Clinical symptoms and survival in non-smoking and smoking HIV-negative patients with non-tuberculous mycobacterial isolation

Background: Non-tuberculous mycobacteria (NTM) cause infections in patients with smoking-related chronic lung diseases and also in non-smoking healthy elderly women. We analyzed the clinical symptoms, underlying diseases and mortality in patients with NTM culture findings, with special emphasis on smoking status. Methods: A total of 120 consecutive adult HIV-negative patients with NTM isolation were followed between 1990 and 1998 by retrieving data from their medical records for a period of at least 4 y, until 8 June 2006. Their clinical pictures and outcomes were analysed according to smoking status. Results: In this study, 42% of the patients had never smoked. Females accounted for 72% of non-smokers, but only 30% of smokers (p < 0.001). Mycobacterium avium complex (MAC) accounted for 72% of all isolates in nonsmokers and 41% in smokers (p = 0.001). Furthermore, 28% of non-smokers and 19% of smokers had no previous pulmonary diseases (p = 0.223). In nearly half of all patients (48%), symptoms of NTM infection started within a year prior to NTM isolation. Smokers had a higher risk of mortality compared to non-smokers (hazard ratio 1.64, p = 0.049), though this was not found after adjusting for underlying diseases. No fatal underlying diseases were found for 82% of non-smokers and 59% of smokers (p < 0.01). Conclusions: Non-smokers with NTM isolates had fewer previous lung diseases but had a higher incidence of MAC and bronchiectasis. Time from symptoms to NTM isolation was shorter than previously reported.