Results and perspective
Dr. Kamps and associates performed a nested case-control study using data from a large Dutch general practice database. All new cases of OA – which included hip, knee, and other peripheral OA – that were logged between the start of 2006 and the end of 2019 were considered and matched to one to four control subjects of a similar age, sex, and type of general practice. In all, there were just under 80,000 people with newly diagnosed OA who were matched to just over 318,000 controls; the mean age in both groups was 64 years.
Of 58 comorbidities that were assessed, 42 showed a positive association with OA and had odds ratios of 1 or more. The highest associations were found for fibromyalgia (OR, 1.9), obesity (1.8), polymyalgia rheumatica (1.5), spinal disc herniation (1.4), and gout (1.4). A further 13 comorbidities had an OR of about 1, and 3 (all neuropsychiatric conditions – dementia, schizophrenia, and multiple sclerosis) had an OR of below 1.
Dr. Kamps conceded that this type of research has its limitations, the two most important being the coding behavior of the GP and the consulting behavior of patients.
“It’s known that the prevalence of osteoarthritis is underestimated if you only use the diagnostic codes, because some GPs will write the diagnosis in free text or use symptom ICPC codes,” she said.
“We have matched on general practice, so the cases and controls were from the same general practice and therefore we hope that this potential underestimation is balanced and did not affect our odds ratios.”
One of the important outcomes for this research is that it will hopefully be used to inform future clinical practice guidelines, said Dr. Dell’isola.
“Guidelines in osteoarthritis report that is important to screen for comorbidities, but they give no indication on how to deal with the presence of multimorbidity,” he added. Looking at which comorbidities may be associated with OA diagnosis could potentially help to give a bit more of a prescriptive guide on what to look out for.
“Maybe people with a certain disease profile should be screened a bit more often by their doctor. For example, if someone has their blood pressure and diabetes under control, maybe there should be also a bit more attention to their joint health and encouragement to do exercise, not only for being active per se, but maybe also to reinforce their lower limbs,” he explained.
The study was funded by the Foundation for Research in Rheumatology (FOREUM). Dr. Kamps and Dr. Dell’isola, had no conflicts of interest to disclose.