Association of serum antibodies against the Mycobacterium avium complex and hemoptysis: a cross-sectional study

Background: Hemoptysis is very common and can be life threatening in clinical practice for nontuberculous mycobacteria. The serum antibody against the Mycobacterium avium complex (MAC-Ab), the majority of nontuberculous mycobacteria species, is well known to reflect the activity of MAC lung disease; however, there is no study investigating the association between the MAC-Ab and hemoptysis in MAC patients. Therefore, we assessed whether the MAC-Ab is a good biomarker for hemoptysis among subjects with MAC lung disease. Methods: This study was conducted as a five-year retrospective survey at the National Hospital Organization Fukuoka National Hospital. A total of 155 patients aged ≥20 years with MAC lung disease were enrolled and separated into seropositive and seronegative groups using the cutoff for MAC-Ab levels of 0.7 U/ml. The prevalence of hemoptysis and odds ratios for the presence of hemoptysis were estimated and compared between the groups. To investigate the linear trends in the relationship between MAC-Ab levels and hemoptysis, the subjects were classified into three groups using the tertile distribution of the MAC-Ab. Results: The prevalence of hemoptysis was twice as high in the seropositive group than in the seronegative group (42.2 and 21.7%, respectively, P = 0.02). The multivariable-adjusted risk of hemoptysis was elevated in the seropositive group as compared with the seronegative group (odds ratio = 2.79 (95% confidence interval 1.15–7.44)). Likewise, when categorizing the subjects into three groups, the risk of hemoptysis increased with increasing MAC-Ab levels (P = 0.03 for trend). Conclusions: A positive MAC-Ab level was a significant risk factor for hemoptysis among patients with MAC lung disease. There were also positive trends in the association between the MAC-Ab titer and the likelihood of hemoptysis. Measuring the MAC-Ab may contribute not only to early detection of the risk of hemoptysis but also to early intervention with anti-NTM therapy and, as a result, to the prevention of hemoptysis in MAC patients.