Introduction Chronic lung disease is common among people living with HIV (PLWH). We hypothesised that PLWH receiving antiretroviral therapy (ART) have faster lung function decline than matched controls.

Methods We performed a prospective matched cohort study by including ART-treated PLWH from the Copenhagen Co-morbidity in HIV Infection Study (n=705) and the INSIGHT Strategic Timing of Antiretroviral Treatment Pulmonary Substudy (n=425) and frequency matched population controls from the Copenhagen General Population Study (n=2895) in a 1:3 ratio. Eligible participants were >= 25 years old and had two spirometry tests separated by at least 2 years of follow-up. Forced expiratory volume in 1 s (FEV1) decline (mL/year) was compared between PLWH and controls using a linear mixed model adjusted for age, sex, ethnicity and smoking status. Effect modification by smoking was investigated in subgroup analyses.

Results The majority of PLWH were virally suppressed (96.1%). The adjusted mean annual decline in FEV1 was faster in PLWH than in controls with 36.4 (95% CI 33.7 to 39.1) vs 27.9 (95% CI 26.9 to 28.8) mL/year, yielding a difference of 8.5 (95% CI 5.6 to 11.4) mL/year. The association between HIV and FEV1 decline was modified by smoking, with the largest difference in current smokers (difference: 16.8 (95% CI 10.5 to 23.0) mL/year) and the smallest difference in never-smokers (difference: 5.0 (95% CI 0.7 to 9.3) mL/year). FEV1 decline >40 mL/year was more prevalent in PLWH (adjusted OR: 1.98 (95% CI 1.67 to 2.34)).

Conclusion Well-treated PLWH have faster lung function decline than controls and smoking seems to modify this association, suggesting that smoking may lead to more rapid lung function decline in PLWH than in controls.