Abstract
BackgroundThere is no proven management for mild cases of Mycobacterium avium complex (MAC) pulmonary disease, who do not immediately receive treatment and are managed with observation alone, because its long term-natural course, factors predictive of deterioration, and the effect of treating the disease remain unclear. Thus, we sought to investigate the natural course of mild cases of MAC pulmonary disease.MethodsWe conducted a multicenter retrospective study. Sixty-five patients with mild MAC pulmonary disease in whom treatment was withheld for at least 6 months after diagnosis were retrospectively recruited after a review of 747 medical records. Longitudinal changes in clinical features were evaluated by using a mixed effects model.ResultsMean follow-up was 6.9 ± 5.7 years. During the follow-up period, 15 patients (23%) required treatment and 50 (77%) were managed with observation alone. At diagnosis, 65 patients had nodular bronchiectatic disease without fibrocavitary lesions. Among clinical features, mean body mass index (BMI), forced expiratory volume in 1 second as percent of forced vital capacity (%FEV1), nodular lung lesions, and bronchiectasis worsened significantly in the observation group during follow-up. In the treatment group, BMI, and %FEV1 were stable, but bronchiectasis significantly worsened. At diagnosis, the polyclonal MAC infection rate in the treatment group was higher than that in the observation group. Other microbiological factors, such as insertion sequences, did not differ significantly between the groups.ConclusionsMild MAC pulmonary disease progresses slowly but substantially without treatment. Treatment prevents the deterioration of the disease but not the progression of bronchiectasis. Polyclonal MAC infection is a predictor of disease progression.
Highlights
The prevalence of nontuberculous mycobacterial (NTM) pulmonary disease is increasing around the world, especially in developed countries [1,2,3,4,5,6,7,8]
Treatment prevents the deterioration of the disease but not the progression of bronchiectasis
Polyclonal Mycobacterium avium complex (MAC) infection is a predictor of disease progression
Summary
The prevalence of nontuberculous mycobacterial (NTM) pulmonary disease is increasing around the world, especially in developed countries [1,2,3,4,5,6,7,8]. Substantial geographic differences are seen in the distribution of the pathogens responsible for NTM pulmonary disease, the Mycobacterium avium complex (MAC) is the most common pathogen in Japan and in other developed, pan-Pacific countries [1,2,3,4,5,6,7,8,9]. Patients with mild pMAC, such as nodular-bronchiectatic disease, do not immediately receive treatment and are managed by observation alone [9, 10]. There is no clearcut management strategy for mild pMAC because its long-term natural course, factors predicting its deterioration, and the effects of treatment are still unclear. There is no proven management for mild cases of Mycobacterium avium complex (MAC) pulmonary disease, who do not immediately receive treatment and are managed with observation alone, because its long term-natural course, factors predictive of deterioration, and the effect of treating the disease remain unclear. We sought to investigate the natural course of mild cases of MAC pulmonary disease
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