Analysis of NAMCS data for multiple sclerosis, 1998-2004

Background: To our knowledge, no study to date has investigated the prescribing patterns of immunomodulatory agents (IMAs) in an outpatient setting in the United States. To address this issue, we performed retrospective data analyses on National Ambulatory Medical Care Survey (NAMCS) data for MS patient visits between 1998 and 2004. Methods: NAMCS data are a weighted estimate of the nationwide frequency of patients' outpatient clinic visits. We analyzed NAMCS data in the following categories: (1) the proportion of MS patient visits to neurologists, family practitioners or internists, (2) age/gender/race/geographical distribution patterns in patient visits, and (3) the proportion of patients on IMA treatment among established MS patients. Results: There were an estimated 6.7 million multiple sclerosis (MS) patient visits to the clinics between 1998-2004. Neurologists recorded the most patient visits, 50.7%. Patient visits were mostly in the fourth and fifth decade age group (57.9%). The male to female ratio was 1:4. No statistical evidence was observed for a decline or increase in IMA usage. About 62% patients visiting neurologists and 92% seen by family practitioners/ internists were not using IMAs. Our results suggest that between the years 1998-2003, the use of interferon-1a tended to decline while the use of interferon- 1b and glatiramer acetate, increased. Conclusion: Strategies that lead to improved use of IMAs in the management of MS in the outpatient setting are needed.