Abstract
ObjectiveResearchers traditionally rely on participant self-report for contraceptive use. We hypothesized that self-reported contraceptive use by clinical research participants may disagree with objectively measured hormonal status. Study designWe enrolled women in Harare, Zimbabwe, aged 18–34, who by self-report had not used hormonal or intrauterine contraception for >30 days, or depot medroxyprogesterone acetate for >10 months, into a study designed to assess biologic changes with contraceptive initiation and use. Blood samples obtained at enrollment and each follow-up visit (N=1630 from 447 participants) were evaluated by mass spectrometry for exogenous hormones. We individually interviewed a subset of participants (n=20) with discrepant self-reported and measured serum hormones to better understand nondisclosure of contraceptive use. ResultsDiscrepant with self-reported nonuse of hormonal contraception, synthetic progestogens were detectable in 120/447 (27%, 95% confidence interval 23%–31%) enrolled women. Measured exogenous hormones consistent with use of contraceptive pills (n=102), injectables (n=20) and implants (n=3) were detected at enrollment, with 7 women likely using >1 contraceptive. In-depth interviews revealed that participants understood the requirement to be hormone free at enrollment (100%). Most (85%) cited partner noncooperation with condoms/withdrawal and/or pregnancy concerns as major reasons for nondisclosed contraceptive use. All interviewed women (100%) cited access to health care as a primary motivation for study participation. Of participants who accurately reported nonuse of hormonal contraception at enrollment, 41/327 (12.5%) had objective evidence of nonstudy progestin use at follow-up that disagreed with self-reported nonuse. ConclusionsWomen joining contraceptive research studies may misrepresent their use of nonstudy contraceptive hormones at baseline and follow-up. Objective measures of hormone use are needed to ensure that study population exposures are accurately categorized. Implications statementAmong Zimbabwean women participating in a contraceptive research study, 27% had objective evidence of use of nonstudy contraceptives at enrollment that disagreed with self-report. Studies that rely on self-report to identify contraceptive hormone exposure could suffer from significant misclassification.
Highlights
Clinical research investigators traditionally rely on participant self-report for important variables including last menstrual period (LMP) and contraceptive use
Overall, enrolled participants who accurately reported compared to misreported contraceptive use at enrollment did not differ on any demographic or sexual behavioral feature (Table 1) except that a greater proportion of women misreporting hormonal status at enrollment reported oral contraceptive pill use at screening compared to evaluable enrollees (79.2% vs. 66.4%, p=.01)
We found frequent discrepancies between self-reported and measured serum contraceptive hormone use
Summary
Clinical research investigators traditionally rely on participant self-report for important variables including last menstrual period (LMP) and contraceptive use. Research to validate self-reported contraceptive use is limited [20]. Studies assessing use of hormonal contraception and HIV acquisition risk show mixed outcome data [19]. In order to untangle possible biological links between hormonal status and risk of acquiring sexually transmitted infections (STIs) and HIV, there is a need to understand if self-reported variables are adequate for cohort assignment. We hypothesized that self-reported contraceptive use by clinical research participants may disagree with objectively measured hormonal status. In order to assess accuracy of self-reported LMP and contraceptive use, we compared laboratory evaluation of serum progestogens and estrogens to participant self-report. We explored reasons for misreporting in a subset of participants with discrepant self-reported and measured serum hormone data
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