Abstract
Background/Objectives:
Little is known about acne incidence in preadolescents and its potential association with body mass index (BMI). Our study aims to determine acne incidence in preadolescents and its association with BMI.
Methods:
A population-based retrospective cohort study identified 7-≤12 year-olds with an initial acne diagnosis during 2010–2018, and incidence was calculated. Two age- and sex-matched controls without acne were randomly selected per case, and BMI was recorded.
Results:
A total of 643 acne patients were identified. Annual age- and sex-adjusted incidence rate was 58.0 per 10,000 person-years, higher in females vs. males (89.2 vs. 28.2 per 10,000 person-years, p<0.001), and increased with age (4.3, 24.4, and 144.3 per 10,000 person-years among 7–8, 9–10, and 11–12 year-olds, respectively, p<0.001). Systemic medication use was associated with increasing BMI (odds ratio=1.43 per 5 kg/m2 increase in BMI, 95% CI 1.07–1.92, p=0.015). Median BMI percentile was higher among acne cases vs. controls (75.0 vs. 65.0, p<0.001), as was the proportion with BMI ≥95th percentile (16.7% vs. 12.2%, p=0.01).
Conclusion:
Acne incidence is higher in preadolescent girls than boys and increases with age. Preadolescents with acne are more likely to be obese than those without acne. Those with higher BMIs are more likely to be given systemic treatment.
Keywords: Acne, Acne Vulgaris, Preadolescent, Adolescent, Child, Body Mass Index, Obesity, Odds, Overweight, Underweight, Pediatrics, Dermatology, Youths, Risk Factors, Race, Retrospective Studies, Public Health, Cohort Studies, Epidemiology, Incidence, United States
Introduction
Acne onset is most common in adolescence but also occurs in preadolescence,1 although there is a paucity of specific information regarding its incidence in children ages 7-≤12 years. Acne in preadolescence is usually associated with the onset of puberty and adrenarche.1 In the United States (US), there is a trend towards a younger age of puberty onset, and possibly earlier acne onset.1
Recently, obesity prevalence has been increasing among preadolescents and adolescents.2 An association between body mass index (BMI) and acne has previously been identified in adults.3–11 However, data are conflicted in adolescents and young adults,3–11 and information concerning younger pediatric patients is very limited.9,12
Here we investigate acne incidence in children ages 7-≤12 years, overall and by sex, and evaluate the relationship of BMI and acne using the incidence acne cases and age- and sex-matched population-based controls.
Methods
The Rochester Epidemiology Project (REP) resources were used to identify all Olmsted County, Minnesota, residents who first received an acne diagnosis between the ages of 7-≤12 years during January 2, 2010 to December 31, 2018 and had not denied access to their records for research. The REP is a unique, National Institutes of Health funded, records-linkage system allowing population-based medical research in Olmsted County.13 Institutional Review Board approval was obtained. Based on 2000 census data, the age, sex, and race/ethnicity of Olmsted County residents was comparable to Minnesota and the Midwestern US. However, Olmsted County is less ethnically diverse, with a relatively higher level of education, wealth, and healthcare employment than the rest of the US.14
Acne diagnoses were identified electronically using ICD-9 and ICD-10 diagnosis codes: 706.1 (Other acne), L70.0 (acne vulgaris), L70.5 (acné excoriée), L70.8 (other acne), and L70.9 (acne, unspecified). For each patient identified, medical records were reviewed to confirm they met study criteria and collect gender, age at diagnosis, race, acne location, BMI (within 8 months of diagnosis), history of menses (in females), acne treatments, and acne-relevant endocrine conditions or medications. Preadolescence was based on accepted acne age group classification and not pubertal maturation.1
For each acne case without relevant pre-existing endocrine disorders (Cushing’s syndrome, precocious puberty, and other puberty disorders), we randomly selected 2 age- and sex-matched (±1 year) controls still residing in Olmsted County at the time of the case’s acne diagnosis (index date) and who had not denied access to their records for research. Controls diagnosed with acne or relevant endocrine disorders prior to the matched case’s index date were replaced as were controls without a BMI recorded within 8 months of the index date.
Age- and sex-specific incidence rates for 7-≤12 year-olds in Olmsted County during 2010–2018 were calculated. The numerator was the number of incident acne cases that met study criteria. The denominator was obtained from the REP enumerated census of residents ages 7-≤12 years during 2010–2018; in 2010 and 2018 there were 11769 and 12939 residents in this age group, respectively.15 Rates were age- and sex-adjusted to the total population structure of the US in 2010. The 95% confidence intervals (CIs) for the rates were calculated assuming a Poisson error distribution.
Age-and sex-specific BMI percentiles were calculated using the US Centers for Disease Control and Prevention growth curves using BMI referent data for age in months of 24 to 240 months.16 BMI percentiles were compared between cases and controls using the Wilcoxon rank sum test. The proportion with a BMI ≥ 95th percentile was compared between the two groups using the chi-square test. Among the cases, differences in acne medications used between BMI classes were evaluated using the chi-square test. The association between BMI percentiles and prescription systemic medication use was evaluated in a logistic regression model. All calculated p-values were two-sided and p-values less than 0.05 were considered statistically significant. Data was analyzed using SAS version 9.4 statistical software (SAS Institute, NC; Cary, NC).
Results
Of 725 patients with an acne diagnosis code, 42 were excluded due to either lack of confirmed acne diagnosis (n=32), diagnosis outside the specified age range (n=4), or calendar range (n=4), or diagnosis prior to becoming an Olmsted County resident (n=2). Of the remaining 683, acne records of 40 were not available due to a transition in electronic medical records, leaving 643 confirmed acne cases.
Overall, the annual age- and sex-adjusted incidence rate for ages 7-≤12 combined was 58.0 (95% CI, 53.5–62.5) per 10,000 person-years. The annual incidence was significantly higher in females versus males (89.2 vs. 28.2; p<0.001). Annual incidence significantly increased with age, with incidence rates of 4.3, 24.4, and 144.3 among those 7–8, 9–10, and 11–12 years of age, respectively (Table 1).
Table 1.
Incidence of acne per 10,000 person-years in 7–≤12 year-olds in Olmsted County, Minnesota, during 2010–2018, stratified by age and sex
| Age group (years) | Females |
Males |
Total |
|||
|---|---|---|---|---|---|---|
| No. | Incidence (95% CI) | No. | Incidence (95% CI) | No. | Incidence (95% CI) | |
|
| ||||||
| 7 – 8 | 13 | 6.8 (3.6, 11.7) | 4 | 2.0 (0.5, 5.0) | 17 | 4.3 (2.5, 6.9) |
| 9 – 10 | 75 | 40.5 (31.9, 50.8) | 18 | 9.2 (5.4, 14.5) | 93 | 24.4 (19.7, 29.9) |
| 11– 12 | 394 | 219.4 (198.3, 242.2) | 139 | 73.2 (61.6, 86.4) | 533 | 144.3 (132.3, 157.1) |
| Overall† | 482 | 89.2 (81.2, 97.2) | 161 | 28.2 (23.8, 32.5) | 643 | 58.0 (53.5, 62.5) |
Abbreviations: CI, confidence interval
The overall rates are age- and sex-adjusted to the population structure of the US total population in 2010.
Characteristics of the 643 incident cases are in Table 2. The most common race was White (75.7%) followed by Black or African American (7.2%); 91.6% were non-Hispanic. Of the 482 females, menses history was documented for 412 of whom 43.0% had menses onset prior to acne diagnosis.
Table 2.
Characteristics of 643 acne incident cases, diagnosed between 7 and ≤12 years of age in Olmsted County, Minnesota, during 2010–2018
| Characteristic | Female (N=482) | Male (N=161) | Total (N=643) |
|---|---|---|---|
|
| |||
| Race | |||
| White | 358 (74.3%) | 119 (73.9%) | 477 (74.2%) |
| Black or African American | 48 (10.0%) | 18 (11.2%) | 66 (10.3%) |
| Asian | 34 (7.1%) | 10 (6.2%) | 44 (6.8%) |
| Hawaiian or Pacific Islander | 1 (0.2%) | 0 (0.0%) | 1 (0.2%) |
| American Indian | 3 (0.6%) | 1 (0.6%) | 4 (0.6%) |
| Other or mixed | 35 (7.3%) | 12 (7.5%) | 47 (7.3%) |
| Unknown or not disclosed | 3 (0.6%) | 1 (0.6%) | 4 (0.6%) |
| Hispanic ethnicity | |||
| Yes | 41 (8.5%) | 13 (8.1%) | 54 (8.4%) |
| No | 441 (91.5%) | 148 (91.9%) | 589 (91.6%) |
| Location of acne at presentation | |||
| Face only | 329 (68.3%) | 128 (79.5%) | 457 (71.1%) |
| Torso only | 10 (2.1%) | 3 (1.9%) | 13 (2.0%) |
| Face and torso | 136 (28.2%) | 29 (18.0%) | 165 (25.7%) |
| Not specified | 7 (1.4%) | 1 (0.6%) | 8 (1.2%) |
| Onset of menses prior to acne diagnosis | |||
| No | 235 (48.8%) | ||
| Yes | 177 (36.7%) | ||
| Unknown | 70 (14.5%) | ||
Among the 643 cases, 27 (4.2%) were diagnosed with an acne relevant endocrine disorder prior to or at the time of acne diagnosis, including Cushing’s syndrome (n=1), precocious puberty (n=24), or other puberty disorders (n=2). The 24 cases with a prior precocious puberty diagnosis included 22 females diagnosed at a mean age of 7.3 (SD, 1.9; range 2.1–10.2) years and 2 males diagnosed at ages 7 and 12. The median duration of follow-up (i.e., visit to any provider for any reason) after initial acne diagnosis among all 643 patients was 4.9 (IQR, 3.1, 7.4) years with a median age at last follow-up of 16.8 (IQR, 14.8–19.4) years. During this period, 4 additional patients were diagnosed with precocious puberty (n=2) or other puberty disorders (n=2). Among the 482 female acne patients, 19 were subsequently diagnosed with polycystic ovary syndrome (incidence rate of 7.6 per 1000 person-years).
Before comparing BMI between cases and controls, we excluded the 27 acne cases with pre-existing acne-relevant endocrine disorders, leaving 616 cases. A BMI was available within 8 months of acne diagnosis for 581 of the cases. Overall, 73.5% were female and the mean (SD) age at the time of the recorded BMI was 11.9 (1.0) years for the 581 cases and 11.7 (1.2) years for the 1162 matched controls. The median age- and sex-specific BMI percentile was significantly higher for the acne cases compared to controls (median [interquartile range], 75.0 [51.2, 91.2] versus 65.0 [36.4, 87.4]; p<0.001). Furthermore, 16.7% (97/581) of the acne cases had a BMI ≥95th percentile compared to 12.2% (142/1162) of the controls (p=0.01; Figure 1).
Figure 1:
Age-and sex-specific BMI percentile classes among 581 acne cases compared to 1162 matched controls.
Ninety-nine percent of acne cases began an acne therapy (Table 3), most commonly prescription topical medications (75.1%), followed by OTC medications (47.7%), and prescription systemic medications (8.2%). Prescription systemic medication use increased with increasing BMI class, with 5.4% use among those underweight or of normal weight, 8.1% among overweight, and 10.3% in those obese. Although the difference in rates was not significantly different between the BMI classes (p=0.18), the odds of using prescription systemic medications was significantly associated with increasing BMI (odds ratio=1.43 per 5 kg/m2 increase in BMI, 95% CI 1.07–1.92; p=0.015).
Table 3.
Initial acne therapy used within the first 6 months of the acne diagnosis, by BMI class
| Type of acne therapy | All acne cases (N=643) | Age- and sex-specific BMI percentile class† |
|||
|---|---|---|---|---|---|
| Underweight or Normal (N=373) | Overweight (N=111) | Obese (N=97) | P-value‡ | ||
|
| |||||
| At least one of the following | 634 (98.6%) | 367 (98.4%) | 111 (100.0%) | 94 (96.9%) | -- |
| Over the counter medication | 307 (47.7%) | 177 (47.5%) | 56 (50.5%) | 47 (48.5%) | 0.86 |
| Prescription topical medication‡ | 483 (75.1%) | 276 (74.0%) | 90 (81.1%) | 69 (71.1%) | 0.20 |
| Topical retinoids | 365 | 207 | 72 | 44 | |
| Topical antibiotics or benzoyl peroxide | 277 | 163 | 45 | 43 | |
| Other | 14 | 9 | 0 | 3 | |
| Prescription systemic medication* | 53 (8.2%) | 20 (5.4%) | 9 (8.1%) | 10 (10.3%) | 0.18 |
| Systemic antibiotics | 52 | 20 | 9 | 9 | |
| Hormonal therapy or oral contraceptives | 3 | 2 | 0 | 1 | |
| Oral isotretinoin | 2 (0.3%) | 2 (0.5%) | 0 (0.0%) | 0 (0.0%) | -- |
| Other^ | 2 (0.3%) | 1 (0.3%) | 0 (0.0%) | 0 (0.0%) | -- |
Results based on the 581 acne cases with available BMI and without pre-existing relevant endocrine disorders.
The use of each type of medication was compared between the three BMI classes using the chi-square test.
Some patients may have used more than one type of prescription topical medication or more than one type of prescription systemic medication.
topical hydrocortisone [1 patient]; comedone extraction [1 patient]
Discussion
Acne Incidence in children 7-≤12 years-old
While acne is common in adolescents, little was known about its incidence in preadolescents. Here we found the annual age- and sex-adjusted incidence rate for ages 7-≤12 combined was 58.0 per 10,000 person-years, higher in female patients, and increasing with age.
Acne in preadolescents is often a sign of approaching puberty.17 However, it can rarely be associated with underlying disease and may require further workup and treatment considerations.18,19 In our study, 4.2% of preadolescents with acne had a diagnosed relevant endocrine disorder prior to or at the time of the acne diagnosis, most commonly precocious puberty with average age of diagnosis of 7 years. In the US, by age 7 years, 10.4% of White, 23.4% of Black, and 14.9% of Hispanic girls have begun thelarche.20 Puberty before age 8 years in girls and 9 years in boys is classified as precocious puberty.21 Thus, a thorough review of systems and exam should be done in this population to look for precocious puberty with a low threshold for systemic evaluation if indicated.
With the trend in the US towards a younger age of onset of puberty, especially in girls,22 there appears to also be a trend towards earlier acne onset.1,17 This may partially explain the higher acne incidence in female preadolescents compared to males. Girls may also be more likely to seek care for acne, reflecting a higher incidence. Similarly, higher incidence with advancing age correlates with pubertal maturation, supported by menses onset before an acne diagnosis in over one third of females.
Relationship between BMI and acne in children ages 7-≤12 years
The knowledge gained regarding BMI and its relationship to acne in this age group is striking. The BMI percentiles of children ages 7-≤12 years with acne were compared to same community controls. BMI percentiles are significantly higher for children diagnosed with acne, and those children are much more likely to be obese, than those without diagnosed acne.
Obesity rates among children and adolescents have been increasing. As of 2016, 18.4% of 6–11 year-olds and 20.6% of 12–19 year-olds were obese.2 High BMI is a strong risk factor for acne development and severity in adults, but until now pediatric studies have revealed mixed information. Two prior studies of children ages 6–11 years12 and 7–19 years7 found overweight/obesity to be risk factors for acne presence. However, another study of 10 to 17-year-old girls did not find a higher prevalence of acne in overweight/obese girls >13 years old,9 though it did in girls ages 10–12 years with higher BMI.9 These prior studies were largely retrospective reviews without controls, highlighting the importance of the results of our true-population based study with case-controls.
While acne severity was not assessed directly in our study, acne treatments used may serve as an indirect indicator of severity. Only 8.2% received systemic prescriptions, suggesting that most had mild-to-moderate disease not requiring systemic medications. Thus far, information regarding the possible role of BMI on acne severity is limited. Among adolescents, one study found increasing BMI was not associated with acne severity,3 yet another did find obese patients were more likely to have papulopustular or nodulocystic acne than peers with lower BMI.23 In our preadolescents, there was an increasing trend of systemic prescription use with increasing BMI percentiles, possibly suggesting more severe acne. Further research is necessary to determine if lifestyle modifications may alter the trajectory of acne in this population.
While dietary habits were not assessed in this study, nutrition as a confounder in the relationship between obesity and acne may be considered.24 Additionally, obesity may influence preadolescent acne development timing through its effect on reaching puberty, as overweight and obese girls achieve puberty earlier than peers with normal BMI,25 thus leading to earlier acne onset. Furthermore, insulin resistance, which may be related to obesity, has been implicated with inducing or worsening acne potentially related to shifts in IGF-1 signaling and hyperandrogenemia.24 Higher acne diagnosis incidence among obese children could also be related to increased visits for comorbidities during which acne is diagnosed.
This study has several limitations. First, this was a retrospective study and may not have accurately captured all patients with acne. Menarche age was unavailable. Some patients may not visit a physician for acne and thus not be included. Additionally, Olmsted County residents are largely non-Hispanic White. Generalizing findings to persons of other races or geographic locations may not be appropriate.
In conclusion, acne incidence is higher in preadolescent girls than boys and increases with age. There is a potential association with precocious puberty which should be considered, especially among those presenting under 8 or 9 years old. Preadolescents with acne are more likely obese than those without acne and those with higher BMIs are more likely to receive systemic acne therapy, potentially indicating more severe acne. Future studies investigating the effect of measures taken to improve BMI status on acne should be considered as appropriate. Increasing understanding of preadolescent acne epidemiology and risk factors may allow earlier intervention and prevent undesirable sequelae.
Acknowledgements
Funding information:
This study was made possible using the resources of the Rochester Epidemiology Project, which is supported by the National Institute on Aging of the National Institutes of Health under Award Number R01AG034676. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
Footnotes
Conflict of Interest Statement: No conflict of interest.
IRB approval status: Approval was obtained from Olmsted Medical Center Institutional Review Board (ID# 011-OMC-20) and from the Institutional Review Board at Mayo Clinic (ID# 20-002445).
Prior presentation: Society for Pediatric Dermatology 2021 Annual Meeting (Presented Virtually)
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