Prevalence of insomnia in patients with chronic back pain.

PURPOSE To estimate the prevalence of insomnia in patients with chronic back pain, and to correlate insomnia with severity of back pain and disability. METHODS 63 women and 57 men aged 24 to 83 (mean, 55) years who presented with chronic back pain for >6 months were asked to complete a self-administered questionnaire to evaluate the Insomnia Severity Index (ISI), Oswestry Disability Index (ODI), and Numerical Rating Scale (NRS) for back pain. RESULTS Of the 120 patients, 25 had no insomnia, 39 had sub-threshold insomnia, and 56 had clinically significant insomnia. According to the ODI, disability was minimal in 12 patients, moderate in 38, severe in 43, bed-binding in 26, and crippling in one. Of the 120 patients, 91 rated their NRS for back pain as 5 to 10 and 29 rated it as 1 to 4. Correlation was stronger between ISI and ODI than between ISI and NRS for back pain (r=0.59 vs. r=0.38). CONCLUSION 47% of patients with chronic back pain had insomnia. The ODI was more reliable than the NRS for back pain to detect insomnia. Back pain should be treated early to avoid serious health problems associated with insomnia.