Red Flag Challenges
Clinical guidelines for spine care routinely recommend screening for red flags because they potentially indicate serious conditions often requiring prompt and specific management. Verhagen and colleagues reviewed 16 clinical guidelines for low back pain including those from North America, Australia, Europe, and Pacific region countries revealing 46 recommended red flag signs or symptoms indicating serious pathology. [1] However, in an age of evidence-based practice, important questions about red flag screening require answers.
• What is a positive red flag finding?
• What is the diagnostic accuracy of red flag signs and symptoms?
• Given the high number of potential red flags and potential inefficiency in screening for each, how can we know when thorough screening has occurred?
Unfortunately, there are no simple answers to these questions. None of the 16 guidelines included a detailed definition of when a red flag finding is “positive.” For example, pain at night or during rest are guideline endorsed red flags for malignancy. However, no guideline provided definitions for pain severity, quality, or how long it should present to be considered positive. Likewise, the presence of osteoporosis can be a red flag for fracture, though further details are absent, leaving clinicians to variously interpret bone density levels in different anatomical regions and to determine when this potential red flag is positive. “Progressive symptoms” indicating malignancy or neurological compromise is another red flag without defining language with respect to severity, timing, or duration.
The diagnostic accuracy of red flags is largely unknown. In fact, discussing red flags in terms of diagnostic accuracy can be misleading. Red flags are often signs, symptoms, or conditions representing increased risk for serious pathology, rather than indicating the pathology itself. Weighing these inaccurate risks increases decision-making challenges for clinicians. Osteoporosis and prolonged corticosteroid use are possible examples of red flags representing increase fracture risk, but are far from being pathognomonic. Likewise, fever suggests higher risk for osteomyelitis, though it is weak diagnostic evidence because fever can be caused by other infections and non-infectious conditions.
Most guidelines developed red flag screening recommendations from expert consensus. This method is often used when objective experimental evidence studying predictability or diagnostic accuracy is not available. Expert opinion is…well… opinion. It may be sound, but it may be biased and inaccurate because it is not based on objective experimental evidence.
Where does all of this leave the practitioner evaluating a patient? Should a clinician screen at all? Again, the answer is not simple. Verhagen and colleagues point out that given the low risk for serious disease among those seeking primary level care for low back pain, screening for red flags is of limited diagnostic use. Therefore, one option would be to eliminate screening. However, despite the challenges and potential inaccuracy surrounding red flags, this option is not a responsible approach and it is clearly inconsistent with established best practices.
Instead, I suggest beginning by reviewing guidelines for your region of the world. Though 46 red flags are identified in many different guidelines, some are redundant and some are naturally screened during patient interviews. For those that are left, I suggest using a checklist and establishing clear definitions of each red flag to help you consistently determine a positive from a negative finding. Such a checklist example, though not including all guideline recommendations, is available in an evidence-based diagnostic classification system for low back pain article I co-authored a few years ago.[2] Incorporating a red flag checklist into your daily routine can help you gather guideline recommended information in an efficient and systematic fashion, and potentially help identify serious pathology when present.
Reference List
1. Verhagen AP, Downie A, Popal N, Maher C, Koes BW: Red flags presented in current low back pain guidelines: a review. Eur Spine J 2016.
2. Vining R, Potocki E, Seidman M, Morgenthal AP: An evidence-based diagnostic classification system for low back pain. J Can Chiropr Assoc 2013, 57: 189-204.