One in two adults is at a serious risk for painful knee arthritis. Now that’s one piece of alarming news. A new study says that almost half of American adults will develop osteoarthritis of the knee by the age of 85. Their odds are increased if they are obese in the middle age.
The study based at the University of North Carolina at Chapel Hill has found that the risk of a person developing the painful knee condition rises with increase in the body mass index (BMI). The highest susceptibility is for those whose weight was normal at 18 years of age but became overweight or obese at 45 or older.
As part of the study researchers analysed data collected over a 13 year period from 3608 men and women who were 45 years or older and lived in Johnston County, NC. Based on self report of the patient’s height and weight at 18 years, researchers also calculated the participant’s BMI at that age. Each participant at 2 separate points of time was given a clinical test exam that comprised of X-ray images of their knees and measurement of the BMI along with being interviewed at home. Two weeks after the clinical exam they were interviewed again.
Dr. Joanne Jordan, principal investigator of the Johnston County Osteoarthritis Project and senior study author, mentioned, “These results show how important weight management is for people throughout their lives. Simply put, people who keep their weight within the normal range are much less likely to develop symptomatic knee osteoarthritis as they get older and thus much less likely to face the need for major surgical procedures, such as knee replacement surgery.”
“The study also sends an important message to physicians. hey need to include the risk of knee osteoarthritis in the discussion when counseling patients about weight management and they need to factor that risk into their treatment plans,” he added further.
Equipped with logistic regression models of statistical analysis, the team estimated the lifetime risk of symptomatic osteoarthritis in at least one knee after analysis of the complete data. They were surprised to discover that the lifetime risk of symptomatic knee osteoarthritis was 44.7 %. A significantly higher lifetime risk of 64.5 % was found in obese patients as against 34.9 % for normal weight while the risk was 44.1 percent for overweight participants. Additionally, those with a history of knee injury had a higher risk of about 56.8 % compared to those without at about 42.3 %.
No particular difference was observed in the risks related to a participant’s sex, race or education level. Furthermore scientists closely examined the BMI across the span of participants. It revealed that those who reported a normal weight at 18 but were overweight or obese at the two later time points had the highest risk 59.9 % while those who had a normal weight at age 18 and at their baseline and follow up visits had the lowest risk 29.2 %.
The team concluded that serious intervention in the form of weight management plans is needed by public health organizations to decrease the risk of this painful knee osteoarthritis.
The findings of the study are published in the Sept. 15, 2008 issue of Arthritis Care & Research.