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 × total lymphocyte count (× 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.