Risk factors for deterioration of nodular bronchiectatic Mycobacterium avium complex lung disease

SETTING: The long-term natural course of Mycobacterium avium complex (MAC) disease with nodular bronchiectasis, the most common pulmonary non-tuberculous mycobacterial disease, is not well described. OBJECTIVE: To identify risk factors for the deterioration of nodular bronchiectatic MAC lung disease over a 5-year follow-up period. DESIGN: Clinical and laboratory data of 67 patients with nodular bronchiectatic MAC lung disease were collected. Chest computerised tomographic images were used to count the number of lung segments involved at diagnosis and measure subcutaneous fat thickness during follow-up. RESULTS: The 34 patients who showed deterioration had significantly lower body mass index (BMI) (P = 0.004) and % predicted forced vital capacity (P = 0.032), higher numbers of lung segments involved (P < 0.001) and MAC-positive sputum cultures (P = 0.028), and thinner chest subcutaneous fat during follow-up (P < 0.001) than patients without deterioration. In particular, patients with both BMI <21.0 kg/m(2) and more than four lung segments involved had a 240-fold increased risk of deterioration (P < 0.001). CONCLUSION: Patients with poor nutritional status and extensive lung involvement tend to experience deterioration of nodular bronchiectatic MAC lung disease.