The evaluation of atopic dermatitis is essential for selecting treatment methods and assessing their effectiveness 26. Many studies are currently being conducted to develop various evaluation methods for atopic dermatitis, and the SCORAD index is the most widely used assessment method. The SCORAD index evaluates both objective symptoms, such as the extent and severity of skin lesions, and subjective symptoms 27. The Objective SCORAD index (OSI) is a score that excludes subjective symptom assessment to enhance the objectivity of the evaluation 28. Using OSI in the study participants, it was found that 53% (44 individuals) of atopic dermatitis patients were classified as mild, and 47% (39 individuals) were classified as moderate, with an average OSI score of 15.4 ± 8.1.
Some studies have reported that the SCORAD score reflects the subjective judgment of the observer and shows variability in the measurements taken by different observers 27. Recently, there has been active research on the applicability of skin barrier function, especially TEWL, as a predictive factor for the onset of conditions such as atopic dermatitis 29. TEWL, which reflects the state of the skin's permeability barrier, along with SCH in the stratum corneum, is commonly used for evaluating skin barrier function 30. In this study, we focused on the presence or absence of atopic dermatitis lesions in 15 specific body areas of the study participants using SCH and TEWL. The importance of monitoring for moisture management in pediatric atopic dermatitis patients was confirmed.
Numerous studies on patients with atopic dermatitis have been conducted investigating the decrease in skin SCH 9 and the increase in TEWL 10,11. In this study, we observed low SCH and high TEWL in patients with atopic dermatitis, but the differences in SCH and TEWL between the control group and the patient group were not statistically significant. However, we were able to identify differences in SCH and TEWL among the 15 specific body areas based on the presence or absence of atopic dermatitis lesions. Body areas without atopic dermatitis lesions showed SCH and TEWL values that were not significantly different from those of the control group. On the other hand, significant differences were observed in SCH for the face, inner elbows, and forearms, and in TEWL for the face and ankles in patients with atopic dermatitis. The face area in infants is known to be a representative site for the onset of atopic dermatitis in early childhood 31. Although there is a lack of previous studies specifically focusing on moisture measurements based on the presence or absence of atopic dermatitis lesions, it has been reported that both impaired skin barrier function and increased moisture evaporation contribute to the development of atopic dermatitis 32–34. Dryness, which is an indicator of moisture loss, is considered a major symptom of atopic dermatitis by the UK Working Group 35. TEWL is used to measure skin barrier function, and it is known to be a scale that reflects the severity of symptoms in atopic dermatitis in some studies 36. In this study, we observed significant differences in SCH and TEWL between patients with atopic dermatitis and other groups in most body areas.
In this study, overall moisture levels (SCH) were highest in the face, neck, and trunk, followed by the limbs, excluding the wrists. Particularly, the moisture content on the forehead was the highest in both the control group and the group without atopic dermatitis lesions. This result is similar to previous findings that generally show higher moisture levels on the forehead compared to the cheek area 37. Among all the body areas, the wrists had the lowest moisture levels and the highest rate of moisture loss. This finding is consistent with studies on exposed and non-exposed areas, which have reported significantly higher TEWL values on exposed areas. This can be attributed to the high moisture loss from the hands due to frequent contact with factors that can worsen the skin condition 38. Additionally, this finding is particularly relevant considering the widespread use of hand sanitizers during the COVID-19 pandemic 39.
This study included participants under the age of 10 with mild to moderate atopic dermatitis. The forehead and cheeks, areas on the face, exhibited particularly low moisture levels (SCH) and high TEWL. Although the proportion of patients with atopic dermatitis lesions on the forehead and neck was low, the Objective SCORAD index (OSI) had the highest average value of 30. This finding was especially pronounced in the group of patients with atopic dermatitis lesions, highlighting the relationship with the presence of these lesions on moisture levels. In the group with lesions, the forehead, cheeks, and ankles had a higher proportion of patients with moderate to severe atopic dermatitis compared to the group without lesions. This suggests that these areas, which have the highest moisture loss, can have a significant impact on the development of skin lesions. In this study, the participants were under the age of 10, and the highest proportion of patients with atopic dermatitis lesions was observed on the arms and legs, ranging from 50–60%, which are typical sites of atopic dermatitis occurrence after the age of 2. However, when considering the proportion of patients with moderate to severe atopic dermatitis based on lesion location, the forehead, ankles, and wrists showed a higher proportion of such patients. Considering that the typical sites of atopic dermatitis lesions and clinical symptoms can vary with age 40, and given that sites like the forehead, neck, ankles, and wrists become prevalent after the age of 12, it can be inferred that individuals under the age of 12 with atopic dermatitis lesions and low moisture levels in these areas are particularly vulnerable to atopic dermatitis. This highlights the need for preventive management of atopic dermatitis based on age and specific areas of the body.
According to a study 41, 93.7% of adult patients with atopic dermatitis had skin lesions on their faces, indicating a correlation between the presence of lesions and facial involvement. Although the proportion of patients with visible lesions was small, it was observed that they had the highest moisture loss. This suggests that if moisture loss persists, it may lead to the development of skin lesions. High moisture loss in the areas where lesions manifest after the age of 12 was confirmed, and it was also observed that areas with high moisture loss in children under the age of 10 were consistent with those seen in adult-onset atopic dermatitis. These findings suggest the need for site-specific moisture monitoring in patients with less severe conditions, as not all body sites are equally susceptible to onset of atopic dermatitis nor are they equally severe in symptom presentation. It also indicates that site-specific moisture monitoring can be utilized for predicting the onset and prognosis based on age as well as being used for preventive measures such as moisture management.
However, in this study, the evaluation based on age and severity of atopic dermatitis patients, including all age groups, could not be conducted. Nevertheless, compared to previous studies on atopic dermatitis, recruiting a larger number of patients and focusing on the presence of atopic symptoms along with the conventional evaluation method of SCORAD have provided significance to the measurements of 15 specific body areas. This study, combined with previous inferences and data from other studies points in a direction that strongly suggests the clinical necessity and benefit of having body-site specific evaluations for treatment. It should be noted that there were limitations in obtaining an adequate control group; however, it was sufficient to explain the lack of differences among patients without atopic lesions. In the future, with consideration given to individual symptom changes and seasonal influences, it is expected that real-time monitoring of skin moisture could be more effective in preventive and therapeutic approaches.