The incidence of acne in preadolescents was higher in girls than in boys, and was associated with higher body mass index (BMI) percentiles, in a large population-based retrospective study that used age- and sex-matched controls.
The investigators also identified “a potential association” with precocious puberty that they said “should be considered, especially among those presenting [with acne] under 8 or 9 years old.” The study was published in Pediatric Dermatology.
Senior author Megha M. Tollefson, MD, and coauthors used resources of the Rochester Epidemiology Project to identify all residents of Olmstead County, Minn., who were diagnosed with acne between the ages of 7 and 12 years during 2010-2018. They then randomly selected two age and sex-matched community controls in order to evaluate the relationship of preadolescent acne and BMI.
They confirmed 643 acne cases, and calculated an annual age- and sex-adjusted incidence rate for ages 7-12 of 58 per 10,000 person-years (95% confidence interval, 53.5-62.5). The incidence rate was significantly higher in females than males (89.2 vs. 28.2 per 10,000 person-years; P < .001), and it significantly increased with age (incidence rates of 4.3, 24.4, and 144.3 per 10,000 person-years among those ages 7-8, 9-10, and 11-12 years, respectively).
The median BMI percentile among children with acne was significantly higher than those without an acne diagnosis (75.0 vs. 65.0; P <.001). They also were much more likely to be obese: 16.7% of the children with acne had a BMI in at least the 95th percentile, compared with 12.2% among controls with no acne diagnosis (P = .01). (The qualifying 581 acne cases for this analysis had BMIs recorded within 8 months of the index data, in addition to not having pre-existing acne-relevant endocrine disorders.)
“High BMI is a strong risk factor for acne development and severity in adults, but until now pediatric studies have revealed mixed information … [and have been] largely retrospective reviews without controls,” Dr. Tollefson, professor of pediatrics and dermatology at the Mayo Clinic, Rochester, Minn., and colleagues wrote.
Leah Lalor, MD, a pediatric dermatologist not involved with the research, said she is happy to see it. “It’s really valuable,” she said in an interview. “It’s actually the first study that gives us incidence data for preadolescent acne. We all have [had our estimates], but this study quantifies it…and it will set the stage for further studies of preadolescents in the future.”
The study also documents that “girls are more likely to present to the clinic with acne, and to do so at younger ages, which we’ve suspected and which makes physiologic sense since girls tend to go through puberty earlier than boys,” said Dr. Lalor, assistant professor of dermatology and pediatrics at the Medical College of Wisconsin and the Children’s Wisconsin Clinics, both in Milwaukee. “And most interestingly, it really reveals that BMI is higher among preadolescents with acne than those without.”
The important caveat, she emphasized, is that the study population in Olmstead County, Minn. has a relatively higher level of education, wealth, and employment than the rest of the United States.
The investigators also found that use of systemic acne medications increased with increasing BMI (odds ratio, 1.43 per 5 kg/m2 increase in BMI; 95% CI, 1.07-1.92; P = .015). Approximately 5% of underweight or normal children were prescribed systemic acne medications, compared with 8.1% of overweight children, and 10.3% of those who were obese – data that suggest that most preadolescents with acne had mild to moderate disease and that more severe acne may be associated with increasing BMI percentiles, the authors wrote.
Approximately 4% of the 643 preadolescents with acne were diagnosed with an acne-relevant endocrine disorder prior to or at the time of acne diagnosis – most commonly precocious puberty. Of the 24 diagnoses of precocious puberty, 22 were in females, with a mean age at diagnosis of 7.3 years.
Puberty before age 8 in girls and 9 in boys is classified as precocious puberty. “Thus, a thorough review of systems and exam should be done in this population [with acne] to look for precocious puberty with a low threshold for systemic evaluation if indicated,” the authors wrote, also noting that 19 or the 482 female patients with acne were subsequently diagnosed with polycystic ovary syndrome.
Dr. Lalor said she “automatically” refers children with acne who are younger than 7 for an endocrine workup, but not necessarily children ages 7, 8, or 9 because “that’s considered within the normal realm of starting to get some acne.” Acne in the context of other symptoms such as body odor, hair, or thelarche may prompt referral in these ages, however, she said.
Obesity may influence preadolescent acne development through its effect on puberty, as overweight and obese girls achieve puberty earlier than those with normal BMI. And “insulin resistance, which may be related to obesity, has been implicated with inducing or worsening acne potentially related to shifts in IGF-1 [insulin-like growth factor 1] signaling and hyperandrogenemia,” Dr. Tollefson and colleagues wrote. Nutrition is also a possible confounder in the study.
“Patients and families have long felt that certain foods or practices contribute to acne, though this has been difficult to prove,” Dr. Lalor said. “We know that excess skim milk seems to contribute … and there’s a correlation between high glycemic load diets [and acne].”
Assessing dietary habits in conjunction with BMI, and acne incidence and severity, would be valuable. So would research to determine “if decreasing the BMI percentile [in children with acne] would improve or prevent acne, without doing any acne treatments,” she said.
The study was supported by the National Institute on Aging and the Rochester Epidemiology Project. The authors reported no conflicts of interest. Dr. Lalor also reported no conflicts of interest.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.
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