PT - JOURNAL ARTICLE AU - Tabor, Evangeline AU - Kneale, Dylan AU - Patalay, Praveetha TI - P47 Measurement of sexual orientation and its impact on sample size and demographic and health outcomes in two UK cohort studies AID - 10.1136/jech-2022-SSMabstracts.141 DP - 2022 Aug 01 TA - Journal of Epidemiology and Community Health PG - A68--A68 VI - 76 IP - Suppl 1 4099 - http://jech.bmj.com/content/76/Suppl_1/A68.1.short 4100 - http://jech.bmj.com/content/76/Suppl_1/A68.1.full SO - J Epidemiol Community Health2022 Aug 01; 76 AB - Background Sexual orientation has been measured in a wide variety of ways which reflect both theoretical and practical considerations. However, choice of sexual orientation measure and data handling can impact sample size, as well as estimates of demographic and health outcomes, in analyses of the sexual minority population. We aimed to explore how choice of sexual orientation dimension and data handling decisions impact estimated outcomes in the sexual minority population in two longitudinal cohort studies in the UK.Methods We used data collected at age 17 in the UK Millennium Cohort Study and at wave six (2012–13) and eight (2017–18) of the English Longitudinal Study of Ageing. Descriptive statistics were used to examine the impact of researcher choice of sexual orientation dimension (identity, attraction and/or experience) and data recoding strategy on achieved sample size. In addition, we examined variation in selected demographic and health outcomes (i.e. gender, ethnicity, socioeconomic status, self-rated health, life satisfaction, and psychological distress) by dimension and recoding choice within and between datasets.Results Dimension choice and recoding decisions resulted in variation in sample size, distributions of demographic characteristics, and health outcomes by sexual orientation. For example, in both datasets more respondents reported some same-sex sexual attraction or experience than reported a non-heterosexual identity. However, we did observe differences between datasets. For example, MCS respondents (N=10,103) were more likely to report a non-heterosexual orientation than ELSA respondents (N=4,776). Demographic outcomes did not vary substantially by dimension choice or data handling. For example, in both datasets sexual minority respondents were more likely to be women, white and in the highest quintiles for income and education than their heterosexual peers. Health outcomes did not vary substantially by dimension choice or data handling, but in both datasets sexual minority respondents reported poorer health outcomes than their heterosexual peers.Conclusion This analysis explores a range of practical and theoretical considerations researchers may wish to weigh up when analysing sexual minority respondents using survey data. In particular, we highlight the impact data handling decisions may have on sample size, and demographic and health outcomes in this understudied population.