The aim of this study is analysis of time to relapse after discontinuation of biologic treatment and identification of factors associated with risk of relapse. The analysis used real-world data of 705 patients treated with biologic drugs (adalimumab [ADA], ustekinumab, infliximab, and etanercept) in Poland in 2013-2019. Time to relapse was analyzed by Kaplan-Meier estimator. Data was stratified by the number of prior relapses. Determinants of risk to relapse were analyzed with Prentice-Williams-Peterson model. Kaplan-Meier estimate of time to the first relapse was 276 days, to the second relapse was 246 days, to the third relapse was 218 days, and to the fourth relapse was 178 days. In multidimensional analysis statistically significant variables affecting risk of relapse were the following: biologic naivety (hazard ratio [HR] 0.707), ADA (HR 0.787), psoriasis area and severity index at the last follow-up visit (HR 1.049), abnormal hemoglobin level (HR 0.794), and abnormal lymphocyte counts (HR 1.278). The findings of this study suggest that periods to relapse after discontinuation of biologic drugs become shorter with the number of prior relapses experienced by the patient. Ninety-five percentage of observed relapses occurred within 613 days of the end of the first treatment cycle, within 478 of the second cycle and within 351 days of the third cycle.
Keywords: Kaplan-Meier curves; Prentice-Williams-Peterson model; biologic drugs; psoriasis; relapse.
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