Risk of Serious Infection in Patients Receiving Systemic Medications for the Treatment of Psoriasis

Importance: There is a need for better understanding of the comparative safety of systemic medications used in the treatment of psoriasis.

Objective: To compare the risk of serious infection associated with biologic and nonbiologic systemic medications in patients with psoriasis.

Design, Setting, And Participants: An observational cohort study was conducted using medical and outpatient pharmacy claims from 2 large US health insurance claims databases from January 1, 2003, through September 30, 2015. We included patients with a diagnosis of psoriasis who were new users of systemic medications for psoriasis.

Exposures: Prescription claims for acitretin, adalimumab, apremilast, etanercept, infliximab, methotrexate, or ustekinumab.

Main Outcomes And Measures: The primary outcome was serious infection, defined by inpatient discharge diagnosis International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes. Cox proportional hazards regression was used to compare rates of serious infection for each exposure (acitretin, adalimumab, apremilast, etanercept, infliximab, and ustekinumab) with the referent group (methotrexate). We used pairwise 1:1 propensity score (PS) matching to adjust for potential confounders, which were assessed during a 180-day baseline period prior to study drug initiation. Results from the 2 databases were pooled via fixed-effects analysis.

Results: The databases included 31 595 patients in the Optum Clinformatics Data Mart and 76 112 patients in Truven MarketScan who were new users of acitretin, adalimumab, apremilast, etanercept, infliximab, methotrexate, and ustekinumab. Users of acitretin, apremilast, infliximab, and methotrexate were older and had higher baseline comorbidity scores than subcutaneous biologic users (adalimumab, etanercept, and ustekinumab). The pooled PS-matched analysis yielded a decreased rate of overall serious infection in users of apremilast (hazard ratio [HR], 0.50; 95% CI, 0.26-0.94), etanercept (HR, 0.75; 95% CI, 0.61-0.93), and ustekinumab (HR, 0.65; 95% CI, 0.47-0.89) compared with methotrexate. We did not find a different rate of overall serious infection among users of acitretin, adalimumab, and infliximab compared with methotrexate. Subanalysis by type of serious infection showed a significantly increased risk of cellulitis among users of acitretin compared with methotrexate (PS-adjusted HR, 1.76; 95% CI, 1.11-2.80).

Conclusions And Relevance: Among patients with psoriasis treated with systemic medications in 2 large US claims databases, new users of apremilast, etanercept, and ustekinumab had a decreased rate of serious infection compared with methotrexate.