Exploring the Interplay: Obesity, Lipid Metabolism, and Clinical Manifestations in Atopic Dermatitis

Abstract

Background: The interest toward the association between atopic dermatitis (AD) and obesity is increasing, yet the possibility of abnormal lipid metabolism has never been investigated before.

Objective: To identify the characteristics of patients with AD who are obese and analyze the serum lipid profiles of these patients.

Methods: This observational study included 167 patients diagnosed with AD and underwent evaluations for serum lipid panels between July 2017 and October 2017. The patients' body mass index was used to determine obesity and the serum lipid panels were analyzed between patients who are obese and non-obese. Also, the disease severity and subjective symptoms were evaluated and serum total immunoglobulin E (IgE) and specific IgE levels were assessed.

Results: Of the 167 patients with AD, there were 36 obese and 131 non-obese subjects. Obese patients were found to have a significantly higher disease severity, as well as higher serum triglyceride and low-density lipoprotein-cholesterol levels and lower high-density lipoprotein-cholesterol levels, which was most pronounced in adult males. Obesity AD patients also had a significantly higher serum total IgE, itch intensity score, and number of allergens sensitized.

Conclusion: Patients with AD who are obese should be monitored for possible abnormalities in lipid metabolism. Obesity may be a factor that contributes to a higher disease severity of AD.

Keywords: Atopic dermatitis; Cholesterol, HDL; Cholesterol, LDL; Immunoglobulin E; Lipid metabolism; Obesity.

Fig. 1. Difference in disease severity between obese and non-obese AD patients (A) Assessment of the severity according to obesity. EASI score of obese AD patients was significantly higher than that of non-obese subjects. (B) When the patients were stratified according to the severity (mild: ≤7, moderate: >7 and ≤21, severe: >21), the percentage of the number of obese patients significantly increased with increased severity (p=0.008).

EASI: eczema area and severity index, AD: atopic dermatitis. ^**p<0.01.

Fig. 2. Comparison of atopic dermatitis severity between obese and non-obese patients among different groups of pediatrics and adults. (A) Assessment of the severity according to obesity. EASI score of obese AD patients was higher than non-obese subjects in both pediatric and adult groups, however, the difference was significant only in adult group (p=0.02). (B) When stratified according to the severity, the percentage of the number of obese patients increased with increased severity, however, the difference was significant only in adult group (p=0.03).

EASI: eczema area and severity index, AD: atopic dermatitis. ^*p<0.05.

Fig. 3. Difference in clinical atopic parameters between obese and non-obese AD patients. (A) Serum total IgE levels of obese and non-obese AD patients. (B) The number of allergens sensitized was assessed by CAP immunoassay and compared between obese and non-obese AD patients. (C) Itch intensity of obese and non-obese AD patients, using the NRS.

IgE: immunoglobulin E, AD: atopic dermatitis, NRS: Numeric Rating Scale. ^*p<0.05.

Fig. 4. Results of simple linear regression analysis. (A) Association between EASI score and various parameters, including BMI, itch intensity, and serum lipid profiles (TG, HDL-cholesterol, and LDL-cholesterol). (B) Association between serum Total IgE level and various parameters, including BMI, itch intensity, and serum lipid profiles (TG, HDL-cholesterol, and LDL-cholesterol).The presence of obesity was defined based on BMI higher than 25 kg/m².

EASI: eczema area and severity index, BMI: body mass index, TG: triglyceride, HDL: high-density lipoprotein, LDL: low-density lipoprotein, IgE: immunoglobulin E, CI: confidence interval, OR: odds ratio. ^*p<0.05, ^**p<0.01. ^†Based on simple linear regression analysis.