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- PATIENTS AND METHODS
Low back pain (LBP) affects 80% of the population at some time (1), and is one of the most frequent reasons both for consulting a primary care physician and for taking time off work (2). The LBP “epidemic” (3), observed in most industrialized countries, and the huge resulting costs led to substantial research starting in the 1960s concerning determinants, preventive maneuvers, and treatments. However, this research mainly focused on biomechanical determinants and was largely sterile. In the meantime, “practice variations, treatment fads and rising disability” were observed (4). The recent US and UK guidelines for management, which propose a de-escalation in diagnostic and therapeutic approaches to this condition, illustrate the failure of the traditional, biomechanical paradigm for conceptualization and management of LBP (5). The role of psychosocial factors in the development of chronic disability and the demand for health care and financial compensation has increasingly become recognized (3, 6–11) and a biopsychosocial analysis of LBP has been suggested (12).
It would therefore be useful to explore health-related quality of life (HRQOL) in relation to LBP (13, 14). HRQOL measurement instruments have been developed over the past 20 years to assess self-perceived health status and its components, such as physical functioning (ability to carry out activities of daily life), psychological functioning (emotional and mental well-being), social functioning (relationships with others and participation in social activities), perception of health status, and pain (15). Measurements of self-perceived health status have been widely used to evaluate the broad impact of various diseases on patients and the effectiveness of interventions (15). In contexts other than LBP, these measurements have recently been shown to predict the outcome of surgical procedures and to be related to the extent of seeking and satisfaction with care associated with various conditions (16–18). This approach may be useful in understanding the natural history of LBP, and HRQOL measurements could help improve the clinical management of patients by extending the assessment process beyond traditional, and clearly insufficient, clinical and functional disability variables.
HRQOL has not previously been evaluated as a predictor of recovery following acute LBP. It is possible that self-reported HRQOL at initial presentation may be a valuable tool for assessing the prognosis of an acute LBP episode. Also, the time course of the impact of the acute LBP episode on HRQOL and its components has not been documented using standard generic instruments, such as the Short Form 36 health survey (SF-36). The identification of factors predictive of a higher impact of LBP on HRQOL would be of great value for defining management strategies.
We report a study with 2 goals: 1) to determine the contributions of biologic and several psychosocial factors, especially HRQOL variables, to the natural history of acute LBP and recovery; and 2) to evaluate the impact of acute LBP on HRQOL. To avoid the main biases of cohort studies (19), we assembled, and for 3 months carefully followed, an inception cohort of patients with acute LBP treated symptomatically and exclusively with acetaminophen.
- Top of page
- PATIENTS AND METHODS
This inception cohort study of acute LBP with complete followup yielded 2 major findings. First, it highlights the large contribution of several psychosocial factors, including work-related factors and especially HRQOL, to the prognosis of LBP. Second, it suggests that LBP impairs HRQOL, especially through temporary compensation and inappropriate biomechanical medical care and that, in turn, impaired HRQOL predisposes the condition to become chronic.
As in a previous study using the same inception cohort design (17), the recovery rate among patients with acute LBP was high: 90% in 2–4 weeks. This is mainly because these studies, unlike others, included truly incident cases and excluded exacerbated chronic LBP and sciatica, which are distinct conditions (24). Acute isolated LBP appears as a condition where the biopathologic course of the natural history is spontaneous recovery. Note that this biologic core of the condition is best assessed by a specific disability measure, such as the RDQ (which has a better predictive value than the SF-36 physical functioning scale and better than pain and clinical symptoms/signs assessment) (7, 27).
Previous back surgery is also a prognostic factor of the LBP episode. This is consistent with certain individuals being highly prone to develop chronic LBP, as previously suggested (7, 27–30). It may also indicate a delayed risk of chronic LBP following back surgery and a iatrogenic component to the process of becoming chronic.
Temporary compensation status appeared in this study, as in many others (7, 24, 28, 31, 32), to hamper recovery substantially. This result is consistent with the extensive scientific evidence against the concept of work injury or accident (33). Our finding is original that HRQOL, and especially the general health scale of the SF-36, is more predictive than objective measures of health, such as treated comorbidities. It suggests that the psychological perception of health makes a major contribution to whether LBP becomes chronic. Self-rated health, with psychological distress, was described as an important predictor of persistent disabling LBP in a previous study (9).
HRQOL also appears a determinant of consultation for LBP and therefore of its inclusion as a medical problem. Our finding of lower than expected scores for several HRQOL components during the month preceding the LBP episode is consistent with several other studies that showed that consultation for LBP may be determined by factors other than LBP symptoms and disability (34–36).
Note that none of the many physical symptoms or signs recorded in this study was predictive of recovery. This result suggests that the identification of the underlying mechanical cause of the pain, i.e., discogenic or facet disease, may be of little interest in this context.
The direct impact on HRQOL of the morbidity of the acute LBP episode, the biologic core itself, appeared short and moderate. Conversely, more profound and lasting was the impact of compensation status and biomechanically oriented medical prescription (sick leave, bed rest). The uselessness and even the negative effect of sick leave and bed rest (compassionate but iatrogenic) (37, 38) and temporary compensation has been demonstrated in acute LBP. These factors contribute to the memorization (33) or stigmatization (39) of LBP and appear to be highly deleterious, as impaired HRQOL was found to be predictive of delayed recovery. Also, the impact of LBP on HRQOL was more profound in medically frail (comorbidity, psychiatric disorders) and culturally or socially marginalized (foreign, unemployed, job dissatisfied) patients.
This study has several limitations. First, the sample studied cannot be considered representative of the general population of acute LBP patients. These unselected self-referred patients were only included if this episode was their first contact with the health system for LBP. Therefore, they constitute the least biased population of LBP patients entering the French health care system for LBP. Nevertheless, all the subjects sought medical care, and this may cause bias for various socioeconomic factors (40). In particular, patients with compensation or work issues were probably overrepresented in the sample, and this could make the apparent prognosis worse than it really is. In contrast, the exclusion criteria, including illiteracy, have led to a clear underrepresentation of poorly educated and foreign-origin patients, who may have poorer prognoses than studied subjects.
Second, the patients received no treatment other than acetaminophen and no recommendation was given to the practitioners regarding bed rest and sick leave. This choice was consistent with our research aim (to study the natural history and test the influence of these 2 factors), but limits the generalization of our results: many adjuvant treatments (of doubtful efficacy) are still widely prescribed, and recommendations for active strategies (to avoid bed rest and encourage early return to work) are increasingly applied (41).
Third, the validity of scores for several scales of the SF-36 need to be considered. Indeed, patients who at entry had recently suffered from LBP or recovered during the followup may have had difficulties rating their status during the 4 weeks preceding the time of evaluation and may have been influenced by their perceptions at the time of assessment. However, there is no indication in the published literature regarding the direction or the amplitude of this potential bias.
Fourth, many statistical tests were performed, either for the construction of the predictive recovery model or for the development of exploratory models predicting SF-36 scale scores. Thus, some associations may have been purely incidental.
Finally, our sample was small in view of the low prevalence of some exposure factors and the number of chronic LBP patients (n = 6). It is indeed difficult to gather an inception cohort of very recent LBP because most patients only consult for LBP after several days (36, 42). However, the inception cohort design is necessary to avoid left truncation biases (19), which, in most previous studies, made prognosis of LBP appear much worse than it actually is.
This study has implications for future research in patient management. It suggests that the de-escalation of the medical care of LBP initiated during the last decade (5) should be pursued. Few diagnostic or therapeutic actions have any proven value and indeed many others are iatrogenic (3–6, 41). Avoiding inappropriate medical treatment of acute LBP appears necessary. Primary care physicians may be in a better position than specialists to care for LBP patients because their activity is less based on biomechanical considerations. Medicalization itself is probably of no value for a large subgroup of subjects (young patients and those with LBP of short duration). For others, it has been suggested that yellow flags indicating psychosocial barriers to recovery should be carefully considered by physicians, as are red flags indicating signs of serious disease (43). In addition to the classic work-related factors, impaired HRQOL (evidenced with instruments such as the SF-36), appears to be a useful yellow flag worthy of further investigation.