Preoperative moderate to severe anemia is associated with increased postoperative major adverse cardiac and cerebral events and pulmonary complications: a propensity score-matched analysis in hip fracture surgery patients over 80 years old

Background Anemia is a common health problem in the elderly. Preoperative anemia is a risk factor for postoperative outcomes in the elderly for hip fracture. The objective of the study was to explore the relationship between preoperative moderate to severe anemia and postoperative morbidity and mortality in hip fracture patients over 80 years old.Methods We performed a retrospective cohort study exploring preoperative moderate to severe anemia and postoperative morbidity and mortality. Patients over 80 years old undergoing hip fracture surgery were included in the study. Data were collected for major adverse cardiac and cerebral events (MACCE), postoperative pulmonary complications (PPCs), in-hospital mortality, delirium, gastrointestinal complication, deep venous thrombus (DVT), acute renal failure, ICU admission, and perioperative transfusion > 2 units rate.Results A total of 912 eligible patients were included for unmatched cohort analysis, and 512 patients were included for matched cohort analysis after propensity score matching. Baseline characteristics between the normal to mild anemia and moderate to severe anemia groups were significantly different. More patients in the moderate to severe cohort had a higher ASA classification grade III and female ratio. Patients in the moderate and severe anemia cohorts had more MACCE (unadjusted: odds ratio [OR] 1.968, 96% CI 1.090-3.555, P 0.023; adjusted: OR 1.929, 95% CI 1.014-3.668, P 0.045) and PPCs (unadjusted: OR 2.616, 95% CI 1.442-4.748, P 0.001; adjusted: OR 2.352, 95% CI 1.225-4.516, P 0.010) than patients with normal or mild anemia. However, the transfusion > 2 units rate was not significantly different between the two cohorts (unadjusted: OR 0.967, 95% CI 0.737-1.270, P 0.811; adjusted: OR 0.941, 95% CI 0.693-1.278, P 0.697). The in-hospital mortality, delirium rate, gastrointestinal complication, ICU admission, and DVT were similar. However, the in-hospital mortality was much higher (3.6%, 21/591 vs 1.6%, 5/321) in the moderate to severe anemia cohort. Furthermore, after propensity score-matched analysis, MACCE and PPCs were also significantly increased in the moderate to severe anemia cohort (OR 2.196 & 3.171, 95% CI 1.0794.470 & 1.563-6.436, P 0.027 & 0.001), which were in accordance with the unadjusted and adjusted results in the unmatched cohorts.Conclusions Moderate to severe preoperative anemia (< 11 g/dl) is associated with increased postoperative major adverse cardiac and cerebral events and pulmonary complications. Additionally, in-hospital mortality was not significant but was higher in the preoperative moderate to severe anemia cohort. Preoperative assessment and correction of hemoglobin level to above 11 g/dl might reduce MACCE, PPCs, and in-hospital mortality in hip fracture patients over 80 years old.