BMC Public Health 2006, 6:127 http://www.biomedcentral.com/1471-2458/6/127 bation, oral sex and sexual intercourse) in the last month and also enabled us to make a sexual dysfunction diagno- sis according to the 10th Edition of the International Clas- sification of Diseases [30] (lack/loss of sexual desire, sexual aversion, and dyspareunia in both sexes; arousal and orgasmic disorders and vaginismus in women and erectile and premature and retarded ejaculatory problems in men) and assessed their satisfaction with their sex life. 9. Total family practice consultations over the preceding two years were collected for those participants who allowed us access to their clinical records. Definition of sexual orientation and physical, psychological and sexual problems a) Sexual Orientation: There is still no universal agreement on how to define sexual orientation [31]. Thus we approached our analysis on the assumption that society is more accepting of people who report largely heterosexual, rather than largely homosexual, experiences. Hence we classified people responding to rating 1 on our sexual experiences scale as unequivocally heterosexual. Simi- larly, we assumed that participants who indicated their experiences had been largely heterosexual or equally het- erosexual and homosexual (ratings 2 to 4) were primarily identifying with heterosexuality (despite sexual experi- ences with both sexes) and classified them as bisexual. Finally we assumed that those who indicated that homo- sexual experiences were a large or entire part of their sex- ual lives (ratings 5 to 7) were likely to be primarily gay or lesbian and were classified accordingly. b) Poor physical function (quality of life) was defined as those scoring below the 25th centile of the physical func- tion subscale score of the short form12 questionnaire. c) Psychological distress The GHQ-12 provides a total score of 36, based on the Likert scoring of 0-1-2-3 or 12 based on a bi-modal (0-0-1-1). We used the latter as it is a more common scoring for psychological symptoms and defined those scoring three or more as likely to have sig- nificant psychological distress [20]. d) Problems with alcohol use were defined as those scoring two or more on the CAGE questionnaire. e) Current smokers were defined as those that admitted to being smokers at the time of interview. f) Sexual experiences in childhood were defined as unequiv- ocal in participants who gave affirmative answers to at least three of the four screening questions. g) Sexual function problems: were defined using responses from the brief sexual function questionnaires. In order to meet conservative criteria for a clinical ICD-10 diagnosis (F52.0 to F52.6) the problem needed to be present all or almost all of the time for each diagnosis [16]. However, to account for variation in sexual practices in same sex rela- tionships, we widened the sexual situations in which arousal and orgasmic disorders might occur to include masturbation and oral sex. As previously described [16], we examined any sexual problem reported without requir- ing that the participant have a sexual partner or report sex- ual intercourse in the preceding four weeks. h) Consultations: people were classed as high consulters if their total consultation rate over the previous two years exceeded the 75th centile for the study population. Analysis We examined the data using descriptive statistics. Differ- ences in the demographic, sexual activity, and health out- come data between gay/lesbian, bisexual and heterosexual classified people were examined using the Chi squared statistic for dichotomous and analysis of var- iance for continuous data. We then explored the influence of age, civil status, ethnicity and current employment on sexual orientation and the primary outcomes of interest. These were physical quality of life (as measured on SF-12) and psychological distress (on the GHQ-12), sexual func- tion, number of sexual partners in the previous month, childhood sexual experiences, CAGE scores, smoking sta- tus and consultation rates. Only civil status (married or living with a partner versus the remainder) and ethnicity (white versus non white) were found to be associated both with sexuality and the health outcomes at a signifi- cance level of 10% or less. Thus, we adjusted the analysis of each health factor against our classification of sexual orientation for each of these confounders by fitting logis- tic models and comparing their fit using the likelihood ratio. We report the p values to indicate whether the adjustments made a significant difference to the model. People in the heterosexual group were used as the index population on the grounds of their overwhelming major- ity. Each multivariate analysis was conducted separately for men and women. We analysed the data using SPSS ver- sion 10 and Stata version 7. Results Response rates and sexuality We approached 37 North London general practices situ- ated in areas of high, medium and low socio-economic deprivation. Thirteen practices (35%) with 55 doctors took part. We found no significant differences in Jarman's underprivileged area scores (that indicate the extent of socio-economic deprivation) between participating and non-participating practices. 1512 (71.6%) people (1065 women and 447 men) of the 2121 eligible general prac- tice attendees participated but only 771 women and 307 Page 3 of 12 (page number not for citation purposes)