Gender-Specific Association of Androgenetic Alopecia With Metabolic Syndrome in a Middle-aged Korean Population

S.M. Yi; S.W. Son; K.G. Lee; S.H. Kim; S.K. Lee; E.R. Cho; I.-H. Kim; C. Shin

Disclosures

The British Journal of Dermatology. 2012;167(2):306-313. 

In This Article

Materials and Methods

Study Cohort

The study cohort, part of an ongoing prospective investigation, is one of the population-based cohorts included in the Korean Genome Epidemiology Study, previously called the Korean and Genome Epidemiology Study (KoGES).[22] Members of the study cohort consisted of 5020 male and female Korean citizens aged above 40 years at baseline who participated in a comprehensive health examination and on-site interviews at Korea University Ansan Hospital. The cohort members were followed biennially with scheduled on-site follow-up visits. For this cross-sectional study, cohort members from January 2008 to February 2010 were enrolled. Among the cohort participants, 3408 participants agreed to have a clinical photograph taken of their hair status and to undergo evaluation for hair loss. Among 3408 participants, 524 participants were excluded for one of the following reasons: other types of alopecia, receipt of hormone replacement therapy with testosterone, use of contraceptives or chronic or acute corticoid therapy, presence of hyperaldosteronism, polycystic ovary syndrome, cutaneous lymphoma or other cancers except for nonmelanoma skin cancer, receipt of lipid-lowering medication, or female pattern hair loss in the male group. Finally, 2884 participants were included in the statistical analysis. Each participant signed an informed consent form that was approved by the Human Subjects Review Committee at the Korea University Ansan Hospital.

Classification of Androgenetic Alopecia

The diagnosis of AGA was based on the pattern of hair loss of the participants. Assessment of the degree of hair loss was performed by two dermatologists. To classify the degree of AGA for men, the Norwood classification, a standard classification scheme with good test–retest reliability, was used.[23] Norwood type IV of AGA represents the starting grade of severe frontal AGA concurrent with vertex AGA. Therefore, AGA was divided into two categories, normal to mild AGA (Norwood types I–III) and moderate or severe AGA (Norwood types IV–VII), to assess its association with other potential risk factors. For women, the Ludwig classification was used.[24]

Components of Metabolic Syndrome and Other Possible Risk Factors

In addition to the classification of AGA, we collected information on possible risk factors during a face-to-face interview. Anthropometric measures, including waist circumference, were recorded. BP was measured twice with at least a 5-min interval between readings. To collect biochemical markers, a venous blood sample was taken after 12 h fasting to check blood glucose, TG and HDL-C. For each subject, a questionnaire regarding the diagnoses of chronic diseases, drug history and smoking status was completed. Prevalence of alopecia among first-, second- and third-degree relatives was also collected with a structured questionnaire administered by trained staff. The degree of hair loss of relatives was recalled by the study subjects.

Definition of Metabolic Syndrome

The definition of MetS was based on criteria defined by the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATPIII, 2001),[25] which were modified to include the World Health Organization's proposed waist circumference cut-off points for Asians.[26] Subjects were required to have three or more of the following: (i) waist circumference > 90 cm in men and > 80 cm in women, (ii) serum TG ≥ 150 mg dL−1 (≥ 1·70 mmol L−1), (iii) HDL-C levels < 40 mg dL−1 (< 1·04 mmol L−1) in men and < 50 mg dL−1 (< 1·70 mmol L−1) in women, (iv) impaired fasting glucose of →100 mg/dL−1 (6·11 mmol L−1) or use of medication for hyperglycaemia, and (v) BP ≥ 130/85 mmHg or use of medication for hypertension.

Statistical Analysis

A logistic regression model was employed to assess the associations between each possible risk factor (waist circumference, fasting plasma glucose, BP, and serum level of lipids, including TG and HDL-C) and the risk of developing AGA (type IV or greater in men, type I or greater in women). In addition, the number of fulfilled components of MetS was used in the analysis to evaluate if subjects with a higher number of components have a higher risk of AGA. To compare the associations of different components of MetS and AGA, all five components of the MetS criteria were put together in a multivariate logistic model in which important confounding factors were included. As age and family history are established risk factors for AGA, they were retained in the model in the multivariate analysis. In addition, smoking status was included in the multivariate analysis. Previous reports[12,13,17,18,21] have shown inconsistent results regarding the association between smoking and AGA. The relationship between smoking and AGA is still unclear and controversial. Smoking status also tends to increase blood cholesterol levels and blood pressure.[27] The statistical significance level was set at 5% for assessing each association. All odds ratios (ORs) and their 95% confidence intervals (CIs) were computed with SAS statistical package (SAS 9.1.3; SAS Institute, Cary, NC, U.S.A.).

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