Long-term assessment of fatigue in patients with culture-confirmed Lyme disease.

BACKGROUND

Fatigue is a common symptom with numerous causes. Severe fatigue is thought to be an important manifestation of post-treatment Lyme disease syndrome. The frequency with which severe fatigue occurs as a long-term sequela in prospectively followed patients with Lyme disease is unknown.

METHODS

Patients with culture-confirmed Lyme disease who originally presented with erythema migrans have been evaluated annually in a prospective study to determine their long-term outcome. In 2011-2013, subjects were evaluated for fatigue using an 11-item Fatigue Severity Scale (FSS-11) that has been used in studies of post-treatment Lyme disease syndrome. An FSS-11 score of ≥4.0 is indicative of severe fatigue.

RESULTS

A total of 100 subjects were assessed, 52% of whom were male; the mean age was 64.9 years (range, 42-86 years). The mean duration of follow-up was 15.4 years (range, 11-20 years). Nine subjects had severe fatigue but in none as a consequence of Lyme disease. Only 3 subjects were thought to possibly have persistent fatigue from Lyme disease. The FSS-11 value for these 3 individuals was less than 4, averaging 2.27, and none had functional impairment.

CONCLUSIONS

Severe fatigue was found in 9 patients (9%) with culture-confirmed early Lyme disease at 11 to 20 years after presentation, but was due to causes other than Lyme disease. Fatigue of lesser severity was possibly due to Lyme disease, but was found in only 3% of 100 patients, and therefore is rarely a long-term complication of this infection.