|Year : 2021 | Volume
| Issue : 5 | Page : 507-513
Androgenetic alopecia: Prevalence and clinical characteristics in a South-West Nigerian population
Sebastine Oseghae Oiwoh1, Adeolu Oladayo Akinboro2, Olayinka Abimbola Olasode3, Emmanuel Olaniyi Onayemi3
1 Dermatology and Venerology Unit, Department of Internal Medicine, Irrua Specialist Teaching Hospital, Irrua, Edo State, Nigeria
2 Dermatology and Venereology Unit, Department of Medicine, Ladoke Akintola University of Technology, Ogbomoso, Oyo State, Nigeria
3 Department of Dermatology and Venereology, Obafemi Awolowo University, Osun State, Nigeria
|Date of Submission||29-May-2021|
|Date of Decision||30-Jun-2021|
|Date of Acceptance||11-Aug-2021|
|Date of Web Publication||11-Oct-2021|
Dr. Sebastine Oseghae Oiwoh
Dermatology and Venereology Unit, Department of Internal Medicine, Irrua Specialist Teaching Hospital, Irrua, Edo State
Source of Support: None, Conflict of Interest: None
Introduction: Androgenetic alopecia (AGA) is a type of nonscarring alopecia with prevalence, pattern, and severity that have not been documented extensively in Nigeria and Africa. This study aimed to document AGA's prevalence and clinical characteristics among adults in Ogbomoso, Southwestern Nigeria. Methods: A community-based cross-sectional study of 260 consenting adults with AGA and 260 age- and sex-matched controls through a multistage sampling method. The survey for AGA was done using a pretested questionnaire. Data were analyzed with IBM SPSS version 20. Results: The overall prevalence of AGA was 29.95%, with a gender prevalence of 24.88% and 5.06% for men and women, respectively. The mean age of AGA was 51.32 ± 16.31 years, with a range of 24–90 years and male-to-female ratio of 4.9:1. The prevalence of premature AGA was 0.38%. Grade II vertex (13.8%) and VI (10.4%) were the most frequent male androgenetic alopecia severity grades, while grade IVa was the least common. Ludwig I was the most frequent female androgenetic alopecia severity grade (7.7%), followed by Ludwig II (6.9%) and III (2.3%). The mixed type of baldness was the most common (73.6%) phenotype, followed by frontal (20.8%), and vertex (4.2%) in men. Conclusion: Overall prevalence of AGA was 29.95%. The prevalence varies with location, age and gender with paternal family history as a significant risk factor. The mixed type of baldness is the most common phenotype.
Keywords: Androgenetic alopecia, pattern, prevalence, severity
|How to cite this article:|
Oiwoh SO, Akinboro AO, Olasode OA, Onayemi EO. Androgenetic alopecia: Prevalence and clinical characteristics in a South-West Nigerian population. Niger J Med 2021;30:507-13
|How to cite this URL:|
Oiwoh SO, Akinboro AO, Olasode OA, Onayemi EO. Androgenetic alopecia: Prevalence and clinical characteristics in a South-West Nigerian population. Niger J Med [serial online] 2021 [cited 2021 Dec 8];30:507-13. Available from: http://www.njmonline.org/text.asp?2021/30/5/507/327943
| Introduction|| |
Androgenetic alopecia (AGA) is a nonscarring alopecia characterized by abnormalities in the hair cycle with eventual hair loss.,,, When AGA occurs in the male gender, it is referred to as male androgenetic alopecia (MAGA) or male pattern baldness, and in the female, it is called female androgenetic alopecia (FAGA) or female pattern baldness.
Studies have shown that the prevalence of AGA is lower in women compared to men, and the prevalence increases with age.,, AGA affects 50% of European men by 50 years, and by 80 years, 80% of men are affected. Some other works also demonstrated that AGA prevalence progressively increases with age., A study from Iran among females showed that 39.6% of females aged between 20 and 70 years had AGA.
Studies have been conducted elsewhere on alopecia generally and AGA specifically, but published studies on AGA are few in Nigeria and Africa. Reports show that AGA and other types of alopecia were reported in most works as part of hospital-based studies that examined the epidemiology of skin diseases in different locations. The prevalence of alopecia in such studies varies with aetiologies and with the location of the study.,,,,, Some other Nigerian studies have reported AGA in relation to prevalence, pattern, dermatoglyphic patterns, smoking, alcohol intake, vitamin, and micronutrient levels.,,,,, Various factors associated with AGA in published studies include genetics, androgen, the hypothetic role of chronic scalp tension, chronic micro-inflammation, and oxidative stress induction to which westernized diet and some environmental factors have been implicated.,,, Therefore, more community-based studies are necessary to elucidate AGA's epidemiology and clinical characteristics. Hence, the present study documented the prevalence, clinical pattern, and severity of AGA in Southwestern Nigeria.
| Methods|| |
This community-based cross-sectional and descriptive study included 260 consenting AGA participants as subjects and 260 age- and sex-matched controls through a multistage sampling method that entails a three-stage proportionate allocation of wards, streets and households until the total sample size was completed. The survey for AGA was done using an interviewer-administered pretested questionnaire. The study population was recruited proportionally from the five local government areas (LGA) in Ogbomoso according to the population size of each LGA.
The study included adults with AGA, 18 years and above, residents in Ogbomoso willing to give informed consent. We excluded individuals younger than 18 years and adults not willing to give their consent. The non-residents and those that had acute medical or surgical illnesses, and chronic diseases such as chronic liver disease, chronic kidney diseases, and human immunodeficiency virus/acquired immunodeficiency syndrome, and individuals on steroids were excluded. The ethical review committee of LAUTECH Teaching Hospital, Ogbomoso, approved the study (LTH/OGB/EC/2017/162).
The survey for AGA was done in the evening using a pretested questionnaire. The history related to AGA, including the duration of baldness, location of hair loss, family history of baldness, conditions that worsen hair loss, and presence or absence of other symptoms such as acne vulgaris and hirsutism were documented. The presence of AGA in at least a relation signified presence in the family lineage. The participants were examined, and the AGA location (frontal, vertex, or the presence of mixed type) was documented. The severity of AGA was assessed using the modified Hamilton–Norwood (MHN) and Ludwig classification for MAGA and FAGA, respectively. The MHN Grade I and II were regarded as normal AGA while stages IIa, IIv, III, IIIa, and IIIv as mild AGA, stage IV, IVa, V, Va as moderate AGA, while stages VI and VII as severe AGA in men. Ludwig I was classified as mild FAGA, Ludwig II as moderate, while Ludwig III as severe AGA.
Clinical photography of the subject was taken with a Tecno camera (5 megapixels) with the participants seated with the head looking straight at zero degrees of the horizontal plane in the field of vision, back well-rested on a comfortable chair. Headgear, caps, and scarfs were removed after permission from participants. Two shots were taken per area of the scalp with a camera at a distance of at least 10–20 cm from the site and zoomed closer when necessary. The frontal, parietal, temporal, vertex, and occipital regions of the scalp had two shots at least taken from each. The occipital region of the scalp was used as a control picture since the occipital region is usually spared in AGA.
| Results|| |
The study participants consisted of 216 (83.10%) males and 44 females (16.90%) with the age range of 24 years to 90 years out of a total of 868 community members reached. Men with AGA were five times more than women (M: F =4.9:1; 83.10% vs. 16.90%, respectively). The subjects and control population were significantly skilled workers, manual workers, and students (X2 = 23.67, P < 0.001), [Table 1].
The overall prevalence of AGA was (260/868) 29.95%, with significant regional variation (X2-12.051, P = 0.017). The prevalence of MAGA was highest in Ogbomoso North LGA (63 [24.20%]) followed by Orire LGA (55 [21.20%]), Surulere (40 [15.40%]), Ogo Oluwa (19 [7.30%]) and lowest in Ogbomoso South LGA (39 [15.00%]). The prevalence of FAGA was also highest in Surulere LGA (14 [15.40%]) followed by Ogbomoso North (12 [4.60%]), Ogo Oluwa (8 [3.10%]) Ogbomoso South LGA (7 [2.70%]) and lowest in Orire LGA (3 [1.20%]), [Table 2].
|Table 2: Prevalence of androgenetic alopecia by local government areas according to gender|
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Subjects with AGA significantly have a positive family history of AGA compared to the control population (46.5% vs. 23.1%, X2 = 31.534; P < 0.001). Similarly, baldness was more likely in male family members of individuals with AGA compared to control population; that is fathers (32.2% vs. 15.8%, X2 = 19.473; P < 0.001), brothers (20.4% vs. 8.5%, X2 = 14.973, P < 0.001), and uncle (16.2% vs. 4.6%, X2 = 31.233, P < 0.001). Participants with AGA expressed a significant level of subjective stress as a worsening factor for alopecia compared to the control population (20.0% vs. 4.2%, X2 = 30.361, P < 0.001), [Table 3].
|Table 3: Risk factors for androgenetic alopecia and associated conditions|
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| Discussion|| |
The prevalence of androgenetic alopecia by age, gender
The prevalence of 29.95% is lower than that of another Nigerian study. The observed difference can be explained by the peculiar differences in patient selection in the two studies from different geopolitical zones of the same country. Variations in AGA have been documented within communities as well as between regions., The Nigerian northern and southern regions have varying tribes that may have impacted the epidemiological pattern of AGA. In addition, the population spread of participants, the larger sample size in this survey may also explain the difference in prevalence. Like the present study, other population-based studies that examined a much larger population for the epidemiology of AGA documented close prevalence (21.3%, 22.4%, and 31.8% respectively in China, Taiwan, and Anatolia).,, However, reports from other studies showed a prevalence of 74.8% in Australia and 63.0% in Norway., Lower prevalences of AGA (1.9% and 0.9%, respectively) were reported in Nigerian studies as part of the all-cause etiology of alopecia.,
The gender-specific prevalence of AGA in this study was 24.88% and 5.06% for MAGA and FAGA, respectively. Previous studies had also reported a higher prevalence of MAGA than FAGA in observational studies worldwide , though a lower prevalence was reported in a Nigerian hospital-based study. The prevalence of MAGA observed in the present study is lower than 67.1% documented in a Turkish study. However, the same Turkish study observed a higher proportion of FAGA (23.9%) than 5.06% obtained in the present study while an Anatolian study reported a prevalence of 47.6% and 19.17% for MAGA and FAGA, respectively. Khumalo et al., in a South African study, found a much lower prevalence of 14.6% for MAGA and 3.5% for FAGA, which are close to the present study's findings.
The mean age of participants with AGA in this study was 51.32 ± 16.31 years, with a wide age range of 24–90 years. There was an incremental trend of baldness until 41–50 years. The prevalence in men was 12.5% in the twenties, 20.8% in the thirties and 23.1% in the forties. A progressive reduction in prevalence was subsequently noticed; 18.1% in the fifties, 10.2% in the sixties and 11.1% in the seventies, 2.8% in the eighties and 1.4% in the nineties. The age-specific progressive increase in prevalence is similar in pattern but lower in prevalence (30% for men in their thirties, 40% for men in their forties and 50% in the fifties) than observation among Caucasians. The initial progressive increase in prevalence is also similar to the work by Wang et al. and Gan and Sinclair, Ayanlowo also reported a progressive increase in the number of subjects with AGA. The sharp decline in prevalence after the age of 50 years could be attributed to the relatively lower population of older people in Nigeria, as exemplified by the life expectancy in Nigeria.
Premature AGA is defined as AGA developing before 35 years and presenting with at least stage 2 of the Norwood-Hamilton classification. This study found a prevalence of 0.38% (49/868) for premature AGA, which is more common in men (98.0%) than women (2.0%). This prevalence (0.38%) recorded for premature alopecia in this study is lower than 47.5%, 68.0%, and 70% reported in Asian studies. Genetic and racial differences might account for the wide variation in the prevalence. The severity of AGA in premature AGA varies from study to study. In the present study, grade II (24.5%) and IV (20.4%) were, respectively, the most common grades, and this is in close semblance to severity reported by Krupa et al. (grade I and II). Wang et al. reported grade II as the most common severity grade while Batra et al. and Swaroop et al. reported higher severity of grades III/IV and III, respectively.,
The risk factors for androgenetic alopecia
Genetic predisposition has been widely implicated in AGA.,, Subjects with AGA in this study had a significant family history of AGA (46.5%, P < 0.001), especially in male family members, including fathers, brothers, and uncles. Several previous studies also confirm the family association.,, Contrary to the increased risk of paternal inheritance pattern in this study, another study established a polygenic inheritance pattern of AGA, with increased risk when a mother is affected. The risk is much increased with the severity of maternal involvement. However, like the present study, Wang et al. and others also documented increased risk when fathers were affected.,,, Some participants believed that psychological stress increases their hair loss, although this has not been previously documented in relation to AGA in this environment. However, stress factors are established in association with other causes of hair loss, such as telogen effluvium. Tellez-Segura confirmed the import of mechanical stress in inducing hair loss while Botchkarev reported the basis for psychosocial, emotional, and environmental stress on hair loss.,
The pattern and severity of androgenetic alopecia
The mixed pattern of MAGA was the most common (73.6%) in this study, followed by frontal (20.8%), vertex location (3.7%), and atypical (1.9%), respectively, [Figure 1]a, [Figure 1]b, [Figure 1]c, [Figure 1]d. Our finding is similar to the findings of a Chinese study and an Anatolian study but different from the predominant frontal type observed in Caucasians and northern Nigerians. The observation is also different from the predominant vertex type observed among the Koreans.
|Figure 1: Clinical types of aga. (a and b) The clinical types of AGA (frontal and vertex respectively). (c and d) The clinical types of AGA (mixed and atypical AGA respectively)|
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The present study shows that typical AGA accounted for 98.4% of all AGA, while atypical AGA accounted for 1.6% using the modified Hamilton-Norwood scale [Figure 2]a, [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12]. Type IIv was the most common grade (13.8%), followed by VI (10.4%) with IVa as the least common (0.8%), [Figure 1], [Figure 2]a, [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12]. The finding was similar to that of Wang et al. and Krupa et al., but differs from Bas et al.'s in which type VI was predominant and Batra study in which type III and IV were predominant. Report of lower atypical AGA as seen in this study had earlier been documented by Bas (0.2%) and Adamu (0.3%). In contrast, the Chinese (3.7%) and Korean studies (11.1%) reported a higher prevalence of atypical AGA.
|Figure 2: Androgenetic alopecia grading. (a and b) Grade IIa: Frontotemporal recession within 2cm from anterior hairline|
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|Figure 3: (a-c) Grade II vertex: Frontotemporal recession with isolated hair loss involving the vertex|
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|Figure 4: (a and b) Grade III: Frontotemporal recession beyond grade II but reaches the coronal plane joining the external auditory meati|
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|Figure 5: (a and b) Grade II anterior: Frontotemporal recession beyond grade II with hair loss extending to the mid-coronal plane joining the external auditory meati|
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|Figure 7: (a and b) Grade IV: Frontotemporal recession beyond grade III with extensive hair loss on both sides of the scalp joined by an area still containing some density of hair|
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|Figure 8: (a and b) Grade IV anterior: Grade IV with hair loss being pronounced beyond the anterior hair line|
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|Figure 9: Grade V and Va: Frontotemporal recession beyond grade IV with hair loss extending to the vertex but with sparse hair in between (a and b respectively)|
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|Figure 10: (a and b) Grade VI: Frontotemporal recession and hair loss beyond grade V reaching the crown|
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|Figure 11: Grade VII: Frontotemporal recession and hair loss beyond grade VI with a horse shoe band of hair lying below the occiput|
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The analysis of FAGA showed that Ludwig I pattern was the most common grade of FAGA (7.7%), followed by II and III (6.9% and 2.3%), respectively [Figure 13]. This pattern was similar to reports by Wang et al. and Xu et al., while Bas in a Turkish community-based study reported Ludwig type I as the most frequent FAGA type and type II as the least common.
|Figure 13: Ludwig grade I-III: progressively wider areas of hair loss on the crown from grade I to III|
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| Conclusion|| |
The overall prevalence of AGA is 29.95%, with gender prevalence of 24.88% and 5.06% in men and women, respectively. It varies across various LGAs, with MAGA increasing with each decade till the forties then declines after that. Grade II vertex (13.8%) and VI (10.4%) are the most frequent severity grades in males, while grade I for females and the mixed type of baldness is the most common phenotype. A family history of baldness in males is a significant risk factor for AGA. This study serves as a template for further studies, possibly with a larger population size and scope on AGA.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13]
[Table 1], [Table 2], [Table 3]