Validation of two novel electronic devices to time-link transcutaneous electrical nerve stimulation and pain report in patients with chronic back pain.

ABSTRACT

OBJECTIVES: The analgesic effectiveness of transcutaneous electrical nerve stimulation (TENS) is uncertain. Negative findings, interpreted as ineffectiveness, might be due to poor methodological quality. Monitoring is necessary to differentiate between ineffectiveness and low implementation fidelity. Electronic data-logging devices, "TLOG" and "TSCORE," were developed to monitor and time-link TENS and pain report. TLOG records the time and duration of TENS use and output parameters; TSCORE records time-stamped pain scores. The purpose was to determine the accuracy, reliability, and acceptability of the devices. METHODS: Forty-two outpatients with chronic back pain consented to use TENS daily for 2 weeks. Treatment times and durations were recorded in paper diaries and compared with TLOG data. Using TSCORE, patients reported pain before, during, and after TENS. Pain scores, reported using TSCORE or paper numerical rating scale at the beginning and end of 2 study visits, were compared using Bland-Altman methodology. RESULTS: The mean (SD) difference between paper and TSCORE pain scores was -0.05 (0.81). Limits of agreement (mean difference ± 1.96 SD) were -1.65 to 1.55. Test-retest reliabilities of paper and TSCORE were comparable Paper mean (SD) difference was -0.33 (0.66), limits of agreement were -1.62 to 0.96; TSCORE mean (SD) difference was -0.10 (0.31), limits were -0.7 to 0.5. TLOG recorded TENS use accurately and worked reliably for 2 weeks in 84% of cases. An overall 79% of participants preferred TSCORE to paper numerical rating scale. DISCUSSION: TLOG and TSCORE are accurate, reliable, and acceptable devices for monitoring TENS implementation fidelity and pain outcome, with potential for improving TENS research methodology and clinical application.