Time-of-day effects on the postural control and symptoms in women with rheumatoid arthritis.

ABSTRACT

The present study was designed to assess time-of-day effects on postural balance and symptoms of rheumatoid arthritis (RA) patients. A total of 15 American College of Rheumatology functional class I and II RA patients and 15 healthy controls aged between 45 and 55 (mean age 50 ± 3) years of age voluntarily participated. We conducted a case-control, repeated-measures in design study. Postural balance, axillary temperature, pain intensity, fatigue, and sleepiness were measured during five test sessions at 0600, 1000, 1400, 1800, and 2200 h. Participants were randomized to the order of test sessions, and each session was separated by >36 hours to minimize/eliminate learning effects. Center of pressure area (CoParea) (p < .001), pain (p < .01), and sleepiness (p < .05) values were significantly higher at 0600 and 2200 h compared to 1000, 1400, and 1800 h in the RA group. Fatigue significantly increased (p < .05) at 2200 h in comparison to 1000, 1400, and 1800 h in the RA group. Axillary temperature was significantly (p < .001) lower at 0600 and at 2200 h compared to 1000, 1400, and 1800 h in the RA group. In the control group, there were no significant time-of-day difference in fatigue, but axillary temperature was significantly lower (p < .01) at 0600 h compared to 1000 h, 1400, 1800, and 2200 h, sleepiness values were significantly higher (p < .05) at 0600 and 2200 h compared to 1000, 1400, and 1800 h, and revealed CoParea values were significantly (p < .05) higher at 0600 h compared to 1400 h. Finally, in the RA group, significant correlations were found between values of CoParea and pain (r = 0.47; p < .001), sleepiness (r = 0.39; p < .01), fatigue (r = -0.46; p < .001), and also axillary temperature (r = -0.35; p < .001). Multiple linear regression analysis further indicated that in the RA group, time-of-day variation in postural balance was predicted collectively by that in pain and fatigue (30.7%) (R2 = 0.307; F = 11.53; p < .001). Our results first suggest that time-of-day significantly affects postural balance, axillary temperature, pain intensity, fatigue, and sleepiness in RA patients and second that the temporal variation observed in pain, fatigue, and somnolence are concomitant with that observed in postural balance.Abbreviations RA Rheumatoid arthritis; H&O questionnaire Horne and Ostberg questionnaire; PSQI Pittsburgh sleep quality index; HAQ Health assessment questionnaire; SF-36 the short form-36; WOMAC Western Ontario and McMaster Universities Osteoarthritis Index; CoP The Center of foot Pressure; CoParea The Center of foot Pressure area; VAS The Visual Analogue Scale; KSS Karolinska Sleepiness Scale.