Given the scarcity of systematic assessments of mortality among sexual minority populations,1 we were eager to review results from the linked General Social Survey-National Death Index (GSS-NDI) data set,2 recently published in the Journal.3 Unfortunately, the distribution of HIV deaths presented in these data are inconsistent with the epidemiology of HIV. For this reason, we believe a more detailed examination of potential biases is required.
The authors report a total of 49 HIV-related deaths among the 7880 men included in the study, only 5 of which occurred among men who reported having sex with men (MSM; estimated by multiplying n = 424 by 1.2%). This proportionate divide in HIV mortality—with only 10% of deaths occurring among MSM—is incompatible with the burden of HIV disease in the United States. Continuously collected surveillance data demonstrate that 64% of men living with HIV are MSM.4 Given that prospective studies show no significant difference in life expectancy postdiagnosis between exposure categories,5 it is implausible that so few HIV deaths in the GSS-NDI cohort would occur in MSM. A further indication of bias is that only 1 HIV death among MSM occurred before 1996, after which HIV-related mortality decreased precipitously in the United States.6
Possible explanations for these discrepancies are misclassification of sexual behavior or undersampling of MSM, both of which merit more fulsome discussion. Same-gender sexual contact is stigmatized and therefore underreported in population-based surveys such as the GSS.7 The degree of this misclassification is not well described, though in a recent Canadian survey of 8382 community-recruited MSM, 30% indicated they would be unwilling to disclose their sexual orientation to a government interviewer (Community-Based Research Centre for Gay Men’s Health, unpublished data, 2014). If the misclassification is nondifferential (unrelated to cause of death), then underreporting of same-gender sexual activity would have a tendency to bias comparative effects—including the hazard ratios in Cochran and Mays’ Table 2—toward the null.8 HIV-related mortality may alternatively be underestimated in MSM if HIV status was negatively associated with disclosure of same-gender sex—perhaps because of additional stigma faced by HIV-positive men—or if HIV-positive MSM were less likely to participate in the survey.
Similar concerns relate to the low rate of suicide mortality among MSM in the study.3 This finding is inconsistent with the epidemiology of suicide attempts, which are consistently elevated among sexual minority men in numerous other studies.9 Further research is needed to evaluate the effects of both misclassification and selection biases on sexual minority health findings derived from broad population-based surveys.
References
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