Having more severe arthritis – measured by referrals to orthopaedic specialists and joint replacement surgeries – further increased CVD risk. Again, the overall risk was greatest among women.

Researchers aren't quite sure why the discrepancies between men and women exist, though Rahman suggests that differences in the prevalence of OA, which affects more women, and CVD, which affects more men, might play a role.

He adds, "One limitation of our study was that our database did not include records of patients treated at emergency care units. Some deaths from myocardial infarction or stroke that occurred at emergency care units or at home were not captured in our study and this may have caused gender differences in the CVD rates."

Despite this and other limitations, however, he believes the study has laid the groundwork for further research into the link between heart disease and OA.

For now, he says, "The findings can inform both clinicians and patients of the cardiovascular disease risks among men and women with arthritis. Patients should be aware of the adverse impact of factors such as chronic inflammation, obesity and metabolic syndrome [a group of symptoms, including high blood pressure and high cholesterol, that can lead to heart disease and other health problems], reduced physical activity, muscle weakness and NSAID drug use."

David Felson, MD, a professor of medicine and epidemiology at Boston University, agrees wholeheartedly that arthritis patients and their doctors need to understand the importance of physical activity and weight management for reducing pain and disability and improving overall health.

But he also feels the Canadian study is flawed.

He explains, "Unfortunately, people with OA tend to have a lot of other illnesses. Eighty percent have one or more comorbid problems, including high rates of diabetes and co-existent heart disease that are generally part of being older and overweight. To figure out whether OA itself is causing things like cardiovascular mortality, you have to adjust for all those other comorbidities."

He notes, for instance, that researchers didn't have obesity statistics and so had to “impute” – or estimate – them. Because obesity is such a large risk factor for heart disease, not being able to properly control for it is a "fatal flaw."

Another problem is that the severity of comorbidities isn't known – only that patients did or did not have them. "High blood pressure has little effect on mortality if it is relatively low, but if it is high, it has a great effect on the heart," he says. "But we don't know if high blood pressure is worse in OA patients than in non-OA patients, so simply adjusting for its presence or absence [isn't enough]."

Still, he reiterates that people with OA can improve arthritis symptoms and reduce heart disease risk by staying active and managing weight, high blood pressure and other risk factors.