Objectives: To compare the characteristics of a self-selected, convenience sample of men who have sex with men (MSM) recruited through the internet with MSM drawn from a national probability survey in Great Britain.
Methods: The internet sample (n = 2065) was recruited through two popular websites for homosexual men in Great Britain in May and June 2003. This sample was compared with MSM (n = 117) from the National Survey of Sexual Attitudes and Lifestyles (Natsal), a probability sample survey of adults resident in Great Britain conducted between May 1999 and February 2001.
Results: No significant differences were observed between the samples on a range of sociodemographic and behavioural variables (p>0.05). However, men from the internet sample were younger (p<0.001) and more likely to be students (p = 0.001), but less likely to live in London (p = 0.001) or report good health (p = 0.014). Although both samples were equally likely to report testing for HIV, men from the internet sample were more likely to report a sexually transmitted infection in the past year (16.9% v 4.8%, adjusted odds ratio 4.14, 95% CI 1.76 to 9.74; p = 0.001), anal intercourse (76.9% v 63.3%; p = 0.001) and unprotected anal intercourse in the past 3 months (45% v 36.6%; p = 0.064).
Conclusions: The internet provides a means of recruiting a self-selected, convenience sample of MSM whose social and demographic characteristics are broadly similar to those of MSM drawn from a national probability survey. However, estimates of high-risk sexual behaviour based on internet convenience samples are likely to overestimate levels of sexual risk behaviour in the wider MSM population.
- aOR, adjusted odds ratio
- MSM, men who have sex with men
- Natsal, National Survey of Sexual Attitudes and Lifestyles
- STI, sexually transmitted infection
- UAI, unprotected anal intercourse
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Published Online First 29 November 2006
Funding: This research was funded by the Economic and Social Research Council. The “Internet and HIV” study was funded by the Medical Research Council (grant number GO 100 159). Natsal 2000 was supported by a grant from the Medical Research Council with funds from the Department of Health, the Scottish Executive and the National Assembly for Wales.
Competing interests: None declared.
Contributors: All authors contributed to the design of the study; ARE and CHM performed the statistical analysis with input from RDW; GJB was responsible for the implementation of the internet and HIV web survey with input from JE; ARE wrote the first draft and coordinated subsequent revisions; all authors read the manuscript, suggested revisions and approved the final version.
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