Bariatric (weight-loss) surgery is linked to a long-term increased risk of anemia, or inadequate red blood cells, according to a new study published in the journal The Lancet Diabetes and Endocrinology.
While the causes of anemia can be complex, the condition is linked to certain nutrient deficiencies, including inadequate intake or absorption of iron and vitamin B12. Since bariatric surgery — such as gastric bypass surgery — potentially reduces a person’s capacity to consume and absorb nutrients, it’s well known that nutrient deficiencies are a risk linked to the surgery. But there haven’t been many studies looking at the long-term risk of health outcomes linked to nutritional deficiencies in people who undergo bariatric surgery. Bariatric surgery has been shown to be a very effective treatment for many people with type 2 diabetes and obesity, often resolving their diabetes completely or greatly reducing the need for insulin or other diabetes drugs.
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Anemia rates years after bariatric surgery
For the latest study, researchers compared health outcomes in people with obesity who underwent bariatric surgery and in those who received “usual obesity care.” Out of a total of 5,335 participants, 2,007 chose bariatric surgery, while 2,040 matched controls — meaning they were otherwise similar based on a number of initial traits — did not undergo the surgery. After undergoing or not undergoing the surgery, participants were followed up for a maximum of 20 years, and a median period of about 10 years. During this period, there were 593 documented cases of of anemia in participants who underwent bariatric surgery — 133 in those who underwent gastric bypass, 359 in those who underwent vertical-banded gastroplasty, and 101 in those who underwent gastric banding. In the control group that didn’t undergo bariatric surgery, there were 261 cases of anemia.
But these raw numbers don’t tell the whole story, since they don’t take into account the follow-up time for each group and what proportion of people underwent each procedure. The researchers found that in the control group, there were 13 cases of anemia per 1,000 person-years. Among participants who underwent gastric bypass, there were 64 cases of anemia per 1,000 person-years. For vertical-banded gastroplasty, the anemia rate was 23 cases per 1,000 person-years, and for gastric banding it was 26 cases per 1,000 person-years. These associations with anemia remained even after the researchers adjusted for small differences in various traits between participants in the different groups.
“Our findings highlight the increased risk of anaemia after bariatric surgery and the importance of long-term compliance to nutritional supplementation and monitoring,” the researchers wrote, to detect nutritional deficiencies as early as possible. This study did not compare other health outcomes between people who underwent bariatric surgery and those who didn’t, so its goal wasn’t to evaluate whether the health benefits of bariatric surgery outweigh the risk for anemia or other health risks. Still, this study shows why it’s important for researchers to look at the long-term health effects of bariatric surgery, so that both doctors and patients can make judgments about the risks and benefits — and take steps to minimize any risks that are linked to the procedure.
Want to learn more about anemia? Read “Anemia: When ‘Tired Blood’ Is Slowing You Down.”
