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Low Back Pain After Traffic Collisions: A Population-Based Cohort Study

Cassidy, J. David, DC, PhD*†‡; Carroll, Linda, PhD*; Côté, Pierre, DC, PhD§; Berglund, Anita, PhD; Nygren, Åke, MD, PhD

doi: 10.1097/01.BRS.0000061983.36544.0D
Occupational Health/Ergonomics

Study Design. A population-based, incidence cohort study was conducted.

Objective. To measure the incidence and prognosis for collision-related low back pain before and after a change in the insurance compensation system.

Summary of Background Data. Low back pain is a common and costly occupational injury. It also occurs after traffic collisions, but less is known about its frequency and recovery in this setting.

Methods. An incidence cohort of 4473 low back pain injury claims was formed between July 1, 1994 and December 31, 1995 in Saskatchewan. On January 1, 1995 the public insurance system changed from a tort system to a no-fault system, eliminating compensation for pain and suffering. The incidence of claims and the time to claim closure were calculated before and after this change. Prognostic models were built using baseline and follow-up data.

Results. The 6-month incidence of claims decreased from 256 to 176 per 100,000 after the insurance change. The median time to claim closure dropped from 505 days for tort claims to 210 days and 216 days for claims made during the first and second 6 months of the no-fault period. Improvements in bodily pain and physical functioning and the absence of depressive symptoms were associated with faster claim closure. High pain intensity, female gender, full-time employment, concentration problems, and lawyer involvement early in the claim process delayed claim closure.

Conclusions. Low back pain is a common traffic injury with a prolonged recovery. Its incidence and prognosis are affected by multiple factors, including the type of compensation system. Our study suggests that biopsychosocial factors are important in determining prognosis.

From the *Epidemiology Program and the Alberta Centre for Injury Control and Research, Department of Public Health Sciences, University of Alberta, Edmonton,

the †Division of Rheumatology, Department of Medicine, University of Alberta, Edmonton,

the ‡Section for Personal Injury Prevention, Karolinska Institutet, Stockholm,

and the §Institute for Work and Health and the Department of Public Health Sciences, University of Toronto, Toronto.

This work was supported by a grant from Saskatchewan Government Insurance. Drs. Cassidy and Carroll are supported by Health Scholar Awards from the Alberta Heritage Foundation for Medical Research. A PhD training award from the Canadian Government’s National Health Research Development Program supported Dr. Côté.

Acknowledgment date: June 14, 2002.

First revision date: September 20, 2002.

Acceptance date: November 5, 2002.

Device status/drug statement: The submitted manuscript does not contain information about medical devices or drugs.

Conflict of interest: Other 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 article.

Address correspondence and reprint requests to J. David Cassidy, DC, Department of Public Health Sciences, University of Alberta, 3080 RTF, 8308-114 Street, Edmonton, Alberta, T6G 2E1 Canada; E-mail

© 2003 Lippincott Williams & Wilkins, Inc.