Rationale: Although intermittent, three-times-weekly therapy is recommended for the initial treatment of noncavitary nodular bronchiectatic Mycobacterium avium complex (MAC) lung disease, supporting data are limited.
Objectives: To evaluate the clinical efficacy of intermittent therapy compared with daily therapy for nodular bronchiectatic MAC lung disease.
Methods: A retrospective cohort study of 217 patients with treatment-naive noncavitary nodular bronchiectatic MAC lung disease. All patients received either daily (n = 99) or intermittent therapy (n = 118) that included clarithromycin or azithromycin, rifampin, and ethambutol.
Measurements and main results: Modification of the initial antibiotic therapy occurred more frequently in the daily therapy group than in the intermittent therapy group (46 vs. 21%; P < 0.001); in particular, ethambutol was more frequently discontinued in the daily therapy group than in the intermittent therapy group (24 vs. 1%; P ≤ 0.001). However, the rates of symptomatic improvement, radiographic improvement, and sputum culture conversion were not different between the two groups (daily therapy vs. intermittent therapy: 75 vs. 82%, P = 0.181; 68 vs. 73%, P = 0.402; 76 vs. 67%, P = 0.154, respectively). In addition, the adjusted proportion of sputum culture conversion was similar between the daily therapy (71.3%; 95% confidence interval, 59.1-81.1%) and the intermittent therapy groups (73.6%; 95% confidence interval, 62.9-82.2%; P = 0.785).
Conclusions: These results suggest that intermittent three-times-weekly therapy with a macrolide, rifampin, and ethambutol is a reasonable initial treatment regimen for patients with noncavitary nodular bronchiectatic MAC lung disease. Clinical trial registered with www.clinicaltrials.gov (NCT 00970801).
Trial registration: ClinicalTrials.gov NCT00970801.
Keywords: Mycobacterium avium complex; ethambutol; macrolides; nontuberculous mycobacteria; treatment.