Association among presentation, severity, and risk factors of acne vulgaris among Chinese college students: A cross-sectional study

Abstract

At present, research on acne among Chinese college students is limited, and the risk factors associated with acne remain to be further explored. This study investigated the prevalence and severity of acne among Chinese college students, while also exploring potential risk factor such as tongue manifestation. In total, 1084 participants (476 cases/608 controls; median age = 19 ± 2.075; range 17–30) were surveyed by collecting face and tongue images and questionnaires, which included basic information and acne questionnaires. Acne diagnoses and severity ratings were performed by trained personnel. The overall prevalence of acne was 43.91%, among which the prevalence of male was 51.18% and female acne was 40.59%. The prevalence of acne was significantly different for students from different regions (c² = 14.095; P = .029). Good social relationships may also be a preventative factor for acne (adjusted odds ratios [OR] = 0.653), and abnormal emotions, such as anxiety and depression, are risk factors for acne (adjusted OR = 1.588). Overweight body mass index as a risk factor for acne (OR = 1.481). Sleep disorders were a risk factor for acne (adjusted OR = 1.351). A significant association between sleep problems and acne remained (adjusted OR = 1.310, 95% confidence intervals: 1.017–1.687, P = .037). The stained tongues (adjusted OR = 1.381) and thick coatings (adjusted OR = 1.526) were significantly associated with acne and were both risk factors. Individuals experiencing digestive issues exhibited a lower likelihood of developing severe acne (adjusted OR = 0.622). Acne is prevalent among young individuals and is associated with distinct risk factors. Risk factors for acne included male sex, sleep issues, negative emotions, tooth-marked tongue, and a thick tongue coating were risk factors for acne presentation, whereas good social relationships and digestive problems served as protective factors. Overweight was a potential risk factor for acne. Male sex and changes in residential region increased the risk of severe acne, while digestive problems served as protective factors.

1. Introduction

Acne vulgaris, commonly known as acne, is a prevalent skin disease affecting about 9.4% of the global population, making it the 8th most common condition worldwide. Over the past 30 years, age-standardized rates of acne vulgaris have risen by about 0.55% annually.^[1] Acne lesions can be divided into papules, pustules, nodules, and cysts according to their size and appearance.^[2] The intensity of individual acne lesions can be roughly classified as mild, moderate, or severe.^[3] Acne often occurs in easily visible skin areas, such as the face, neck, and upper torso, leading to serious psychological distress, including depression and anxiety.

Identifying the risk factors for acne can help efficiently prevent and conduct early interventions. We reviewed the risk factors for acne severity, including demographic characteristics, body mass index (BMI), and other physical signs. We observed a significant correlation between acne and factors such as family history, age, and BMI.^[4,5] Many epidemiological studies have explored the contributing factors to acne. However, These studies have primarily focused on countries such as Europe and the United States, while research on acne populations in China-particularly among college students-remains limited.^[5,6] A systematic review provided valuable insights but relied on fragmented data and lacked practical case studies.^[7] In recent years, the number of college students affected by acne has been steadily increasing. Moreover, as this population has not yet developed stable psychological cognition, acne tends to have a greater psychological impact on them, warranting heightened attention and concern.

Therefore, this research examined the occurrence and severity of acne, and its related risk factors in a cohort of Chinese college students. Given that traditional tongue diagnosis is commonly used in China to assess a patient’s physical condition, we included potential risk factors-such as tongue manifestations-that have not been mentioned in previous epidemiological studies. This strategy not only helps to identify possible risk factors associated with acne for more effective prevention, but also provides preliminary clinical evidence to support the use of tongue diagnosis in traditional Chinese medicine.

2. Materials and methods

In a 2019 cross-sectional study from May to November, 1164 college students from Central China were examined to assess the epidemiology and severity of acne. As shown in the flowchart, 77 participants were excluded because of incomplete data or poor image quality (Fig. 1). Three students from other countries were excluded to avoid sampling bias. In total, 1084 participants were included in this study after excluding international students and those without sufficient data integrity. Facial images, demographic information, medical history, health status, and other information were collected. The Ethics Committee of Shuguang Hospital, affiliated with Shanghai University of Traditional Chinese Medicine, reviewed and approved this study (IRB No. 2018-626-55-01). The study was approved under protocol number 2018-626-55-01 and registered with the clinical trial number ChiCTR1900026008.

Figure 1.

Flowchart of materials and methods: participant recruitment, acne presentation, and severity.

Based on their acne presentation, the participants were divided into acne cases and controls using a definition designed to determine whether participants had acne. In total, 476 participants with facial acne at the time of data collection were included in the acne group. The remaining 608 participants were assigned to the control group. The participants were diagnosed and assessed for acne severity by medical staff, with a PhD student trained by a dermatologist and cross-validated by a dermatologist. Acne cases were classified into 3 categories according to severity based on the Global Acne Classification System. This system is based on the Global Evaluation Acne scale.^[8]

In this study, a two-part information recording form completed by the patients under the guidance of the researcher was used to collect participant data. The first part recorded the patients’ demographic and personal information, including height, weight, nationality, and hometown, and weight (kg) was divided by height (m) squared to calculate BMI. At baseline, height and weight were measured in light clothing and without shoes, respectively. In the second part, participants’ health status was evaluated, including life attitude, anxiety, depression, sleep, menstruation, and digestive problems. We took tongue images and recorded tongue features, including tongue shape and coating characteristics.

3. Statistical analysis

SPSS 23 was used for the statistical analysis in this study. A binary logistic regression model was employed to examine the relationship between acne occurrence and possible risk factors. Moderate and severe acne were combined into one category and analyzed when acne severity was compared because of the small sample size of patients with severe acne. Univariate analyses were conducted first, followed by multivariate analyses adjusted for age, sex, BMI, and ethnicity. For multivariate adjustment, participants were categorized into 2 groups according to sex (male, female), 2 groups according to age (≤19, 19–24), 3 groups for BMI (≤18.5, 18.5–23, and > 23), and 2 groups for ethnic (ethnic Han and ethnic minority). A multivariable logistic regression analysis was performed to examine the risk factors, with statistical significance set at P < .05. The results were presented as odds ratios (OR) with 95% confidence intervals (CI).

4. Results

4.1. Prevalence of acne and acne severity grades

We analyzed data from 1084 participants whose population profile are shown in Table 1. The age of the participants ranged from 18 to 25 years (median 19, standard deviation = 2.075), and 947 (87.36%) Han people and 139 minority people were included. The overall prevalence of acne was 43.91%, among which the prevalence of male was 51.18% and female acne was 40.59%. A notable disparity was found in the distribution between males and females with respect to the occurrence of acne (c² = 10.616; P = .001). The occurrence of acne was markedly greater in men compared to women. China is a large territory. The prevalence of acne was significantly different for students from different regions (c² = 14.095; P = .029), with the highest prevalence in the northeastern region of China and the lowest in the southern region of China (Fig. 2). No significant difference was observed in the acne case or control distribution between age groups (c² = 0.064; P = .801) and ethnic groups (c² = 0.263; P = .608). Most patients with acne (73.32%) had mild acne, and approximately 5% had severe acne.

Table 1.

Demographic characteristics of acne cases and controls and prevalence of severity among acne cases.

Variable	Case (n = 476)	Control (n = 608)
Gender
Male	174 (56.55)	166 (24.41)
Female	302 (43.45)	442 (72.70)
Age
20–24 years	58 (12.18)	80 (13.16)
≤19 years	418 (87.82)	528 (86.84)
Ethnic
Ethnic Han	419 (88.03)	528 (86.84)
Ethnic minority	55 (11.55)	79 (12.99)
Not stated	2 (0.42)	1 (0.16)
Region
Central region of China	307 (64.4)	431 (70.8)
North region of China	38 (7.9)	44 (7.2)
East region of China	37 (7.7)	28 (4.6)
South region of China	24 (5.0)	40 (6.5)
Southwest region of China	25 (5.2)	33 (5.4)
Northwest region of China	29 (6.0)	21 (3.4)
Northeast region of China	14 (2.9)	9 (1.4)
Not stated	2 (0.4)	2 (0.3)
Acne severity grades
Mild	349 (73.32)
Moderate	102 (21.43)
Severe	25 (5.25)

Values are frequencies (%).

Figure 2.

Incidence of acne in different regions of China.

4.2. Risk factors for the presence of acne

The risk factors closely linked to acne occurrence are listed in Table 2. Psychological and social factors remained significantly linked to acne presentation, independent of age, sex, and BMI. Compared with people with acne, people without acne are more likely to have normal social interactions and good interpersonal relationships. Patients with acne are more likely to experience negative emotions, such as anxiety and depression. Good social relationships may also be a preventative factor for acne (adjusted OR = 0.653), and abnormal emotions, such as anxiety and depression, are risk factors for acne (adjusted OR = 1.588).

Table 2.

Association of selected demographic, psychosocial factors, tongue characteristics, and comorbidities with acne presentation.

Variable	Unadjusted		Adjusted*
	OR (95% CI)	P	OR (95% CI)	P
Demographic
Gender (NCase/NControl)
Male (57/117)	1.534 (1.185–1.986)	.001	1.532 (1.175–1.996)	.002
Female (69/232)	1.00	–	1.00	–
Psychosocial factors
Good social and interpersonal relationships (NCase/NControl)
Yes (328/466)	0.675 (0.515–0.885)	.004	0.653 (0.496–0.860)	.002
No (148/142)	1.00	–	1.00	–
Anxiety and depression (NCase/NControl)
Yes (46/39)	1.566 (1.004–2.443)	.048	1.588 (1.012–2.491)	.044
No (427/567)	1.00	–	1.00	–
Tongue characteristics
Teeth marks around the tongue (NCase/NControl)
Yes (292/324)	1.391 (1.090–1.775)	.008	1.381 (1.079–1.768)	.010
No (184/284)	1.00	–	1.00	–
Thick coating on the tongue (NCase/NControl)
Yes (112/105)	1.474 (1.094–1.987)	.011	1.526 (1.126–2.066)	.006
No (164/503)	1.00	–	1.00	–
Comorbidities
BMI class (Asian) (NCase/NControl)
18.5–23 (278/347)	1.00	–	1.00	–
<18.5 (87/140)	1.074 (0.784–1.471)	.658	1.149 (0.843–1.566)	.380
>23 (104/113)	1.481 (1.015–2.160)	.041	1.314 (0.892–1.937)	.168
Sleeping problems† (NCase/NControl)
Yes (191/202)	1.353 (1.055–1.736)	.017	1.351 (1.049–1.740)	.020
No (283/405)	1.00	–	1.00	–

Values are odds ratio (95% CI). Bold values indicate statistically significant differences (P < .05).

BMI = body mass index, CI = confidence intervals, OR = odds ratios.

^*Adjusted for age, gender, ethnic and BMI.

^†Sleeping problems including difficulty falling asleep, easy to wake up and much dreaming.

The development of acne was associated with certain comorbidities (Table 2). BMI was associated with acne presentation, with overweight BMI as a risk factor for acne (OR = 1.481). After adjusting for confounders (adjusted OR = 1.314, 95% CI: 0.892–1.937, P = .168), the risk effect may be related to sex and not age. Additionally, the presentation of acne is significantly associated with sleep quality. Thus, sleep disorders were a risk factor for acne (adjusted OR = 1.351). To prove that sleep disorders are risk factors independent of negative emotions, we added controls for anxiety, depression, and other adverse emotions by controlling for sex, age, and BMI. At this time, a significant association between sleep problems and acne remained (adjusted OR = 1.310, 95% CI: 1.017–1.687, P = .037).

Furthermore, we conducted an exploratory study on the relationship between acne and tongue features. We found that stained tongues (adjusted OR = 1.381) and thick coatings (adjusted OR = 1.526) were significantly associated with acne and were both risk factors. To prove that tongue features are independent of other risk factors, we controlled for emotional sleep factors. The results suggest that tooth-marked tongue (adjusted OR = 1.396, 95% CI: 1.088, P = 1.789) and greasy tongue coating (adjusted OR = 1.534, 95% CI: 1.130–2.083, P = .006) are significant risk factors for acne.

4.3. Risk factors for acne severity

The risk factors closely linked to acne severity are shown in Table 3. Gender demonstrated a strong correlation with acne severity. The male sex remained a significant risk factor for moderate-to-severe acne even after controlling for confounders. In addition to sex, digestive problems were closely associated with acne risk. Individuals experiencing digestive issues, including loss of appetite and upset stomach, exhibited a lower likelihood of developing severe acne, with digestive problems showing a significant protective effect (adjusted OR = 0.622) against severe acne. Changes in living area and environment were significantly correlated with the severity of acne, and those who had frequent changes in residence (adjusted OR = 1.697) were more likely to have severe acne.

Table 3.

Association of selected demographic, comorbidities, lifestyle factors with acne severity grades.

Variable	Acne severity
	Unadjusted		Adjusted*
	OR (95% CI)	P	OR (95% CI)	P
Demographic
Gender (NModSev/NMild)
Male (57/117)	1.615 (1.067–2.444)	.023	1.591 (1.034–2.449)	.035
Female (69/232)	1.00	–	1.00	–
Comorbidities
Digestive problems† (NModSev/NMild)
Yes (38/143)	0.609 (0.394–0.942)	.026	0.622 (0.399–0.969)	.036
No (89/204)	1.00	-	1.00	-
Lifestyle
Change of long-term resident region‡ (NModSev/NMild)
Yes (63/130)	1.685 (1.117–2.541)	.013	1.697 (1.111–2.590)	.014
No (63/219)	1.00	-	1.00	-

Values are odds ratio (95% CI). Bold values indicate statistically significant differences (P < .05).

CI = confidence intervals, OR = odds ratios.

^*Adjusted for age, gender, and BMI.

^†Digestive problems including bad breath, loss of appetite, upset stomach, and other symptoms.

^‡Have long-term resident region change within the last year.

5. Discussion

Acne is a common skin disease with a high incidence worldwide. The prevalence of acne in this study was 43.91%, which was slightly lower than the 51.3% and 46.8% reported in other studies conducted in Chinese populations.^[9,10] This may be because the diagnosis of acne in our study was based on the current condition of the participants, and participants who had only a history of acne were excluded. Directly comparing our results with those of other studies is challenging as no reliable consensus on the criteria for grading acne severity is available. Overall, in our patients with acne, the proportion of mild acne was 73.32%, and the proportion of moderate and severe acne was 26.68%, which was similar to or slightly higher than the results of other Chinese studies.^[9–11] In previous studies. However, no consensus on sex differences in the incidence of acne is available. Some studies tend to show that females are more susceptible to acne,^[11,12] whereas other studies tend to show that males are more susceptible to acne.^[5,10,13,14] In our study, a significant sex difference was observed in the prevalence of acne, with males having a higher risk than females. Sex also had a significant impact on the severity of acne. Additionally, the incidence of acne showed significant regional differences, even though all participants were from China. Regarding student origin, the highest incidence of acne was observed in the northeastern region of China (60.8%), while the lowest was observed in the southern region of China (37.5%).

Among the assessed factors, psychosocial factors and sleep were considered important risk factors for acne. Patients with acne showed significant differences in social and emotional aspects than those without acne. The influence of psychosocial factors and acne may be mutual; that is, owing to the influence of acne on appearance, many patients experience negative emotions, such as anxiety and depression. Long-term negative emotions can cause or aggravate acne. This can be explained by the findings of other studies. For example, hormone disturbance is an important pathogenesis of acne, and several studies have shown that sex hormone levels are significantly correlated with negative emotions, such as anxiety and depression. Sex hormone disturbances are also an important pathogenesis of acne.^[15–17]

Related studies have shown a strong link between sleep quality and various factors, including anxiety and depression.^[18–21] As a result, we added control over psychological and emotional factors. Sleep problems remain an independent risk factor for acne, and poor sleep can increase the risk of acne. People with acne were more likely to have sleep problems, such as difficulty falling asleep and dreamy with waking easily, than those without acne. A significant association was observed between sleep quality and the occurrence of acne, which may be related to sebum hormone level.^[22–24] Our study showed that sleep problems markedly elevated the likelihood of developing acne; however, no link was found between sleep and the severity of acne.

Regarding BMI, we observed that overweight was a significant risk factor for acne. The risk did not attain statistical significance after controlling for age and sex, overweight individuals had a higher prevalence of acne than healthy individuals. Regarding classification of BMI and acne severity, no statistically significant correlation was observed, and neither being underweight nor overweight affected acne severity. The correlation between BMI and acne obtained in this study was consistent with most similar studies.^[24–27]

In addition to these common risk factors, this study conducted exploratory research in areas of less concern to other scholars, such as the correlation between acne development and factors, including tongue characteristics, digestive problems, and residential changes. This study was inspired by Traditional Chinese Medicine. After conducting innovative research on the correlation between tongue characteristics and acne progression, decent results were obtained. In Traditional Chinese Medicine, the tongue is an external representation of the human body. The patient’s internal qi, blood, and body fluid states can be understood by observing the tongue. Notably, tooth-marked tongue (adjusted OR = 1.381) and thick tongue coating (adjusted OR = 1.526) were significantly associated with acne, and people with these features were more likely to have acne. Compared with people without acne, patients with acne are more likely to have a tooth-marked tongue and a thick greasy tongue coating. A correlation between these tongue features and acne was observed for the first time and has not been previously reported. These findings are significant and have application value. Understanding this feature can play an auxiliary role in determining the risk of acne and serve to prevent it better.

Among the factors affecting the severity of acne, digestive problems were a good protective factor against moderate and severe acne. The association between diet and acne was adequately established; however, this association has rarely been mentioned in other studies.^[28–30] People with digestive problems possibly pay more attention to gastrointestinal protection and have better dietary habits.

Numerous studies have demonstrated a significant correlation between acne incidence and regional environments.^[31–33] Our research also found notable differences in acne incidence across various regions in China. However, relevant studies on whether changes in the regional environment affect acne remain unavailable. In this study, the association between changes in the resident region and the risk of acne was not statistically significant; however, a higher prevalence of acne was observed among people who changed their resident region (adjust OR = 1.119, 95% CI: 0.879–1.429, P = .369). A significant association was observed between changes in the residential region and the occurrence of moderate and severe acne (P < .05). This association persisted even after controlling other related variables. Sudden changes in the long-term living environment can affect acne, and this factor should be considered in preventing and treating acne.

Furthermore, other risk factors, such as smoking, drinking, exercise, positive attitude, defecation, menstruation, and many other factors, were assessed. However, the results did not indicate a statistically meaningful correlation between the incidence and severity of acne.

Our study had some limitations. First, because the sample included all college students, the results of this study cannot be extrapolated to other occupational groups of the same age. Second, the participants in this study came from all regions of China, including the northern region; however, the majority of participants (68.08%) came from Central China, which may have caused bias in the results. Furthermore, this study evaluated factors, such as social psychology, sleep, and digestion; however, the assessment scale used was not professional, comprehensive, or detailed. Relevant conclusions need to be supplemented and improved through more targeted studies.

6. Conclusion

A significant correlation was found between sex and both the occurrence and severity of acne. Social relationships and negative emotions, such as anxiety and depression, interacted with acne. The relationship between weight and the occurrence of acne showed no statistical significance; however, the relationship remains remarkable. Sleep problems are risk factors for acne, whereas gastrointestinal problems protect against moderate and severe acne. The appearance of acne is associated with tongue characteristics, including marked teeth and greasy tongue coating, which are risk factors for acne. Acne is also significantly affected by the regional environment. This study revealed the causes and related factors of acne and may provide insights into the epidemiology of acne for researchers and clinicians, particularly in the Chinese population. Some new acne risk factors were discovered in this study, which is expected to provide a reference and direction for future research on acne risk factors and help conduct more effective prevention and intervention.

Acknowledgments

We appreciate the revisions made by editor Aarti M to this manuscript.

Author contributions

Conceptualization: Mengyao Duan.

Data curation: Chuhao Wang, Mengyao Duan.

Formal analysis: Chuhao Wang.

Funding acquisition: Mengyao Duan.

Supervision: Mengyao Duan.

Writing – original draft: Chuhao Wang.

Writing – review & editing: Mengyao Duan.