One Size Does Not Fit All: Reassessment of The Prognostic Nutritional Index Among Geriatric Distal Femur Fracture Patients.

BACKGROUND

Poor Nutrition status is often associated with perioperative complications and poor outcomes following orthopedic surgical interventions. The prognostic nutrition index (PNI), based on serum albumin and lymphocyte count, is commonly used to appraise nutrition status, with an index score > 38 indicating healthy nourishment, and lower scores generally indicating worse nutrition status. However, in many pathological settings, the components of PNI can often be acutely influenced. The purpose of this study is to evaluate the prognostic utility of PNI for 30-day mortality in geriatric distal femur fracture (DFF) patients.

METHODS

Patients ≥ 65 years with closed isolated DFF treated between 2005 and 2021 were identified by the National Surgical Quality Improvement Program (NSQIP) database. The primary outcome was comparison of 30-day mortality across PNI categories (< 35, 35-38, > 38). Sub-cohort analyses were performed for congestive heart failure (CHF) and dialysis patients. Logistic regression analyses identified independent risk factors for 30-day mortality. Receiver Operating Characteristic (ROC) analysis determined PNI thresholds and area under the curve (AUC) for the total cohort and subgroups.

RESULTS

The mean age of the 1,842 DFF patients (82.4% female, 17.6% male) was 76.7 years. The 30-day mortality rate was 5.0%, with higher rates in CHF (18.5%) and dialysis patients (8.3%). The mean PNI was 34.0, with 51.9% of patients having a PNI < 35. Each unit increase in PNI was associated with 7.0% decreased odds of mortality (OR: 0.93, 95% CI: 0.89-0.97, p < 0.001). Total cohort ROC analysis revealed an AUC of 0.66. Sub-cohort ROC analysis of CHF patients and dialysis patients demonstrated limited predictive value with PNI, with an AUC of 0.61 and 0.47 respectively.

CONCLUSION

In geriatric DFF patients, PNI was insufficient as a standalone prognostic tool for 30-day mortality risk. Combining PNI with markers of inflammation, frailty, or renal function may improve preoperative risk assessment.

LEVEL OF EVIDENCE: Prognostic Level III.