Background Recent research suggests that knee symptoms in most patients with established OA are stable over the long term . Thus, a person may begin to belong to a particular stable pain/function trajectory before the onset of OA. We hypothesized that diabetes, which is one of the proposed OA risk factors, leads to development of stable knee pain and function impairment in persons with asymptomatic/mildly symptomatic preosteoarthritis.
Objectives To evaluate overall and time-dependent longitudinal effects of diabetes on knee pain and function in persons at risk for OA having no or mild knee symptoms.
Methods For the current analysis we used sample of participants from the Osteoarthritis Initiative (OAI) Incidence Subcohort who had WOMAC pain score <4 at baseline. The evaluated outcomes were WOMAC pain and function subcategories measured annually from baseline to year 5. Participants with self-reported treated diabetes were matched 1:1 to participants who did not report diabetes either at baseline or during the follow-up period. Propensity score matching was performed based on baseline demographic parameters, BMI, history of prior knee surgery, and baseline WOMAC pain and function scores. Longitudinal missing data were imputed using multiple imputation technique. Generalized estimating equations (GEE) were used for regression modelling. To evaluate overall and time-dependent differences between diabetic and non-diabetic participants we used diabetes and diabetes*time (as factor) interaction as predictor variables.
Results Ninety eight OAI participants with diabetes were matched to 98 non-diabetic ones. Participants with diabetes had on average higher WOMAC scores during the follow up (β =0.34, p=0.008). Positive association between diabetes*time and WOMAC pain was significant only on year 1 (β =0.57, p=0.046). Similar overall and time-dependent effects of diabetes were found for WOMAC function scores (β=0.62, p=0.027 and β =0.33, p=0.02 for diabetes and diabetes*time interaction on year 1, correspondingly).
Conclusions In early preosteoarthritis, the detrimental effects of diabetes on knee pain and function reached their plateau during the first year of observation and remained stable thereafter.
Collins JE, Katz JN, Dervan EE, Losina E. Trajectories and risk profiles of pain in persons with radiographic, symptomatic knee osteoarthritis: data from the osteoarthritis initiative. Osteoarthritis Cartilage 2014;22(5):622-30 doi: 10.1016/j.joca.2014.03.009 [published Online First].
Disclosure of Interest None declared
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