Association of body morphotypes with disease severity and its dynamic changes following treatment in patients with nontuberculous mycobacterial lung disease: a sex-stratified analysis

BACKGROUND: Patients with nontuberculous mycobacterial lung disease (NTM-LD) tend to be thin, particularly among females. The association between body morphotypes-such as skeletal muscle mass-and NTM-LD remains unclear in both sexes. METHODS: This prospective study was conducted at two medical centers in northern region of our country. NTM-LD patients, individuals with NTM colonization, and healthy controls were recruited. Severe NTM-LD was defined as a radiographic score≥5 at baseline. Body morphotypes were assessed at baseline and follow-up using a commercial bioelectrical impedance analysis (Tanita BC-751). Factors associated with disease status, severity, and treatment response were analyzed. RESULTS: From 2015 to 2023, 146 NTM-LD patients, 115 with NTM colonization, and 65 healthy controls were included. Body mass index (BMI), visceral fat scale, and skeletal muscle mass were lower in NTM-LD patients compared to colonization and healthy groups (all p < 0.001 versus both groups). In NTM-LD patients, reduced skeletal muscle mass was observed in the subgroup with higher radiographic severity among both sexes. Skeletal muscle mass was independently protective against severe disease in both females and males (adjusted odds ratios: 0.83795% CI: 0.722-0.972, p = 0.019; 0.8650.759-0.986, p = 0.030). Following treatment, skeletal muscle mass significantly increased in patients with radiographic improvement compared to those without (p = 0.002 overall; p = 0.052 in females, p = 0.015 in males). CONCLUSIONS: NTM-LD is associated with lower BMI, visceral fat scale, and skeletal muscle mass. Skeletal muscle mass correlated with disease severity and treatment response in both sexes, suggesting its potential as a monitoring marker.