Clinical utility of the geriatric nutritional risk index in patients with Mycobacterium avium complex lung disease: A multicenter retrospective study

BACKGROUND: Mycobacterium avium complex lung disease (MAC-LD) is a chronic pulmonary infection associated with significant long-term morbidity and mortality. The Geriatric Nutritional Risk Index (GNRI) is a simple nutritional indicator derived from serum albumin levels and the actual-to-ideal body weight ratio. Although host nutritional status is thought to influence the prognosis of patients with MAC-LD, the clinical importance of the GNRI in this population remains unclear. METHODS: This multicenter retrospective cohort study included 588 patients diagnosed with MAC-LD between 2006 and 2020. Patients were categorized into four groups according to GNRI: ≥98 (no risk), 92-<98 (low risk), 82-<92 (moderate risk), and <82 (high risk). Furthermore, the association between the GNRI and clinical outcomes was evaluated. RESULTS: The 5-year survival rates in the no-, low-, moderate-, and high-risk groups were 94%, 78%, 65%, and 46%, respectively (p < 0.01). In the multivariable Cox model, a higher-risk group based on GNRI was independently associated with a higher risk of all-cause mortality (hazard ratio 1.89, 95% confidence interval 1.45-2.44), and the GNRI category-based model yielded a Harrell's C-index of 0.888 (95% confidence interval, 0.841-0.920) for all-cause mortality. In the multivariable Fine-Gray model, a higher-risk group based on GNRI was significantly associated with a higher risk of respiratory-related mortality (subdistribution hazard ratio 2.08, 95% CI 1.52-2.86). CONCLUSION: These findings suggest that the GNRI is a useful prognostic marker for all-cause and respiratory-related mortalities in patients with MAC-LD.