Relationship Between Preoperative Hypoalbuminemia and Postoperative Pneumonia Following Geriatric Hip Fracture Surgery: A Propensity-Score Matched and Conditional Logistic Regression Analysis

Background: Pneumonia is a devastating complication following geriatric hip fracture surgery, and preoperative hypoalbuminemia may be a potentially modifiable factor leading to improved outcome. This study aimed to quantify the relationship between preoperative hypoalbuminemia and postoperative pneumonia. Methods: We retrospectively reviewed the medical records of elderly patients (≥60 years) who underwent surgeries for hip fracture in a tertiary referral center between 2016 and 2020. According to the preoperative serum albumin level, they were divided into two groups: <35 g/ L and ≥35 g/ L. To reduce potential confounding, propensity score matching (PSM) in a 1:1 ratio was performed, with the caliper value set as 0.002; and further conditional logistic regression analysis was used to control the other potential confounders to determine the association strength. Results: Among 3,147 eligible patients included, PSM yielded 1,318 matched patients, with 659 in each respective group, suggesting significantly improved balance in most variables (standardized mean deviation improvement range, 20.7% to 99.1%), except for basophil count. The conditional logistic regression analysis, adjusted for PS and other intra- or post-operative variables, showed 6.18-fold (relative ratio, 6.18; 95% CI, 3.15-11.98; P<0.001) increased risk of postoperative pneumonia associated with preoperative hypoalbuminemia. Conclusion: Preoperative hypoalbuminemia was identified to be independently and highly associated with development of postoperative pneumonia in elderly patients undergoing hip fracture surgeries. However, whether the patients who had such condition may benefit from preoperative targeted nutritional support needs to be clarified by more prospective studies.