Physical exercise promotion and related health benefits for people with knee osteoarthritis and additional other chronic non-communicable diseases: a pilot study

Purpose: Multimorbidity, the simultaneous occurrence of more than 2 diseases, is no longer an exception. Especially non communicable chronic diseases like Osteoarthritis (OA), Diabetes mellitus Type 2 (DMT2), overweight (OW) and obesity (OB) as well as cardio-vascular diseases (CVD) are examples of the most prevalent chronic conditions in industrial nations. The treatment of multimorbidity has not gained much attention in research so far. Especially conservative therapies other than medication have not been established for this specific population. Physical exercise (PE) has been shown to be a treatment option with little adverse events and many positive effects for many single diseases, and physical activity (PA) promotion in general has found its way in many disease management programs. However, a shortfall of research on the effectiveness of specific PE interventions in the treatment of multimorbidity must be stated. The objective of this study therefore was to evaluate a pilot model aiming for behavior change towards the initiation and maintenance of regular PE and its related health benefits in patients with multimorbidity. This abstract focuses on a subsample of participants with knee osteoarthritis. Strength measures of the knee flexors and extensors and self-reported disease related symptoms were analyzed. Methods: Participants with at least two severe risk factors or manifested disease signs for hip and/or knee OA, DMT2, OW/OB, CVD were included in the study. The following analysis relates to the subsample of subjects with or at risk for knee OA. The intervention consisted of two 12-week successive phases. The first phase included different types of supervised aerobic and strength training sessions. Dosage parameters were based on the national PA recommendations. The intervention further comprised theoretical background information on training science, nutrition and behavioral change techniques as well as two personal counselling sessions with the aim to enable participants towards an autonomous exercise participation. The second intervention phase enhanced the self-organized maintenance of the same level of PE. In this phase, participants were contacted via email on a regular base. They received weekly training logs and feedback on their logs as well as another personal counselling session. Data were assessed at baseline (t0), after the first (t3) and after the second intervention phase (t6). Outcomes of this analysis relate to self-reported disease-related symptoms (WOMAC subscale pain and physical functioning) and isometric peak torque measures for knee flexion and extension. The study was conducted in two recruitment waves for organizational reasons. Due to the Covid-19 induced nationwide contact restrictions, strength measures could not be assessed for wave two at t3 in March 2020, therefore only t6 was used for further analysis of strength measures. Wilcoxon Tests were calculated for non-parametric data to assess the changes between t0-t3 and t0-t6. Effect sizes were calculated using r. The study is registered at the German clinical trial register (DRKS00016702). Results: N=39 patients were included in the study, thereof n=23 participants (females=19, males=4) showed disease signs or self-reported risk factors for knee OA. The mean BMI of them was 30.3 ± 3.2 kg/m2 and the mean age was 58.3 ± 6.3 years. Of the subsample, n=22 were also overweight or obese, n=16 had a diagnosis of hypertension, n=2 were diagnosed with DMT2 and n=16 had an elevated risk for DMT2. The WOMAC score was not answered by three participants at t3. One participant did not perform the knee extension test due to pain at t0 and t6. One participant did not perform the isometric torque at t6 due to an elevated blood pressure. 2 participants were lost to follow-up due to family illness (n=1) and shortage of time caused by Covid-19 induced overtime (n=1) and did not provide any data at t6. Median values for WOMAC pain decreased from t0 to t3 but not from t0 to t6, this was not statistically significant. The decrease for the subscale physical function from t0 to t3 and t6 was not statistically significant as well (Table 1). [Formula presented] There was a statistically significant change for isometric peak torque of knee extension. Strength values for knee flexion increased as well, however this was not statistically significant (Table 2, Figure 1). [Formula presented] [Formula presented] Conclusions: Results of this study indicate that a systematic, initially supervised training can lead to objective health benefits in people with knee OA and multimorbidity. Participants of the study showed an increase in maximal isometric force of knee extension with a large effect size. This is an important finding for patients with risk factors as well as already manifested knee OA, as quadriceps strength is known as a protective factor for knee OA and its progression. Results for the WOMAC showed marginal improvement throughout the intervention period. The majority of people only had minor complaints at the beginning of the study, reducing the potential for positive change. One limitation of the study is the onset of the Covid-19 related contact restrictions that prohibited strength measures as well as physical exercise training sessions in gyms and other public places for participants of wave 2 from the 9th intervention week on. The influence of this force majeure on the results of the study cannot be conclusively assessed at this point. Further limitations are related to the small sample size, especially for the subgroup of patients with OA, and the lack of a control group. This was a pilot study for a randomized controlled trial in health services research which is already initiated. Results of this pilot trial therefore indicate the feasibility and the potential benefit of this intervention for multimorbid patients with knee OA that will now be implemented and evaluated in a real health services setting in the near future.