OBJECTIVES: The aims of this study were to estimate the effects of demographics, location, severity of multiple sclerosis (MS), comorbidities, plan type, coinsurance levels, and time of entry into the sample on the use of disease-modifying agents.
METHODS: A retrospective analysis of medical claims data from 1996 through 2000 was conducted with a sample of MS patients covered by self-insured, employer-sponsored health plans. Proportional hazard analysis with the SAS procedure for proportional hazards regression was used to estimate the impact of the factors of interest on the use of disease-modifying agents. A simulation was conducted to assess the impact of changing drug copayments on the use of disease-modifying agents for MS.
RESULTS: The sample included 1807 patients. Patients were followed for as long as possible, but most were observed for <3 years; the mean (SD) follow-up time was 972.88 (440.59) days. Most factors associated with the use of disease-modifying agents were immutable. They included the following: high severity of illness (only marginally related; P = NS); history of seizures (P = 0.03), depression (P < 0.01), or heart disease (P = 0.01); census region of location (P < 0.01); union membership or association with a union member (P < 0.01); drug copayment requirements (P < 0.05); and year of entry into the sample (P < 0.01). In the simulation, a 50% reduction in drug copayments was associated with an increase of the proportion of patients treated with disease-modifying drugs from 41.2% to 54.7%. Patients' and physicians' preferences for treatment could not be measured directly. The true onset of MS may be unknown for many patients, but this would be the case even if medical records or other data were used for this study.
CONCLUSIONS: Our analyses showed an association between copayments and the use of disease-modifying drugs for MS. Insurance policies can be tailored to influence the use of disease-modifying drugs, enhancing the quality of care for MS patients and reducing price-related barriers to beneficial treatment. Future research should test whether reducing copayments for MS treatment would reduce the use of other health care services (via better MS treatment that modifies the course of illness), or whether the use of disease-modifying drugs would increase total costs to the plan, resulting in slightly higher premiums.
