Transcutaneous electrical nerve stimulation (TENS) for pain management in sickle cell disease

Background Sickle cell disease (SCD), one of the most common inherited disorders, is associated with vaso‐occlusive pain episodes and haemolysis leading to recurrent morbidity, hospital admissions and work or school absenteeism. The crises are conventionally treated with opioids, non‐opioids and other adjuvants with the risk of developing complications, addictions and drug‐seeking behaviour. Different non‐pharmacological treatments, such as transcutaneous electrical nerve stimulation (TENS) have been used for managing pain in other painful conditions. Hence, the efficacy of TENS for managing pain in SCD needs to be reviewed. Objectives To assess the benefits and harms of TENS for managing pain in people with SCD who experience pain crises or chronic pain (or both). Search methods We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Haemoglobinopathies Register, comprising of references identified from comprehensive electronic database searches and handsearches of relevant journals and books of conference proceedings. We also searched online trial registries and the reference lists of relevant articles and reviews. Date of the last search: 26 Febraury 2020. Selection criteria We included randomised controlled trials (RCTs) and quasi‐RCTs, where TENS was evaluated for managing pain in people with SCD. Data collection and analysis Two review authors independently assessed the eligibility of the trials identified by the literature searches according to the inclusion criteria. Two review authors then independently extracted data, assessed for risk of bias using the Cochrane standard tool and rated the quality of evidence using the GRADE guidelines. Main results One double‐blind cross‐over RCT with 22 participants with SCD (aged 12 to 27 years) was eligible for inclusion. Following stratification into four pain crises severity grades, participants were then randomised to receive TENS or placebo (sham TENS). The trial was concluded after 60 treatment episodes (30 treatment episodes of each treatment group). There is a lack of clarity regarding the trial design and the analysis of the cross‐over data. If a participant was allocated to TENS treatment for an episode of pain and subsequently returned with a further episode of a similar degree of pain, they would then receive the sham TENS treatment (cross‐over design). For those experiencing a pain episode of a different severity, it is not clear whether they were re‐randomised or given the alternate