Obesity Linked to Atopic Dermatitis Severity, Pathophysiological Data Gaps Remain

Obesity is substantially associated with clinician- and patient-assessed atopic dermatitis disease severity, according to recent findings, though the investigators acknowledge the corresponding effect sizes indicate limited clinical relevance.¹

These findings represented the conclusion of a prospective, observational cohort study known as TREATgermany. This research was led by Stephan Traidl, MD, of Hannover Medical School’s department of dermatology and allergy in Hannover, Germany.

Traidl et al. noted that there was still widespread division among epidemiological studies as far as arriving at a definitive conclusion on obesity’s link with increased severity of atopic dermatitis.² The investigators added that some studies in Europe contradict the results of American studies on the topic.³

“The purpose of this study was to investigate associations between obesity and subjective as well as physician-reported measures of disease severity in addition to comorbidities in AD patients,” Traidl and colleagues wrote. “For this purpose, real-life, reliable data from the TREATgermany registry, one of the largest AD registries worldwide, were analysed.”

Background and Methods

The investigators designed the TREATgermany registry as a prospective observational cohort study which aimed at subjects with moderate-to-severe atopic dermatitis. In 2023, their cohort exceeded 1800 individuals recruited across 69 total recruitment centers. A prior outline explaining the registry's criteria for subject inclusion, methodologies, and goals was acknowledged.⁴

In short, the research team summarized that adults in the age range of ≥18 years would have to have been diagnosed with eczema using the UK Working Party criteria for diagnosis, with identification occurring through objective Scoring Atopic Dermatitis (oSCORAD) evaluations >20. Subjects would also have to have undergone systemic therapy for atopic dermatitis within the previous 24 months.

Following their first interactions with TREATgermany participants, the team assessed subjects’ baseline characteristics and implemented these qualities to stratify based upon their reported Body Mass Index (BMI).

Specifically, the investigators separated subjects into 3 cohorts: those who were labeled underweight (BMI < 18.5 kg/m2), those labeled normal weight/overweight non-obese (18.5 ≤ BMI < 30 kg/m2), and those labeled obese (BMI ≥ 30 kg/m2). They also assessed and recorded participants’ educational background, age, sex, smoking habits, age at the time of disease onset, employment status, marital status, and disease severity.

The research team looked at Eczema Area and Severity Index (EASI), SCORing Atopic Dermatitis (oSCORAD), and Investigator's Global Assessment (IGA). The team also evaluated allergological data, including subjects’ sensitization profiles, total IgE, and comorbidities like allergic rhinitis and bronchial asthma.

Findings

Overall, there were 1416 participants involved in the research, 16.5% of which were shown to have a BMI ≥30 kg/m2 that suggested obesity. The investigators reported that obesity was shown to correlate with lower education levels as well as an increased prevalence of cigarette-smoking.

Despite these findings, apart from these specific factors, the research team found that obese and non-obese subjects with atopic dermatitis had similar baseline characteristics. The team added that a BMI increase was associated with increased oSCORAD (adjusted β: 1.24, 95% CI: 1.05–1.46, P = .013) as well as POEM scores (adjusted β: 1.09, 95% CI: 1.01–1.17, P = .038).

The investigators showed that there were modest distinctions as far as participants’ overall oSCORAD between obese and non-obese individuals with atopic dermatitis. Additionally, the team found that allergic comorbidities had been shown to be similar across all arms of the study, with asthma being the singular exception due to its prevalence among obese individuals (P < .001).

“One limitation of the presented study is the low number of underweight AD study participants,” they wrote. “This prevented any adequate analysis from being conducted on this subgroup. However, the overall sample size was sufficiently large and well-characterized to investigate obese patients.”

References

1. ^{Traidl S, Hollstein MM, Kroeger N, Fischer S, Heratizadeh A, Heinrich L, et al. Obesity is linked to disease severity in moderate to severe atopic dermatitis—Data from the prospective observational TREATgermany registry. J Eur Acad Dermatol Venereol. 2024; 00: 1–9. https://doi.org/10.1111/jdv.20042.}
2. ^{Nahm DH. Associations of atopic dermatitis with obesity and unmarried status in young adults: evidence for atopic dermatitis as a life-style disorder with high social impact. Allergy Asthma Immunol Res. 2016; 8: 89–91. https://doi.org/10.4168/AAIR.2016.8.2.89.}
3. ^{Treudler R, Zeynalova S, Walther F, Engel C, Simon JC. Atopic dermatitis is associated with autoimmune but not with cardiovascular comorbidities in a random sample of the general population in Leipzig, Germany. J Eur Acad Dermatol Venereol. 2018; 32: e44–e46.}
4. ^{Siegels D, Haufe E, Heinrich L, Werfel T, Weidinger S, Schmitt J, et al. Status report on the atopic dermatitis registry TREATgermany. Allergol Select. 2021; 5: 274–286.}