Time Differences in Reaching Minimal Erythemal Doses among Different Fitzpatrick Skin Types Irradiated with NB-UVB

1. Introduction

Indonesia is one of the tropical countries that receives sunlight throughout the year. Sun exposure to the skin has both positive and negative effects (Fivenson et al, 2021). Ultraviolet (UV) exposure is one of the significant risk factors for skin diseases, such as skin cancer and premature aging. UVB is the most harmful type of ultraviolet radiation, which causes skin damage (Rodríguez et al, 2021). UVB is the primary component of UV radiation that induces sunburn or erythema caused by UV exposure.

Exposure to UV-B rays can also increase the production of reactive oxygen radicals in the skin. These reactive oxygen radicals can damage cell structures and trigger inflammatory reactions (Tan et al., 2020). Inflammation is the body's defense mechanism against injury or infection. The main manifestations of acute inflammation include blood vessel dilation causing erythema, warmth and itching sensation, plasma and protein fluid extravasation (edema), and increased vascular permeability. Erythema is a characteristic skin lesion, such as red patches, that can occur due to UV exposure (Jacoeb et al., 2020).

Military cadet students are frequently exposed to UV radiation due to their outdoor activities, especially during training and field exercises. The high level of outdoor activity results in significant UV exposure without adequate protection. Therefore, it is important to determine the differences in the time required to reach the minimal erythemal dose (MED), which is the time it takes for the skin to become red (erythema) due to UV exposure (Sabzevari et al, 2021). MED is the minimum amount of UV radiation required to induce erythema on the skin with well-defined borders, appearing 24 hours after ultraviolet exposure.

Previous studies have shown that the characteristics of each skin type based on Fitzpatrick vary. However, these results were obtained from the general population, whereas cadet students may have different skin responses to UV radiation (Tan et al, 2020). Therefore, it is necessary to conduct research focusing on this group to determine the differences in the time required to reach the minimal erythemal dose (MED). Research on the differences in the time to reach MED across different Fitzpatrick skin types has important implications for public health policies (Valbuena et al, 2020).

The results of this study can enhance understanding of the importance of routine skin protection against UV exposure. Additionally, this research can serve as a basis for developing more effective skin protection strategies. This will help reduce the risk of skin damage and skin diseases that can affect the health of personnel and improve the quality of life of military personnel (Hailun, 2021).

2. Methods

2.1. Research Methodology

This study will employ an experimental research method using a pretest-posttest two-group design. This experimental design involves two randomly selected groups, given a pretest before the intervention and a posttest afterward. This design compares the time to reach the Minimal Erythema Dose (MED) across various skin types based on the Fitzpatrick scale (Mukrimaa et al., 2016). In this research, the investigators will assess the MED on skin exposed to UV-B radiation according to the sample's skin type. The MED assessment will follow four steps: preparing UV exposure, conducting UV exposure, evaluating the MED, and determining the MED. For another control group, sunscreen intervention will be provided to compare the MED values under UV-B exposure. The MED evaluation will distinguish the time required to reach MED across different skin types based on the Fitzpatrick scale.

2.2. Study Selection

The population in this study consists of Cadet Students from the Faculty of Medicine at the Defense University of the Republic of Indonesia. The sample will be selected using purposive sampling, which selects samples based on specific considerations. These considerations include a population that meets the inclusion criteria for the study (Mukrimaa et al., 2016).

The sample size will be calculated using the Slovin formula:

Description:

·       n: sample size

·       N: population size

·       e: error rate

Based on the calculation above, the sample size required for this study is 15.002, rounded to 15 research samples.

Included studies had to meet these criteria: 1) All participants in this study must be between 18 and 24 years old 2) Must not have any skin conditions or diseases that affect the response to UV exposure, such as photosensitivity (dermatitis), autoimmune diseases (e.g., Lupus Erythematosus), etc. 3) Cadet students must fall into Fitzpatrick skin type categories I, II, III, or IV.

2.3. Data Extraction

The data processing technique will utilize SPSS Statistics. The collected data will be analyzed using appropriate statistical methods. The Shapiro-Wilk Normality Test will determine whether the data is normally distributed. Subsequently, an Independent Sample T-test will be used to examine the differences in the time required to reach the Minimal Erythema Dose (MED) across various Fitzpatrick skin types.

3. Result and Discussion

Phototherapy is a therapy that utilizes ultraviolet or visible light for therapeutic purposes. Since the early 20th century, Broadband UVB (BB-UVB) and Narrowband UVB (NB-UVB) have been widely used for treatment. NB-UVB phototherapy operates in the range of 311–313 nm; nowadays, 311 nm is the most used wavelength for phototherapy. Ultraviolet light sources include Narrowband (NB-UVB), Broadband (BB-UVB), and UVA. Different wavelengths of ultraviolet radiation used in phototherapy have varying efficacies. (Widodo et al., 2018)

The inflammatory response in the skin due to UV-B exposure involves the release of inflammatory mediators such as histamine, prostaglandins, and leukotrienes. These mediators cause vasodilation and increase vascular permeability, resulting in erythema on the skin. Erythema is a skin inflammation characterized by redness due to capillary dilation caused by chemical toxins or sunburn. This temporary skin condition is marked by skin or mucosal swelling (wheal) and redness (erythema), often accompanied by itching and sometimes pain (Jacoeb et al., 2020).

The Minimal Erythema Dose (MED) is the minimum amount of UV radiation required to produce clearly defined erythema on the skin, appearing 24 hours after UV exposure (Sabzevari et al, 2021).  Measuring the MED involves exposing the skin to UV light for a specific period to determine an individual's skin sensitivity to ultraviolet radiation. Common sites for MED measurement include areas rarely exposed to sunlight, such as the lower back and the inner forearm.

This study was conducted at the Faculty of Medicine, Defense University of the Republic of Indonesia. Researchers screened study subjects in November 2023. From three cohorts of cadet students at the Faculty of Medicine, totaling 227 potential subjects, 15 subjects meeting the inclusion and exclusion criteria were selected through a research form. These 15 subjects underwent NB-UVB phototherapy on the right back area. MED readings were taken 24 hours after phototherapy using the NB-UVB device.

The subjects included 15 male participants aged 18–22 years, divided into five participants with Fitzpatrick skin type 1 (33.33%), five with type 2 (33.33%), and five with type 3 (33.34%). Skin type was determined based on an assessment of the back area using the Fitzpatrick Scale. All participants had no history of skin disease, skin allergies, or medication use in the past month.

The results showed that the data distribution for MED times was statistically normal. Fitzpatrick skin type was associated with longer average MED times. Subjects were classified into three Fitzpatrick skin types: 1, 2, and 3.

·       For Fitzpatrick skin type 1, the minimum MED time was 60, the maximum was 90, and the average time was 90 ± 21.21.

·       For Fitzpatrick skin type 2, the minimum MED time was 90, the maximum was 150, and the average time was 114 ± 25.09.

·       For Fitzpatrick skin type 3, the minimum MED time was 90, the maximum was 150, and the average time was 126 ± 25.09.

Table 1: Time characteristics to reach MED based on Fitzpatrick Skin Types

The study before, MC Valbuena's study found that MED values vary across skin types due to differences in melanin pigment levels. The findings indicate that the MED time for Fitzpatrick skin type 1 was lower than for type 2. Statistically, the difference between Fitzpatrick skin types 1 and 2 was not significant, with a p-value of 0.141. However, the MED time for type 1 was significantly lower than for type 3, with a p-value of 0.040. The difference between types 2 and 3 was not significant, with a p-value of 0.471.

Table 2: Differences Between Fitzpatrick Skin Type 1 and 2

Table 3: Differences Between Fitzpatrick Skin Type 1 and 3

Table 4: Differences Between Fitzpatrick Skin Type 2 and 3

MC Valbuena's previous study found that MED values vary across skin types due to differences in melanin pigment levels. The findings indicate that the MED time for Fitzpatrick skin type 1 was lower than for type 2. Statistically, the difference between Fitzpatrick skin types 1 and 2 was insignificant, with a p-value of 0.141. However, the MED time for type 1 was significantly lower than for type 3, with a p-value of 0.040. The difference between types 2 and 3 was insignificant, with a p-value of 0.471.

The differences in erythema onset times can be mitigated using sunscreen, which protects the skin from UV exposure by absorbing or reflecting UV rays, thereby reducing the amount of UV radiation reaching the skin (Fivenson et al., 2021).

This study measured and examined the differences in MED times across Fitzpatrick skin types. Previous research evaluated average MED values without assessing the onset time for each skin type. However, not all skin types were included in this study, so the results cannot be generalized to indicate that every skin type has a different MED time.

4. Conclusions

This study examined the differences in the time required to reach Minimal Erythemal Doses (MED) across various skin types based on the Fitzpatrick scale, evaluated 24 hours after exposure to NB-UVB phototherapy. The researchers concluded the following:

·       The time required to reach MED varies across different skin types, each with a distinct average time.

·    There is a significant difference between Fitzpatrick Skin Types 1 and 3, while there are insignificant differences between Types 1 and 2 or Types 2 and 3.