Investigating predictors of pain events during trials of knee osteoarthritis: A post-hoc analysis of two phase III trials.

Objective: This study aims to explore the associations between clinical characteristics, including medical history, and the frequency, severity, and type of pain events (PEs) over a two-year period in patients with knee osteoarthritis (OA). Design: A post-hoc analysis was conducted on data from two double-blinded, randomized, placebo-controlled, multicenter phase-III trials assessing the efficacy and safety of salmon calcitonin in patients with painful and radiographic knee OA. 2206 patients aged 51-80 years were included. Adverse events (AEs) were recorded and categorized into PEs and non-PEs. Logistic regression models were used to assess associations, adjusting for confounders such as age, sex, and body mass index (BMI). Results: Of the 8183 AEs recorded, 27.6 % were classified as PEs. Higher BMI was associated with lower odds of reporting PEs (OR: 0.94, p = 0.02), while male patients reported fewer PEs than females (OR: 0.83, p = 0.04). Insomnia and depression were linked to increased odds of PEs. In the PE population, higher BMI was associated with increased odds of moderate and severe PEs. KL grade 3 was linked to lower odds of moderate and severe PEs. Conclusions: The study identifies female sex and certain medical histories as significant predictors of PEs in knee OA patients. A higher BMI was associated with lower odds of reporting PEs but for those who reported PEs, higher BMI was associated with more severe PEs. These results should be interpreted with caution due to methodological limitations, however the findings indicate risk factors for pain events and suggest further research into these associations.