Previous studies have suggested a correlation between low preoperative hemoglobin (Hb) levels and postoperative pneumonia (POP) in elderly patients with hip fractures. However, the exact inflection point of Hb level that increases the risk of POP remains unclear. This study aimed to investigate the quantitative relationship between preoperative Hb levels and the incidence of POP in this patient population. This retrospective study included 1417 elderly patients with hip fractures who were admitted to the Department of Orthopedics at Shenzhen Second People’s Hospital between January 2012 and December 2021. Demographic and clinical data, including laboratory test results, were analyzed and compared to explore the relationship between Hb levels at admission and the incidence of POP in this patient population. This study included 1417 elderly patients with hip fractures, comprising 382 males and 1035 females, with a mean age of 77.57 ± 8.73 years. The incidence of POP was 6.21% (88/1417) in this patient population. After adjusting for confounding factors in model II, the regression equation showed that the incidence of POP decreased by 2% with each 1 g/L increment in Hb levels (OR: 0.98, 95% CI: 0.97–1.00; P = .0211). Additionally, a two-piecewise regression model was used to explore the relationship between Hb levels and POP incidence, after adjusting for confounding factors. Threshold effect analysis showed that the inflection point was 83.5 g/L. On the left side of the inflection point, Hb levels were negatively correlated with the incidence of POP (OR: 0.91, 95% CI: 0.86–0.97, P = .0030). There was a nonlinear relationship between preoperative Hb level and POP in elderly patients with hip fractures. When Hb levels were lower than 83.5 g/L, preoperative Hb levels were negatively correlated with POP.

Background and Aim Postoperative pneumonia (POP) is a common complication in elderly patients with hip fracture. Low preoperative hemoglobin (Hb) levels have shown strong associations with POP including, but the cut-off value of Hb level remains to be elusive. In this study, we investigated the quantitative relationship between preoperative Hb levels and the accidence of POP in elderly patients with hip fracture. Methods This study was a retrospective cohort study. A total of 1444 elderly patients with hip fracture admitted to the Department of Orthopedics, Shenzhen Second People's Hospital from January 2012 to December 2021 were retrospectively included. Demographic and clinical data (including laboratory tests) were analyzed and compared to explore the relationship between Hb level at admission and POP. Results There were 389 males and 1055 females with an average age of 77.55 ± 8.75 years. The incidence of POP in elderly patients with hip fracture was 6.30% (91/1444). The regression equation showed that, without adjustment for covariates, the incidence of POP decreased by 52% (P = 0.0136) and 59% (P = 0.0047) in Q3 and Q4 in comparison to Q1, respectively. After adjusting for confounding factors, a nonlinear relationship was achieved between Hb and pneumonia. Threshold effect analysis showed that the inflection point was 82.3 g/L. On the left side of the inflection point, Hb level was negatively correlated with the incidence of POP (OR: 0.90, 95%CI: 0.84–0.96, P = 0.00178). On the right side of the inflection point, there was no correlation between Hb levels and POP (OR: 1.00, 95%CI: 0.98–1.01, P = 0.7938). Conclusion There is a nonlinear relationship between preoperative Hb level and POP in elderly patients with hip fracture. When the Hb level was lower than 82.3 g/L, the preoperative Hb level was negatively correlated with POP, but when the Hb level was higher than 82.3 g/L, no correlation was observed.

Objective The relationship between the preoperative red blood cell distribution width and postoperative pneumonia in elderly patients with hip fractures remains unclear. This study investigated whether the preoperative red blood cell distribution width was associated with postoperative pneumonia in elderly patients with hip fractures. Methods Clinical data of patients with hip fractures in the Department of orthopedics of a hospital from January 2012 to December 2021 were retrospectively analyzed. A generalized additive model was used to identify both linear and nonlinear relationships between red blood cell distribution width and postoperative pneumonia. A two-piecewise linear regression model was used to calculate the saturation effect. Subgroup analyses were performed using stratified logistic regression. Results This study included a total of 1444 patients. The incidence of postoperative pneumonia was 6.30% (91/1444), the mean age of the patients was 77.55 ± 8.75 years, and 73.06% of them (1055/1444) were female. After full adjustment for covariates, the preoperative red blood cell distribution width showed a nonlinear relationship with postoperative pneumonia. The two-piecewise regression model showed an inflection point at 14.3%. On the left side of the inflection point, the incidence of postoperative pneumonia increased by 61% for every 1% increase in red blood cell distribution width (OR: 1.61, 95% CI 1.13–2.31, P = 0.0089). The effect size was not statistically significant on the right side of the inflection point (OR: 0.83, 95% CI 0.61–1.12, P = 0.2171). Conclusion The relationship between preoperative red blood cell distribution width and incidence or postoperative pneumonia was nonlinear in elderly patients with hip fractures. The incidence of postoperative pneumonia was positively correlated with red blood cell distribution width when it was < 14.3%. A saturation effect was observed when the red blood cell distribution width reached 14.3%.