Patients who live in areas with high levels of sun exposure may require higher than normal doses of botulinum toxin A to the glabella to achieve maximal results, results from a comparative cohort study suggested.
"Botulinum toxin A to the glabella is a popular cosmetic intervention," researchers led by Kim L. Borsky, MD, MBBS, of the Department of Plastic and Reconstructive Surgery at Stoke Mandeville Hospital, Aylesbury, United Kingdom, and colleagues wrote in their abstract, which was published in July in Plastic and Reconstructive Surgery. "Functional musculature differences may arise from chronic behavioral adjustment to high sun exposure levels, requiring greater doses. This could affect clinical practice globally."
To investigate the effect of climate on real-world doses of the product, the researchers enrolled 523 women aged 35-60 years who received glabellar botulinum toxin treatment at two centers between 2012 and 2019: One in the United Kingdom and one in Malta. They evaluated data on 292 patients treated during the summer months at the Malta center (classified as the high sun-exposure group), and 231 patients treated during the winter months at the UK center (classified as the low sun-exposure group). The primary outcomes of interest were the required top-up doses and the total dose to achieve full paralysis. Smokers were excluded from the analysis, as were those who did not seek maximal paralysis, those documented as not compliant with posttreatment advice, and those with colds or fevers. They used univariable and multivariable analyses to compare the high vs low sun-exposure groups.
The researchers found that 68.5% of women in the high-sun group required a top-up dose to achieve full paralysis compared with 61.5% in the low-sun group, a difference that did not reach statistical significance (P = .1032). All patients achieved full paralysis with the treatment protocol used. However, in the high-sun group, the mean top-up dose was significantly higher than that in the low-sun group (a mean of 9.30 vs 7.06 units, respectively; P = .0009), as was the mean total dose (a mean of 29.23 vs 27.25 units; P = .0031).
"Patients subject to less sun exposure require a lower dose than patients with high sun exposure, and this was present and persisted when controlling for potential confounders," the researchers wrote. "Although robustly demonstrated, the difference in doses seen here was small, and so may not directly impact at a health economic level, as the difference would not necessarily change the number of vials used. However, it may be of relevance to training and protocolization of treatments. Rigid protocols about doses and distributions may lead to undertreatment if applied in sunnier climates."
They acknowledged certain limitations of their study, including its unblinded design and the fact that they did not evaluate or control for ethnicity. They also characterized the population of Malta as "very homogenous, mainly made up of Maltese with less than 5% foreigners," while the demographics of the United Kingdom and especially London, where the injections were performed, "are much more diverse."
Asked to comment on the results, Pooja Sodha, MD, director of the Center for Laser and Cosmetic Dermatology at George Washington University, Washington, DC, said that the study highlights the importance of tailoring neuromodulator treatment to the individual patient based not just on gender but also on lifestyle and climate. "The conclusion [of the study] is logical, but it's encouraging that the data supports this," Sodha told this news organization. "The potential confounders, such as injection technique (5 point vs 3 point), nonblinding of the evaluator, history of prior treatments, and variation in treatment effect by different botulinum toxin products may be important as well in how we consider this data in practice."
This study did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Neither the researchers nor Sodha reported having financial disclosures.
Source:
Medscape
