INTRODUCTION: Lyme disease (Lyme borreliosis) is caused by the tick-borne spirochete Borrelia burgdorferi. Long-term persistent illness following antibiotic treatment is not uncommon, particularly when treatment is delayed. Current treatment guidelines for persistent disease primarily rely on findings from four randomized, controlled trials (RCTs), strongly advising against retreatment.
METHODS: We performed a biostatistical review of all published RCTs evaluating antibiotic retreatment, focusing on trial design, analysis and conclusions.
RESULTS: Four RCTs met the inclusion criteria; all examined the efficacy of intravenous ceftriaxone versus placebo at approximately 3 or 6 months. Design assumptions for the primary outcomes in the two Klempner trials and two outcomes in the Krupp trial were unrealistic and the trials were likely underpowered to detect clinically meaningful treatment effects. The Klempner trials were analyzed using inefficient statistical methods. The Krupp RCT was well-designed and analyzed for fatigue, finding statistically significant and clinically meaningful improvement. Fallon corroborated this finding. Fallon also found improvement in cognitive functioning, a primary outcome, at 12 weeks which was not sustained at 24 weeks; improvements in physical functioning and pain were demonstrated at week 24 as an interaction effect between treatment and baseline symptom severity with the drug effect increasing with higher baseline impairment.
DISCUSSION: This biostatistical review reveals that retreatment can be beneficial. Primary outcomes originally reported as statistically insignificant were likely underpowered. The positive treatment effects of ceftriaxone are encouraging and consistent with continued infection, a hypothesis deserving additional study. Additional studies of persistent infection and antibiotic treatment are warranted.