Cost of illness in inclusion body myositis: results from a cross-sectional study in Germany

Background: Inclusion body myositis (IBM) is the most frequent type of myositis in elder patients with a slow chronic progression and refractory to treatment. Previous cost of illness (COI) studies in IBM used claims data to estimate direct costs in the US. No evidence exists globally on both direct and indirect costs in IBM from a societal perspective. We conducted a survey in patients registered in the German IBM patient registry. Self-developed items were used to assess the utilized healthcare resources and estimate the cost. The German Self-Administered Comorbidity Questionnaire (SCQ-D), the sIBM Physical Functioning Assessment (sIFA) and patient-reported measures for satisfaction and improvements in healthcare were applied for an explorative analysis.

Results: In total, 82 patients completed the survey. We estimated the mean total annual per capita COI of US$102,682 (95% CI US$82,763-US$123,090) in 2021. 92.7% of the total COI were direct costs. Medical costs were similar to nonmedical costs, with substantial costs for pharmacotherapy and informal care. Depending on the prevalence estimate, the total national COI per year were US$42.7 million-US$213.7 million. Significant differences in total COI were identified for the degree of disability, marital and employment status (p < 0.05).

Conclusions: We identified remarkable and heterogenous cost in IBM. As informal care costs represented the most relevant cost driver, caregiver burden is a major factor in the patient journey. For the first time, comprehensive economic potentials were identified as a basis to improve the actual care situations and prioritizing future activities for research, pharmaceutical and digital product development as well as health politics.