Differentiating societal costs of disability worsening in multiple sclerosis

Background In multiple sclerosis (MS), confirmed disability progression (CDP) can be either the result of progression independent of relapse activity (PIRA) or relapse-associated worsening (RAW). However, the economic effect of PIRA and RAW on societal economic costs in patients with MS is not well understood. Objective To determine societal economic costs of patients achieving disease activity free status (DAF) and compare them with those having PIRA and RAW events. Methods We used a roving EDSS score analysis to detect PIRA and RAW events with confirmation after at least 6 months. We estimated the age-, gender-, EDSS-adjusted effects of PIRA and RAW on total, direct medical, direct non-medical and indirect societal economic costs. Patients achieving DAF were assigned to as reference. Results Overall, 1959 patients were analyzed. Total mean quarterly societal economic costs including disease-modifying therapies (DMTs) were 6929€ (SD: 2886€) per patient averaged over a period of 2 years. Excluding DMTs, patients achieving DAF had total mean quarterly costs of 1703€ (SD: 2489€). PIRA caused 29% (IRR: 1.29; CI 1.06–1.50, p  < 0.05) higher total costs compared to DAF. On the contrary, RAW increased total costs by factor 1.56 (CI 1.30–1.87, p  < 0.001). The effect of PIRA and RAW was striking for direct medical costs which increased by factor 1.48 (95% CI 1.13–1.95, p  < 0.01) and 2.25 (95% CI 1.72–2.94, p  < 0.001), respectively. Conclusion Disease progression increases societal economic costs significantly. Thus, delaying or even preventing disease progression in MS may reduce the societal economic burden of MS.