Prognostic nutritional index (PNI) is an independent predictor for functional outcome after hip fracture in the elderly: a prospective cohort study

The prognostic nutritional index (PNI) is a useful tool for assessing nutritional status using serum albumin and lymphocyte count. This study indicates that a higher preoperative PNI correlates with improved mobility and health-related quality of life during the initial postoperative period in elderly patients with hip fractures. Purpose To investigate the prognostic value of the prognostic nutritional index (PNI) in predicting mobility and health-related quality of life (HRQoL) in elderly hip fracture patients after surgery. Methods We prospectively involved patients aged 65 and above, who could walk freely before injury and underwent surgery between 2018 and 2019. Admission PNI was calculated as serum albumin (g/L) + 5 x total lymphocyte count (x 109/L). Patients were classified into two groups based on PNI median value. All patients were followed up by telephone for four times (30-day, 120-day, 1-year, and 3-year after surgery). The Fracture Mobility Score (FMS) and EuroQol 5-Dimension 5-Level (EQ-5D 5L) were used to evaluate mobility and HRQoL, respectively. Results Of 705 eligible patients, 487 completed all assessments. Patients in the higher PNI group had a significantly increased possibility of achieving unrestricted mobility at the 120-day follow-up (OR 1.69, 95% CI 1.10-2.61, P.adj = 0.017), while no significant differences were observed at other follow-ups. Additionally, patients in the higher PNI group had a significantly higher EQ-5D utility value at the 30-day follow-up (P.adj = 0.015). A linear regression model with adjusting for all confounders showed that admission PNI value was positively associated with EQ-5D utility values at 30-day, 120-day, and 1-year follow-up assessments (P.adj = 0.011, P.adj = 0.001, and P.adj = 0.030, respectively). However, this correlation was not observed at the 3-year time point (P.adj = 0.079). Conclusion The PNI is a valuable predictor of functional outcomes in elderly patients with hip fractures following surgery.