Prescription of antimicrobials in primary health care as a marker to identify people living with undiagnosed HIV infection, Denmark, 1998 to 2016

BACKGROUND: Development of additional diagnostic strategies for earlier HIV diagnosis are needed as approximately 50% of newly diagnosed HIV-infected individuals continue to present late for HIV care. AIM: We aimed to analyse antimicrobial consumption in the 3 years preceding HIV diagnosis, assess whether there was a higher consumption in those diagnosed with HIV compared with matched controls and whether the level of consumption was associated with the risk of HIV infection. METHODS: We conducted a nested case–control study, identifying all individuals (n = 2,784 cases) diagnosed with HIV in Denmark from 1998 to 2016 and 13 age-and sex-matched population controls per case (n = 36,192 controls) from national registers. Antimicrobial drug consumption was estimated as defined daily doses per person-year. We used conditional logistic regression to compute odds ratios and 95% confidence intervals. RESULTS: In the 3 years preceding an HIV diagnosis, we observed more frequent and higher consumption of antimicrobial drugs in cases compared with controls, with 72.4% vs 46.3% having had at least one prescription (p < 0.001). For all antimicrobial classes, the association between consumption and risk of subsequent HIV diagnosis was statistically significant (p < 0.01). The association was stronger with higher consumption and with shorter time to HIV diagnosis. CONCLUSION: HIV-infected individuals have a significantly higher use of antimicrobial drugs in the 3 years preceding HIV diagnosis than controls. Prescription of antimicrobial drugs in primary healthcare could be an opportunity to consider proactive HIV testing. Further studies need to identify optimal prescription cut-offs that could endorse its inclusion in public health policies.