Risk Factors Associated with Clinical Insomnia in Chronic Low Back Pain: A Retrospective Analysis in a University Hospital in Korea

BACKGROUND Insomnia is becoming increasingly recognized as a clinically important symptom in patients with chronic low back pain (CLBP). In this retrospective study, we have determined risk factors associated with clinical insomnia in CLBP patients in a university hospital in Korea. METHODS Data from four-hundred and eighty one CLBP patients was analyzed in this study. The Insomnia Severity Index (ISI) was used to determine the presence of clinical insomnia (ISI score ≥ 15). Patients' demographics and pain-related factors were evaluated by logistic regression analysis to identify risk factors of clinical insomnia in CLBP. RESULTS It was found that 43% of patients reported mild to severe insomnia after the development of back pain. In addition, 20% of patients met the criteria for clinically significant insomnia (ISI score ≥ 15). In a stepwise multivariate analysis, high pain intensity, the presence of comorbid musculoskeletal pain and neuropathic pain components, and high level of depression were strongly associated with clinical insomnia in CLBP. Among these factors, the presence of comorbid musculoskeletal pain other than back pain was the strongest determinant, with the highest odds ratio of 8.074 (95% CI 4.250 to 15.339) for predicting clinical insomnia. CONCLUSIONS Insomnia should be addressed as an integral part of pain management in CLBP patients with these risk factors, especially in patients suffering from CLBP with comorbid musculoskeletal pain.