BARCELONA – Overweight women who follow a 2.5-year diet and exercise program showed a significant reduction in incident knee osteoarthritis, judging from the findings of a new Dutch study.
Jos Runhaar, a research scientist from the department of general practice at Erasmus University Medical Center, Rotterdam, the Netherlands, presented findings from the first-ever preventive randomized controlled trial on osteoarthritis (OA) at the World Congress on Osteoarthritis.
Jos Runhaar
The already high number of people with OA worldwide is set to rise further with the growing incidence of obesity and an aging population. "Associated financial costs will also rise substantially to reflect this," he said.
Mr. Runhaar pointed out that the research community was already well informed in terms of the course and burden of OA, definitions of disease status, progression, and risk factors but lacked evidence on prevention. "We felt it was time to take the next step and investigate prevention of the disease and associated medical costs in people at risk," he noted.
The Prevention of Knee Osteoarthritis in Overweight Females (PROOF) study aimed to evaluate the preventive effects of a weight-loss program and of oral glucosamine sulphate on incident knee OA. After selection for study criteria, 407 women from the Rotterdam area were randomized to study interventions or placebo. "We selected a high-risk group of women between 50 to 60 years of age, BMI [body mass index] of at least 27, and without any clinical or radiographic signs of knee OA at baseline," said Mr. Runhaar. Half of the knees had a Kellgren-Lawrence (K&L) grade 0 at baseline.
The study assessed the effectiveness of two interventions: a weight-reduction program and oral glucosamine sulphate (1,500 mg/day). At the meeting, Mr. Runhaar presented only the results of the weight-reduction intervention.
The trial involved 200 women who received the weight-reduction intervention and 200 who served as controls, and in both groups half received glucosamine and half placebo.
"It was a pragmatic intervention. It was intended to be a regimen that could be easily implemented in daily life," Mr. Runhaar explained.
The weight-reduction program involved a weekly group session that featured a variety of low-impact sports to re-encourage interest and enjoyment in physical activity, and aimed to maintain this over the long term. "Women were referred to a dietician to develop dietary targets and have motivational discussions," he added.
"The supportive sessions were important because these women generally had inactive lifestyles and poor nutritional habits that were difficult to change, especially by the age of 50-60 years," he said.
Three possible incidence measures were used to represent the primary outcome of incident knee OA after 2.5 years. Participants needed to have a knee OA incidence with a K&L grade of at least 2; incidence of clinical knee OA according to clinical and radiographic American College of Rheumatology criteria; or joint-space narrowing of at least 1.0 mm.
The researchers combined both radiographic and clinical outcomes to ensure they had enough data to provide meaningful results.
After 2.5 years, women who complied with the weight-reduction program showed a mean weight reduction of 1.4 ± 5.5 kg, compared with 0.1 ± 6.3 kg in controls.
Also after 2.5 years of intervention, the researchers saw an incidence of knee OA, adjusted for BMI and K&L grade at baseline, of 22% in all knees, which equated to 36% of all women with one or more knees affected. On an intention-to-treat basis, 25% of the controls had knee OA versus 19% in the weight-reduction group (odds ratio, 0.62; 95% confidence interval, 0.38-1.04). The per-protocol analysis showed a greater difference of 25% incidence of knee OA in the controls versus 10% in the intervention arm (OR, 0.28).
"In the per-protocol analysis, we see the effect of the intervention in women who actually complied with the program. They exercised and followed the diet. This is what happens if you stay with the program. The incidence rate over halved with a statistically significant odds ratio," Mr. Runhaar reported at the meeting, which was sponsored by the Osteoarthritis Research Society International.
When asked whether this program really had practical application, he said that only a quarter of women were compliant with the intervention. "It is really difficult to change the habits of these women. This is one possible way of doing it, but we need to look at other ways of getting these women active and on a diet. If we can achieve this, then we are likely to prevent more OA."
Mr. Runhaar reported no relevant financial disclosures.