Establishment of clinical evaluation criteria for scalp seborrheic dermatitis

To evaluate the three symptom indicators of scalp seborrheic dermatitis (SSD), namely scalp flaking, maximum erythema area, and pruritus, to develop a “16‐point scale,” to explore its relationship with the severity of SSD, and verify the reliability of the 16‐point scale.


| Data collection
After obtaining consent, relevant details of patients with SSD who conformed to the inclusion criteria were evaluated and recorded by the evaluator.Since dermatological examinations are routine and necessary in the clinical diagnosis of SSD, there is no need for ethical approval, but we still strictly follow the principles outlined in the Declaration of Helsinki.

| Statistical analysis
Data analysis was done using SPSS 26.0 software.The measurement data are expressed as (mean ± SD), and the inter-group comparison was performed using non-parametric test.Bivariate correlation analysis was used for correlation analysis.The relationship between nonnormal distribution data variables were analyzed using Spearman's correlation coefficient.p < 0.05 indicated that the difference was statistically significant.

| General profile
A total of 109 patients with SSD were included, and after excluding 4 cases with incomplete information, final analysis was done on 105 respondents, which included 49 male and 56 female patients.Their ages ranged from 10 to 53 years, with a mean age of 30 years The duration of disease ranged from 2 weeks to 10 years, with a mean duration of 6 months.

| Correlation of each indicator with the SSD severity
Spearman's correlation coefficients of adherent scalp flaking score, erythema, pruritus, and the total SSD severity score were 0.638, 0.213, 0.367, and 0.715, respectively.Spearman's correlation coefficients of erythema and pruritus were smaller than 0.4, indicating a weak correlation, and Spearman's correlation coefficients of adherent scalp flaking score and the total score were between 0.6 and 0.8, indicating a strong correlation with the SSD severity.p values were less than 0.05, showing statistical significance.See Table 1.

| Difference in the indicators between different SSD severity groups
The K-W test was performed based on independent samples for the adherent scalp flaking score, erythema, pruritus, and total score.Significant difference between mild and moderate patients was found for the adherent scalp flaking score (p = 0.156), for erythema (p = 0.012), for pruritus (p = 0.022), and for the total score (p = 0.002).Significant difference between mild and severe patients was found for the adherent scalp flaking score (p = 0.000), for erythema (p = 0.066), for pruritus (p = 0.000), and for the total score (p = 0.000).Significant difference between moderate and severe patients was found for the adherent scalp flaking score (p = 0.000), for erythema (p = 1.000), for pruritus (p = 0.213), and for the total score (p = 0.000.)(The above p values were adjusted using the Bonferroni correction method).The results showed that (1) the adherent scalp flaking score cannot distinguish well between mild and moderate patients, but can be taken as the indicator for differentiating moderate and severe patients; (2) erythema score, and pruritus score can distinguish between mild and moderate patients, but cannot distinguish between moderate and severe patients; and (3) the total score of patients with different degrees of SSD severity was significantly different, and the total score can be used to evaluate the severity of SSD.

| DISCUSS ION
SSD is a chronic, recurrent, inflammatory skin disease commonly found in seborrheic areas.It is very common among infants, adolescents, and adults, especially males.The main symptoms include oily scalp, folliculitis, scaling, pruritus, and even alopecia.
This study included data from 105 patients treated in Beijing from January to June.Previous studies have shown a seasonal distribution of SSD, as being more common in winter and less common in summer, 8,9 and other studies have also shown that the proportion of patients was highest in spring and the lowest in summer.SSD may be aggravated by the impairment of the epidermal barrier function due to the decrease in the extensibility and hydration of the stratum corneum, as affected by low temperature and humidity. 10In this study, patients showing symptoms from winter-spring to early summer were included.The data were quite representative since this is the high-incidence season.In terms of regional distribution, it was found that heat and humidity were risk factors for the onset of SSD 11 ; however, the study only compared patients between tropical and subtropical regions, and the applicability of the findings to temperate regions needs to be further confirmed.SSD symptoms were found to be related to the increase in PM10, the high level of urbanization, living conditions, new furniture, burning of incense, cockroaches, and rats/mice.Additionally, the high level of economic development and the use of air conditioning in the hot season could lead to mild SSD symptoms. 12Beijing has a typical northern climate, featuring hot summers and cold winters, with dry air.Patients from Beijing better represent those with SSD in northern cities.In this study, the male-female ratio was about 1:1, the age ranged from 10 to 60 years, and most were 20-50 years old.The findings mainly reflect the SSD conditions in adults.
The course of disease and severity of SSD may vary from person to person, and no uniform criteria have been developed for the evaluation of its severity.The standardization of evaluating the severity of SSD can help in formulating and selecting treatment plans as well as in evaluating treatment effects.As for the disease evaluation indicators, the four-point scale (0-3) for erythema, scalp flaking, and lesion area, 13 Adherent Scalp Flaking Score (ASFS) 14,15 and Investigators' Global Assessment (IGA) 7,16 are commonly used in China and abroad.Erythema, scalp flaking, and pruritus are the three most used indicators of symptoms in studies.In addition, there are also some physiological and biochemical indicators, such as sebaceous gland secretion rate, transepidermal water loss (TEWL), stratum corneum hydration (SCH), skin surface pH, 14 and some molecular markers. 17 therefore, it is evident that the total score best reflects the severity.
For the specific correlation between the severity of SSD and the score, comparison was performed in this study at the level of α = 0.05.
There was a significant difference in total score between mild, moderate, and severe patients, which indicates that the total score of the "16point scale" could differentiate the severity of SSD well.As for ASFS, the difference between mild and moderate patients were not statistically significant (p > 0.05), while the difference between moderate and severe patients was statistically significant.This indicates that the scalp flaking score was more useful in distinguishing mild-moderate patients from severe patients.As for the maximum erythema area and pruritus degree, there were significant differences between mild and moderate patients, and between mild and severe patients, while there was no significant difference between moderate and severe patients.
Therefore, the indicators of the maximum erythema area and pruritus are more suitable for differentiating mild patients from moderatesevere patients.In terms of clinical manifestations, mild patients had mild scalp flaking, erythema, and pruritus; moderate patients had mild scalp flaking, with erythema and pruritus; while severe patients had severe scalp flaking, generally accompanied by erythema and pruritus.
The total score of the three indicators can help better distinguish between mild, moderate, and severe patients.
Finally, the severity and total score were statistically analyzed, and the total score of the "16-point scale" was used to quantify the severity of SSD.The scores of mild patients were generally [0, 5], the scores of moderate patients were generally, 4,8 and those of severe patients were generally.Since the patients in this study were mainly urban adults in northern China, it is necessary to continue to expand the sample size to further verify the effectiveness of the clinical evaluation criteria.
Compared with physiological and biochemical indicators, symptom indicators have the following advantages: (1) They can be easily collected and applied, and can be widely used in clinical diagnosis and treatment scenarios;(2) They are highly consistent with the subjective experience of the patients and well-accepted, with a high clinical application value.Therefore, based on these evaluation criteria, the indicators of scalp flaking, maximum erythema area, and pruritus were finally selected for evaluating the patients, that is, the "16-point scale" was used to explore their relationship with the severity of SSD.It was found in this study that overall, the total score of the "16point scale" strongly correlated with the severity of SSD.ASFS was TA B L E 1 Spearman's correlation coefficient of each indicator correlated with SSD severity.severity, and the scores of maximum erythema area and pruritus were weakly correlated with severity, showing statistical significance (p < 0.05).When the three indicators were correlated with severity of SSD, the correlation of scalp flaking was the strongest, and a scalp flaking score of 10 out of the total score of 16 could better reflect SSD severity.The correlation of the total score with severity was higher than that of each individual score; 8,15 Therefore, we recommend the following evaluation criteria for severity of SSD: a total score of 0-5 points indicates mild SSD, 6-9 points indicates moderate SSD, and 10-16 points indicates severe SSD.This method can be used to evaluate the severity of SSD patients more objectively, avoid the influence of subjective factors of different evaluators, guide and standardize the diagnosis and treatment of SSD, and better evaluate the efficacy.The advantages of this study are: (1) adequate sample size was ensured as the incidence of SSD was high from winter and spring to early summer, namely the season-changing period.(2) The Hair Research Center of Beijing Jishuitan Hospital admitted a large number of patients with alopecia and with poor scalp conditions.The proportion of patients with severe SSD was high.Therefore, in this study, there were complete sample data of severe patients, ensuring that the evaluation methodology covered various types of SSD severity adequately.(3) In this study, the evaluation on severity was independently completed by one person, avoiding possible subjective errors caused by different evaluators.It should be noted that this study only evaluated adult SSD patients in Beijing, from winter and spring to early summer.There were certain limitations, and the applicability to southern patients, other seasons, infants, and adolescents needs to be further verified based on more samples.In conclusion, the study looks at the SSD conditions of adults in northern cities of China from winter and spring to early summer.The "16-point scale," consisting of the adherent scalp flaking score (0-10), maximum erythema area (0-3), and pruritus (0-3), was used to evaluate patients with SSD, and the total score was strongly correlated with and differentiated the severity of SSD.Recommended scoring criteria are: For the total score, a total score of 0-5 points indicates mild SSD, 6-9 points indicates moderate SSD, and 10-16 points indicates severe SSD.These criteria can help to standardize disease diagnosis and treatment as well as in efficacy assessment.