Quantitative assessment of erector spinae muscles in patients with Mycobacterium avium complex lung disease

Abstract

Background and objective: No reports exist regarding skeletal muscle involvement in patients with Mycobacterium avium complex lung disease (MAC-LD). The cross-sectional area of the erector spinae muscles (ESM_CSA) reflects physical activity and can be assessed by computed tomography (CT). We investigated the relationship between ESM_CSA and physiological parameters and prognosis in MAC-LD patients.

Material and methods: In this prospective observational study, the ESM_CSA was measured on single-slice axial CT images. MAC-LD patients and sex- and age-matched controls (non-MAC-LD participants) were evaluated. We evaluated the relationship between the ESM_CSA and physiological parameters and prognosis.

Results: A total of 260 patients (209 female; median age, 69 years; 190 with nodular/bronchiectatic disease; 74 with cavitary lesions) were enrolled. The ESM_CSA was not different between MAC-LD patients and controls. In MAC-LD patients, the ESM_CSA was significantly associated with age, body mass index (BMI), pulmonary function, CT severity, and health-related quality of life (HRQL). Multivariate Cox proportional hazards analyses revealed that an ESM_CSA < -1 standard derivation (hazards ratio [HR], 2.76; P = 0.047) was significantly associated with all-cause mortality, along with BMI < 18.5 kg/m² (HR, 3.67; P = 0.02) and presence of cavitary lesions (HR, 5.84; P = 0.001). However, the ESM_CSA was not significantly associated with all-cause mortality when current treatment status, % predicted functional vital capacity, and forced expiratory volume in 1 s were added to the analyses.

Conclusions: Although the prognostic impact was limited, ESM_CSA was significantly associated with HRQL and prognostic physiological parameters, such as BMI and pulmonary function.

Keywords: Computed tomography; Mycobacterium avium complex (MAC); Nontuberculous mycobacteria (NTM); Respiratory function tests; St. George's respiratory questionnaire (SGRQ); The 36-Item short-form health survey (SF-36).