Anemia before surgery increases the risk of serious complications

Summary: anemia at the time of surgery, even mild anemia, increases the risk of serious complications including death.There is a large body of evidence that even borderline anemia has profound implications (see earlier posts). Anemia affects the ability of every cell in the body to do perform its functions by diminishing the amount of oxygen available. A study recently published in The Lancet documents the serious effects of anemia on surgical outcomes. The authors state:

"Preoperative anaemia is associated with adverse outcomes after cardiac surgery but outcomes after non-cardiac surgery are not well established. We aimed to assess the effect of preoperative anaemia on 30-day postoperative morbidity and mortality in patients undergoing major non-cardiac surgery."

They analyzed data for 227,425 patients, of whom 69,229 had preoperative anaemia, undergoing surgery in 2008 from The American College of Surgeons' National Surgical Quality Improvement Program database from 211 hospitals worldwide with reference to mortality and morbidity due to cardiac, respiratory, CNS, urinary tract, wound, sepsis, and venous thromboembolism complications. This was correlated with anaemia, defined as mild with a hematocrit or more than 29d% to 39% in men and 29 to 36% in women, or moderate-to-severe, less than 29% in both sexes. What did the data show?

"After adjustment, postoperative mortality at 30 days was higher in patients with anaemia than in those without anaemia; this difference was consistent in mild anaemia and moderate-to-severe anaemia. Composite postoperative morbidity at 30 days was also higher in patients with anaemia than in those without anaemia, again consistent in patients with mild anaemia and moderate-to-severe anaemia. When compared with patients without anaemia or a defined risk factor, patients with anaemia and most risk factors had a higher adjusted OR for 30-day mortality and morbidity than did patients with either anaemia or the risk factor alone."

The preoperative diagnosis and treatment of anemia is rarely undertaken before surgery. Indeed, I often find on delving into the medical histories of complex chronic cases that anemia, whose causes can be a significant clue to unlocking a case, is 'swept under the rug'. The authors state:

"Our findings should lead to a careful consideration of appropriate interventions aimed at correction of preoperative anemia in the most patients...At least in elective surgical cases, the treatment of preoperative anemia before surgical intervention should be strongly considered."

This should be the standard of care for patients undergoing elective surgery. The authors conclude:

"Preoperative anaemia, even to a mild degree, is independently associated with an increased risk of 30-day morbidity and mortality in patients undergoing major non-cardiac surgery."

Even mild anemia is a complicating factor, impediment to improvement, and important clue to underlying causation in many chronic conditions.