The effect of climate on the dose requirements of botulinum toxin A in cosmetic interventions

Abstract

Background: Botulinum toxin A to the glabella is a popular cosmetic intervention. Functional musculature differences may arise from chronic behavioral adjustment to high-sun exposure levels, requiring greater doses. This could affect clinical practice globally. This study investigated the effect of climate on real-world doses. Methods: We conducted a comparative cohort study using data from a registry from a single provider practicing across two centers: the United Kingdom (U.K.) and Malta. We classed one center as low-sun exposure (U.K. winter month treatment) and the other high-sun exposure (Malta summer months). Patients were followed up once every 3 weeks and received top-up doses until full clinical paralysis was achieved. To standardize the comparison, we only included women aged 35-60 undergoing glabellar botulinum toxin treatment by experienced clinicians following standard procedures from 2012-2019. Smokers, those not seeking maximal paralysis, those documented as not compliant with post-treatment advice, those with colds/fevers and broken cold supply chains were excluded. Univariable and multivariable analyses were undertaken. Results: 523 patients were included: 292 “high-sun” and 231 “low-sun”. Mean total doses were significantly higher in the high-sun group (29.2U vs. 27.3U, p=0.0031). When correcting for age in multivariable analysis, the low-sun group still had lower total dose requirements (p=0.00574). Conclusion: Patients injected with glabellar botulinum toxin in high-sun climates may have significantly increased dose requirements to achieve maximal paralysis.