Rituximab for Pemphigus Linked to Higher Risk for COVID-19, CMV, Parasitic Infections

Patients with pemphigus who received rituximab were found to be at increased risk for COVID-19, parasitic, and cytomegalovirus (CMV) infections compared with those who received first-line corticosteroid-sparing agents. These study results were published in the British Journal of Dermatology.

A global, population-based retrospective cohort study was performed between 2010 and 2022. Researchers evaluated the risk for 26 different infections among patients with pemphigus who received rituximab compared with those who received first-line corticosteroid-sparing agents, including azathioprine and mycophenolate mofetil. Propensity-score matching was performed to balance the treatment groups, with patients matched by demographic variables and comorbidities at baseline. The risk for infection was estimated at several time intervals following treatment initiation (<6 months, 6-12 months, <12 months, and ≥12 months). The Kaplan-Meier method was used to perform survival analyses, and Cox regression was used to assess the risk for infection.

Among patients in groups 1 (n=963) and 2 (n=963), the mean age was 56.5 and 55.7 years, 52.6% and 53.7% were women, and 57.6% and 55.0% were White, respectively. The mean follow-up duration for both groups was 4.4 years.

Compared with patients in group 2, those who received rituximab had an increased risk for COVID-19 (hazard ratio [HR], 1.82; 95% CI, 1.06-3.14; P =.028), parasitic (HR, 3.22; 95% CI, 1.04-9.97; P =.032), and CMV infections (HR, 1.63; 95% CI, 1.04-2.58; P =.033).

Addition comparisons showed receipt of rituximab was significantly associated with a greater risk for sepsis (HR, 1.63; 95% CI, 1.01-2.63; P =.042) and parasitic diseases (HR, 4.69; 10 95% CI, 1.01-21.73; P =.029) within the first 6 months after treatment initiation. However, this association was not significant when assessed between months 6 and 12.

Further evaluation of patients who received rituximab at 1 year indicated an increased risk for infection with COVID-19 (HR, 1.87; 95% CI, 1.49-2.33; P <.001), herpes simplex virus (HR, 2.06; 95% CI, 1.03-4.11; P =.037), and CMV (HR, 1.63; 95% CI, 1.07-2.49; P =.023).

Limitations of this study include potential misdiagnosis, misclassification, and residual confounding. Infection severity also was not assessed.

According to the researchers, “Patients with pemphigus prescribed rituximab ought to be carefully monitored for fever, should adhere to social distancing, and avoid traveling to endemic regions in the initial months after infusion.”