Post-surgery death risk high for skinny

Researchers at the University of Virginia in the US found that people with a body mass index (BMI) of 23 or less were 40 per cent more likely to die within a month of a surgical procedure, compared to people whose BMI was between 26 and 29.

BMI is an indicator of body fatness. Less than 18.5 BMI is considered underweight, 18.5 to 24.9 is normal weight, 25 to 29.9 is overweight and above 30 is considered obese.
The study results held even after the researchers took in to account the patients’ conditions that required surgery and the risk of death linked to the surgery, LiveScience reported.

The findings suggested that low BMI should be recognised as an important risk factor for death following surgery, said study researcher George Stukenborg. Doctors should take into account thinness when planning a patient’s care after surgery, and should tell thin patients about their increased risk of death, Stukenborg said.

Past studies have found that being obese did not increase people’s risk of dying after surgery. Some studies have even suggested that being moderately obese might protect against death after surgery. But, many of these studies were small and had a short follow-up period, Stukenborg said.

For the new study, published in the journal Archives of Surgery, Stukenborg and team analysed information from more than 189,500 patients from 183 centers who underwent surgery between 2005 and 2006.

The researchers divided patients into five groups based on their BMI and calculated the death risk for each group as compared to the risk of death for those in the middle group.

About 3200 patients died within 30 days of surgery. Among those with a BMI of 23.1 or less, 2.8 per cent died within 30 days, whereas 1.5 per cent of patients with a BMI between 26.3 and 29.7 died.

There was no difference in the risk of death between patients who were overweight, and patients who were obese or very obese, the researchers found. This study cannot tell us why thin people are at an increased risk of death after surgery, Stukenborg said.

One idea is that these patients may be more frail, or may have recently experienced weight loss, Stukenborg said. The researchers want to conduct further studies to find what puts thin patients at risk, he said.