Diagnostic utility of patient history, clinical examination, and screening tool data to identify neuropathic pain in low back related leg pain: a systematic review and narrative synthesis

Key points

1. 01A cluster of eight signs (age, disease duration, paroxysmal pain, leg pain worse than back pain, dermatomal distribution, pain with coughing or sneezing, finger-to-floor distance, and paresis) showed moderate sensitivity (72%) and moderate-high specificity (80%) for lumbosacral nerve root compression
2. 02The StEP screening tool showed high sensitivity (92%) and specificity (97%) for lumbar radicular pain, supported by moderate-quality evidence
3. 03Nine of the eleven included studies were at risk of bias, limiting the strength of conclusions that can be drawn
4. 04No gold standard exists for diagnosing neuropathic pain in low back-related leg pain, which undermines all reference standard comparisons in included studies
5. 05Further high-quality diagnostic accuracy studies with consistent terminology and reference standards are needed before firm clinical recommendations can be made

How it was conducted

Design

Systematic review with narrative synthesis (meta-analysis not possible due to heterogeneity)

Databases searched

CINAHL, EMBASE, MEDLINE, Web of Science, Cochrane Library, AMED, Pedro, PubMed, key journals, and grey literature from inception to July 2019

Included studies

11 cross-sectional observational studies

Participants

3908 adults across all included studies, ages ranging 30 to 70 years

Index tests evaluated

Patient history items, clinical examination tests (SLR, slump, slump knee bend, nerve palpation, SQST), and screening tools (StEP, S-DN4, ID Pain, painDETECT, S-LANSS)

Risk of bias and evidence quality

QUADAS-2 for risk of bias; modified GRADE for evidence quality

What they found

• Cluster of 8 signs (Vroomen et al.): sensitivity 72%, specificity 80% for lumbosacral nerve root compression; GRADE moderate quality
• StEP tool (Scholz et al.): sensitivity 92%, specificity 97% for lumbar radicular pain; GRADE moderate quality
• Cluster of 3 signs - dermatomal pain distribution, history of nerve injury, and pain provocation with movement (Smart et al.): sensitivity 86.3%, specificity 96% for peripheral neuropathic pain; GRADE low quality
• Straight leg raise (Capra et al.): sensitivity 36%, specificity 74% for sciatica; GRADE low quality
• Straight leg raise (Poiraudeau et al.): sensitivity 79%, specificity 37% for sciatica associated with disc herniation; GRADE low quality
• Slump knee bend (Trainor et al.): sensitivity 100%, specificity 83% for upper/mid lumbar nerve root compression; GRADE very low quality
• Slump test (Urban et al.): sensitivity 91%, specificity 78% for neuropathic pain in lower limb; GRADE very low quality
• Nerve palpation (Walsh et al.): sensitivity 83%, specificity 73% for low back-related leg pain; GRADE low quality
• SQST (Lin et al.): sensitivity 62%, specificity 95% for lumbar lateral stenosis at L5 nerve root; GRADE low quality
• S-DN4: sensitivity 58.5%, specificity 98%; ID Pain: sensitivity 70.7%, specificity 84.3%; painDETECT: sensitivity 76.8%, specificity 78.4%; S-LANSS: sensitivity not specified, specificity 13%; all GRADE low quality

Limitations

• No gold standard exists for diagnosing neuropathic pain in low back-related leg pain, making all reference standard comparisons indirect and uncertain
• Nine of 11 studies were at risk of bias, primarily due to inadequate blinding, poor description of index and reference test procedures, and flow or timing issues
• Heterogeneous phenomena of interest across studies (sciatica, radicular pain, nerve root compression, LBLP) made direct comparison and pooling impossible
• Moderate-quality evidence for the two most promising tools (8-sign cluster and StEP) each comes from a single study, limiting generalisability

Why it matters

For patients

People with leg pain related to their lower back cannot yet rely on a single reliable bedside test or questionnaire to confirm whether neuropathic mechanisms are driving their pain, so diagnosis still depends on specialist assessment.

For clinicians

The StEP tool and a cluster of eight history and examination signs are the most diagnostically promising options currently available, but both are supported by single moderate-quality studies and should be used alongside clinical judgement rather than as standalone decision rules.

For readers

This first systematic review in this area confirms a gap in the evidence, highlights the absence of a validated gold standard, and provides a clear agenda for future high-quality diagnostic accuracy research in low back-related leg pain.