Background: Neuropathic pain is defined as pain caused by a lesion or disease of the somatosensory nervous system and is a major therapeutic challenge. Several screening tools have been developed to help physicians detect patients with neuropathic pain. These have typically been validated in populations pre-stratified for neuropathic pain, leading to a so called "Catch-22 situation:" "a problematic situation for which the only solution is denied by a circumstance inherent in the problem or by a rule". The validity of screening tools needs to be proven in patients with pain who were not pre-stratified on basis of the target outcome: neuropathic pain or non-neuropathic pain. This study aims to assess the validity of the Dutch PainDETECT (PainDETECT -Dlv ) in a large population of patients with chronic pain. Methods: A cross-sectional multicentre design was used to assess PainDETECT -Dlv validity. Included where patients with low back pain radiating into the leg(s), patients with neck-shoulder-arm pain and patients with pain due to a suspected peripheral nerve damage. Patients' pain was classified as having a neuropathic pain component (yes/no) by two experienced physicians ("gold standard"). Physician opinion based on the Grading System was a secondary comparison. Results: In total, 291 patients were included. Primary analysis was done on patients where both physicians agreed upon the pain classification (n = 228). Compared to the physician's classification, PainDETECT -Dlv had a sensitivity of 80% and specificity of 55%, versus the Grading System it achieved 74 and 46%. Conclusion: Despite its internal consistency and test-retest reliability the PainDETECT -Dlv is not an effective screening tool for a neuropathic pain component in a population of patients with chronic pain because of its moderate sensitivity and low specificity. Moreover, the indiscriminate use of the PainDETECT -Dlv as a surrogate for clinical assessment should be avoided in daily clinical practice as well as in (clinical-) research. Catch-22 situations in the validation of screening tools can be prevented by not pre-stratifying the patients on basis of the target outcome before inclusion in a validation study for screening instruments.

Clinical assessment, Low back pain, Neck shoulder arm pain, Neuropathic pain, Pain, PainDETECT questionnaire, Peripheral nerve damage, Reliability, Screening tool, Sensitivity, Specificity, Validity,
BMC Neurology
Department of Anesthesiology

Timmerman, H. (Hans), Wolff, A, Bronkhorst, E.M, Wilder-Smith, O.H.G, Schenkels, M.J. (Marcel J.), van Dasselaar, N.T. (Nick T.), … Vissers, K.C.P. (2018). Avoiding Catch-22: Validating the PainDETECT in a in a population of patients with chronic pain. BMC Neurology, 18(1). doi:10.1186/s12883-018-1094-4