The risk of malignancy among biologic-naïve pediatric psoriasis patients: A retrospective cohort study in a US claims database

Background Little published literature exists regarding malignancy risk in pediatric psoriasis patients. Objective To compare malignancy risk in biologic-naïve pediatric psoriasis patients with a matched pediatric population without psoriasis. Methods This retrospective cohort study used IMS LifeLink Health Plan Claims data covering 1998-2008. Cancer incidence was compared with the US Surveillance, Epidemiology, and End Results (SEER) data using standardized incidence ratios (SIR), and between cohorts using Cox models. Results Among 9045 pediatric psoriasis patients and 77,206 comparators, 18 probable or highly probable cancers were identified. Pediatric psoriasis patients had a nonsignificantly lower incidence than comparators (hazard ratio [HR] 0.43, 95% confidence interval [CI] 0.05-3.54). The HR increased to 1.67 (95% CI 0.54-5.18) when cancer diagnosed during the first 90 days of follow-up was included. The pediatric psoriasis cohort had a significantly increased lymphoma rate compared with SEER (SIR 5.42, 95% CI 1.62-12.94), but no significant increase relative to the comparator cohort. Limitations Misclassification of disease and outcome might have occurred with patients in the claims database. Conclusion Patients with pediatric psoriasis showed no significant increase in overall cancer risk compared with those without psoriasis. A potential increased risk for lymphoma was observed when compared with the general population.