Assessing neuropathic pain in sickle cell disease: How useful is quantitative sensory testing?

Quantitative sensory testing (QST) is a psychophysical test of sensory function which may assist in assessing neuropathic pain (NP). This study compares QST findings with a standardized NP questionnaire to assess their agreement among Jamaicans with sickle cell disease (SCD). A cross sectional study consecutively recruited SCD patients 14 years and older, not pregnant, and without history of clinical stroke or acute illness in Kingston, Jamaica. QST identified thresholds for cold detection, heat detection, heat pain and pressure pain at the dominant thenar eminence, opposite dorsolateral foot and the subjects most frequent pain site. The Douleur Neuropathique 4 (DN4) was interviewer-administered to diagnose NP. Subjects were divided into low and high sensitization groups if below the 5th and above the 95th percentiles, respectively on QST measures. Kappa agreement coefficients, and receiver operator characteristic (ROC) curves were performed to compare QST with the DN4. Two-hundred and fifty-seven SCD subjects were recruited (mean age 31.7 {+/-} 12.2 years, 55.7% female, 75% SS genotype). Kappa agreements were fair (0.2-0.4) to good (0.6-0.8) between DN4 individual items of itching, hypoesthesia to touch, hypoesthesia to pinprick and brush allodynia with various QST sensitization groups. However, kappa agreements between the NP overall diagnosis on the DN4 with sensitization groups were poor (<0.2). Only heat detection (0.75) and heat pain (0.75) at the leg as a pain site showed satisfactory area under the curve (>0.7). QST may assist in assessing individual components of NP but its use should be limited as a tool to augment clinical assessments.