Population-based, prospective cohort.
To estimate incidence and course of severity-graded low back pain (LBP) episodes in adults.
Past studies report variable estimates that do not differentiate LBP severity.
An incidence cohort of 318 subjects free of LBP and a course cohort of 792 prevalent cases was formed from respondents to a mailed survey. Incident, recurrent, persistent, aggravated, improved, and resolved episodes were defined by the Chronic Pain Questionnaire. The follow-up at 6 and 12 months was 74% and 62%, respectfully. Annual estimates were age and sex standardized.
The cumulative incidence was 18.6% (95% confidence interval [CI], 14.2%–23.0%). Most LBP episodes were mild. Only 1.0% (95% CI, 0.0%–2.2%) developed intense and 0.4% (95% CI, 0.0%–1.0%) developed disabling LBP. Resolution occurred in 26.8% (95% CI, 23.7%–30.0%), and 40.2% (95% CI, 36.7%–43.8%) of episodes persisted. The severity of LBP increased for 14.2% (95% CI, 11.5%–16.8%) and improved for 36.1% (95% CI, 29.7%–42.2%). Of those that recovered, 28.7% (95% CI, 21.2%–36.2%)had a recurrence within 6months,and 82.4% of it was mild LBP. Younger subjects were less likely to have persistent LBP (incidence rate ratio, 0.88; 95% CI, 0.80–0.97) and more likely to have resolution (incidence rate ratio, 1.26; 95% CI, 1.02–1.56).
Most new and recurrent LBP episodes are mild. Less than one third of cases resolve annually, and more than 20% recur within 6 months. LBP episodes are more recurrent and persistent in older adults.
The annual incidence and course of low back pain episodes were investigated in the adult population. The age- and sex-standardized cumulative incidence proportion was 18.6%, and most of it was mild. Resolution occurred in 26.8%, but 28.7% experienced a recurrence within 6 months. While 36.1% showed some improvement, 40.2% remained unchanged and 14.2% got worse.
From the *Division of Outcomes and Population Health, Toronto Western Hospital Research Institute, University Health Network, Toronto, Ontario, Canada; †Department of Public Health Sciences, University of Toronto, Toronto, Ontario, Canada; ‡Section for Personal Injury Prevention, Department of Clinical Neurosciences, Karolinska Institute, Stockholm, Sweden; §Institute for Work & Health, Toronto, Ontario, Canada; and ∥Department of Public Health Sciences and the Alberta Centre for Injury Control and Research, University of Alberta, Edmonton, Alberta, Canada.
Acknowledgment date: August 10, 2004. First revision date: November 22, 2004. Acceptance date: January 11, 2005.
Supported by a research grant from the Chiropractors’ Association of Saskatchewan. Dr. Cassidy is supported by a research fellowship at the University Health Network and was supported by a Health Scholar Award from the Alberta Heritage Foundation for Medical Research. Dr. Carroll is supported by a Health Scholar Award from the Alberta Heritage Foundation for Medical Research. Dr. Côté is supported by the Canadian Institutes of Health Research through a New Investigator Award and by the Institute for Work & Health by the Workplace Safety and Insurance Board of Ontario. Vicki Kristman is supported by a Doctoral Training Award from the Canadian Institutes of Health Research in partnership with the Physical Medicine Research Foundation’s Woodbridge Grants and Awards Program and by the Institute for Work & Health by the Workplace Safety and Insurance Board of Ontario.
The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication.
Professional Organization funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.
Address correspondence and reprint requests to J. David Cassidy, DC, PhD, Division of Outcomes and Population Health, Toronto Western Hospital Research Institute, Fell4–114, 399 Bathurst Street, Toronto, Ontario M5T 2S8 Canada; E-mail: email@example.com