Prevalence of Metabolic Syndrome in Vitiligo Patients in Comparison With the Control Group

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hmj.hums.ac.ir http features of participants (age, gender, waistline, and BMI) and duration of the lesions were collected after obtaining a written consent form. Then, systolic (SBP) and diastolic blood pressure (DBP) were measured 2 times with an interval of 10 minutes after 5 minutes of rest, and mean numbers were recorded as well. Finally, laboratory markers, including fasting blood glucose (FBS), highdensity lipoprotein (HDL), and triglyceride (TG) were measured, and the prevalence of MS was estimated based on Adult Treatment Plan (ATP)-III.
The collected data were analyzed by SPSS, version 16 (software IBM, Armonk, NY, USA). Prevalence, relative prevalence, and mean ± standard deviation (SD) were used for descriptive analyses. Comparisons between the two groups for qualitative and quantitative data were applied by Chi-square and independent t tests, respectively. The effect of the duration of vitiligo on the occurrence of MS was evaluated by the logistic regression analysis.

Results
One hundred and thirty participants (65 patients with vitiligo and 65 participants in the control group) were enrolled in the study. There was no significant difference in the demographic features of participants (age and gender) and BMI between the two groups ( Table 1). The lower extremity (27.51%) was the most common site of involvement in vitiligo patients. Trunk and upper extremity (each 25.92%), as well as head and neck (20.63%), were involved with lower frequencies. The mean duration of vitiligo was 6.39 ± 5.57 years (in the range of 1-25 years).
MS was observed in 54.29% and 60% of vitiligo patients and the control group, respectively, but the difference was not significant (P = 0.5). Although the mean ± SD of MS syndrome parameters was not significant between the two groups, systolic hypertension (HTN) was significantly higher in vitiligo patients compared to the control group (Tables 2 and 3). The effect of the duration of vitiligo on the occurrence of MS was investigated by the logistic regression analysis. An increase in the length of the disease by one year could increase the chance of MS occurrence by 7% [P = 0.04, OR (95% CI) = 1.07 (1.00-1. 15)].

Discussion
MS is characterized by dyslipidemia, diabetes mellitus, HTN, and abdominal obesity. This syndrome is associated with cardiovascular cerebrovascular diseases and diabetes mellitus. A higher mortality rate related to MS has been reported in previous studies. Although the pathogenesis of MS is not well-known, factors such as chronic inflammatory process, oxidative stress, and hyperhomocysteinemia have been proposed in the pathogenesis of this syndrome (5)(6)(7). Previous studies demonstrated an association between chronic inflammatory skin diseases such as psoriasis and lichen planus with MS. It was reported that increased pro-  inflammatory cytokines and decreased anti-inflammatory cytokines are contributing factors in the development of MS in these diseases (9)(10)(11).
To date, a few studies have reported increased insulin resistance, diabetes mellitus, and dyslipidemia in vitiligo patients (12,13). In this study, for the first time in Iran, the prevalence of MS in vitiligo patients was compared with the control group. In the present study, MS has been reported to be most prevalent in the vitiligo group (45.7%) than in the control group (40%), but the difference was not significant (P = 0.5). Moreover, systolic HTN was significantly higher in vitiligo patients compared to the control group. Although the other risk factors of MS (i.e., waist circumference, BMI, and FBS) were higher in vitiligo patients than in the control group, they were not statistically significant.
In a similar study in Turkey, Karadag et al reported no significant difference between vitiligo patients and the control group regarding TG, FBS, BMI, and waist circumference. In their study, systolic HTN was significantly higher in the vitiligo group than in the control group (12), which is in line with the result of the current study.
Atas et al demonstrated a significantly higher prevalence of MS in vitiligo patients (38.1%) than in the control group (21.5%). Additionally, the latter study reported a higher prevalence of MS in patients with a longer duration of the disease. In the current study, similar to the abovementioned study, MS was more common in the vitiligo group (45.7%) than in the control group (40%), but the result was not significant. In the study by Atas et al, the level of FBS was higher in vitiligo patients compared to the control group, but the difference was not statistically significant (13), which corroborates with the finding of our study. In the present study, an increase in the length of the disease by one year led to a 7% increase in the chance of the MS occurrence In one study in India, Sharma et al revealed a significantly higher prevalence of MS (24% vs. 12%), hyperglycemia (25% vs. 16%), low HDL (58% vs. 53%), and hypertriglyceridemia (41% vs. 24%) in vitiligo patients in comparison with control groups, respectively. In the present study, the frequencies of hyperglycemia (22.8% vs. 13.8%), low HDL (80% vs. 77.14%), and hypertriglyceridemia (3.08% vs. 1.43%) were higher in vitiligo patients than in the control group, but the result was not statistically significant. In the aforementioned study, there was no significant difference in waist circumference and BMI between the two groups 14, which matches the result of our study.
In the present study, systolic HTN was significantly higher in vitiligo patients (18.57%) compared to the control group (6.15%). In previous studies, an association was found between chronic inflammatory diseases such as psoriasis and seborrheic dermatitis and HTN (15,16). In the study by Linder, a significantly higher prevalence of HTN was reported in seborrheic dermatitis patients (27.1%) than in the control group (24.7%) (15). In another study by Cohen, the prevalence of HTN was significantly higher in psoriasis patients in comparison to the control groups (38.8% vs. 29.1%) (16). Several factors such as the increased level of homocysteine, C-reactive protein, ROS, and pro-inflammatory cytokines, especially TNF-α have been involved in the higher rate of HTN in these diseases. Likewise, the endocannabinoid system and its role in the regulation of adipogenesis, BP, and vascular function have been confirmed in the pathogenesis of HTN. Thus, previously mentioned factors can also be the contributing causes of HTN in vitiligo patients (15,16).
The increased levels of pro-inflammatory cytokines related to TH1 (IL-1, IL-6, and TNF-α) and decreased levels of anti-inflammatory cytokines such as IL-10 have been reported in the pathogenesis of vitiligo similar to inflammatory diseases such as psoriasis. Oxidative stress and increased level of ROS are other factors that have been involved in the dysfunction of lipids and pathogenesis of vitiligo (17,18).

Conclusion
The findings of this study indicated a significantly higher prevalence of systolic HTN in vitiligo patients compared to the control group. In addition, a higher frequency of MS was observed in vitiligo patients relative to the control group, but the difference was not significant. Thus, with regard to the possibility of the higher occurrence of MS in vitiligo patients, it is recommended that the screening laboratory test be conducted for early recognition and treatment of cardiovascular risk factors.

Conflict of Interests
The authors declare that they have no conflict of interest.