RESUMEN
BACKGROUND: People with HIV (PWH) smoke tobacco at much higher rates than the general population. Previous research has shown that PWH have faster nicotine metabolism than HIV-uninfected individuals, which may underlie this disparity, but the cause is unknown. We investigated whether higher nicotine metabolite ratio (NMR; 3-hydroxycotinine:cotinine), a validated biomarker of nicotine metabolism through CYP2A6, was associated with antiretroviral use among HIV-infected smokers. METHODS: We conducted a retrospective cohort study of HIV-positive smokers in the University of Pennsylvania Center for AIDS Research cohort. We compared the NMR before viral suppression (>10,000 copies/mL) and after viral suppression on antiretroviral therapy (<200 copies/mL). We used mixed-effects linear regression to analyze the change in NMR after viral suppression and assessed for effect modification by efavirenz use. RESULTS: Eighty-nine individuals were included in the study. We observed effect modification by efavirenz use (interaction term for efavirenz use, P < 0.001). Among those on nonefavirenz regimens, the mean NMR increased by 0.14 (95% confidence interval: 0.05 to 0.23, P = 0.002). Among those on efavirenz-containing regimens, the mean NMR increased by 0.53 (95% confidence interval: 0.39-0.66, P < 0.001). CONCLUSIONS: We observed a clinically and statistically significant increase in NMR after viral suppression among smokers with HIV, which more than doubled among those on efavirenz-based regimens. Higher NMR among HIV-positive smokers on antiretroviral therapy may help explain the higher rates of tobacco use and lower quit rates among PWH in care. These findings suggest that regimen choice and other modifiable factors may be targets for future attempts to increase success rates for tobacco cessation among PWH.