A 5-Year Longitudinal Study of Knee Pain Among Natural Disaster Survivors

Abstract Background: Knee pain is a common symptom among natural disaster survivors as well as general population. However, its long-term course is unclear. The purpose of this study was to clarify the course of knee pain, especially focusing on the association between prior and subsequent knee pain, among people living in disaster-stricken areas. Methods: This was a 5-year longitudinal study of 1,821 participants. Knee pain was assessed at two, four, and seven years after the Great East Japan Earthquake. Multiple logistic regression analyses were examined to assess the association of knee pain at two and five years after the disaster and knee pain at seven years after the disaster. Results: The prevalence of knee pain was 18.0%, 18.2%, and 19.7% at two, four, and seven years after the disaster, respectively. Throughout the 5-year period, 34.7% of the participants had knee pain at any time point and 6.2% had knee pain at all three time points. Knee pain at two and four years after the disaster was significantly associated with knee pain at seven years after the disaster (adjusted odds ratios (95% confidence intervals): 3.17 (2.32–4.34) for knee pain at either of the two time points and 12.49 (8.42–18.54) for knee pain at both time points (p for trend <0.001)). Conclusions: In the present 5-year cohort study, the prevalence of knee pain was gradually increased. Among the people with knee pain at any time point, approximately one fifth of them had consistent pain. Prior knee pain was associated with subsequent knee pain, which was stronger in those with more prior knee pain episodes. Clinicians should pay attention to prior knee pain episodes to consider methods to treat knee pain.