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Published on: March 27, 2018
Does preoperative hemoglobin independently predict short-term outcomes after coronary artery bypass graft surgery?
Melanie L Bell1, Gary K Grunwald, Janet H Baltz
1Department of Preventive and Social Medicine, University of Otago, Dunedin, New Zealand.
Insights
Preoperative low hemoglobin (less than 10 g/dL) did not independently predict 30-day mortality or complications in coronary artery bypass graft (CABG) surgery. Other factors like serum creatinine are stronger predictors.
Area of Science:
- Cardiovascular Surgery
- Hematology
- Outcomes Research
Background:
- The predictive value of preoperative hemoglobin for short-term outcomes after coronary artery bypass graft (CABG) surgery remains unclear.
- This study examined the relationship between preoperative hemoglobin levels and 30-day operative mortality and perioperative complications.
Purpose of the Study:
- To investigate the association between preoperative hemoglobin levels and 30-day mortality and perioperative complications in patients undergoing CABG.
- To determine if preoperative hemoglobin is an independent predictor of outcomes in CABG surgery.
Main Methods:
- Utilized deidentified records of 36,658 patients undergoing CABG-only with cardiopulmonary bypass from the Department of Veterans Affairs Continuous Improvement in Cardiac Surgery Program database (1997-2005).
- Employed univariate and multivariate statistical models to assess the impact of varying hemoglobin levels on mortality and morbidity outcomes.
Main Results:
- Unadjusted analysis showed significantly higher odds of 30-day mortality for patients with hemoglobin < 10 g/dL (OR 2.37, p < 0.0001).
- However, the multivariable effect of low hemoglobin on 30-day mortality was considerably reduced (OR 1.29, p = 0.064), indicating it was not a strong independent predictor.
- Serum creatinine showed a stronger association with mortality than hemoglobin.
Conclusions:
- Preoperative hemoglobin level < 10 g/dL was not a strong independent predictor of 30-day operative mortality or perioperative morbidity in multivariate models for on-pump CABG-only patients.
- Anemia may be intertwined with other risk factors such as serum creatinine or congestive heart failure, limiting the predictive power of isolated hemoglobin levels.
- Risk-model approaches may be limited in identifying predictors for anemic patients with complex preoperative profiles.
Background:
The role of preoperative hemoglobin in predicting short-term coronary artery bypass graft (CABG) surgery outcomes has not been well established. This study investigated the association between preoperative hemoglobin level with 30-day operative mortality and perioperative complications.
Methods:
For the period from 1997 to 2005, the Department of Veterans Affairs Continuous Improvement in Cardiac Surgery Program database was used to extract 36,658 CABG-only deidentified records for patients undergoing cardiopulmonary bypass. Univariate and multivariate statistical models were used to predict both mortality and morbidity outcomes for varying levels of hemoglobin.
Results:
Unadjusted odds of 30-day operative mortality for patients with preoperative hemoglobin level less than 10 g/dL were 2.37 times higher than for patients with hemoglobin levels of 10 g/dL or greater (95% confidence interval: 1.84 to 3.05; p < 0.0001). Multivariable effect upon 30-day operative mortality decreased considerably (odds ratio = 1.29, 95% confidence interval: 0.99 to 1.68; p = 0.064).
Conclusions:
As several risk factors may occur concurrently with low hemoglobin, preoperative hemoglobin level less than 10 g/dL was not a strong independent predictor of 30-day operative mortality or perioperative morbidity in multivariate models for on-pump CABG-only patients. Hemoglobin and serum creatinine were correlated, with creatinine exhibiting the stronger association with mortality. These findings suggest that moderate or severe anemia may be intertwined with other risk factors, such as serum creatinine or congestive heart failure. For a CABG patient subgroup presenting with a complex clinical preoperative profile, therefore, risk-model approaches may be inherently limited in separately identifying the predictors of anemic patients' outcomes.
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