Previous studies have shown that patients with osteoarthritis have a higher risk of developing comorbidities; however, much research has focused on only a few conditions, or did not consider the chronology of disease onset relative to osteoarthritis. Dr Anne Kamps and colleagues set out to determine the risk of comorbidity following knee or hip osteoarthritis using electronic health records from patients in the Netherlands.
The study population consisted of over 1.8 million patients, and examined 58 comorbidities. Overall, there was increased risk of being diagnosed with 11 of these comorbidities after a diagnosis of knee osteoarthritis. The comorbidities were extremely varied, ranging from other rheumatic and musculoskeletal complaints such as gout, back and neck pain, to anaemia, cataracts, chronic kidney disease, coronary heart disease, hearing loss, obesity, sleeping disorders, and thromboembolic disease.
Following the original abstract submission, Dr Kamps adds an update that for 30 of the 58 studied comorbidities, exposure to knee OA showed a HR statistically significant larger than 1. Largest positive associations (HR with (99.9% CIs)) were found for obesity 2.55 (2.29-2.84), fibromyalgia 2.06 (1.53-2.77), polymyalgia 1.72 (1.38-2.14), drug abuse 1.40 (1.21-1.94), and rheumatoid arthritis (RA) 1.52 (1.28-1.81). For COPD 0.80 (0.70-0.91) and tobacco abuse 0.86 (0.75-0.99) there was a statistically significant negative association (HR<1) with exposure to knee OA. All other comorbidities did not show an association with previous exposure to knee OA.
For 26 comorbidities, exposure to hip OA showed a statistically significant HR larger than 1. The largest positive associations were found for polymyalgia rheumatica 1.81 (1.41-2.32), fibromyalgia 1.70 (1.10-2.63), spinal disc herniation 1.64 (1.49-1.80), thromboembolic disease 1.47 (1.28-1.70) and alcohol abuse 1.44 (1.11-1.88). There were no negatively associated comorbidities as for all other comorbidities the HRs of hip OA were non-significant.” For people with osteoarthritis in the hip, 7 comorbidities showed a statistically significant link. As for knee osteoarthritis, this included anaemia and sleeping disorders. The other linked diseases were fibromyalgia and spinal disc herniation, as well as atrial fibrillation, peripheral vascular disease, and solid malignancies.
These findings suggest that the management of osteoarthritis should consider the risk of other long-term-conditions, but further research on causality is needed.
In another presentation, Dr Sultana Monira Hussain showed trajectories of body mass index (BMI) from early adulthood to late midlife, and their correlation with the incidence of total knee arthroplasty (TKA) for osteoarthritis. The study examined almost 25,000 participants from the Melbourne Collaborative Cohort Study.
Using group-based trajectory modelling, six distinct trajectories of BMI were identified. Over a period of 12.4 years, 5.4% of participants had TKA. When compared to the trajectory of people with lower normal to normal BMI, the hazard ratios for TKA increased in all other BMI trajectories. Most of the burden of TKA and associated healthcare costs occurred in those who had a normal body mass index in young adulthood and transitioned to overweight or just obese in midlife.
The authors estimated that 28.4% of TKA would be reduced if individuals followed the trajectory that was one lower – representing a saving to the national health system of $AUD 373 million. This would require a weight difference of 6-8 kg and mean that at a population level, a significant reduction in TKA and associated healthcare costs could be achieved by preventing this level of weight gain from young adulthood to midlife.
Body weight was also addressed in a study from Zubeyir Salis and colleagues. Scores from radiographic analyses of knees at baseline and at 4–5 years’ follow up were obtained from three independent data sets in the Netherlands and the US.
Results showed that change in BMI was positively associated with both the incidence and progression of knee osteoarthritis. Change in BMI was also positively associated with narrowing of joint space on the medial but not the lateral side of the knee. Osteophytes of the tibial and femoral surfaces were also seen on the medial but not the lateral side of the knee.
The group concluded that each one-unit reduction in BMI is associated with a 5–8% decrease in the odds of the incidence and progression of the structural defects of knee osteoarthritis. This supports the idea that weight loss is of benefit in people with and at-risk of osteoarthritis.