An Ecologically Valid Experimental Model for Repeated Evoked Pain Using a Wearable Device in Pain-Free Individuals: A Pilot Feasibility Study.

Evoked experimental pain is a central method for studying basic pain mechanisms in humans. However, traditional methods of evoked pain delivered in controlled lab settings lack ecological validity and limits testing to short intervals. This study tested the feasibility, tolerability and construct validity of a new model for experimental evoked pain in participants' daily environments, using a wearable device that delivered electric shocks to the wrist. Ten pain-free individuals received 7 electric shocks over a period of one day (between 10:00 and 21:00) and completed ecological momentary assessment (EMA) following each stimulus. Shocks were individually calibrated to 4 out of 10 (NRS; 0 = No shock felt, 10 = Shock is intolerable). All participants completed the full study protocol, and no adverse events were reported. Overall, 84.1% of shocks were rated above 1.5 on pain intensity (VAS 0-10; 0 = No pain, 10 = Extreme pain). On average, pain intensity was rated 4.10 (SD = 1.99; VAS 0-10), consistent with individual calibration. Shock interference, rated retrospectively at the end-of-day EMA, was relatively low (M = 2.05, SD = 1.52; 0-10 VAS; range = 0-3.7), and most reported carrying out activities as planned. These results indicate that this model of experimental pain is feasible and tolerable for participants and successfully evokes pain in an ecologically valid setting. In future studies, this method may be applied over multiple days to investigate pain perception over time, with manipulating stimulus parameters, or in connection with daily activities.