Modified frailty index-11 (mFI-11) measured frailty as a predictor of postoperative outcomes in Parkinson's disease patients undergoing deep brain stimulation: A national inpatient sample analysis

Background: Parkinson's disease (PD) presents with tremor, rigidity, bradykinesia, and postural instability. Commonly, PD is diagnosed around age 60 with the rate of diagnosis increasing with age. Deep brain stimulation (DBS) is an invasive surgical treatment for PD. Older patients, who are more likely to be frail, may experience higher risk of adverse outcomes following DBS. Methods: This retrospective cohort study analyzed NIS data from 2016 to 2020, identifying PD patients who received DBS. Frailty was determined using the 11-item Modified Frailty Index (mFI-11), with patients classified into frail and non-frail groups. Primary outcomes included prolonged length of stay (LOS) beyond the 75th percentile, non-routine discharge, and postoperative complications. Secondary outcomes involved total hospital costs. Univariate and multivariate analyses were performed, adjusting for demographics, comorbidities (CCI), and hospital characteristics. Results: A total of 3,472 patients met the inclusion criteria. In univariate analysis, frailty was significantly associated with increased odds of unfavorable discharge (OR: 1.76, 95 % CI: 1.44-2.16), prolonged length of stay (OR: 1.99, 95 % CI: 1.57-2.54), postoperative complications (OR: 1.89, 95 % CI: 1.22-3.01), and higher hospital costs (mean difference: $6,780; p = 0.001). After adjustment for demographic, clinical, and hospital factors, frailty remained independently associated with unfavorable discharge (aOR: 1.27, 95 % CI: 1.01-1.60), but not with prolonged length of stay, complications, or cost. In stratified analysis, frailty was significantly associated with adverse outcomes in patients with lower comorbidity burden (CCI < 2), but not in those with higher CCI scores. Conclusions: Frailty is a strong predictor of adverse outcomes in PD patients undergoing DBS, particularly nonroutine discharge. These findings suggest that incorporating frailty assessments into preoperative planning may improve outcomes and reduce healthcare costs.