Prognostic Significance Of Serum Urea Concentration at Admission in older patients with hip fracture

Background: There are unmet needs in objective prognostic indicators for Hip Fracture (HF) outcomes. Objectives: To evaluate the determinants and prognostic impact of elevated serum urea, a key factor of nitrogen homeostasis, in predicting hospital mortality, inflammatory complications and length of stay in HF patients. Methods: In 1819 patients (mean age 82.8±8.1 years; 76.4% women) with osteoporotic HF, serum urea level at admission along with 22 clinical and 35 laboratory variables were analysed and outcomes recorded. The results were validated in a cohort of 455 HF patients (age 82.1±8.0 years, 72.1% women). Results: Elevated serum urea levels (>7.5mmol/L) at admission were prevalent (44%), independently determined by chronic kidney disease, history of myocardial infarction, anaemia, hyperparathyroidism, advanced age and male gender, and significantly associated with higher mortality (9.4% vs. 3.3%, p<0.001), developing a high postoperative inflammatory response (HPIR, 22.1% vs.12.1%, p=0.009) and prolonged hospital stay (>20 days: 31.2% vs. 26.2%, p=0.021). The predictive value of urea was superior to other risk factors, most of which lost their discriminative ability when urea levels were normal. Patients with two abnormal parameters at admission, compared to subjects with the normal ones, had 3.6-5.6 -fold higher risk for hospital mortality, 2.7-7.8-fold increase in risk for HPIR and 1.3-1.7-fold higher risk for prolonged hospital stay. Patients with increased admission urea and a high inflammatory response had 9.7 times greater mortality odds compared to patients without such characteristics. Conclusion: In hip fracture patients admission serum urea is an independent and valuable predictor of hospital outcomes, in particular, mortality.