PARIS – Greater walking disability is an independent predictor of all-cause death and major cardiovascular events in patients with symptomatic hip or knee osteoarthritis, according to a population-based study that confirms previous research.
For the composite cardiovascular disease (CVD) outcome of hospitalization for angina, acute myocardial infarction, coronary revascularization, congestive heart failure, stroke, or transient ischemic attack, the risk associated with a Health Assessment Questionnaire (HAQ) walking disability score of 2 was the same as that of diabetes and pre-existing CVD.
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Dr. Gillian Hawker
Total joint replacement reduced those risks by about 40%, Dr. Gillian A. Hawker said at the World Congress on Osteoarthritis (OA).
"I think the key piece here is that these data at least suggest that walking disability is a cardiovascular risk factor similar to diabetes," she said. "When we’re talking about risk assessment for cardiovascular outcomes, which everyone does pretty routinely in medicine, walking disability, which is really osteoarthritis, is one of the risk factors that they should be assessing ... If we can just start asking, hopefully it will get us thinking about, ‘Wow, this person has OA,’ and we need to start assessing it."
Session comoderator Ana M. Valdes, Ph.D., of the University of Nottingham (England) commented that the results are fascinating because this is not the first study to identify these associations. In 2011, British investigators reported that all-cause mortality, particularly due to CVD causes, was significantly related to baseline walking disability in patients with knee or hip OA (Br. Med. J. 2011;342:d1165).
"One of the things that happens often with OA is that it’s seen as just pain and if we can give them plenty of relief, they’ll be OK, but it’s actually life-threatening because if we do not address their disability, they are at risk of dying," Dr. Valdes said in an interview. "I think this should be put on the front pages of the weekly medical journals, so that people are aware of the dangers of not treating osteoarthritis properly."
Comorbidity is a barrier to OA care, and 90% of those aged 65 years and older with OA have at least one other chronic condition, such as diabetes and heart disease, observed Dr. Hawker, professor of medicine at the University of Toronto and physician-in-chief of medicine, Women’s College Hospital in Toronto.
Her group reported in a separate presentation at the meeting that walking disability also raises the risk for diabetes complications in those with both OA and diabetes.
For the current population-based study, the investigators linked provincial health administrative databases to baseline surveys from a population cohort of 2,156 patients with symptomatic moderate to severe OA who were recruited in 1996-1998 through a screening survey in Ontario.
Their mean age was 71 years (all were 55 years or older), 72% were female, 34% obese, 20% had diabetes, and 40% had prebaseline CVD. Their average HAQ walking disability score was 2 on a 3-point scale, and they had a mean WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) summary score of 41. Overall, 44% used a walking aid. (A walking disability score of 2 corresponds with walking outdoors on flat ground with much difficulty, whereas a score of 3 means the person is unable to do it.)
After a median follow-up period of 13.2 years, 57% of patients had died, and 38% experienced the composite CVD outcome with a median of 9.2 years follow-up.
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Dr. Ana Valdes
In multivariable analysis, there was a very clear dose-response, where increased walking disability was associated with increasing risk of all-cause death, Dr. Hawker said. The adjusted hazard ratio per unit increase in HAQ walking score was 1.30 (P less than .001), after controlling for confounders including age, sex, preexisting CVD, diabetes, hypertension, body mass index, and smoking status.
A HAQ walking score of 2 was associated with an adjusted hazard ratio of 1.69, which was actually greater than that associated with preexisting cardiovascular disease or diabetes, she said.
For the composite CVD outcome, there was also a significant association with HAQ walking score (adjusted HR, 1.17; P = .001).
Sensitivity analyses performed in 402 patients (18%) receiving postbaseline total joint arthroplasty (TJA ) showed that controlling for TJA did not change the effect of baseline disability but was protective for both all-cause death (HR, 0.62; P less than .001) and CVD events (HR, 0.66; P less than .001), Dr. Hawker said at the meeting sponsored by the Osteoarthritis Research Society International.
Although the data were not dichotomized, she noted that there was "beautiful discrimination" when they looked at the outcomes based on whether or not patients used a walking aid.