Perioperative Anemia Development and Recovery in Adult Surgical Patients: An Observational Cohort Study

Anemia affects more than two billion people worldwide and is common among surgical patients. Despite growing recognition of the risks associated with preoperative anemia, we have limited understanding of the epidemiology of anemia development and recovery.

This is an observational cohort study of adults undergoing surgery at a large tertiary care medical center from August 2012 to July 2023. Hemoglobin concentrations were obtained preoperatively, during postoperative hospitalization, and through 12 months after surgery. Anemia was defined primarily using World Health Organization criteria (hemoglobin <12 g/dL in women, <13 g/dL in men) and secondarily with a gender-neutral threshold of <13 g/dL. Descriptive analyses summarize preoperative anemia prevalence, postoperative anemia prevalence and incidence, and post-hospitalization anemia recovery across demographic, clinical, and surgical features.

281,217 patients undergoing 423,066 procedures (51.9% among women) were included. Among those with available preoperative hemoglobin assessments (n = 308,959), 28.9% had anemia, with similar prevalence in men (29.5%) and women (28.4%) using World Health Organization (WHO) definitions, but with prevalence increasing to 51.0% in women when using the gender-neutral anemia definition. Preoperative anemia was most common in Black patients (44.0%) and in those ≥75 years (39.6%). Surgical subspecialties showed wide variation in preoperative anemia prevalence, ranging from 18.6% in spine surgery to 45.8% in vascular surgery. Among previously nonanemic patients admitted to the hospital postoperatively, 76.9% developed new postoperative anemia, with the highest incidence in cardiac surgery (97.5%). Women experienced more severe postoperative anemia than men. Overall, 81.1% of patients were anemic at hospital discharge. Recovery was gradual and incomplete: among those discharged with mild, moderate, or severe anemia, 28.5%, 51.9%, and 66.3%, respectively, remained anemic at 12 months. Among patients who were nonanemic preoperatively but developed new postoperative anemia, 29.3% remained anemic at 12 months.

Preoperative and postoperative anemia are highly prevalent, and anemia frequently persists for months after hospitalization. Older adults, women, and Black patients bear a disproportionate burden. Despite this, anemia evaluations and treatments remain underutilized. These findings highlight substantial opportunities for patient blood management (PBM) programs to improve perioperative anemia detection, optimization, and post-discharge management.