Psychological Factors and Pain Exacerbation in Knee Osteoarthritis: A Web Based Case-Crossover Study

Abstract

Purpose: While pain from knee osteoarthritis (OA) has long been considered a persistent condition, the symptoms experienced by OA patients are neither constant nor stable. If the risk factors for these pain exacerbations could be identified and avoided, many such episodes could be prevented. A range of psychological and social environmental processes can potentially affect a patient's response to pain. Using a web based case-crossover approach, we evaluated whether psychosocial factors (specifically pain coping and mood) are risk factors for pain exacerbations in people with knee OA. Method(s): Participants with a diagnosis of symptomatic knee OA (i.e., Kellgren and Lawrence> 2 or radiographic patellofemoral OA and knee pain on most days on the past month) were recruited and followed for 3 months at 10 day intervals (control periods). Subjects were instructed to log on to the study website if they experienced a knee pain exacerbation during the follow-up period (hazard periods). Via the internet we collected data on triggers occurring during "control periods" (i.e., periods without pain exacerbation) and "hazard periods" (i.e., periods immediately preceding the pain exacerbation). Pain exacerbation was defined as an increase of 100 units in a subject's WOMAC knee pain score (VAS 0-500) over the follow-up from his/her mildest pain score reported at the baseline visit. We collected data on potential triggers, including psychosocial factors, on 1 day prior, 2 days prior, and 3-7 days prior to the index dates (i.e., date of pain exacerbation for hazard period, and date of data assessment for control periods). We assessed daily mood (Negative/ Positive) using the Profile of Mood States (PANAS) and pain coping in the previous 30 days using the Pain Coping Inventory. We examined the relation of psychological factors to the risk of pain exacerbation using the conditional logistic regression model. Result(s): Of 267 participants (women: 61%, mean age: 62 years, mean BMI: 29.8 kg/m2) recruited in the study, 160 subjects experienced at least one episode of knee pain exacerbation. Of them 46 subjects had their pain coping assessed 30-days apart between some case periods and control periods. Higher negative affect (mood items e.g., distressed, irritable, nervous) and passive coping strategies (e.g. of items. I restrict my social activities; I focus on the location and intensity of pain) were significantly associated with increased risk of flares (Table). In contrast higher positive affect (mood items e.g., excited, proud, inspired) score and active coping strategies (e.g. of items. I stay busy or active, I clearmy mind of bothersome thoughts) trended to an association with a protective effect from pain exacerbation. Conclusion(s): Our findings demonstrate that a significant and likely clinically important predictive association exists between worsened scores on psychosocial measures (negative mood and the use of passive coping strategies) and OA pain flares. Further work to better elucidate this connection will be important, as psychosocial factors such as mood and pain coping are modifiable and may represent an important target for efforts designed to prevent and treat OA pain flares. (Table presented).