Factors associated with efficacy of botulinum toxin a injections in primary axillary hyperhidrosis: A retrospective study of ninety patients.

Primary focal hyperhidrosis (PFH) is a frequent condition which can seriously affect the quality of life. Intradermal injections of botulinum toxin A (BTA) is a safe temporary treatment. The objective was to assess the factors associated with the efficacy of the axillary injections of abobotulinumtoxinA in PFH. Among a cohort of 236 patients followed for axillary injections of BTA between 2001 and 2020 for severe PFH, we included patients treated with 150 units per armpit of abobotulinumtoxinA with a minimum follow-up of three years. We described the characteristics of the patients and then searched for association between variables (sex, age, multifocal PFH and duration of efficacy of the first injection [<6 or ≥6 months]) and the number of injections received in three years, counted at the second injection date, by univariate and multivariate logistic regression. Ninety patients were included (62 women, median age of 29 years and 12.2% of multifocal PFH). The median duration of efficacy of the first injection was six months (interquartile range 3-9). The duration of efficacy of the first injection ≥6 months was significantly associated with less injections during the 3-year follow-up in univariate (odds ratio [OR]: -1.18 [95% confidence interval (CI): -1.80 to -0.55]; p < 0.01) and multivariate (OR: -1.16 [95% CI: -1.79 to -0.53]; p < 0.01) logistic regression. There was no significant difference with female sex, age, or multifocal PFH. A duration of efficacy of the first injection greater than six months seems to indicate a better response profile to BTA.