Estimating direct medical costs and their variation across heterogeneous Multiple Sclerosis (MS) patients in the Veterans Health Administration (VHA)

Background: Multiple Sclerosis (MS) is one of the most common diseases of the central nervous system. Previous studies have shown the cost of MS to be significantly higher than many other chronic conditions and estimated that non-VHA MS patients had a mean annual all cause health care cost of $18,829 and MS related cost of $8,839.1,2 The incremental cost of MS and factors that influence total direct medical cost among MS patients in the VHA have not been previously studied. Objective: Estimate the annual incremental direct medical cost of MS as well as the marginal effect of demographic and clinical factors on the total direct medical cost of MS in the VHA during fiscal year 2009. Methods: This study consisted of two aims based upon a one year cross sectional, retrospective matched control design and a generalized linear model using a VHA registry of MS patients. Results: MS cases had a higher mean annual prescription cost than the controls ($4,885 vs $1,445), a higher mean annual cost for outpatient encounters than the controls ($5,417 vs $4,408), a higher mean annual inpatient stay cost than the controls ($32,305 vs $25,703), and had a higher mean total cost than the controls ($14,800 vs $7,381). The mean annual incremental costs for an MS patient were $ 3,254 for prescriptions, $1,168 for outpatient encounters, $12,596 for inpatient stays, which resulted in a total annual incremental cost of MS of $7,419. Individual factors associated with a positive marginal effect on the annual total direct medical cost for an individual with MS included: progressive form of MS; higher Elixhauser Conditions Score; current use of disease modifying therapy medication; and race. Level of self-reported MS related disability and educational attainment, age, age at onset, duration of MS since onset, and gender did not influence the annual total direct medical cost of MS. Conclusions: Direct medical costs were significantly higher for MS cases than for controls in the VHA and were consistent with costs seen outside the VHA. Demographic and clinical factors were shown to be significant predictors of direct medical costs