Further information: Evaluation of Patients for Noncardiac Surgery (see p2487) from Cardiovascular Medicine, 3rd Edn*

ESC Clinical Practice Guidelines for Pre-operative Cardiac Risk Assessment and Perioperative Cardiac Management in Non-Cardiac Surgery (2009) (ESC website accessed 08/28/09)   Full text

Note: You may need subscriptions to access content from links on this page. You are responsible for obtaining these subscriptions.

* To view the online text from the book, please navigate to SpringerLink or use the DVD to access electronic content. SpringerLink is a subscription service. For further information, click here.

Preoperative hematocrit levels and postoperative outcomes in older patients undergoing noncardiac surgery

This retrospective cohort study [1] uses data from the National Surgical Quality Improvement Program (NSQIP) to examine the prevalence of preoperative anemia and polycythemia and their effects on 30-day post-operative outcomes in elderly patients who underwent major noncardiac surgery.

The NSQIP is a Veterans Health Administration (VHA) initiative that collects data from 132 VHA hospitals nationwide with the goal of improving the quality of surgical care through prospective collection of clinical data on major surgeries and reporting of comparative risk-adjusted postoperative outcomes. Between 1997 and 2004, a total of 326,124 surgery cases for veterans ≥65 years of age were identified. Of this total, 310,311 were included in the study. The primary outcome measure was death within 30 days of the index surgery. A secondary outcome was a composite end point of death or cardiac events (cardiac arrest or Q-wave myocardial infarction) within 30 days of the index surgery. Using preoperative hematocrit levels, the study population was stratified into standard categories of anemia (hematocrit <39.0%), normal hematocrit (39%–53.9%), and polycythemia (hematocrit ≥54%).

This categorization resulted in 42.8% of the population with preoperative anemia, 56.9% with normal preoperative hematocrit values and 0.2% with polycythemia. Increases in 30-day postoperative cardiac event and mortality risks were estimated in relation to each hematocrit point deviation from the normal category. For patients with progressively lower or higher hematocrit values than the reference category, mortality and cardiac event rates increased monotonically with higher rates at both extremes of the hematocrit spectrum. A 1.6% (95% confidence interval, 1.1%–2.2%) increase in the risk of 30-day postoperative mortality was found for every percentage point of hematocrit deviation from the normal range (39.0%–53.9%). The adjusted risk of 30-day postoperative mortality and cardiac morbidity rose when hematocrit levels decreased to less than 39% or went beyond 51%.
The authors concluded that their “results suggest that in elderly patients, even minimal degrees of anemia or polycythemia are associated with a significant increase in the risk of 30-day postoperative mortality and cardiac event.” They note that this increase was seen in the majority of the 14 subgroups analyzed. The notable exceptions were seen in the female populations and those patients who underwent emergent surgery. They speculate that for women this exception may be related to fact that women are known to have different cutoffs for a normal hermatocrit range than men and the limited sample size might have failed to detect a significant relationship between hematocrit and postoperative mortality. The exception for patients with emergent surgery may be related to an overshadowing effect by the severity of the underlying disease and/or the preoperative hematocrit value might not reflect the actual value at the time of the emergency surgery. The authors point out that “[their] results constitute the first large study to associate borderline polycythemia with increased postoperative mortality, starting at the previously considered normal hematocrit values of 51% and greater.” Several study limitations were noted that included: 1) Approximately 21% of the preoperative hematocrit values were obtained more than 4 weeks prior to surgery and, thus, may not accurately reflect hematocrit levels at the time of surgery. 2) Due to the smaller sample size, conclusions for patients with polycythemia may not be as robust as those found for patients with anemia. 3) The casual relationship between low or high hematocrit values and risk of postoperative adverse events could not be determined. They authors emphasize that “among older men undergoing elective surgery, the lowest risk of adverse outcomes was in those with preoperative hematocrit values between 39.0% and 50.9%” and suggest that “future studies should determine if treatment of preoperative anemia and polycythemia improve the postoperative outcomes of this vulnerable population.”

[1] Wu, W-C, Schifftner TL, Henderson WG, et al. Preoperative hematocrit levels and postoperative outcomes in older patients undergoing noncardiac surgery. JAMA 2007;297(22):2481-2488

Note: You will need a subscription to access this linked reference. You are responsible for obtaining this subscription.

AHA/ACC 2006 Guideline Update on Perioperative Cardiovascular Evaluation for Noncardiac Surgery: Focused Update on Perioperative Beta-Blocker Therapy.  (Circulation 2006;113:2662-2674)   Full text

ESC 2001 Diagnosis and management of aortic dissection (Eur Heart J 2001;22:1642-1681)   Full text