provide appro -\npriate measures and programs to promote health in \npatients with endometriosis, and the first step is to mea -\nsure the impacts of the disease on the lives of affected \nwomen. Therefore, considering the prevalence and \nimportance and chronic nature of endometriosis, the \nimportance of measuring the impacts of the disease in \naffected women in order to measure and design appro -\npriate interventions; also the lack of valid and reliable \ntools to measure prolonged impacts of endometriosis in \nIranian women, the present study aimed to “translate and \npsychometrically analyze the Persian version of the EIQ \nQuestionnaire” .\nMethods\nStudy participants\nThe present study was confirmed by the Ethics Council \nof Mashhad University of Medical Sciences (ethics code: \nIR.MUMS.NURSE.REC. 4,010,521). This descriptive-\nanalytical cross-sectional study, which was done in 2022 \nfrom August to November, recruited women of repro -\nductive age (15–49 years), with endometriosis who were \nreferred to the endometriosis clinic of Imam Reza Hospi -\ntal in Mashhad-Iran.\nInclusion criteria included women of reproductive \nage (15–49 years old) with endometriosis, endometrio -\nsis diagnosis by open surgery or laparoscopy or histo -\nlogical diagnosis or the presence of endometrioma cyst \nand diagnosis by ultrasound and MRI and confirmed \nby a gynecologist, at least one year after diagnosed with \nendometriosis, Iranian women, married women, liter -\nate and able to answer questions, not menopausal (stop -\nping menstruation for more than one year), not suffering \nfrom other major diseases including mental disorders \n\nPage 3 of 10\nMirghafourvand et al. BMC Women's Health          (2024) 24:135 \nincluding depression, eating disorders and obesity, poly -\ncystic ovary syndrome (PCOS), infertility, insomnia, \nschizophrenia and chronic diseases including diabetes, \nkidney disease and rheumatology, absence of cancer and \nany life-threatening diseases according to the reports of \nresearch units. Exclusion criteria included incomplete \ncompletion of the questionnaire by not answering more \nthan 10% of the questions.\nSample size\nFor construct validity and factor analysis, Hair et al. state \nthat the sample size should be more than 100 samples, \nand according to the strategy proposed by Hair et al. \nthe minimum required sample size is 3 samples and the \nmaximum is 20 samples per item [ 14]. Considering the \n63 questions of the EIQ questionnaire, the total sample \nsize was determined approximately 200 women. The \nsample size was different in each stage of psychoanaly -\nsis. For content validity: 10 experts; for face validity: 10 \nqualified women with endometriosis; to evaluate internal \nconsistency: 20 women with endometriosis. For reliabil -\nity (retest): 20 women with endometriosis; for construct \nvalidity (confirmatory factor analysis): 200 women with \nendometriosis.\nIntroducing the tool\nThe Endometriosis Impact Questionnaire (EIQ) is a self-\nreport questionnaire that examines how endometriosis \nhas affected women’s lives over the three recall periods \nincluding ‘last 12 months’ , ‘1 to 5 years ago’ ,and ‘more \nthan 5 years ago’ . EIQ items are rated on a 5-point Likert \nscale, ranging from 0 (not at all) to 4 (very much), with \nthe additional option of 9 (not applicable). Each item \ncontributes equally and higher scores indicate a greater \nimpact. The EIQ was developed in Australia and a psy -\nchometric evaluation was conducted, using face, content, \nconstruct (factor analysis), concurrent validity, and reli -\nability (internal consistency and test-retest reliability). \nthe study by Moradi et al. used a methodological design \nthat involved the development and evaluation of data col-\nlection instruments, scales, or techniques. To evaluate \nconstruct and concurrent validity and reliability, a cross-\nsectional study was conducted via a web-based survey. \nAll data were analyzed using SPSS version 20, and proba -\nbility values of p < 0.05 were considered to be statistically \nsignificant [11].\nTranslation process\nBecause the translation and psychometry of the tool in \nquestion have not been done in Iran, in this study, the \ntranslation and psychometry of the Persian version of \nthis tool were done. In the first step, translation (For -\nward & Backward Translation), the desired tool was \ntranslated from English to Farsi by a fluent colleague in \nboth languages (at least two people). In the second step, \nthe primary translations were combined into a single \ntranslation. In the third step, the final translated ver -\nsion was returned from the target language to the origi -\nnal language. In the fourth step, the translated version \nwas revised from the target language to the original lan -\nguage. In this step, literal translation was not meant, but \nsemantic translation will be done. The meanings hidden \nand present in the original version and its transfer to the \nPersian language were considered instead of the exact \ntranslation of the words. The questions and words of the \noriginal questionnaire must have the same meaning as \nthe translated version [15].\nData collection\nThe researcher was presented at the endometriosis clinic \nof Mashhad University of Medical Sciences, located at \nImam Reza Hospital. Eligible women were invited to par -\nticipate in the study by referring to the medical records \nof women with endometriosis available in the endome -\ntriosis clinic. After introducing herself to the women \nand explaining the purpose of the study, the researcher \ninvited eligible and willing women to participate in the \nstudy after obtaining written and informed consent. \nWomen entered the study after an explanation about the \nstudy and obtaining informed consent.\nData analysis\nAfter collecting the data, it was coded and the data was \nentered into the SPSS version 21 software. Descrip -\ntive statistics including frequency (percentage) and \nmean ± standard deviation were used to describe socio-\ndemographic characteristics. To check construct valid -\nity, the Corrected Item-Total Correlation was used. To \nverify the reliability of the current scale, Cronbach’s alpha \nmethods were utilized to calculate internal consistency \nand test-retest reliability was determined through ICC \nanalysis.\nFace validity\nFor face validity, quantitative and qualitative approaches \nwere used. The quantitative approach was evaluated \nby calculating the impact score, and the qualitative \napproach was based on the opinions of the expert com -\nmittee and target groups’ views. Questionnaire items in \nthe face validity form include the first part (qualitative \nevaluation), checking in terms of difficulty levels, irrel -\nevance, and ambiguity. The second part (quantitative \nevaluation) was included in calculating the impact score, \nchecking the importance of the items based on a 5-point \nLikert scale (completely important, important, moder -\nately important, slightly important, and not important). \nThen, the convenience sampling questionnaire was given \nto 10 eligible women and their husbands. Lastly, the score \n\nPage 4 of 10\nMirghafourvand et al. BMC Women's Health          (2024) 24:135 \nof each item was calculated using the following formula: \nImpact Score = Frequency (%) × Importance. Finally, \nthe items with an impact score of more than 1.5 were \naccepted.\n(Frequency: percentage of women who responded to \na specific Likert in the desired item. Importance: Likert \nnumber chosen by women [16].\nContent validity\nQuantitative and qualitative methods were used to evalu-\nate content validity. In the qualitative component, ten \nspecialists across midwifery and reproductive health \nwere asked to examine and provide corrective opin -\nions on the translation of each question concerning its \ngrammar, appropriateness of wording, and th sentence \nstructure. After collecting the experts’ evaluations, the \nrequired changes were given in the tool. Content valid -\nity was quantitatively calculated based on the opinions of \nexperts and by calculating two indexes: content validity \nratio (CVR = Content Validity Ratio) and content validity \nindex (CVI = Content Validity Index). The content validity \nindex of the questions was assessed regarding relevance, \nclarity, and simplicity based on a 4-point Likert scale.\nConstruct validity\nDue to the large number of missing values of the scoring \nof the questionnaire; Confirmatory factor analysis was \nnot feasible for evaluating construct validity. Therefore, \nthe item-to-total correlation method was employed for \nthis purpose. The cut-off point for this method was set \nat 0.3, which implies that any variable with a corrected \nitem-total correlation value less than 0.3 should be elimi -\nnated [17– 19].\nTool Reliability\nFor the reliability of the instrument, internal consistency \nwas used by calculating Cronbach’s alpha with the SPSS \n21 software. Also, to determine the repeatability, the test-\nretest method through determining the intra-class cor -\nrelation coefficient (ICC) was used. Twenty women with \nendometriosis answered the questions of the Persian ver -\nsion two times with an interval of 2 weeks.Results.\nParticipants’ characteristic\nIn this study, 200 women with endometriosis were \nassessed. The results of Table  1 show the socio-demo -\ngraphic characteristics of participants. The participants’ \nmean age was 35.6 years (SD: 6.2). In terms of educa -\ntion level, the number (percent) of academic degrees \nwas 123 (61.5%). More than half of women (58.5%) were \nhousewives. In terms of monthly income adequacy, two \nthirds of women (69%) had a sufficient income for living \nexpenses.\nFace and content validity\nIn the face validity review, all items were described as \nappropriate and without ambiguity and difficulty and \nreceived a minimum score of 1.5, except items 61, 62, and \n63 which scored less than 1.5. Also, in the content valid -\nity evaluation, all items obtained the minimum accept -\nable value of CVR and CVI. CVR for the whole tool was \n0.94 and CVI for the whole tool was 0.97 (Table 2).\nThe whole tool and its dimensions had a minimum \nstandard of internal consistency above 0.7. ICC for the \nphysical, psychological, social, sexual, occupational, and \nfinancial effects and education dimensions was found to \nbe above 0.7, which indicates an acceptable agreement \nfor the questionnaire (Table 3).\nConstruct validity\nIn the construct validity review of EIQ, all items dem -\nonstrated a minimum corrected item-total correlation \nvalue of 0.3, except for items 61, 62, and 63 (as shown in \nTable 4).\nDiscussion\nThe present research was conducted to determine the \npsychometric properties of the EIQ for Iranian women \naffected by endometriosis. It was demonstrated that the \nPersian version of this scale is valid and reliable tool to \nmeasure the impact of endometriosis on women’s lives \nwith a long-term perspective. Validity was assessed and \nconfirmed using face validity (qualitative and quantita -\ntive), content validity (qualitative and quantitative), and \nconstruct validity (item to total correlation). The reliabil -\nity of the tool was also examined and approved through \ninternal consistency (Cronbach’s alpha coefficient) and \ntest-retest stability.\nThe EIQ with eight dimensions including physical, psy-\nchological, social, marital intimacy and sexual relations, \nreproductive, occupational and financial, and education \nTable 1 Characteristics of the study participants for Construct \nvalidity (n = 200)\nCharacteristics Number (Percentage)\nAge (Year) 35.6 (6.2) *\nLevel of Education\nElementary/Secondary school 20 (10.0)\nHigh School/Diploma 57 (28.5)\nAcademic 123 (61.5)\nJob\nHousewife 117 (58.5)\nEmployed 83 (41.5)\nAdequacy of monthly income\nLess than living expenses 43 (21.5)\nEqual of living expenses 138 (69.0)\nMore than living expenses 19 (9.5)\n*Mean (SD)\n\nPage 5 of 10\nMirghafourvand et al. BMC Women's Health          (2024) 24:135 \nItems Impact factor*\nn = 10 women\nCVI† CVR‡\nn = 10 experts\nEIQ 1 4.5 1 1\nEIQ 2 3.6 1 1\nEIQ 3 3.2 1 1\nEIQ 4 3.6 1 1\nEIQ 5 2.7 0.96 1\nEIQ 6 3.4 1 1\nEIQ 7 2.3 0.83 0.80\nEIQ 8 4 1 1\nEIQ 9 2.8 1 1\nEIQ 10 1.7 1 1\nEIQ 11 3.2 1 1\nEIQ 12 3.5 1 1\nEIQ 13 2.5 0.96 1\nEIQ 14 3 1 1\nEIQ 15 3.3 0.86 0.80\nEIQ 16 6 0.90 0.80\nEIQ 17 4.2 1 1\nEIQ 18 2.8 1 1\nEIQ 19 2.4 1 1\nEIQ 20 1.7 0.90 0.80\nEIQ 21 3.4 0.90 0.80\nEIQ 22 2.4 0.90 0.80\nEIQ 23 2.7 0.90 0.80\nEIQ 24 3.6 1 1\nEIQ 25 4.3 1 1\nEIQ 26 3.2 1 1\nEIQ 27 2.7 0.96 1\nEIQ 28 2.2 1 1\nEIQ 29 3.8 1 1\nEIQ 30 2.6 1 1\nEIQ 31 2.1 1 1\nEIQ 32 2.2 1 1\nEIQ 33 1.9 1 1\nEIQ 34 2 1 1\nEIQ 35 3 1 1\nEIQ 36 3.2 1 1\nEIQ 37 2.7 1 1\nEIQ 38 3.3 1 1\nEIQ 39 2.7 1 1\nEIQ 40 3.6 0.86 0.80\nEIQ 41 4 1 1\nEIQ 42 4.1 0.90 0.80\nEIQ 43 3.4 1 1\nEIQ 44 1.9 0.90 0.80\nEIQ 45 2.7 1 1\nEIQ 46 2.1 1 1\nEIQ 47 2.2 1 1\nEIQ 48 2.7 1 1\nEIQ 49 1.9 0.90 0.80\nEIQ 50 1.9 1 1\nEIQ 51 2 1 1\nEIQ 52 1.9 1 1\nTable 2 Impact coefficient, index and content validity ratio of the items of the Endometriosis Impact Questionnaire (EIQ)\n\nPage 6 of 10\nMirghafourvand et al. BMC Women's Health          (2024) 24:135 \naspects had a proper face and content validity except for \nthe lifestyle aspects. Face validity means that items com -\nprehensively covers the different components of endo -\nmetriosis impacts to be measured and content validity \nindicates that items are sensible, appropriate, and rel -\nevant to the women who use the measure [20].\nThe results of the psychometric evaluation of the Endo-\nmetriosis Impact Questionnaire (EIQ) in an Iranian \npopulation, showed that the lifestyle dimension with \n3 questions that raised the use of alcohol and drugs to \nadapt to the disease impact, scored below the minimum \ncut-off in the construct validity and impact score. The \nreason for this result could be related to cultural differ -\nences and beliefs of Iranian women. In Iranian women’s \nculture, the use of these substances is considered taboo \nand it is considered disrespectful for a woman.\nAccording to the results of previous studies, caffeine, \nalcohol, and smoking can cause changes in the synthe -\nsis of known sex steroids (SHBG), which may affect the \nrisk of hormone-related diseases, such as endometriosis \n[21– 25]. In contrast the results of Hemmert et al. ’s study \nwhich is unique in its capture of lifestyle exposures before \nincident endometriosis diagnosis, largely found no asso -\nciation between alcohol, caffeine, smoking, and physical \nactivity and risk of endometriosis [24]. Also, studies dem-\nonstrated the relationship between certain foods or life -\nstyle modifications is limited. The result of the Manaker \net al. study showed that increasing consumption of cer -\ntain fruits, omega-3 fatty acids, and dairy foods may \nreduce the risk of developing endometriosis. Dietary and \nlifestyle modifications and how they are related to endo -\nmetriosis risk factors and/or symptoms associated with \nendometriosis are discussed [25].\nThe EIQ (2014) is the first questionnaire to measure \nthe multi-dimensional impacts of endometriosis with a \nlong-term perspective. Considering its recurring nature, \nsymptoms may continue despite seemingly adequate \ntreatment [ 26]. Also, the other standard tools such as \n(EHP-30 or ERHQ) are available. For example the ERHQ \n(2021) was designed in Iran. ERHQ is a new, valid and \nreliable patient-generated instrument to measure the \nreproductive health of women with endometriosis. The \nnumber of items in the EHRQ questionnaire is 35. Four \nfactors explained the questionnaire’s factor structure: \nphysical problems (9 items), psychological problems (12 \nitems), counteracting strategies (6 items), and instability \nof marital life (8 items) [13].\nTable 3 Internal consistency and retest stability of endometriosis effects questionnaire with 20 women with endometriosis\nDimensions of endometriosis \neffects\nLast 12 months Last 1–5 years Last 5 years\nCronbach’s \nalpha\nICC (95% CI) * Cronbach’s \nalpha\nICC (95% CI) * Cronbach’s \nalpha\nICC (95% CI) *\nPhysical effects 0.90 0.89 (0.86–0.91) 0.88 0.86 (0.89 − 0.84) 0.73 0.94 (0.93–0.95)\nPsychological effects 0.81 0.93 (0.94 − 0.91) 0.87 0.95 (0.94–0.96) 0.87 0.98 (0.98 − 0.97)\nSocial effects 0.91 0.90 (0.92 − 0.88) 0.93 0.94 (0.92–0.95) 0.93 0.97 (0.97 − 0.96)\nSexual relationships 0.92 0.81 (0.75–0.86) 0.84 0.94 (0.92–0.95) 0.93 0.96 (0.95–0.97)\nReproductive 0.99 0.78 (0.71–0.84) 0.95 0.77 (0.69–0.84) 0.93 0.86 (0.82–0.90)\nOccupational and financial 0.72 0.93 (0.91–0.95) 0.74 0.94 (0.93–0.96) 0.70 0.96 (0.95–0.97)\nEducation 0.85 0.88 (0.78–0.95) 0.82 0.94 (0.97 − 0.89) 0.84 0.96 (0.98 − 0.92)\nLifestyle 0.93 (0.92–0.95)0.94 0.94 (0.96 − 0.94) 0.96 0.95 (0.94–0.96) 0.94\n*Intra-class Correlation Coefficient (95% Confidence Interval)\nItems Impact factor*\nn = 10 women\nCVI† CVR‡\nn = 10 experts\nEIQ 53 2.7 0.90 0.80\nEIQ 54 3.1 1 1\nEIQ 55 2.7 1 1\nEIQ 56 2.8 1 1\nEIQ 57 1.9 0.93 1\nEIQ 58 1.9 1 1\nEIQ 59 1.9 0.96 1\nEIQ 60 1.7 0.96 0.80\nEIQ 61 0.18 0.83 0.80\nEIQ 62 1.1 0.86 0.80\nEIQ 63 0.44 0.90 0.80\nOverall score of EIQ 0.97 0.94\n*Impact Score, †Content Validity Index, ‡Content Validity Ratio\nTable 2 (continued) \n\nPage 7 of 10\nMirghafourvand et al. BMC Women's Health          (2024) 24:135 \nItems Last 12 months Last 1–5 years Last 5 years\nCronbach’s alpha Item-Total Correlation Cronbach’s alpha Item-Total Correlation Cronbach’s alpha Item-Total Correlation\nEIQ 1 0.88 0.68 0.87 0.64 0.85 0.52\nEIQ 2 0.88 0.56 0.87 0.54 0.85 0.62\nEIQ 3 0.88 0.55 0.87 0.51 0.85 0.35\nEIQ 4 0.88 0.30 0.87 0.35 0.85 0.37\nEIQ 5 0.88 0.67 0.87 0.61 0.85 0.67\nEIQ 6 0.88 0.67 0.87 0.65 0.85 0.58\nEIQ 7 0.88 0.58 0.87 0.57 0.85 0.53\nEIQ 8 0.88 0.67 0.87 0.62 0.85 0.66\nEIQ 9 0.88 0.73 0.87 0.69 0.85 0.73\nEIQ 10 0.88 0.72 0.87 0.65 0.85 0.65\nEIQ 11 0.88 0.48 0.87 0.54 0.85 0.55\nEIQ 12 0.88 0.49 0.87 0.45 0.85 0.38\nEIQ 13 0.88 0.38 0.87 0.48 0.85 0.37\nEIQ 14 0.94 0.72 0.94 0.73 0.96 0.79\nEIQ 15 0.94 0.52 0.94 0.55 0.96 0.74\nEIQ 16 0.94 0.62 0.94 0.70 0.96 0.78\nEIQ 17 0.94 0.68 0.94 0.73 0.96 0.81\nEIQ 18 0.94 0.74 0.94 0.81 0.96 0.79\nEIQ 19 0.94 0.78 0.94 0.76 0.96 0.76\nEIQ 20 0.94 0.57 0.94 0.51 0.96 0.55\nEIQ 21 0.94 0.78 0.94 0.78 0.96 0.81\nEIQ 22 0.94 0.65 0.94 0.59 0.96 0.74\nEIQ 23 0.94 0.56 0.94 0.60 0.96 0.65\nEIQ 24 0.94 0.73 0.94 0.75 0.96 0.84\nEIQ 25 0.94 0.72 0.94 0.78 0.96 0.88\nEIQ 26 0.94 0.67 0.94 0.68 0.96 0.77\nEIQ 27 0.94 0.77 0.94 0.80 0.96 0.83\nEIQ 28 0.94 0.57 0.94 0.62 0.96 0.64\nEIQ 29 0.94 0.74 0.94 0.81 0.96 0.83\nEIQ 30 0.90 0.82 0.90 0.82 0.89 0.82\nEIQ 31 0.90 0.80 0.90 0.78 0.89 0.77\nEIQ 32 0.90 0.77 0.90 0.78 0.89 0.80\nEIQ 33 0.90 0.76 0.90 0.76 0.89 0.67\nEIQ 34 0.81 0.54 0.83 0.60 0.88 0.72\nEIQ 35 0.81 0.40 0.83 0.46 0.88 0.51\nEIQ 36 0.81 0.67 0.83 0.68 0.88 0.77\nEIQ 37 0.81 0.69 0.83 0.69 0.88 0.74\nEIQ 38 0.81 0.65 0.83 0.65 0.88 0.73\nTable 4 Construct validity of the items of the Endometriosis Impact Questionnaire (EIQ) with 200 women with endometriosis\n\nPage 8 of 10\nMirghafourvand et al. BMC Women's Health          (2024) 24:135 \nItems Last 12 months Last 1–5 years Last 5 years\nCronbach’s alpha Item-Total Correlation Cronbach’s alpha Item-Total Correlation Cronbach’s alpha Item-Total Correlation\nEIQ 39 0.81 0.42 0.83 0.44 0.88 0.52\nEIQ 40 0.81 0.48 0.83 0.61 0.88 0.71\nEIQ 41 0.82 0.63 0.86 0.72 0.92 0.84\nEIQ 42 0.82 0.72 0.86 0.77 0.92 0.91\nEIQ 43 0.82 0.68 0.86 0.75 0.92 0.79\nEIQ 44 0.93 0.84 0.91 0.76 0.89 0.57\nEIQ 45 0.93 0.84 0.91 0.81 0.89 0.69\nEIQ 46 0.93 0.67 0.91 0.65 0.89 0.65\nEIQ 47 0.93 0.64 0.91 0.56 0.89 0.57\nEIQ 48 0.93 0.71 0.91 0.65 0.89 0.70\nEIQ 49 0.93 0.84 0.91 0.81 0.89 0.58\nEIQ 50 0.93 0.77 0.91 0.65 0.89 0.70\nEIQ 51 0.93 0.74 0.91 0.68 0.89 0.53\nEIQ 52 0.93 0.69 0.91 0.69 0.89 0.54\nEIQ 53 0.93 0.81 0.91 0.76 0.89 0.74\nEIQ 54 0.93 0.46 0.91 0.43 0.89 0.65\nEIQ 55 0.96 0.59 0.90 0.35 0.92 0.59\nEIQ 56 0.96 0.98 0.90 0.96 0.92 0.94\nEIQ 57 0.96 0.96 0.90 0.77 0.92 0.75\nEIQ 58 0.96 0.91 0.90 0.79 0.92 0.78\nEIQ 59 0.96 0.96 0.90 0.87 0.92 0.95\nEIQ 60 0.96 0.87 0.90 0.74 0.92 0.71\nEIQ 61 0.12 0.10 -0.4 -0.1 -0.1 -0.1\nEIQ 62 0.12 0.10 -0.4 -0.2 -0.1 -0.0\nEIQ 63 0.12 -0.02 -0.4 -0.1 -0.1 -0.1\nTable 4 (continued)\n \n\nPage 9 of 10\nMirghafourvand et al. BMC Women's Health          (2024) 24:135 \n [11]. Also, the EHP-30 is the disease-specific 30-items \nquestionnaire to measure the HRQoL3 with the strongest \nvalidity evidence. The EHP-30 has subscales of relation -\nship with medical professionals, treatment, and children \n[27].The EIQ has two new subscales of education and life-\nstyle, comparedwith the EHP-30 [ 12]. Both EHP-30 and \nERHQ or other tools measure the effect of endometriosis \nduring last four weeks. So some impacts could be missed \nby only looking at the last four weeks, because of chronic \nnature of endometriosis. Also, other questionnaires are \nnot able to investigate occupational goals, loss of job or \npromotion opportunities, address women’s regrets from \nliving with endometriosis, or measure the impacts on a \nwoman who lost her sexual-intimate relationship. Future \nstudies should be conducted to measure the impact of \nendometriosis on lifestyle, as well as education and work \n[28, 29].\nThis questionnaire with 30 items includes five scales of \npain, control and disability, emotional well-being, social \nsupport, and self-image. Six central section’s consist -\ning of 23 questions measure sexual intercourse, work, \nand relationship with children, feelings about the medi -\ncal profession, treatment, and infertility (124). However, \ndue to the chronic and recurrent nature of this disease, \nsome of the effects of the disease can be ignored in the \npast four weeks. EIQ is the first questionnaire that mea -\nsures multidimensional effects with a long-term perspec -\ntive. Validation of a tool includes collecting empirical \nevidence about its use. Similar to EIQ, instruments such \nas ETSQ and EPBD were designed from focus group \ndiscussions and interviews with patients. EHP-30 items \nwere designed based on open exploratory interviews with \n25 women with endometriosis. The process used to vali -\ndate the EIQ was somewhat similar to that used for the \nECQ, however, the development processes were different. \nCompared to the EHP-30, the EIQ has two new subscales \nof education and lifestyle, while the EHP-30 has subscales \nof communication with children, medical professionals, \nand therapy (123).\nStrengths and limitations\nThis is the first approved translation and adaptation \nof the EIQ in Iran as a Middle-Income Country and it \nperforms in the same manner as the Australian tool, \nexcept for lifestyle dimension. It could evaluate the \nmulti-dimensional impacts of endometriosis to provide \ndetailed information in population health surveys and to \ncompare different management options or different areas \nand stages of patients’ lives. It could consider all three \nrecall periods or each period independently because each \nhas satisfactory validity and reliability. The total score for \neach dimension at three recall periods, for all dimensions \n3  Health related quality of life.\nat each recall period, and the total impact score could \nbe calculated. Combining the scores will depend on the \nresearch objectives. The recall period of ‘last 12 months’ , \ncould be used to investigate outcomes in clinical trials. \nIt could help patients communicate with health profes -\nsionals and be useful to guide the development of an \nindividualized disease management plan. It could also \nbe used to assess of patients’ needs or as a burden esti -\nmation to provide information for making health policy \ndecisions to improve services for affected women’s lives. \nThe limitations of this study include that the question -\nnaire contained questions that led to a large number of \nempty responses because the participants did not have \nthe conditions at that time to answer those questions. \nThis limitation resulted in a high amount of missing data, \npreventing the conduct of confirmatory factor analysis \nand divergent validity and convergent validity in con -\nstruct validity.\nConclusion\nThe results showed that the EIQ is a valid and reliable \ntool to measure the impacts of endometriosis on differ -\nent aspects of Iranian women’s lives with a long-term \nview. It can be used by researchers and health providers \nto provide a better understanding of the impact of endo -\nmetriosis on various aspects of reproductive health over \ntime and to meet the needs of patients with the disease. \nIn future studies, it is recommended to conduct studies \nwith a more robust methodology and larger sample sizes \nin various communities and other countries as well as \ndifferent languages with different sociocultural contexts \nto achieve more generalizable results and to make multi -\nnational studies possible.\nAcknowledgements\nWe express our appreciation to the librarians at Mashhad University of Medical \nSciences, Mashhad, Iran for assistance in providing informational support for \nthis study. We thank the volunteer participants for sharing their experiences \nand giving their time and help to make this study possible.\nAuthors’ information (optional):\n(1) PhD. Social Determinants of Health Research Center, Tabriz University of \nMedical Sciences, Tabriz, Iran. (2) PhD. Department of Biostatistics, School of \nHealth, Social Determinants of Health Research Center, Mashhad University of \nMedical sciences, Mashhad, Iran. (3) PhD. Senior Research Fellow. Department \nOf General Practice, School Of Public Health and Preventive Medicine, Faculty \nOf Medicine, Nursing and Health Science, Monash University, Melbourne, \nAustralia. (4) PhD. Nursing and Midwifery Care Research Center, Mashhad \nUniversity of Medical Sciences, Mashhad, Iran Sciences, Mashhad, Iran. (5) PhD \ncandidate at the department of Midwifery, Research Student Committee, \nMashhad University of Medical Sciences, Mashhad, Iran.\nAuthor contributions\nAuthors’ contribution: All authors participated in the editing of this manuscript \nand approved the final version for publication. All authors jointly planned \nand designed the study. SM identified potential participants and recruited \nthe participants. SM and M.Mojgan&M. Maryam has made substantial \ncontributions to the conception and design, acquisition of data, analysis, \nand interpretation of data. V.GH has made substantial contributions to the \nconception and design, acquisition of data, analysis, and interpretation of \ndata. KH. M has made substantial contributions to conception and design. All \nauthors have been involved in drafting the manuscript or revising it critically \n\nPage 10 of 10\nMirghafourvand et al. BMC Women's Health          (2024) 24:135 \nfor important intellectual content. All authors read and approved the final \nmanuscript.\nFunding\nMashhad University of Medical science.\nData availability\nThe datasets generated and/or analyses during the current study are available \nfrom the corresponding author on reasonable request.\nDeclarations\nEthics approval and consent to participate\nThe present study was confirmed by the Ethics Council of Mashhad University \nof Medical Sciences (ethics code: IR.MUMS.NURSE.REC. 4010521). All methods \nwere carried out in accordance with relevant guidelines and regulations in the \ndeclaration of Helsinki. The researcher invited eligible and willing women to \nparticipate in the study after obtaining written and informed consent from all \nsubjects and/or their legal guardian(s).\nConsent for publication\nNot applicable.\nCompeting interests\nThe authors declare no competing interests.\nReceived: 21 July 2023 / Accepted: 14 February 2024\nReferences\n1. Overton C, Shaw RW, McMillan L, Davis C. 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