Association between sleep disturbance and new-onset subjective knee pain in Great East Japan Earthquake survivors: A prospective cohort study in the Miyagi prefecture.

BACKGROUND: The Great East Japan Earthquake (GEJE) and Tsunami devastated the northeastern coast of Japan on March 11, 2011. This study aimed to determine whether sociopsychological factors, such as sleep disturbance and psychological distress, influenced new-onset subjective knee pain in survivors during the post-disaster phase of the GEJE.

METHODS: From November 2012 to February 2013 (2 years after the GEJE) and from November 2013 to February 2014 (3 years after the GEJE), survivors (≥18 years) completed self-reported questionnaires. A total of 1470 survivors responded to the questionnaires and were included in this study. New-onset subjective knee pain was defined as knee pain by encircled response absent at 2 years but present at 3 years after the GEJE. Two years after the GEJE, ≥10/24 points on the Kessler Psychological Distress Scale, and ≥6/24 points on the Athens Insomnia Scale defined the presence of psychological distress and sleep disturbance, respectively. Multiple logistic regression analysis was used to estimate the odds ratio (OR) and 95% confidence interval (CI) of the association between new-onset subjective knee pain and psychological distress or sleep disturbance.

RESULTS: Among the participants, 10.9% (160/1470) reported experiencing new-onset subjective knee pain. Sleep disturbance was significantly associated with new-onset subjective knee pain (OR, 1.57, 95% CI, 1.08-2.29, P = 0.017); however, psychological distress was not (OR, 1.07, 95% CI, 0.65-1.78, P = 0.80).

CONCLUSIONS: This is the first study to indicate an association between sleep disturbance and new-onset subjective knee pain among survivors of the GEJE. 247/300.