Progress and lack of progress in hyperhidrosis research 2015-2020. A concise systematic review.

Hyperhidrosis is excessive sweating that is uncontrollable and occurring regardless of temperature. Quality of life is significantly impaired, and psychiatric comorbidity is common. The objective of the study is to undertake a systematic review of research in the last 5 years regarding hyperhidrosis. Five databases were searched from July 2015 to July 2020 for all research on hyperhidrosis. High-quality research articles were sought for progress in diagnosis, etiology and epidemiology, and use of patient reported outcomes (PROs) as well as randomized clinical trials (RCTs) on any treatment intervention. Outcomes of interest were disease severity, sweat rate, quality of life, patient satisfaction, and adverse events. Trial quality was assessed by the Cochrane risk-of-bias tool. A narrative synthesis was presented. Twenty-nine papers were included in the review: 13 investigational articles, 10 RCTs, three cohort studies, and three reviews. The studies varied in terms of quality, population, intervention, and methods of outcome assessment. The majority were very small studies, and most RCTs were at high risk of bias. Few studies on diagnosis, epidemiology, and etiology were of sufficient quality to be presented. The interventions discussed were iontophoresis, botulinum toxin, anticholinergic medication, curettage, and energy-based technologies. Progress in the diagnostics and etiology of hyperhidrosis is limited with the same being true for treatment. In a 5-year-old systematic review, it was concluded that there was moderate-quality evidence to support the use of botulinum toxin for axillary hyperhidrosis. It was advocated to conduct a trial comparing BTX and iontophoresis for palmar hyperhidrosis. Unfortunately, this has not yet been performed. Hyperhidrosis is still as underserved and under-studied as before.