Around one in ten (10.7 per cent) UK adults have symptomatic OA which has been clinically diagnosed. On average, there are 6.8 new cases per 1,000 people each year, but incidence in adults ranges from being very rare in people under the age of 30 at 0.08 per 1,000 person-years, to 27 per 1,000 person years in the 75-79 age group.
Knees are most commonly affected, followed by hips, wrists/hands and then ankles/feet. Women are more likely to have OA than men.2
Obesity (BMI ≥30kg/m2) increases the risk of developing knee OA from anywhere between two to six times, compared to ‘healthy’ body weight (<25kg/m2). The average BMI of people having hip replacements is 28.8kg/m2 (overweight) and the average BMI of people having a knee replacement is 31.0 kg/m2.1
Other factors that increase the risk of OA can include genetics (a factor in perhaps 60 per cent of hand and hip OA and 40 per cent of knee OA), developmental joint abnormalities and occupation.
Pain is a major concern in OA. Up to three quarters of people with the condition report being in constant pain, and one in eight describe their pain as unbearable. Being physically active may help reduce the risk of OA pain in the hip and knee by 6 per cent.1
Four out of five people with OA have a comorbidity such as hypertension, cardiovascular disease (with an increased hospitalisation risk of 15 to 17 per cent in the over 65s) or depression (which affects 20 per cent of people with OA). Pain and functional limitation associated with arthritis can make it harder to cope with these other conditions, increasing the likelihood of fatigue and depression.