Risk factors for postoperative pneumonia in patients undergoing hip fracture surgery: a systematic review and meta-analysis

Postoperative pneumonia (POP) is a devastating complication that can frequently occur after hip fracture surgery. This study aimed to quantitatively and comprehensively summarize the risk factors for POP following hip fracture surgery. PubMed, Embase, and Cochrane Library were systematically searched for studies assessing risk factors for POP following hip fracture surgery. The pooled odds ratio (OR) and standardized mean difference (SMD) between patients with and without POP were calculated. Evidence was assessed using the Newcastle-Ottawa scale. Ten studies including 37,130 patients with hip fractures were selected. POP occurred in 1768 cases with an accumulated incidence of 7.8% (95% confidence interval [CI]: 0.061-0.094). Advanced age (SMD: 0.50, 95% CI: 0.10-0.90), male sex (OR: 1.50, 95% CI: 1.12-2.01), American Society of Anesthesiologists physical status scale ≥3 (OR: 3.17, 95% CI: 1.25-8.05), chronic obstructive pulmonary disease (OR: 2.05, 95% CI: 1.43-2.94), coronary heart disease (OR: 1.82, 95% CI: 1.27-2.60), arrhythmia (OR: 1.49, 95% CI: 1.04-2.15), congestive heart failure (OR: 1.41, 95% CI: 1.14-1.75), chronic kidney disease (OR: 2.09, 95% CI: 1.28-3.41), and cerebrovascular accident (OR: 2.14, 95% CI: 1.60-2.85) were risk factors for POP. Hemoglobin (SMD: -0.14, 95% CI: - 0.25 to - 0.03), albumin (SMD: -0.97, 95% CI: - 1.54--0.41), blood urea nitrogen (SMD: 0.20, 95% CI: 0.03-0.37), alanine aminotransferase (SMD: 0.27, 95% CI: 0.10-0.44), arterial oxygen pressure (SMD: -0.49, 95% CI: - 0.71--0.27), time from injury to surgery (SMD: 0.13, 95% CI: 0.08-0.17), and surgery within 48 h (OR: 3.74, 95% CI: 2.40-5.85) were associated with the development of POP. Patients with the aforementioned risk factors should be identified preoperatively, and related prophylaxis strategies should be implemented to prevent POP following hip fracture surgery.