Prevalence of and screening for serious spinal pathology in patients presenting to primary care settings with acute low back pain

Abstract

Objective. To determine the prevalence of serious pathology in patients presenting to primary care settings with acute low back pain, and to evaluate the diagnostic accuracy of recommended "red flag" screening questions.Methods. An inception cohort of 1,172 consecutive patients receiving primary care for acute low back pain was recruited from primary care clinics in Sydney, Australia. At the initial consultation, clinicians recorded responses to 25 red flag questions and then provided an initial diagnosis. The reference standard was a 12-month followup supplemented with a specialist review of a random subsample of participants.Results. There were 11 cases (0.9%) of serious pathology, including 8 cases of fracture. Despite the low prevalence of serious pathology, most patients (80.4%) had at least 1 red flag (median 2, interquartile range 1-3). Only 3 of the red flags for fracture recommended for use in clinical guidelines were informative: prolonged use of corticosteroids, age >70 years, and significant trauma. Clinicians identified 5 of the 11 cases of serious pathology at the initial consultation and made 6 false-positive diagnoses. The status of a diagnostic prediction rule containing 4 features (female sex, age >70 years, significant trauma, and prolonged use of corticosteroids) was moderately associated with the presence of fracture (the area under the curve for the rule score was 0.834 [95% confidence interval 0.654-1.014]; P ‫؍‬ 0.001).Conclusion. In patients presenting to a primary care provider with back pain, previously undiagnosed serious pathology is rare. The most common serious pathology observed was vertebral fracture. Approximately half of the cases of serious pathology were identified at the initial consultation. Some red flags have very high false-positive rates, indicating that, when used in isolation, they have little diagnostic value in the primary care setting.

Low Back Pain

“…In the vast majority of patients with low back pain, symptoms can be attributed to non-specific mechanical factors. However, in a much smaller percentage of patients, the cause of back pain may be something more serious, such as cancer, 79 cauda equina syndrome, 81 spinal infection, 303 spinal compression fractures, 142 spinal stress fractures, 143 ankylosing spondylitis, 125 or aneurysm. 94 Clinical findings that increase the level of suspicion that there is a serious medical condition presenting as common, non-serious, musculoskeletal conditions, are commonly described as “red flags.” Table 4 lists serious medical conditions that can cause low back pain and their associated red flags.…”

Red flags presented in current low back pain guidelines: a review

“…An Australian population-based prospective cohort study of 1172 consecutive patients presenting to primary care for low back pain calculated the increased probability of fracture when a combination of red flags were positive [43]. When any three of the red flags 'female', 'age [70', 'severe trauma', and 'prolonged use of corticosteroids' were present, the probability of fracture increased from 4 % (pre-test) to 90 % (95 % CI 34-99 %).…”

“…Nevertheless, the majority of guidelines inferred that the presence of a red flag was absolute by recommending further diagnostic workup (e.g., advanced imaging). Given that up to 80 % of patients presenting to primary care may have at least one positive red flag [43], when combined with weak evidence in support of many red flags, this advice may cause harm to many patients through unnecessary imaging (increased radiation and health care costs), unnecessary alarming the patients (resulting in reduction of quality of life) and unnecessary treatment (including unnecessary surgery) [42,44].…”

“…Therefore, diagnostic models that demonstrate an increased ability to detect serious disease should be explored. Some diagnostic models of red flags for fracture have been developed to identify patients with a greater risk of a fracture (up to 90 %), but they are yet to be validated [43,49].…”

Diagnosing acute nonspecific low back pain: Time to lower the red flags?

“…Osteoporotic fractures of the spine are a relatively common presentation in primary care but represent Ͻ1% of the presentations in the study by Henschke and colleagues (6). Clinician judgment, however, has a positive predictive value similar to that of the formulaic red flag-based diagnostic rule (6).…”