Treatment of Erythema Migrans With Doxycycline for 10 Days Versus 15 Days

BACKGROUND: The efficacy of 10-day doxycycline treatment in patients with erythema migrans has been assessed in the United States but not in Europe. Experts disagree on the significance of post-Lyme borreliosis symptoms. METHODS: In a noninferiority trial, the efficacies of 10 days and 15 days of oral doxycycline therapy were evaluated in adult European patients with erythema migrans. The prevalence of nonspecific symptoms was compared between patients with erythema migrans and 81 control subjects without a history of Lyme borreliosis. The efficacy of treatment, determined on the basis of clinical observations and microbiologic tests, was assessed at 14 days and at 2, 6, and 12 months. Nonspecific symptoms in patients and controls were compared at 6 months after enrollment. RESULTS: A total of 117 patients (52%) were treated with doxycycline for 15 days, and 108 (48%) received doxycycline for 10 days. Twelve months after enrollment, 85 of 91 patients (93.4%) in the 15-day group and 79 of 86 (91.9%) in the 10-day group had complete response (difference, 1.6 percentage points; upper limit of the 95% confidence interval, 9.1 percentage points). At 6 months, the frequency of nonspecific symptoms in the patients was similar to that among controls. CONCLUSIONS: The 10-day regimen of oral doxycycline was not inferior to the 15-day regimen among adult European patients with solitary erythema migrans. Six months after treatment, the frequency of nonspecific symptoms among erythema migrans patients was similar to that among control subjects. CLINICAL TRIALS REGISTRATION: NCT00910715.