Studying Kidney Failure
Participants in Ejerblad’s study were in their late 50s, on average, and lived in Sweden.
Most had ‘moderately severe’ chronic kidney failure, the researchers write. The study doesn’t show that any of the patients had end-stage renal disease or were on dialysis.
Participants completed mailed questionnaires covering these topics:
- Current weight
- Weight at 20, 40, and 60 years
- Highest lifetime weight
- Alcohol consumption
- Tobacco use
Participants were also interviewed in person and had their medical records checked. The researchers calculated participants’, which is based on height and weight.
BMI of 30 or more is considered obese. BMI of at least 25 but less than 30 is considered overweight. There are other ways to measure, but this study (like many others) only tracked BMI.
Weight, Kidney Failure
Few participants had been obese at age 20. But those who had BMI of 25 or more at that age were three times as likely to have chronic kidney failure during the study.
There was nothing magic about being 20 years old. Having ever been obese tripled to quadrupled men’s odds of having chronic kidney failure during the study, compared with men with a BMI of less than 25.
Women were a bit different. If they had ever been what the researchers call “morbidly obese” (BMI of at least 35), they were three to four times more likely to have chronic kidney failure during the study, compared with women with a BMI of less than 25.
The links between excess weight and chronic kidney failure were strongest for-related kidney problems but also applied to other types of chronic kidney failure. The patterns included patients who reported not having diabetes or , two conditions that make chronic kidney failure more likely.
It’s possible that some participants may have had high blood pressure or diabetes and not known it, the researchers point out.
In the U.S., high blood pressure and diabetes are common, and a lot of people don’t know they have those conditions. The CDC estimates that in 2005, 20.8 million people in the U.S. had diabetes and that 6.2 million of them have undiagnosed diabetes. According to the American Heart Association, recent estimates have shown that one in three U.S. adults have high blood pressure but almost a third of them don’t know it.
Participants in Ejerblad’s study may not have reported their weight perfectly. For instance, several decades may have passed since participants were 20 years old, the youngest age for which they reported weight.
Current BMI wasn’t linked to chronic kidney failure. That result may be due toassociated with chronic kidney failure, note Ejerblad and colleagues.