Methodologic concerns in defining lesbian for health research.

A recent report from the Institute of Medicine recommends more methodologic and substantive research on the health of lesbians. This study addresses one methodologic topic identified in the Institute of Medicine report and by a subsequent scientific workshop on lesbian health: the definition and assessment of sexual orientation among women. Data are from the Women Physicians' Health Study, a questionnaire-based U.S. probability sample survey (N = 4,501). The two items on sexual orientation (current self-identity and current sexual behavior) had a high response rate (96%), and cross-tabulation of responses indicated several combinations of identity and behavior. Three conceptually different definitions of "lesbian" are compared on the basis of (1) identity only, (2) sexual behavior only, and (3) both identity and sexual behavior. Suggestions and cautions are given to researchers who will add items on sexual orientation to new or ongoing research on women's health.