Would Reducing Obesity Save Thousands of Knees?

On most days, our obesity clinic could easily be confused with an orthopedic clinic given the sheer number of patients who present with severe pains in their backs, knees, hips, and ankles – often to the point of immobility.

It turns out (perhaps not surprisingly) that today, obesity and knee osteoarthritis are among the most frequent chronic conditions affecting Americans aged 50 to 84 years – my guess is that these conditions are no less frequent among Canadians.

Given the high prevalence of both obesity and knee osteoarthritis and their very significant impact on quality of life, Losina and a team of researchers from Harvard, Boston University, Chapel Hill, Yale and the University of Sydney undertook the rather momentous task of estimating the impact of these conditions on morbidity and mortality in older Americans. Their results were now published in the Annals of Internal Medicine.

The researchers based their analyses on U.S. Census and national obesity data with estimated prevalence of symptomatic knee osteoarthritis, whereby they assigned the US population aged 50 to 84 years to four subpopulations: nonobese without knee osteoarthritis (reference group), nonobese with knee osteoarthritis, obese without knee osteoarthritis, and obese with knee osteoarthritis.

They then used a computer simulation model (The Osteoarthritis Policy Model) to estimate quality-adjusted life-year losses due to knee osteoarthritis and obesity and to determine health benefits of reducing obesity prevalence to levels observed a decade ago.

It turns out that the estimated total losses of per-person quality-adjusted life-years ranged from around 2 years in nonobese persons with knee osteoarthritis to about 3.5 years for persons affected by both conditions. Although these numbers may not sound shocking, they actually represent 10% to 25% of the remaining quality-adjusted survival of persons aged 50 to 84 years.

When calculated for the entire US population in that age range, this amounts to a staggering 86 million quality-adjusted lost to these conditions.

The researchers also calculate that reversing obesity prevalence to levels seen 10 years ago would avert just over 110,000 total knee replacements – so reducing obesity (even to where it was just 10 years ago) could indeed save a substantial number of knees.

What the paper of course does not disclose is how exactly such a reversal in obesity rates could possibly be achieved.

Clearly, the impact of weight loss on knee (and other) pain that we see in our clinic is often dramatic, but achieving weight loss for someone who is already immobilised by knee (or other) pain is definitely a challenge.

I’d certainly love to hear from my readers on how knee (or other) pain has affected their weight and whether or not they have experienced improvement in their knee (or other) pain with weight loss.

Edmonton, Alberta

Losina E, Walensky RP, Reichmann WM, Holt HL, Gerlovin H, Solomon DH, Jordan JM, Hunter DJ, Suter LG, Weinstein AM, Paltiel AD, & Katz JN (2011). Impact of obesity and knee osteoarthritis on morbidity and mortality in older americans. Annals of internal medicine, 154 (4), 217-26 PMID: 21320937