Can the Assessment of the Circadian Rhythm of Pain Be Shortened? A Study of Community-Dwelling Participants with Chronic Pain

Yoichi Tanaka,1,2 Ren Fujii,2,3 Hayato Shigetoh,2,4 Gosuke Sato,2 Shu Morioka2 1Department of Occupational Therapy, School of Rehabilitation, Hyogo Medical University, Hyogo, Japan; 2Neuro Rehabilitation Research Center, Kio University, Nara, Japan; 3Musashigaoka Clinical Research Center, Musashigaoka Hospital, Kumamoto, Japan; 4Department of Physical Therapy, Faculty of Health Science, Kyoto Tachibana University, Kyoto, JapanCorrespondence: Yoichi Tanaka, Department of Occupational Therapy, School of Rehabilitation, Hyogo Medical University, 1-3-6 Minatojima Chuo-ku, Kobe, Hyogo, Japan, Tel +81 78-304-3180, Email yi-tanaka@hyo-med.ac.jpPurpose: This study aimed to juxtapose the circadian rhythm of pain with the conventional 7-day assessment and ascertain the feasibility of condensing the evaluation of the circadian rhythm of pain into a 3-day timeframe.Patients and Methods: Seventy-three patients with pain persisting for a minimum of 3 months and a numerical rating scale (NRS) score of ≥ 2 were recruited from three medical centers. The circadian patterns of pain were appraised over a 7-day period by quantifying the intensity of pain at six temporal junctures each day using a 10-cm visual analog scale (VAS). Cluster analysis was performed using six standardized variables derived from the VAS score of each participant at six designated time points to identify cohorts with analogous circadian rhythms of pain. The clusters were discerned for the 7- and 3-day assessments (Tuesday–Thursday, Friday–Sunday, and Sunday–Tuesday), according to the research objectives. Cohen’s kappa coefficient was calculated to gauge the intra-observer variability to assess the consistency between the outcomes of the cluster analysis for the 7-day assessment and each of the 3-day assessments.Results: The highest Cohen’s kappa coefficient was observed for the 3-day evaluation spanning from Friday to Sunday, indicating a substantial concordance with the results of the 7-day assessment.Conclusion: Our results suggest that it may be prudent to consider implementing a condensed 3-day evaluation of the circadian rhythm of pain that is tailored to individual characteristics. This approach will allow a better understanding of the diurnal rhythms of chronic pain in patients and implement more targeted and specific pain management strategies. Furthermore, it will contribute to increased patient satisfaction through early intervention.Keywords: pain, chronic pain, physical activity, circadian rhythm