Natural history ofMycobacterium aviumcomplex lung disease in untreated patients with stable course

Abstract

Little is known about the long-term natural history of complex lung disease (MAC-LD) in untreated patients with stable course.The aim of this study was to investigate the natural course of untreated stable MAC-LD, with a focus on factors associated with clinical deterioration, spontaneous sputum conversion and prognosis.Of 488 patients diagnosed with MAC-LD between 1998 and 2011, 305 patients (62.5%) showed progressive MAC-LD resulting in treatment initiation within 3 years of diagnosis and 115 patients (23.6%) exhibited stable MAC-LD for at least 3 years with a median follow-up duration of 5.6 years. Patients with stable MAC-LD were more likely to have higher body mass index and less systemic symptoms at initial diagnosis compared with patients with progressive MAC-LD, while positive sputum acid-fast bacilli smear, fibrocavitary type and more extensive disease in radiological findings were more associated with progressive MAC-LD. Of the untreated patients with stable MAC-LD, 51.6% underwent spontaneous sputum conversion, with younger age, higher body mass index and negative sputum acid-fast bacilli smear at initial diagnosis found to be predictors of this occurrence.Advanced age, fibrocavitary type and abnormal pulmonary function were negative prognostic factors for survival in patients with stable MAC-LD.

Characteristic chest CT findings for progressive cavities in Mycobacterium avium complex pulmonary disease: a retrospective cohort study

“…The progression of the cavity leads to destruction of the lungs, which results in respiratory failure and poor prognosis. Unlike previous studies [6][7][8][9] that assessed prognostic factors but yielded recommendations that were somewhat complicated to apply in daily clinical practice, our results indicate that the combination of two simple findings can predict disease Fig. 2 Rates of progressive cavities stratified by maximum inner diameter and consolidation around the initial cavity.…”

“…Poor prognostic factors for MAC-PD include old age, low body mass index (BMI), low lung function, anemia, high blood deposition, malignancy, and hemosputum. Notably, the presence or absence of cavities is the most important factor [6][7][8][9]. Enlarged progressive cavities destroy lungs, leading to respiratory failure and poor prognosis [10,11].…”

A survey of clarithromycin monotherapy and long‐term administration of ethambutol for patients with MAC lung disease in Japan: A retrospective cohort study using the database of health insurance claims

“…Although there are cases in which bacilli negative conversion spontaneously occurred, development of drug‐resistant bacterial strains can be very problematic, particularly if bacteria also develop resistance to other treatments. Reports suggest that some MAC bacteria acquire genes from external bacterial species and mutate accordingly .…”

The new “Hesitation Blues”: initiating Mycobacterium avium complex lung disease therapy

“…This manuscript re-emphasises important differences between FC MAC lung disease and NB MAC lung disease, the former being a more serious process with higher mortality than the latter [7]. Patients with FC MAC lung disease cannot be managed expectantly.…”

“…In this issue of the European Respiratory Journal, HWANG et al [7] compared the clinical characteristics of 305 MAC lung disease patients who had a progressive course resulting in treatment initiation within 3 years of diagnosis with 115 patients who exhibited a stable course for at least 3 years. Compared to patients with stable MAC lung disease, patients with progressive MAC lung disease had lower body mass index (BMI) and more systemic symptoms, positive sputum AFB smears, and fibrocavitary (FC) radiographic findings.…”