Introduction: Research concerning the development of low back pain (LBP) has traditionally focused on risk factors in search of explanations. This review focuses on comorbidity as a first step in identifying a frail subpopulation with a higher risk of developing low back pain, in particular persistent low back pain. Research into comorbidity might yield a greater understanding of the underlying mechanism for low back pain. Data sources Medline was searched from the beginning of the data base to December 2000, followed by a search through the authors' personal collections of epidemiologic literature regarding low back pain. All articles written in English were included if they related LBP to at least one other physical disorder. Articles were excluded if the prevalence of such disorders could not be compared to that of a control group or to the expected prevalence in a normal population. Data extraction The retrieved articles were evaluated for quality based on predefined methodological criteria, whereupon information about associations between low back pain and other physical disorders was extracted.
Results: Twenty-three articles were included. They showed positive associations to all disorders investigated (headache/migraine, respiratory disorders, cardiovascular disease, general health, and others) with the exception of diabetes. There was very little information regarding temporality, therefore there are no clues as to causal mechanisms.
Conclusion: The literature leaves no doubt that diseases cluster in some individuals and that low back pain is part of this pattern. However, the nature of the relationship between low back pain and other disorders is still unclear.