A structured review of the epidemiologic literature was performed. Thirty-eight studies published in peer-reviewed journals were reviewed. The methodologic strengths and weaknesses of the studies were described and assessed qualitatively. Four studies were excluded because of difficulties in design or interpretation.
To provide a systematic analysis of the literature to assess the evidence as to whether smoking is associated with the prevalence and incidence of nonspecific back pain and related outcomes.
Evidence has been gathering regarding the association of smoking with nonspecific back pain and other back disorders, but a comprehensive summary and evaluation of the data have not been published.
Positive associations between current smoking and nonspecific back pain were found in 18 of 26 studies in men and 18 of 20 studies in women. For sciatica and herniated discs, there were four of eight and one of five positive studies in men and women, respectively. The majority of these studies were cross-sectional (18 in men and 16 in women), with only a handful of prospective studies. Positive associations between past smoking and nonspecific back pain were reported in five of nine studies in men and five of six studies in women. In addition, increases in the prevalence and/or incidence of nonspecific back pain were found in the majority of studies in which level of consumption was analyzed and reported. An attempt was made to assess whether these results could be artifactual arising from selection bias, confounding bias, publication bias, or errors in measurement. As well, the biologic mechanisms were summarized that have been suggested by various investigators.
The available data are consistent with the notion that smoking is associated with the incidenceand prevalence of nonspecific back pain, but there are too few studies to make any conclusions for the other end points (e.g., sciatica, herniated discs). It cannot be ruled out that the association is a statistical artifact arising from either selection or confounding factors, because the evidence for nonspecific low back pain derives mostly from cross-sectional studies. In addition, it cannot be stated unequivocally that smoking preceded back pain. Long-term follow-up studies are needed to eliminate the possibility that chronic back pain preceded smoking, to better estimate dose–response correlations, and to perform biologic measurements to elucidate possible mechanisms.
From the *Epidemiology and Biostatistics Unit, Research Centre on Human Health, INRS-Institut Armand-Frappier, University of Quebec, Laval, Quebec; the †Department of Epidemiology, Biostatistics and Occupational Health and the §Department of Medicine, McGill University, Montreal, Quebec; and the ‡Department of Clinical Epidemiology, Division of Medicine, The Royal Victoria Hospital, McGill University Montreal, Quebec, Canada.
Acknowledgment date: February 17, 1998.
First revision date: September 3, 1998.
Acceptance date: July 21, 1999.
Address reprint requests to
Dr. Mark Goldberg
Epidemiology and Biostatistics Unit
Research Centre on Human Health
University of Quebec
531, boulevard des Prairies
Laval, Quebec, Canada H7V 1B7
Funding for this review was provided in part by a grant from the National Health and Research and Development Program (NHRDP) of Health Canada (project number 6605–4166-55) and from a contract with the Attorney General of Washington State.
Dr. Goldberg received support from NHRDP through a National Health Research Scholar Award and from les Fonds de la recherche en santé du Québec (FRSQ), and Dr. Mayo is the recipient of a Health Scientist Career award from the FRSQ.
Device status category: 1.
Conflict of interest category: 14.