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

Abstract

Objectives: The pain experienced by osteoarthritis (OA) patients is neither constant nor unchanging and patients experience episodes of pain exacerbations. Using an innovative web based case-crossover design, we evaluated whether psychological factors are risk factors for pain exacerbations in patients with knee OA. Methods:In a 3-months internet-based case-crossover study, participants with symptomatic knee OA were recruited and followed at 10-day intervals (control periods). Participants were also instructed to log on to the study website if they experienced a knee pain exacerbation (case periods). Pain exacerbation was defined as an increase of ≥ 2 on a participant's numerical rating scale (0-10) from his/her usual background pain score reported at baseline visit. The periods were 10 days for affect measures and 30 days for pain coping/perceived stress measures. The relation of psychological factors to the risk of pain exacerbation was examined using conditional logistic regression. Results:Of 298 participants recruited, 149 and 54 provided both case and control periods with no overlap for examining affect and pain coping/perceived stress factors respectively. Higher negative affect (negative affect score ≥ 18: odds ratio (OR) 6.49; 95% CI 3.45-12.2) and passive coping strategies (OR 1.26; 95% CI 1.05-1.50) were associated with increased risk of pain exacerbations; while higher active coping strategies (OR 0.81; 95% CI 0.66-0.98) had a protective effect. Conclusion:The findings emphasize the need for avoidance of negative affect and passive pain coping strategies and conversely reinforce the benefit of active pain coping strategies in prevention and management of OA pain exacerbations.