Comorbidity

The majority of people with osteoarthritis have at least one co-morbidity, with 3 out of 4 Australians with osteoarthritis reporting at least one other chronic health condition.

This multimorbidity is associated with lower health-related quality of life.

Just over half (51%) of Australians with osteoarthritis reporting also having cardiovascular disease, more than 3 times the rate of those without osteoarthritis (15%).

A recent systematic review found moderate quality evidence of an association between worsening pain and/or physical function and having at least one co-morbidity, with cardiovascular disease associated with worse function although not worse pain, and people with diabetes having worse pain (Calders & Van Ginckel, 2018).

Comorbidity may influence the perceived ability of people to exercise, although tailored exercise is safe and effective for people with osteoarthritis and comorbidities, with improvements at 3 months post intervention in patient reported outcome measures (WOMAC) and physical functioning (15% improvement in 6-minute walk test).

A recent GLAD cohort study looking at GLAD outcomes and people with comorbidities reported that whilst people with comorbidities had worse baseline scores in all outcomes than those without comorbidities, however people with comorbidities had similar levels of improvement at 3 months and 12 months to those without. This suggests exercise is effective for people with co-morbidities as well as those without.

See also risks and complications with surgery

Obesity is a known modifiable risk factor for the development of knee osteoarthritis, with the risk twice as high in people with a body mass index (BMI) over 25 to 30 compared to those with a BMI less than 25; and even higher for obese people (BMI ≥30).

The risk of knee osteoarthritis increases by 36% for every 2 units of BMI (5kg) weight gain (March & Bagga, 2004).

High BMI is associated with progression of knee OA. This may be due to a combination of biomechanical factors (load, decreased muscle strength and altered biomechanics) as well systemic effects (elevated adipocytokine levels and inflammatory effects).

The association of obesity and an increased rate of radiographic progression of knee osteoarthritis is less clear, with conflicting findings.

Studies have reported being overweight or obese is associated with lower quality of life and higher risk of disability.  Being overweight or obese are risk factors for pain in the general population, and a higher BMI has been associated with higher pain severity in knee OA.

Obesity has also been reported to be associated with an increased risk of both hip and knee arthroplasty.

The mechanism of action of weight loss improving symptoms may be two-fold, with reduced joint load as well as reduced pro-inflammatory markers.

People with diabetes have an increased risk of developing osteoarthritis (Williams et al., 2016)

Diabetes associated with worsening pain with both hip and knee osteoarthritis

People with diabetes and knee osteoarthritis have a 2 fold increase in rate of arthroplasty compared with non-diabetic patients (Schett et al., 2013).

Diabetes is an independent factor for greater knee pain with osteoarthritis independent of other factors such as body mass index or severity of radiographic changes, suggesting changes at a cellular level may influence the inflammatory pathway, as well as central pain processing (Eitner et al., 2020).

Just over half (51%) of Australians with osteoarthritis reporting also having cardiovascular disease, more than 3 times the rate of those without osteoarthritis (15%).

People with severe knee osteoarthritis and cardiovascular disease were able to obtain improvements in cardiovascular function with a 10 minutes per day walking program