Similarly, moderate drug use was significantly associated with having an HIV positive serostatus, such that 35% of moderate substance users reported being HIV+, as compared to 15% of heavy users, 10% of light users, and 9% of non-users. Similar findings were noted for younger MSM in the sample. Although it may be expected that the heaviest drug users would be more likely to engage in risky sex, the authors propose one possible explanation for the findings.