Epidemiology of bronchiectasis at a single center in Japan: a retrospective cohort study

Abstract

Background: The characteristics of bronchiectasis (BE) in Asia, including Japan, remain largely unknown. We aimed to provide insights into the clinical characteristics and treatment outcomes of BE, especially regarding nontuberculous mycobacteria (NTM) infection and its poorly understood impact on prognosis. We also aimed to clarify the effect of long-term macrolide antibiotic use in patients with BE, who had no history of exacerbations.

Methods: In this single-center, retrospective study, the medical records of patients who satisfied the BE criteria between January 1, 2012, and August 31, 2023, were reviewed. Severe exacerbations and mortality during the observation period were recorded. Baseline characteristics and overall survival of patients with and without NTM infection, and factors influencing the time to the first exacerbation and death were analyzed. Additionally, the effects of long-term macrolide antibiotic use in patients without a history of severe exacerbations were estimated.

Results: In a cohort of 1044 patients with BE, the rate of severe exacerbation was 22.3%, with mortality rates of 3.2% over 3 years. Notably, the high prevalence of NTM infection (n = 410, 39.3%) in this cohort was distinctive. NTM infection was not associated with either the time to first severe exacerbation (p = 0.5676, adjusted hazard ratio = 1.11) or mortality (p = 0.4139, adjusted hazard ratio = 0.78). Compared with the NTM group, the non-NTM group had a higher proportion of elevated inflammatory markers, with significant differences in C-reactive protein levels (p = 0.0301) and blood neutrophil counts (p = 0.0273). Pseudomonas aeruginosa colonization was more frequent in the non-NTM group (p = 0.0003). Among patients with non-NTM infection and without a history of exacerbation in the past 2 years, 38.2% received long-term macrolide antibiotics that did not invariably prolong the time to first severe exacerbation (p = 0.4517, IPW p = 0.3555).

Conclusions: This study highlights BE epidemiology in Japan, noting that the presence of NTM infection may not necessarily worsen the prognostic outcomes and advising caution in the casual use of macrolides for milder cases without a history of exacerbations.

Clinical trial registration: UMIN Clinical Trials Registry Number: UMIN000054726 (Registered on 21 June 2024).

Keywords: Bronchiectasis; Macrolides; Nontuberculous mycobacteria; TB.

Fig. 1

Kaplan–Meier analysis was performed to compare the overall survival of patients with bronchiectasis was compared between NTM (n = 410) and non-NTM (n = 634) groups. Abbreviations: NTM, nontuberculous mycobacteria

Fig. 2

The time to the first exacerbation of patients with non-NTM BE who had no history of severe exacerbation for two years before diagnosis of BE between 138 who received long-term macrolide and 223 who did not, before (a) and after (b) the adjustment for multiple covariates (sex, age, BMI, mMRC, smoking, cystic bronchiectasis and cavities on CT, CRP, neutrophil count, and P. aeruginosa colonization) by using IPW. Abbreviations: NTM, nontuberculous mycobacteria; IPW, inverse probability weighting; BMI, body mass index; mMRC, modified Medical Research Council dyspnea scale; CT, computed tomography; CRP, C-reactive protein; P. aeruginosa, Pseudomonas aeruginosa