Costs of illness progression for different multiple sclerosis phenotypes: a population-based study in Sweden

BACKGROUND: Little is known of how the cost of illness and health-related quality of life changes over time after a diagnosis of multiple sclerosis. OBJECTIVES: The aim was thus to explore the progression of annual direct and indirect costs and health-related quality of life among people with multiple sclerosis of working ages, following diagnosis with relapsing–remitting multiple sclerosis (RRMS), primary progressive multiple sclerosis (PPMS) or conversion to secondary progressive multiple sclerosis (SPMS) after RRMS. METHODS: Swedish nationwide registers were linked to estimate the annual cost of illness in 2006–2013 among people with a registered new multiple sclerosis phenotype, including: direct costs, indirect costs, and health-related quality of life. RESULTS: Drugs and indirect costs for sick leave were the main cost drivers after diagnosis with RRMS. After conversion to SPMS, the RRMS cost drivers were replaced by indirect costs for disability pension. The main cost driver in newly diagnosed PPMS was indirect costs for sick leave, later replaced by disability pension. Health-related quality of life scores were similar after RRMS and SPMS. CONCLUSIONS: After initial high indirect costs for sick leave, people with RRMS had higher drug costs compared to people with PPMS. Cost drivers during SPMS initially followed the pattern in the RRMS population, but were replaced by indirect costs for disability pension.