Fatigue is a common symptom in multiple sclerosis (MS) and is an important determinant of overall well-being and disability.

To assess the frequency with which fatigue precedes the diagnosis of MS using a retrospective database analysis.

Between January 1, 2003 and September 30, 2008, patients diagnosed with fatigue with and without fatigue-related medications within a 3-year period prior to newly diagnosed MS were identified from the MarketScan Databases. All statistical analysis was performed using SAS.

Of the 16,976 patients with MS in the overall population, 5305 (31.3%) were newly diagnosed with MS and had three years of continuous healthcare coverage prior to MS diagnosis. Of these patients, 1534 (28.9%) were labeled with chronic fatigue syndrome (ICD9-780.71) or malaise or fatigue (ICD9-780.79) prior to the diagnosis of MS. One-third of these patients were labeled with fatigue one to two years before the diagnosis; 30.8% were diagnosed only with fatigue and had no other MS symptoms prior to their MS diagnosis. Among the patients diagnosed with fatigue, 10.4% were also prescribed medication for fatigue.

This study demonstrates that fatigue may herald MS, often by years. A careful history for transient neurological symptoms and a physical examination is warranted in any patient presenting with fatigue.