The risk of acute infections in new users of antidepressants: An observational cohort study

Preclinical studies suggested that drugs that functionally inhibit acid sphingomyelinase (FIASMA)may enhance immune cell longevity and potentially offer protection against infections. Many antidepressants have shown FIASMA activity.

We conducted a cohort study using primary-care data from the UK-based Clinical Practice Research Datalink (2000-2021). We assessed the association of composite diagnosed acute infections in new users of fluoxetine, sertraline, paroxetine, or venlafaxine aged 18-80 years compared to citalopram. We compared SARS-CoV-2 infections between groups in a secondary analysis. We estimated incidence rates (IR) and IR ratios (IRR) of acute infections in four pairwise comparisons using negative binomial regression. We applied propensity score (PS) fine stratification to control for confounding.

In the PS-weighted cohorts, we included 353,138 fluoxetine, 222,463 sertraline, 69,963 paroxetine, 32,608 venlafaxine, and between 515,996 and 516,583 new citalopram users. PS-weighted IRs ranged between 76.8 acute infections /1000 person-years (py) (sertraline) and 98.9 infections/1000 py (citalopram). We observed PS-weighted IRRs around unity for paroxetine (0.97, 95 % CI, 0.95-1.00), fluoxetine (0.94, 95 % CI, 0.92-0.95), and venlafaxine (0.90, 95 % CI, 0.87-0.94) vs citalopram. Reduced IRR for sertraline vs citalopram (0.84, 95 % CI, 0.82-0.85), became null within subgroups by cohort entry date. In the analysis of SARS-CoV-2 infection, no statistically relevant risk reduction was seen.

Analysis not limited to patients with diagnosed depression, possible underestimation of infection incidence, and unclear FIASMA activity of citalopram.

Fluoxetine, sertraline, paroxetine, and venlafaxine were not associated with a reduced risk of acute infection when compared with the presumably weak FIASMA citalopram.