The impact of comorbidities on interleukin-17 inhibitor therapy in psoriatic arthritis: a Danish population-based cohort study

Abstract Objective To investigate the influence of comorbidities on treatment response, disease activity and persistence with first-line IL-17 inhibitor (IL-17i) treatment in patients with PsA. Methods Patients were divided into three groups depending on the presence and/or severity of comorbidities using the Charlson Comorbidity Index (CCI). Groups were CCI 0: no comorbidities, CCI 1: one comorbidity and CCI ≥2: two or more comorbidities or one or more severe comorbidities. Outcomes in the groups were compared for treatment persistence, treatment response and disease activity. Results A higher CCI score was associated to an elevation in baseline CRP, swollen joint count and frequency of depression and/or anxiety. The median drug persistence in the groups were CCI 0: 1.8 years, CCI 1: 1.9 years and CCI ≥2: 1.5 years, but was not statistically significant to the CCI score. There were no significant differences in clinical response rates between the groups. Conclusion The presence of comorbidities was associated with increased baseline disease activity and frequency of depression and/or anxiety, but was not associated with shorter treatment persistence or lower clinical response rates in a cohort of 155 Danish patients with PsA treated with first-line IL-17i. Lay Summary What does this mean for patients? Choosing the right biologic treatment for people with PsA can be problematic. It is not unusual for these patients to shuffle between multiple treatments before a satisfactory treatment is found. The first-line biologic treatment for people with PsA is usually a TNF inhibitor (TNFi). However, TNFis have been shown to be less effective in those with comorbidities (i.e. people with two or more simultaneous medical conditions) compared with those without. People with comorbidities are also less likely to continue to take the TNFi for the prescribed period of time. Since >50% of people with PsA have one or several comorbidities, we wondered if IL-17 inhibitors (IL-17is; another type of biologic drug) act in this same manner. We studied 155 people with PsA treated with IL-17is and found that, unlike TNFis, IL-17is were not less effective in people with comorbidities. Likewise, people with comorbidities were not more likely to discontinue treatment with IL-17is than those without comorbidities. Because we investigated a small group of patients, these results must be reproduced in larger groups. However, we think that these results are novel and could be an importa