To the Editor: We are interested in determining the factors that predict the trajectory of androgenic alopecia (AA). Some previous studies suggest that men of certain races are likely to experience specific balding patterns, but different races are rarely compared.1,2 This report characterized the incidence of balding patterns within a large cohort of men of different races.
We analyzed data from the UK Biobank ( project #66911), where balding data were collected through a touchscreen questionnaire. After excluding women and ambiguous or missing data, 188,814 male residents of the UK were included in the final analysis. Table I depicts unadjusted means and frequencies by ethnicity/race. These data were adjusted for age, smoking status, body mass index, testosterone, and sex hormone binding globulin using regression analysis. Balding pattern 1 (minimal to no hair loss) and White race were chosen as reference groups.
Table I.
Unadjusted correlation of race/ethnicity within androgenic alopecia balding patterns and covariates in UK Biobank from 2006–2010
| AA (n=188,814) |
|||||
|---|---|---|---|---|---|
| Ethnicity/Race |
|||||
| N | White* | South Asian† | Chinese | Black‡ | |
|
| |||||
| Age, y | |||||
| Mean (SD) | 56.8 (8.2) | 57.0 (8.1) | 53.3 (8.7) | 52.5 (8.0) | 51.7 (8.2) |
| Minimum-maximum | 38–73 | ||||
| BMI, kg/m2 | |||||
| Mean (SD) | 27.8 (4.2) | 27.8 (4.3) | 27.0 (4.0) | 25.1 (3.1) | 28.3 (4.2) |
| Testosterone, nmol/L | |||||
| Mean (SD) | 12.0 (3.7) | 12.0 (3.7) | 11.4 (3.5) | 12.5 (3.4) | 12.4 (4.1) |
| SHBG, nmol/L | |||||
| Mean (SD) | 39.6 (16.7) | 39.9 (16.7) | 32.5 (14.4) | 34.0 (15.0) | 36.9 (15.9) |
| Balding pattern§,∥ | |||||
| 1 (%) | 60,801 (32.2) | 57,999 (31.9) | 1455 (35.5) | 256 (54.0) | 1091 (40.6) |
| 2 (%) | 43,090 (19.8) | 41,842 (23.0) | 634 (15.5) | 81 (17.1) | 533 (19.8) |
| 3 (%) | 50,458 (26.7) | 48,433 (26.7) | 1314 (32.1) | 100 (21.1) | 611 (22.7) |
| 4 (%) | 34,465 (18.3) | 33,283 (18.3) | 694 (16.9) | 37 (7.8) | 451 (16.8) |
| Smoking status∥ | |||||
| Never(%) | 92,431 (49.0) | 87,888 (48.4) | 2640 (64.4) | 295 (62.2) | 1608 (59.9) |
| Former (%) | 73,067 (38.7) | 71,503 (39.4) | 828 (20.2) | 114 (24.1) | 622 (23.2) |
| Current (%) | 23,316 (12.3) | 22,166 (12.2) | 629 (15.4) | 65 (13.7) | 456 (17.0) |
AA, Androgenic alopecia; BMI, body mass index; N, total study population; SHBG, sex hormone binding globulin.
White race/ethnicity includes British and Irish.
South Asian race/ethnicity includes Indian, Bangladeshi, and Pakistani.
Black race/ethnicity includes Caribbean and African.
Pattern 1, no or minimal hair loss; pattern 2, temporal balding; patten 3, vertex balding; pattern 4, severe or total hair loss.
Percent is listed as the percentage within the total study population or race/ethnicity group.
There was a significant variation in AA between races/ethnicities. As shown in Fig 1, South Asians had greater odds for vertex balding but lower odds for temporal balding compared to White men. Chinese men were less likely than White men to experience balding in any pattern. Black participants also had lower odds for temporal, vertex, and severe balding but to a lesser extent than Chinese men.
Fig 1.
Forest plots depicting odds ratios (ORs) and 95% confidence intervals (CIs) of South Asian, Chinese, and Black men compared to White men with androgenic alopecia patterns of baldness in UK Biobank from 2006–2010. Significance denoted in bold.
Racial differences in AA patterns among White and Black men have been previously evaluated.1 Consistent with our results, Black men were 4 times more likely than White men to exhibit no/minimal balding. Our results were also consistent with another previous study demonstrating that the most common type of hair loss in Chinese men was vertex balding, and the overall prevalence of AA in Chinese men was lower than the reported rates in Europeans.2
To individualize future treatment plans, it is important to be able to predict the distribution of balding patterns. The success of hair maintenance is dependent on the balding pattern. For instance, finasteride is generally more efficacious in vertex than bitemporal recession.3 Therefore, race/ethnicity may be useful for predicting the response to therapy.
Limitations of this study include self-selection to participate in the UK Biobank; therefore, patterns in the database may differ from the general population in the UK. Respondents were required to select only 1 of 4 balding patterns even though all men may not clearly fit into 1 of the 4 choices. Moreover, mild balding may go unnoticed in self-reported data. Our data implicate race as an important predictor of AA. Our study was limited to the races and ethnicities present in sufficient numbers in the UK Biobank. Future research involving men of additional races and ethnicities may further clarify the association between race/ethnicity and AA.
Funding sources:
William Weldon Endowment Fund.
Footnotes
Conflicts of interest
None disclosed.
IRB approval status: No applicable.
REFERENCES
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