Validity of Self-reported Endometriosis

A Comparison Across Four Cohorts

A.L. Shafrir; L.A. Wise; J.R. Palmer; Z.O. Shuaib; L.M. Katuska; P. Vinayak; M. Kvaskoff; K.L. Terry; S.A. Missmer


Hum Reprod. 2021;36(5):1268-1278. 

In This Article

Abstract and Introduction


Study Question: How accurately do women report a diagnosis of endometriosis on self-administered questionnaires?

Summary Answer: Based on the analysis of four international cohorts, women self-report endometriosis fairly accurately with a > 70% confirmation for clinical and surgical records.

What is Known Already: The study of complex diseases requires large, diverse population-based samples, and endometriosis is no exception. Due to the difficulty of obtaining medical records for a condition that may have been diagnosed years earlier and for which there is no standardized documentation, reliance on self-report is necessary. Only a few studies have assessed the validity of self-reported endometriosis compared with medical records, with the observed confirmation ranging from 32% to 89%.

Study Design, Size, Duration: We compared questionnaire-reported endometriosis with medical record notation among participants from the Black Women's Health Study (BWHS; 1995–2013), Etude Epidémiologique auprès de femmes de la Mutuelle Générale de l'Education Nationale (E3N; 1990–2006), Growing Up Today Study (GUTS; 2005–2016), and Nurses' Health Study II (NHSII; 1989–1993 first wave, 1995–2007 second wave).

Participants/Materials, Setting, Methods: Participants who had reported endometriosis on self-administered questionnaires gave permission to procure and review their clinical, surgical, and pathology medical records, yielding records for 827 women: 225 (BWHS), 168 (E3N), 85 (GUTS), 132 (NHSII first wave), and 217 (NHSII second wave). We abstracted diagnosis confirmation as well as American Fertility Society (AFS) or revised American Society of Reproductive Medicine (rASRM) stage and visualized macro-presentation (e.g. superficial peritoneal, deep endometriosis, endometrioma). For each cohort, we calculated clinical reference to endometriosis, and surgical- and pathologic-confirmation proportions.

Main Results and the Role of Chance: Confirmation was high—84% overall when combining clinical, surgical, and pathology records (ranging from 72% for BWHS to 95% for GUTS), suggesting that women accurately report if they are told by a physician that they have endometriosis. Among women with self-reported laparoscopic confirmation of their endometriosis diagnosis, confirmation of medical records was extremely high (97% overall, ranging from 95% for NHSII second wave to 100% for NHSII first wave). Importantly, only 42% of medical records included pathology reports, among which histologic confirmation ranged from 76% (GUTS) to 100% (NHSII first wave). Documentation of visualized endometriosis presentation was often absent, and details recorded were inconsistent. AFS or rASRM stage was documented in 44% of NHSII first wave, 13% of NHSII second wave, and 24% of GUTS surgical records. The presence/absence of deep endometriosis was rarely noted in the medical records.

Limitations, Reasons For Caution: Medical record abstraction was conducted separately by cohort-specific investigators, potentially introducing misclassification due to variation in abstraction protocols and interpretation. Additionally, information on the presence/absence of AFS/rASRM stage, deep endometriosis, and histologic findings were not available for all four cohort studies.

Wider Implications of the Findings: Variation in access to care and differences in disease phenotypes and risk factor distributions among patients with endometriosis necessitates the use of large, diverse population samples to subdivide patients for risk factor, treatment response and discovery of long-term outcomes. Women self-report endometriosis with reasonable accuracy (>70%) and with exceptional accuracy when women are restricted to those who report that their endometriosis had been confirmed by laparoscopic surgery (>94%). Thus, relying on self-reported endometriosis in order to use larger sample sizes of patients with endometriosis appears to be valid, particularly when self-report of laparoscopic confirmation is used as the case definition. However, the paucity of data on histologic findings, AFS/rASRM stage, and endometriosis phenotypic characteristics suggests that a universal requirement for harmonized clinical and surgical data documentation is needed if we hope to obtain the relevant details for subgrouping patients with endometriosis.

Study Funding/Competing Interest(S): This project was supported by Eunice Kennedy Shriver National Institute of Child Health and Development grants HD48544, HD52473, HD57210, and HD94842, National Cancer Institute grants CA50385, R01CA058420, UM1CA164974, and U01CA176726, and National Heart, Lung, and Blood Institute grant U01HL154386. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. AS, SM, and KT were additionally supported by the J. Willard and Alice S. Marriott Foundation. MK was supported by a Marie Curie International Outgoing Fellowship within the 7th European Community Framework Programme (#PIOF-GA-2011-302078) and is grateful to the Philippe Foundation and the Bettencourt-Schueller Foundation for their financial support. Funders had no role in the study design, conduct of the study or data analysis, writing of the report, or decision to submit the article for publication. LA Wise has served as a fibroid consultant for AbbVie, Inc for the last three years and has received in-kind donations (e.g. home pregnancy tests) from Swiss Precision Diagnostics, Sandstone Diagnostics,, and for the PRESTO cohort. SA Missmer serves as an advisory board member for AbbVie and a single working group service for Roche; neither are related to this study. No other authors have a conflict of interest to report. Funders had no role in the study design, conduct of the study or data analysis, writing of the report, or decision to submit the article for publication.

Trial Registration Number: N/A.


Endometriosis, in which endometrial-like tissue is found outside of the uterus, affects approximately 10% of reproductive-aged women and can lead to debilitating pelvic pain, diminished quality of life, infertility, and significant health care costs (Missmer et al., 2004; Shafrir et al., 2018; Zondervan et al., 2018; Ghiasi et al., 2020). It is a heterogeneous disease in terms of lesion characteristics, symptom presentation, and response to treatment (Zondervan et al., 2020). As such, studies with large sample sizes that include diverse populations are needed to identify and adequately analyze informative endometriosis subgroups. Grouping all endometriosis participants into one category may bias estimates towards the null if some subgroups but not others are associated with certain risk factors or with predicting treatment responses.

Currently, definitive diagnosis of endometriosis requires surgical visualization, with some arguing for the additional requirement of histologic confirmation of endometrial glands and/or stroma in at least one excised lesion (Agarwal et al., 2019). Thus, many studies rely on medical record abstraction. However, conducting medical record abstraction in large epidemiologic studies can be costly and time-consuming while still yielding inconsistent information (Becker et al., 2014; Vitonis et al., 2014). Consequently, many studies include small samples from single clinical sites that may provide care to biased subsets of the general population of women at risk for endometriosis. Indeed, the prevalence of endometriosis alone may differ by an order of magnitude when comparing specialty clinic populations to general populations (Ghiasi et al., 2020). Additionally, analyses of insurance claims data (e.g. International Classification of Diseases (ICD)-10 codes), which capture a more comprehensive population, are limited to patients who received an ICD-10 code for billing purposes and have been shown to inadequately capture the full extent of endometriosis disease (Whitaker et al., 2019). For example, endometriosis remains coded within 'non-inflammatory disorders of female genital tract,' which is entirely inconsistent with current knowledge, and thus may be overlooked. In addition, there is no coding option to define endometriosis subgroups such as superficial or deep disease (Whitaker et al., 2019).

Currently, overcoming these limitations requires reliance on self-reported endometriosis via self-administered questionnaires. To date, only a few studies have assessed the validity of self-reported endometriosis, finding a wide range of validation proportions—32–89%––across different populations and using different data sources (e.g. medical records and inpatient hospital registries) as the gold standard for confirmation (Treloar et al., 2000; Missmer et al., 2004; Saha et al., 2015, 2017). No study has compared the validity of self-reported endometriosis against medical records across populations that differ with respect to age and race/ethnicity.

Therefore, we compared endometriosis diagnoses reported via self-administered questionnaires to medical record notation across four diverse cohorts. We also assessed the availability of endometriosis phenotypic details, including American Fertility Society (AFS) or revised American Society of Reproductive Medicine (rASRM) stage and visualized macro-presentation of endometriosis lesions (e.g. superficial peritoneal, endometrioma, deep endometriosis).