Association Between Body Mass Index Changes and All-Cause Mortality in Parkinson's Disease.

Background: Whether body weight changes are associated with Parkinson's disease (PD) mortality remains uncertain. Objective: To investigate the association between changes in body mass index (BMI) and all-cause mortality in patients with PD. Methods: This nationwide cohort study enrolled 20,703 individuals with new-onset PD (ICD-10 code: G20 and a rare intractable disease registration code: V124) who underwent health screening program by the Korean National Health Insurance Service within two years from pre- and post-PD diagnosis. We identified nine BMI change groups based on three BMI status: underweight (BMI < 18.5 kg/m2), normal or overweight (18.5 kg/m2≤BMI < 25 kg/m2), and obese (BMI≥25 kg/m2). Results: Of 20,703 individuals, 3,789 (18.0%) died during the follow-up period. Excessive weight loss to underweight in the obese group (hazard ratio [HR] = 3.36, 95% CI:1.60-7.08), weight loss in the normal to overweight group (HR = 2.04, 95% CI:1.75-2.39), sustained underweight status (HR = 2.05, 95% CI:1.67-2.52), and weight gain from underweight to normal or overweight (HR = 1.52, 95% CI:1.15-2.02) were associated with increased mortality. Sustained obese status (HR = 0.80, 95% CI:0.74-0.87) and weight gain in the normal to overweight group (HR = 0.82, 95% CI:0.71-0.95) were associated with reduced mortality. Conclusions: We found that BMI change at diagnosis was associated with mortality in patients with PD. Specifically, being underweight either before or after diagnosis as well as experiencing weight loss, were associated with increased mortality. These findings provide valuable insights for weight management planning in PD, highlighting the importance of individualized approach that consider pre-diagnosis BMI.