(264) - Dose-response of surface neurostimulation in chronic pain

Abstract

Surface neurostimulation in the form of wearable devices is available as a non-pharmacological option for managing chronic pain. This cross-sectional study evaluated users of a surface neurostimulator treating chronic pain. The device semi-continuously stimulates cutaneous sensory nerves at the upper calf and monitors utilization and biometric parameters. A companion smartphone app collects this data as well as demographics, painful health conditions, pain sites, and pain intensity/interference (11-point NRS). Active users were those using the device for ≥3 consecutive calendar months (first period used). Inclusion criteria were active users providing demographic/clinical information and consenting to use of anonymized data for research. The cross-sectional analysis was conducted on the second month data. Typical and maximum pain intensity were the median and maximum value, respectively, logged during the assessment month. Users were stratified according to days of use (irrespective of amount of use) within the assessment month (low 1–15, intermediate 16–26, high ≥27). Group differences were evaluated using one-way ANOVA and two-sample t-test. The effect size for high versus low utilization was quantified by Cohen's d. A total of 4058 users met the inclusion criteria (low N = 1382, intermediate N = 1237, high N = 1439). No group differences were found for gender, BMI, stimulation intensity and maximum pain intensity. Small statistically significant differences were found for age, pain duration, number painful health conditions and number pain sites. Statistically and clinically significant differences were found for typical pain intensity between low (6.04 ± 2.19), intermediate (5.54 ± 2.16) and high (5.05 ± 2.17) groups (P < .0001). The effect size between high and low utilization was .46. High versus low device utilization was associated with a 1-point pain intensity difference and moderate effect size in a large heterogeneous population of chronic pain subjects using surface neurostimulation. This result suggests the possibility of a dose-response relationship. Optimal pain relief is most likely achieved with daily device use.