Frequency and interrelations of risk factors for chronic low back pain in a primary care setting
From: PLoS ONE. 2009;4(3):e4874. Epub 2009 Mar 16
General practitioners are often consulted for low back pain. The point prevalence of low back pain is reported to be about 15% to 30% in the Western world. For about 6% to 10% of patients, the disease may recur or become chronic and the demand on the health-care system is great and costly. These patients are also a cause of major disability and absence from work. Fewer than half of individuals disabled for longer than 6 months return to work, and after 2 years of absence from work, the return-to-work rate is close to zero. Moreover, back pain is the most common chronic illness in subjects younger than 65 years.
Early identification of risk factors for chronic low back pain is important in understanding and preventing the progression to chronic disease and disability.
Many studies in Western industrialized countries have attempted to identify risk factors for low back pain, with a good evidence of relation between chronic low back pain and history of low back pain (including pain severity, duration, disability, leg pain, related sick leave and history of spinal surgery), low level of job satisfaction and poor general health. Only moderate evidence exists for a relation between chronic low back pain and psychosocial factors such as employment status, amount of wages, workers’ compensation, and depression or physical factors such as lifting time per day and work posture.
The literature on risk factors for chronic low back pain is abundant with numerous prospective studies done on relatively small samples of patients assessing only a specific category of chronic low back pain risk factors. Moreover, the major drawback in prospective and cross-sectional studies of chronic low back pain risk factors is the use of simplistic methodological approach without considering the interrelations of the known risk factors. These studies do not allow for analyzing the structure of the existing relations between risk factors and discovering the underlying dimensions explaining the links between risk factors.
This study considered all the previously identified chronic low back pain risk factors and aimed to investigate their frequency and their interrelations with adapted multiple correspondence analysis in a French national sample of patients consulting their general practitioners for chronic low back pain.
This cross-sectional national study in a large sample of chronic low back pain patients in primary care confirmed a high frequency of previously identified risk factors, which suggests that our sample resembles those previously reported on this topic. The strength of this study is the variety of risk factors addressed and the use of multiple correspondence analysis, which allows for analyzing the interrelations among these risk factors by defining dimensions of risk factors for chronic low back pain and determining the contribution of each risk factor to the dimensions. Very few surveys examined the interrelation of identified chronic low back pain risk factors and evaluated the contribution of risk factors to professional, medical and psychological dimensions of chronic low back pain.
The literature on risk factors for chronic low back pain is abundant, but numerous prospective studies assessed only a specific category of chronic low back pain risk factors (professional, psychological or medical). These studies give only limited information because they do not allow for 1) analyzing the structure of the existing relations between all the risk factors or 2) discovering the underlying dimensions explaining the interfactor links. For example, in the prospective study of Valat et al., which is methodologically valid, the authors selected explicit risk factors using only statistical criteria. Thus, they did not (wrongly) take into account an important clinical factor “satisfaction with professional activity” because it was not found to be statistically significant. Moreover, no psychological factor was studied to explain “chronicity”. This study, although methodologically valid, does not take into account several risk factors previously identified.
The strength of the multiple correspondence analysis was its ability to examine the relevant importance of work-related factors in the working population as compared with psychological and other social factors. Indeed, multiple correspondence analysis analysis revealed that the “work-related” dimension was the most important for patients with chronic low back pain. Poor job satisfaction and lack of recognition at work contributed largely to this dimension, which suggests that “social work-related” factors probably weigh more than “physical work-related” ones. Moreover, patients with more than 2 years’ duration of chronic low back pain tended to report dissatisfaction with their jobs more often than those with 2 years’ or less duration. Our results are in agreement with other studies showing poor job satisfaction and lack of recognition associated with chronic low back pain.
Among professional factors, beliefs about the harmfulness of posture and physical activities as being responsible for chronic low back pain were frequently cited and largely contributed to the “work-related” dimension. These results are in accordance with those from an increasing number of studies concerning the influence and consequences of pain-related fears and associated avoidance behavior in the development and maintenance of disabling low back pain. Self-reported feelings of disability and irrational and/or negative beliefs about pain such as kinesiophobia and fear avoidance have been associated with chronic evolution of low back pain. This the first report comparing the contribution of these risk factors with other risk factors.
As expected, a history of anxiety and depression largely contributed to the “psychological” dimension. Relationships with employers and co-workers, categorized as professional factors, also contributed to this dimension. Indeed, these variables could reflect more general behavioral attitudes with others than specific work-related attitudes.
The “health-related” dimension was the least important in this sample. This dimension concerned previously identified medical risk factors such as pain intensity or presence of sciatica at the onset of the current episode of low back pain, initial limitation of ADL, history of recurrent low back pain, absence from work due to low back pain before the current episode and history of lumbar spine surgery.
For the nonworking patients, multiple correspondence analysis revealed that general practitioners’ poor opinion of their patients’ general health status represents a dimension by itself. Poor general health status has already been reported as a risk factor of severity in several pathologic situations, but this is the first report to describe the contribution of this risk factor in terms of other risk factors. As was observed for working patients, for nonworking patients, the second and third dimensions were the “psychological” and “health-related” dimensions, with history of anxiety and depression largely contributing to the “psychological” dimension.”
The results shed light on the interrelation and respective contribution of several previously identified risk factors for chronic low back pain. They suggest that risk factors representing a “work-related” dimension are the most important risk factors for chronic low back pain in the working population. Among these factors, patients’ job satisfaction and job recognition largely contribute to this dimension and must be considered in prospective studies. Such feelings about professional conditions in low back pain patients should be systematically recorded and taken into account by professionals. As previously recommended by the European guidelines for the management of low back pain, educational and behavioral therapy programs on these topics should be proposed and evaluated in chronic low back pain.
