Multicentre retrospective observational study for development and validation of MAC prognostic score model

The global incidence and mortality rates of Mycobacterium avium-intracellulare complex pulmonary disease (MAC-PD) are increasing. We conducted a multicentre retrospective cohort study across 18 hospitals to develop a scoring system for predicting respiratory infection-related mortality in patients with MAC-PD. A total of 1,165 patients newly diagnosed with MAC-PD between 2010 and 2017 were enrolled and randomly allocated to a 4:1 ratio to derivation (n = 932) and validation (n = 233) groups. Among them, 656 patients (56.3%) received MAC-PD treatment within 5 years. During the observation period, all-cause mortality occurred in 183 patients (15.7%), and respiratory infection-related mortality occurred in 67 patients (5.8%). To identify the risk factors for respiratory infection-related mortality, Cox proportional hazards analysis was conducted in the derivation group, which informed the development and validation of the prognostic scoring model. Five independent risk factors were identified: age ≥ 65 years, male sex, interstitial pneumonia, albumin < 3.5 g/dL, and cavitary lesions. A prognostic score was developed by assigning 2 points to albumin < 3.5 g/dL and 1 point to each of the other factors. The score demonstrated good predictive performance, with areas under the receiver operating characteristic curves of 0.86 and 0.81 in the derivation and validation groups, respectively. Patients with scores ≥ 3 had significantly poorer prognoses than those with scores ≤ 2. The strength of this study lies in its multicentre validation and focus on respiratory infection-related mortality, providing a clinically useful risk stratification tool for MAC-PD.