Clinical Interpretation of Quantitative Sensory Testing as a Measure of Pain Sensitivity in Patients With Sickle Cell Disease

Abstract

Patients with sickle cell disease (SCD) display significantly lower mean/median thermal and mechanical pain thresholds compared with controls. This suggests impaired pain sensitivity where stimuli produce exaggerated pain. Despite these mean/median differences, clinicians need to understand if patients meet criteria for impaired pain sensitivity. We defined thresholds for impaired cold, heat, and mechanical pain sensitivity in SCD patients. Using quantitative sensory testing (QST) we assessed cold, heat, and mechanical pain thresholds in SCD patients and African American controls aged 7 years and above. Impaired pain sensitivity was defined as: (1) cold pain threshold 1 SD above control median threshold; (2) heat pain threshold 1 SD below control median threshold; and (3) mechanical pain threshold 1 SD below control median threshold. Fifty-five SCD patients and 57 controls participated in this study. Impaired pain sensitivity thresholds were: (1) cold: 17.01°C, (2) heat: 43.91°C, and (3) mechanical: 4.42 g. Impaired cold pain sensitivity was the most common finding (63.6%), then heat (60%), and mechanical (38.2%). Impaired pain sensitivity to ≥1 testing modalities occurred in 81.8% of SCD patients. Determining impaired pain sensitivity thresholds increases clinical utility of QST. QST could be a screening tool to phenotype SCD pain, an outcome for pain interventional trials, or guide pain neurobiology investigations.

Figure 1

Pictorial description of the spread of individual sickle cell disease patient pain thresholds that were in the impaired or non-impaired range for cold, heat, and mechanical pain

Figure 2

Proportion of patients with sickle cell disease with varying numbers of impaired pain sensitivities