Is the disease-related pain and cortisol levels related in women with osteoarthritis?
Osteoarthritis is a common joint disease affecting mostly the middle aged population which causes the wear and tear of the joint cartilage and underlying bone. A study was performed to study if (1) Osteoarthritis (OA)-related pain is concerned with the diurnal cortisol pattern and cortisol levels; (2) the diurnal pattern of cortisol varies with severity of OA pain and (3) the association between OA pain and cortisol is regulated by daily experience variables (DEV).
Total 31 participants were involved in this study. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale was used to determine the severity of OA-related pain. Multilevel regression analyses estimated relationships between OA pain and diurnal cortisol levels and slopes, controlling for body mass index (BMI), medication use, time and day. Mediation analyses scrutinized DEV as potential mediators of association between OA pain and cortisol.
These participants had mean WOMAC pain subscale score of 8.8. Throughout the day, women with higher WOMAC pain scores had higher cortisol. The approximate association of WOMAC with cortisol [β 0.083(0.02, 0.15) P = 0.009] reveals a ∼9% increase in cortisol for every unit increase in WOMAC pain score. Women with WOMAC pain scores ≥9 had increased cortisol levels than those with scores <9. Investigation of DEV showed no significant mediated associations between these relationships at the daily level.
Hence, disease-related pain is positively associated with cortisol production, particularly with greater pain severity in the woman with OA. Although, future studies are required to discover biologic mediating variables between OA pain and cortisol.