Nocturnal pain in patients with osteoarthritis of knee and/or hip: an exploratory cross-sectional study

Abstract

Background: Nocturnal pain is common in patients with osteoarthritis (OA) of knee and/or hip. Despite its impact on quality of life in patients with knee and/or hip OA, nocturnal pain is still under-investigated. Qualitative research shows nocturnal pain might differ from daytime pain. Aim: To explore characteristics of nocturnal pain and to identify differences in patient characteristics and OA symptoms between patients with and without nocturnal pain in patients with knee and/or hip OA. Method: An exploratory cross-sectional study was conducted in subjects with (self-reported) knee and/or hip OA. A survey was spread through social media. Intensity, localization, dimension, and impact on sleep of nocturnal pain were described and compared to daytime pain. A comparison is made between participants with and without nocturnal pain considering participant characteristics and OA symptoms. Between-group differences were assessed using Student’s t-tests (for continuous variables) and Pearson’s chi-squared tests (for categorical variables). Results: Out of 230 respondents, 123 (89 knees and 34 hips) subjects were included in this study. Mean age was 61.6 years, mean OA symptoms longevity was 7.3 years, and 78% of respondents reported nocturnal pain. Participants with nocturnal pain reported higher visual analogue scale scores for nocturnal pain than for daytime pain (p=0.01). Contrarily, pain rating indexes of sensory-discriminative dimension showed higher intensity of daytime pain (p<0.01). Comparison between participants with and without nocturnal pain showed significant between-group differences on the Intermittent and Constant OA questionnaire (p<0.01), comorbidities (p<0.001), and Knee injury/Hip disability and OA Outcome Score subscales pain (p=0.01), activities in daily life (p<0.01), and quality of life (p=0.04). Conclusion: In comparison with daytime pain, participants reported contradicting scores of intensity of nocturnal pain. Comparing participants with and without nocturnal pain, indications were found that participants with nocturnal pain had more often comorbidities, more pain-related problems, more disabilities in daily life, and less quality of life, but larger research is needed to support these findings. Key findings: Our study is first to explore characteristics of nocturnal pain in patients with knee and/or hip OA. Moreover, our findings showed significant differences in OA symptoms between participants with and without nocturnal pain.