Direct and Indirect Benefits Reported by Users of Transcutaneous Electrical Nerve Stimulation for Chronic Musculoskeletal Pain

There is no consensus with regards the efficacy of Transcutaneous Electrical Nerve Stimulation (TENS) for chronic musculoskeletal pain or chronic low back pain. A recent review of previous trial methodology identified significant problems with low treatment fidelity. There a lack of available information to direct selection of Patient Reported Outcome Measures appropriate for TENS evaluation. This study sought to explore the experiences of secondary care Pain Clinic patients who successfully used TENS to help manage chronic musculoskeletal pain. These key informants were selected due to their having the potential to generate knowledge which could inform research design and clinical practice. A mini focus group informed the development of a discussion guide for semi-structured interviews with nine patients (6 women). Thematic analysis was used as the primary data analysis method, and this was enhanced by a case level analysis of the context and processes of TENS use of each individual. Data analysis suggested that distraction from pain, and a decrease in the sensations associated with muscle tension/spasm, should be considered as separate outcomes from pain relief. These three direct benefits resulted in a wide range of indirect benefits dependent upon patient decision-making including medication reduction, enhanced function, psychological benefits and enhanced ability to rest.

The findings suggest that it is likely that evaluating TENS using a unidimensional pain scale will overlook potential benefits. The complex pattern of TENS usage as well as multiple direct and indirect outcomes suggest that TENS could be thought of as a complex intervention.