Review Article
A systematic review identifies five “red flags” to screen for vertebral fracture in patients with low back pain

https://doi.org/10.1016/j.jclinepi.2007.04.013Get rights and content

Abstract

Objective

To determine the accuracy of clinical features in diagnosing vertebral fracture in low back pain patients and assess the psychometric properties of the Quality Assessment of Studies of Diagnostic Accuracy Included in Systematic Reviews (QUADAS) scale.

Study Design and Setting

A diagnostic systematic review was performed on all available records in MEDLINE, CINAHL, and EMBASE. Studies were considered eligible if they investigated clinical features associated with vertebral fracture in a cohort of low back pain patients. All eligible studies were assessed for methodological quality using the QUADAS scale, and two authors extracted true-positive, true-negative, false-positive, and false-negative data for each clinical feature.

Results

Twelve studies were identified by the review, investigating 51 clinical features. Five clinical features were useful to raise or lower the probability of vertebral fracture: age >50 years (likelihood ratio [LR]+ = 2.2, LR− = 0.34), female gender (LR+ = 2.3, LR− = 0.67), major trauma (LR+ = 12.8, LR− = 0.37), pain and tenderness (LR+=6.7, LR− = 0.44), and a distracting painful injury (LR+ = 1.7, LR− = 0.78). The QUADAS had low internal consistency, and only three items had high inter-rater reliability. There was inadequate reporting of many methodological quality items.

Conclusion

Five clinical features were identified that can be used to screen for vertebral fracture. The psychometric properties of the QUADAS scale raise concerns about its use to rate the quality of low back pain diagnosis studies.

Introduction

It is widely agreed that acute low back pain is common, can be seriously disabling, and imposes an enormous social and economic burden on the community. To improve the management of back pain, clinical practice guidelines have been developed in at least 12 countries [1]. A common theme among the guidelines is that acute low back pain should be managed in primary care because it is generally benign, and the few cases of serious disease can be readily detected with a clinical assessment [1]. The exclusion of specific pathologies is one of the primary purposes of the clinical assessment, and the clinical guidelines recommend that the identification of “red flags” is the ideal method to accomplish this purpose [1]. “Red flags” are features of the patient's medical history and clinical examination thought to be associated with a high risk of serious disorders, such as infection, inflammatory disease, cancer, or fracture [2].

Vertebral fracture is associated with significant pain and disability [3] and with increased mortality [4]. The prevalence of vertebral fracture in patients presenting to primary care practitioners with acute low back pain has been estimated to be between 0.5% [5] and 4% [6], yet it is estimated that only 30% of vertebral fractures are diagnosed in clinical practice [7] because the presentation is similar to that of nonspecific low back pain [7], [8]. Vertebral fracture not only requires specific appropriate treatment, but is a contraindication to spinal manipulative therapy, a common treatment that is endorsed in clinical practice guidelines for acute nonspecific low back pain [9]. Therefore, accurate diagnosis in primary care is essential to prevent poor outcomes [10].

As a first step in identifying fracture in patients presenting with acute low back pain, clinical guidelines [11], [12], [13], [14] generally recommend the following red flags: recent history of trauma [12], [13]; prolonged use of corticosteroids [11], [13]; age >50 years [11], [13], [14]; and structural deformity [11], [12], [14] (Table 1). The inclusion of these features in the guidelines is often justified by reference to previous guidelines [14], unpublished data [11], or single studies of questionable methodological quality [12] (Table 1). No study has reviewed the available literature in a systematic manner. Without evaluation of the diagnostic accuracy of the red flags, their usefulness in clinical practice will remain uncertain. This review incorporated a sensitive search strategy and quality assessment of primary studies using a validated tool [15] as recommended in guidelines for performing diagnostic systematic reviews [16], [17].

To determine the accuracy of the clinical examination available to primary care practitioners, we conducted a systematic review of studies evaluating clinical features for diagnosing fracture in low back pain patients [18]. A secondary aim was to determine the psychometric properties of the Quality Assessment of Studies of Diagnostic Accuracy Included in Systematic Reviews (QUADAS) scale [15] when used to rate the quality of retrieved studies.

Section snippets

Data sources

A systematic literature search was performed to identify all relevant original, peer-reviewed articles evaluating vertebral fractures in patients presenting with low back pain. The primary search was performed from the earliest available dates to 5 February 2007, on the MEDLINE, EMBASE, and CINAHL electronic databases. A subject-specific search strategy was used, combining sensitive searches of the diagnostic (index) tests available to primary care practitioners, and the target disease (low

Search results

The electronic database search retrieved 6,027 articles (Fig. 1). After review of the titles, 5,272 articles were excluded because they were clearly outside the scope of the review. The remaining 755 articles were classified into study types to identify those evaluating a cohort of patients [21]. There were 175 review articles, of which four [24], [25], [26], [27] were systematic reviews related to fracture or back pain, but did not focus on diagnosis or clinical features of fracture.

The titles

Discussion

Clinical guidelines for the management of low back pain advocate the use of red flags to raise the index of suspicion concerning serious spinal pathology. This study provides the first diagnostic systematic review of these red flags and other clinical features for identifying vertebral fracture in low back pain patients. It contains a more detailed analysis of the red flags by summarizing the diagnostic accuracy quantitatively and exploring methodological quality of the primary studies. By

Acknowledgments

N.H. is under scholarship awarded by the National Health & Medical Research Council of Australia. C.M. is a senior research fellow funded by the National Health & Medical Research Council of Australia.

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