Background/Purpose The introduction of biologics has greatly changed the treatment of psoriatic arthritis (PsA) and psoriasis (PsO). However, there are concerns regarding the risk of malignancy associated biologic medications. This analysis evaluated the association between malignancy and biologics among US patients with PsA or PsO enrolled in the Medicare program

Methods

Using data from 2006-2011 for 100% of patients with patients with PsA and PsO, we defined separate PsA and PsO cohorts based upon >= 1  rheumatologist visit for PsA or >= 1 dermatologist visit for PsO, followed by a prescription or administration of etanercept (ETA), adalimumab (ADA), ustekinumab (UST), methotrexate (MTX), cyclosporine (CIC) or ultraviolet light therapy (UV). Patients could be in both cohorts if they meet criteria for each cohort. We identified new treatment episodes, defined specific to each drug as no use of that therapy in the prior 6 month ‘baseline’ period. Patients contributing treatment episodes with history of organ transplantation, infection with human immunodeficiency virus, advanced kidney (hemodialysis-dependent), severe liver disease, or cancer diagnoses were excluded. Eligible subjects were continuously enrolled in Medicare Parts A, B and D in baseline and throughout follow-up. We excluded treatment episodes of UV if patients were on biologics or DMARDS at baseline, and episodes of non-biologic therapy if patients were on biologics during the baseline. Follow up started from the drug initiation date and ended at the earliest date of: malignancy (exclude non-melanoma skin cancer), a 90 day gap in current exposure, death, loss of coverage or Dec 31, 2011. We identified malignancy using validated claims-based algorithm using physician diagnoses (ICD9 140-208, except 173.x), cancer-related procedures and chemotherapy. We calculated the incidence rate (IR) of malignancy for each exposure. Using pairwise propensity scores (PS) to balance multiple confounders, we compared malignancy risk using Cox regression, adjusting for PS quintile.

Results We identified 10,261 PsA and 31,052 PsO new treatments episodes. For the PsA cohort, 50% of treatment-episode exposure time was in common with the PsO, and 20% of PsO exposure time was in common with PsA exposures. During follow up, patients in the PsA cohort experienced 13 (ADA), <11 (CIC), 10 (ETA), 50 (MTX), <11 (UV) malignancies, the PsO cohort experienced 29 (ADA), 26 (CIC), 28 (ETA), 123 (MTX), 64 (UV) malignancies.  The overall IR in PsA was 8.1/1000, ranging from a low of 4.2 (UV) to a high of 11.3 (MTX). None of the hazard ratios for comparisons between biologic and non-biologic exposure groups reached statistical significance. The overall IR in the PsO cohort was 9.2/1000 ranging from 5.0(ETA) to 12.9 (CIC).  After multivariable adjustment, there was a significantly lower risk for ETA compared to non-biologic therapies: ETA versus CIC (HR: 0.50 95% CI: 0.27-0.93), ETA versus MTX (HR: 0.56 95% CI: 0.35-0.87), ETA versus UV (HR: 0.49 95% CI: 0.29-0.83).

Conclusion

Among older patients with psoriasis and psoriatic arthritis, there was no evidence of an increased risk of malignancy for patients treated with biologics compared to non-biologic therapies, and some possibility of a reduced risk.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/risk-of-malignancy-among-medicare-psoriasispsoriasis-arthritis-patients/