Quantitative sensory testing, which allows for standardization of subjective feelings of pain and function, may offer a quantifiable way to assess safety and efficacy of pain treatments for sickle cell disease (SCD), according to results published in the British Journal of Haematology.
Researchers enrolled 57 patients with SCD and 60 healthy controls, all aged 8 years to 20 years, to undergo thermal and pain threshold testing. For thermal testing, a thermode was pressed to the patient’s forearm, and its temperature increased or decreased from a baseline of 32°C until the patient first felt a sensation of heat or cold, and again until the patient reported feeling pain. For pressure testing, an electric algometer was used to steadily increase pressure against the patient’s forearm and trapezius muscle until the patient reported feeling pain.
Patients were tested at baseline and at 3 months, and patients with SCD were tested once more at 6 months. Patients with SCD were also asked to maintain a daily pain diary.
No adverse events were reported. No significant difference in thermal thresholds between patient groups was found, and thermal thresholds remained consistent over time. Thermal thresholds were not found to associate with age, gender, genotype, clinical characteristics, or any collected biomarkers.
Patients with SCD exhibited higher sensitivity to pressure pain at the forearm but not at the trapezius.
Of note, patients with SCD who initiated hydroxycarbamide treatment for vaso-occlusive pain exhibited decreased thermal sensitivity over time.
Although compliance with maintaining the pain diary was low, the available data showed no correlation between thermal thresholds and number of pain days.
These results demonstrated that quantitative sensory testing was reliable and consistent over time and can therefore serve as an objective outcome measure when evaluating preventative pain therapies in SCD. The researchers further “[cautioned] against the use of a predefined ‘abnormal’ range for quantitative sensory testing thresholds” and instead suggesting “[evaluating] changes in an individual patient’s quantitative sensory testing thresholds over time.”
- Miller RE, Brown DS, Keith SW, et al. Quantitative sensory testing in children with sickle cell disease: additional insights and future possibilities [published online March 28, 2019]. Br J Haematol. doi: 10.1111/bjh.15876