Validation of Case Identification for Alopecia Areata Using International Classification of Diseases Coding

Risks of alopecia areata in long COVID: Binational population-based cohort studies from South Korea and Japan

Previous studies have proposed alopecia areata (AA) as a potential outcome of COVID-19 infection among autoimmune diseases, yet the findings might be inconclusive and difficult to generalize due to limited sample sizes and evidence levels. Thus, we aimed to investigate in detail the long-term risk of AA following SARS-CoV-2 infection based on large, binational, general population-based cohort studies. Our study investigated the long-term AA risk after SARS-CoV-2 infection by analyzing bi-national, claim-based cohorts in South Korea and Japan: a Korean nationwide cohort (K-COV-N cohort; discovery cohort; total n = 10 027 506) and a Japanese claims-based cohort (JMDC cohort; validation cohort; total n = 12 218 680). AA was identified based on the international classification of diseases 10th revision code (L63) requiring at least three claims within 1 year. After exposure-driven propensity score matching, SARS-CoV-2 infection was associated with an increased risk of incident AA (aHR, 1.66; 95% CI, 1.38-1.99). This increased risk was observed and persisted for up to 6 months. A similar pattern was observed in the validation cohort. As modifiable factors, severe COVID-19 increased the risk of AA, whereas receiving two or more doses of the COVID-19 vaccine before infection decreased the risk of AA. Through a bi-national cohort study in South Korea and Japan, SARS-CoV-2 infection was associated with an elevated risk for incident AA in the aspect of long COVID.

Epidemiology and Healthcare Expenditure for Skin Disease in Emergency Departments in Alberta, Canada

BACKGROUND

There are limited data on the epidemiology and costs associated with managing dermatologic conditions in emergency departments (EDs).

OBJECTIVE

To assess the incidence and mean cost per case of skin diseases in EDs in Alberta.

METHODS

Alberta Health Services' Interactive Health Data Application was used to determine the epidemiology and costs associated with nonneoplastic dermatologic diseases in EDs in the province of Alberta, Canada, from 2018 to 2022. Skin conditions were identified using the International Classification of Disease 10th edition diagnostic groupings.

RESULTS

Skin disease represented 3.59% of all ED presentations in Alberta in 2022. The total costs associated with managing dermatologic conditions have remained stable over time at approximately 15 million Canadian Dollars (CAD) annually, but the mean cost per case has risen from 188.88 (SD 15.42) in 2018 to 246.25 CAD (SD 27.47) in 2022 (7.59%/year). Infections of skin and subcutaneous tissue were the most expensive diagnostic grouping. The most common dermatologic diagnostic groupings presenting to the ED were infections of skin and subcutaneous tissue [mean age-standardized incidence rate (ASIR) of 143.67 per 100,000 standard population (SD 241.99)], urticaria and erythema [mean ASIR 33.57 per 100,000 standard population (SD 59.13)], and dermatitis and eczema [mean ASIR 18.59 per 100,000 standard population (SD 23.65)]. Cellulitis was both the most common and the costliest individual diagnosis. The majority of patients were triaged as less urgent or nonurgent.

CONCLUSIONS

Skin disease represents a substantial public health burden in EDs. Further research into drivers of cost change and areas for cost savings is essential.

Validation of alopecia coding in US claims data among women of childbearing age

BACKGROUND

Accurately identifying alopecia in claims data is important to study this rare medication side effect.

OBJECTIVES

To develop and validate a claims-based algorithm to identify alopecia in women of childbearing age.

METHODS

We linked electronic health records from a large healthcare system in Massachusetts (Mass General Brigham) with Medicaid claims data from 2016 through 2018 to identify all women aged 18 to 50 years with an ICD-10 code for alopecia, including alopecia areata, androgenic alopecia, non-scarring alopecia, or cicatricial alopecia, from a visit to the MGB system. Using eight predefined algorithms to identify alopecia in Medicaid claims data, we randomly selected 300 women for whom we reviewed their charts to validate the alopecia diagnosis. Positive predictive values (PPVs) were computed for the primary algorithm and seven algorithm variations, stratified by race.

RESULTS

Out of 300 patients with at least 1 ICD-10 code for alopecia in the Medicaid claims, 286 had chart-confirmed alopecia (PPV = 95.3%). The algorithm requiring two diagnosis codes plus one prescription claim for alopecia treatment identified 55 patients (PPV = 100%). The algorithm requiring 1 diagnosis code for alopecia plus 1 procedure claim for intralesional triamcinolone injection identified 35 patients (PPV = 100%). Across all 8 algorithms tested, the PPV varied between 95.3% and 100%. The PPV for alopecia ranged from 94% to 100% in White and 96%-100% in 48 non-White women. The exact date of alopecia onset was difficult to determine in charts.

CONCLUSION

At least one recorded ICD-10 code for alopecia in claims data identified alopecia in women of childbearing age with high accuracy.

Treatment Patterns for Alopecia Areata in the US

Importance

Alopecia areata (AA) is characterized by hair loss ranging from patches of hair loss to more extensive forms, including alopecia totalis (AT) and alopecia universalis (AU). There is a lack of consensus for treatment. Understanding current practice patterns could help the identification of treatment needs and development of standards of care.

Objective

To review treatment patterns for adults with AA in the US between 2015 and 2020.

Design, Setting, and Participants

This retrospective cohort study used medicine and pharmacy claims for commercially insured individuals from the IBM MarketScan Research Database to assess adults (≥18 years) newly treated for AA between October 15, 2015, and February 28, 2020. Alopecia areata was identified based on having at least 1 diagnosis of International Statistical Classification of Diseases and Related Health Problems, Tenth Revision code L63.x. Patients were required to have at least 365 days of continuous health plan enrollment before and after the cohort entry date. Patients were required to be free of AA diagnosis codes 365 days before the cohort entry date. Statistical analyses were conducted between 2019 and 2023.

Main Outcomes and Measures

Main outcomes were treatment patterns for all patients with AA and subgroups of (1) patients with AT or AU and (2) those cared for by a dermatologist on the cohort entry date. Longitudinal therapy course during the first year after the diagnosis was also examined.

Results

The study cohort consisted of 45 483 individuals (mean [SD] age, 43.8 [14.2] years; 29 903 [65.7%] female). During the year of follow-up, 30 217 patients (66.4%) received at least 1 AA treatment. The most common treatments were intralesional (19 014 [41.8%]), topical (18 604 [40.9%]), intramuscular (17 328 [38.1%]), and oral (9378 [20.6%]) corticosteroids. Compared with patients without AT or AU, patients with AT or AU a lower frequency of intralesional steroid (359 [11.1%] vs 18 655 [44.1%], P < .001) and higher frequency of topical corticosteroid (817 [25.4%] vs 17 787 [42.1%], P < .001) use. Almost half of patients (21 489 [47.2%]) received no treatment on the day of diagnosis. By 12 months, 32 659 (71.8%) were not receiving any treatment, making no treatment the largest study group.

Conclusions and Relevance

In this large cohort study of commercially insured individuals, corticosteroids were the most commonly used treatment for adults with AA between 2015 and 2020. At 365 days after diagnosis, more than two-thirds of patients were no longer receiving any AA treatment. Further studies are needed to understand the reasons for the absence of treatment.

Real-World Treatment Patterns among Patients with Alopecia Areata in the USA: A Retrospective Claims Analysis

Alopecia areata is an autoimmune disorder characterized by hair loss, for which there are few treatment options. This claims-based study characterized recent real-world treatment patterns among patients in the USA with alopecia areata, including the subtypes alopecia totalis and alopecia universalis, in the first year after diagnosis of an episode of alopecia areata. Approximately 5% of all patients (adults (age ≥ 18 years), n = 7,703; adolescents (age 12-17 years), n = 595) had alopecia totalis or alopecia universalis. Corticosteroids were the most common first-line (1L) and second-line (2L) treatments. The mean time from diagnosis of alopecia areata to initiation of 1L treatment was 2.2 days for adults and 2.6 days for adolescents; mean 1L duration was 76.9 and 64.3 days, respectively. For adults (57.5%) and adolescents (59.7%) with 2L therapy, the mean time from 1L discontinuation to 2L initiation was 57.2 and 53.6 days, respectively; the mean duration of 2L treatment was 55.5 and 50.1 days, respectively. More patients with vs without alopecia totalis or alopecia universalis initiated 2L therapy (adults: 71.9% vs 56.8%; adolescents: 71.4% vs 58.9%). The proportion of days covered during the first year post-diagnosis was 36.7% (adults) and 34.1% (adolescents). These results highlight the substantial disease burden of alopecia areata and a need for more effective treatments.

Validity of Lichen Planus and Lichen Planopilaris Case Identification Using Diagnostic Codes from a Clinical Database

BACKGROUND

Case identification strategies to conduct population-based studies have not been developed for lichen planus (LP) or lichen planopilaris (LPP).

OBJECTIVES

The aim of this study was to assess the validity of using diagnostic codes to establish both a cutaneous (non-oral) LP cohort and an LPP cohort from a large clinical database.

METHODS

A retrospective chart review was performed to determine whether patients with ICD-9 or ICD-10 codes for LP and ICD-10 codes for LPP are confirmed cases of LP and LPP. Validation samples were used to estimate the positive predictive value (PPV) of three case definitions any LP, non-oral LP, and LPP defined as: at least one code by any physician, at least two codes by any physician, and at least one code by a dermatologist.

RESULTS

Among the 199 reviewed LP charts, 166 and 123 were confirmed cases of any LP and non-oral LP, respectively. The PPVs for any LP were: 83.4% (166/199) for one code by any physician, 84.6% (77/91) for two codes by any physician, and 95.1% (97/102) for one code by a dermatologist. The PPVs for non-oral LP were: 61.8% (123/199) for one code by any physician, 70.3% (64/91) for two diagnoses by any physician, and 86.3% (88/102) for one diagnosis by a dermatologist. Of the 139 patients with at least one code for LPP, 122 were confirmed cases of LPP. The case definition for one LPP code applied by any physician had a PPV of 87.8% (122/139) to identify a true case of LPP, whereas two diagnoses by any physician had a PPV of 96.2% (76/79) and a diagnosis by a dermatologist had a PPV of 93% (107/115).

CONCLUSIONS

Diagnosis codes for LP and LPP, restricted by the diagnosing physician's specialty, may be used to accurately identify case cohorts of overall LP, non-oral LP, or LPP in large clinical databases.

Overall and Racial and Ethnic Subgroup Prevalences of Alopecia Areata, Alopecia Totalis, and Alopecia Universalis

Importance

Prevalences of alopecia areata (AA), alopecia totalis (AT), and alopecia universalis (AU) are poorly established.

Objective

To estimate overall and subgroup prevalences of AA and its subtypes.

Design, Setting, and Participants

This cross-sectional study using electronic records comprising the Explorys database (Watson Health, IBM Corporation) included children, adolescents, and adults seeking healthcare across the 4 census regions in the US between January 1, 2019, and December 31, 2019. The statistical analysis was conducted between July 21, 2022, and December 22, 2022.

Main Outcomes and Measures

Prevalent cases of AA, AT, and AU.

Results

Of the 1 093 176 patients who met inclusion criteria, 1812 had at least 1 code for AA, 1216 female (67%) and 596 male (33%) patients. Overall age-and-sex standardized prevalences among adults and among children and adolescents were observed to be 0.18% and 0.10%, respectively. The age-standardized prevalence ratio in women to men was 1.32. Standardized prevalence was highest in those aged 30 to 39 (297 per 100 000; 95% CI, 263-335) and 40 to 49 (270 per 100 000; 95% CI, 240-303) years. The highest standardized prevalence was observed among Asian patients (414 per 100 000; 95% CI, 306-548), followed by patients reporting another race or multiple races (314 per 100 000; 95% CI, 266-368), Black (226 per 100 000; 95% CI, 199-255), and Hispanic/Latino (212 per 100 000; 95% CI, 129-328) patients. White patients had the lowest standardized prevalence (168 per 100 000; 95% CI, 157-179) among racial and ethnic subgroups. Relative to White patients, standardized prevalence ratios for Asian, Black, and Hispanic/Latino patients were 2.47 (95% CI, 2.17-2.81), 1.35 (95% CI, 1.26-1.44), and 1.26 (95% CI, 1.03-1.55), respectively. Cases of AT and AU comprised approximately 9% of patients diagnosed with AA.

Conclusions and Relevance

The findings of this cross-sectional study suggest that there is a significant burden of AA, AT, and AU in the US in which people of color, particularly Asian Americans, appear to be disproportionately affected.

Trends in Prevalence and Incidence of Alopecia Areata, Alopecia Totalis, and Alopecia Universalis Among Adults and Children in a US Employer-Sponsored Insured Population

Importance

Alopecia areata (AA) is characterized by nonscarring hair loss of the scalp, face, and/or body. Alopecia totalis (AT) and alopecia universalis (AU) involve complete loss of the scalp and body hair, respectively. The epidemiology of AA in the US remains unclear, having previously been extrapolated from older studies that were limited to specific geographic areas or clinical settings, or from self-reported data.

Objective

To estimate the annual prevalence and incidence of AA and AT and/or AU (AT/AU) in the US.

Design, Setting, and Participants

This retrospective, population-based cohort study was conducted from January 2016 to December 2019 and included enrollees in the IBM MarketScan Commercial Claims and Encounters and Medicare Supplemental databases and their dependents, with plan enrollment during each study calendar year and the year prior.

Exposures

Prevalent cases were identified by 1 or more claims for AA or AT/AU (International Statistical Classification of Diseases, Tenth Revision, Clinical Modification [ICD-10-CM] codes L63.x, L63.0, L63.1) during each year of interest or the year prior. Incident cases were identified by 1 or more claims for AA or AT/AU during a specific year and no diagnosis the year prior.

Main Outcomes and Measures

Annual incidence and prevalence rates were calculated and stratified by age, sex, and region. National employer-sponsored insurance population estimates were obtained using population-based weights.

Results

Among eligible patients (2016: n = 18 368 [mean (SD) age, 40.6 (17.9) years; 12 295 women (66.9%)]; 2017: n = 14 372 [mean (SD) age, 39.6 (17.7) years; 9195 women (64.0%)]; 2018: n = 14 231 [mean (SD) age, 38.9 (17.3) years; 8998 women (63.2%)]; 2019: n = 13 455 [mean (SD) age, 39.1 (17.4) years; 8322 women (61.9%)]), AA prevalence increased from 0.199% (95% CI, 0.198%-0.200%) in 2016 to 0.222% (95% CI, 0.221%-0.223%) in 2019. Roughly 5% to 10% of prevalent and incident cases of AA were AT/AU. The prevalence of AT/AU increased from 0.012% (95% CI, 0.012%-0.013%) to 0.019% (95% CI, 0.018%-0.019%) from 2016 to 2019. Incidence of AA per 100 000 person-years ranged from 87.39 (95% CI, 86.84-87.96) in 2017 to 92.90 (95% CI, 92.35-93.45) in 2019. Incidence of AT/AU ranged from 7.09 (95% CI, 6.94-7.25) in 2017 to 8.92 (95% CI, 8.75-9.09) in 2016. Prevalence and incidence of AA and AT/AU were higher among female vs male individuals, adults vs children and adolescents, and in the Northeast vs other regions.

Conclusions and Relevance

The results of this cohort study suggest that these recent AA prevalence and incidence estimates could help improve current understanding of the disease burden. Further research is warranted to elucidate subpopulation differences and trends in AA in the broader US population.

Healthcare Utilization and Costs Among US Adolescents With Alopecia Areata

Background: Alopecia areata (AA) is an autoimmune disease of hair loss affecting people of all ages. Alopecia totalis (AT) and universalis (AU) involve scalp and total body hair loss, respectively. AA significantly affects quality of life, but evidence on the economic burden in adolescents is limited. Objectives: To assess healthcare resource utilization (HCRU) and all-cause direct healthcare costs, including out-of-pocket (OOP) costs, of US adolescents with AA. Methods: IBM MarketScan® Commercial and Medicare databases were used to identify patients aged 12-17 years with ≥2 claims with AA/AT/AU diagnosis (prevalent cases), from October 1, 2015, to March 31, 2018, enrolled for ≥12 months before and after the first AA diagnosis (index). Patients were matched 1:3 to non-AA controls on index year, demographics, plan type, and Charlson Comorbidity Index. Per patient per year HCRU and costs were compared post-index. Results: Patients comprised 130 AT/AU adolescents and 1105 non-AT/AU adolescents (53.8% female; mean age, 14.6 years). Post-index, AT/AU vs controls had more outpatient (14.5 vs 7.1) and dermatologist (3.6 vs 0.3) visits, higher mean plan costs ($9397 vs $2267), including medical ($7480 vs $1780) and pharmacy ($1918 vs $487) costs, and higher OOP costs ($2081 vs $751) (all P<.001). The non-AT/AU cohort vs controls had more outpatient (11.6 vs 8.0) and dermatologist (3.4 vs 0.4) visits, higher mean plan costs ($7587 vs $4496), and higher OOP costs ($1579 vs $805) (all P<.001). Discussion: This large-sample, real-world analysis found that adolescents with prevalent AA had significantly higher HCRU and all-cause costs than matched controls. The greater burden was driven by more frequent outpatient visits, and higher payer medical and pharmacy costs in comparison with controls. Oral corticosteroid use was higher among patients with AT/AU; topical and injectable corticosteroid use was higher for non-AT/AU. Although the data preclude the identification of AA-attributable costs, the matched-control design allows an estimation of incremental all-cause costs associated with AA. Conclusions: Adolescents with AA incurred substantial incremental healthcare costs, with greater costs incurred among those with AT/AU. Study findings suggest that AA incurs costs as a medical condition with a high burden on adolescent patients and health plans.

Economic Burden and Healthcare Resource Use of Alopecia Areata in an Insured Population in the USA

INTRODUCTION

Comparative data on the economic burden of alopecia areata relative to the general population are limited. The objective of this retrospective database analysis was to evaluate healthcare resource utilization and direct medical costs among patients with alopecia areata from the US payer perspective compared with matched controls.

METHODS

Validated billing codes were used to identify patients with alopecia areata from the IQVIA PharMetrics Plus (2016-2018) who had continuous pharmacy and medical enrollment for 365 days both before (baseline period) and after (evaluation period) the index date. Demographic and clinical characteristics were characterized, and baseline comorbidities were assessed with the Quan Charlson Comorbidity Index.

RESULTS

Using the exact matching feature from Instant Health Data, 14,340 patients with alopecia areata were matched with 42,998 control patients aged ≥ 12 years. Patients with alopecia areata had higher healthcare resource utilization and adjusted total all-cause mean medical costs versus matched controls ($8557 versus $6416; p < 0.0001), because of higher inpatient costs, emergency department visits, ambulatory visits, number of prescriptions and prescription costs, and other costs such as durable medical equipment and home healthcare. The number of inpatient visits did not significantly differ between the two groups. Mean ambulatory costs were $3640 for patients with alopecia areata and $2062 for controls, and mean pharmacy costs were $3287 and $1843, respectively (p < 0.0001 for both). Pharmacy costs related to immunologic agents represented 50.0% of the total difference in pharmacy spending between patients with alopecia areata and controls. Surgery on the integumentary system accounted for 9.5% of the total difference in ambulatory costs.

CONCLUSION

Alopecia areata is associated with significant incremental healthcare resource utilization and costs relative to matched controls due to increased spending in areas such as surgical procedures and psychological and pharmacological interventions. Costs are primarily driven by ambulatory and pharmacy spending.

All-cause health care resource utilization and costs among adults with alopecia areata: A retrospective claims database study in the United States

BACKGROUND: Alopecia areata (AA) is an autoimmune disorder characterized by hair loss. Patients may present with hair loss of the scalp, eyelashes, eyebrows, and/or body. Alopecia totalis (AT), total scalp hair loss, or alopecia universalis (AU), total body hair loss, are extensive forms. Although the impact of AA on quality of life is understood, evidence of its economic burden is limited. A better understanding of the all-cause health care costs for health plans and patients with AA is critical to comprehend disease burden. OBJECTIVE: To evaluate all-cause health care resource utilization and direct health care costs in US adults with AA with or without AT or AU, vs matched control subjects. METHODS: Patients (≥ 18 years) with AA with no less than 2 claims of AA at diagnosis (October 31, 2015, to March 3, 2018) were identified in the IBM MarketScan Commercial Claims and Encounters and Medicare Supplemental databases. Patients were enrolled no less than 12 months before and after first diagnosis (index). Patients were grouped according to AT or AU status (AT/AU group) or AA without AT/AU (non-AT/AU group) and matched 1:3 to control subjects without AA/AT/AU. Summary statistics were calculated for demographic and clinical characteristics at baseline and follow-up. RESULTS: At baseline, there were 14,972 adult patients with AA and 44,916 control subjects. Of patients with AA, 1,250 and 13,722 were in the AT/AU and non-AT/AU groups, respectively. A significantly greater proportion of patients with AA had atopic and autoimmune comorbidities vs control subjects. After index, patients with AA used significantly more corticosteroid treatments (injectable/oral/topical) than control subjects. A greater mean number of annual outpatient and dermatologist visits was observed for both AA groups vs control subjects (outpatient visits: AT/AU group: 17.8 vs 11.8; non-AT/AU group: 15.4 vs 11.2; dermatologist visits: AT/AU group: 3.4 vs 0.4; non-AT/AU group: 3.4 vs 0.4; P < 0.001 for all). Mean total all-cause medical and pharmacy costs (2018 US$) were higher in both AA groups vs control subjects (AT/AU group: $18,988 vs $11,030; non-AT/AU group: $13,686 vs $9,336; P < 0.001 for both). Patient out-of-pocket costs were higher for AA vs control subjects (AT/AU group: $2,685 vs $1,457; non-AT/AU group: $2,223 vs $1,341; P < 0.001 for both). CONCLUSIONS: Compared with control subjects, patients with AA are more likely to have atopic and autoimmune comorbidities, to use corticosteroids, and to make outpatient visits. Patients with AA have greater all-cause medical (including pharmacy) and out-of-pocket costs. The difference in total medical costs for patients with AT/AU vs control subjects is higher than the difference for patients with non-AT/AU vs control subjects. DISCLOSURES: This study was sponsored by Pfizer Inc. Pfizer Inc was involved in the study design; collection, analysis, and interpretation of data; writing of the report; and the decision to submit this report for publication. A. Mostaghimi reports consulting fees from Pfizer Inc, Concert, Lilly, AbbVie, hims, and Digital Diagnostics; reports equity from Lucid and hims; and is an associate editor at JAMA Dermatology. K. Gandhi, M. Ray, and V. Sikirica are former employees of Pfizer Inc and held stock and/or stock options with Pfizer Inc at the time of writing. N. Done, W. Gao, C. Carley, T. Wang, and E. Swallow are employees of Analysis Group, Inc, a consultancy that received payment from Pfizer Inc for participation in this analysis.

Incidence of Venous Thromboembolism in Patients With Dermatologist-Diagnosed Chronic Inflammatory Skin Diseases

Importance

Several studies have linked chronic inflammatory skin diseases (CISDs) with venous thromboembolism (VTE) in a range of data sources with mixed conclusions.

Objective

To examine the incidence of VTE in patients with vs without CISD.

Design, Setting, and Participants

A cohort study using commercial insurance claims data from a nationwide US health care database from January 1, 2004, through 2019 was conducted. A total of 158 123 patients with dermatologist-recorded psoriasis, atopic dermatitis, alopecia areata, vitiligo, or hidradenitis suppurativa were included. Risk-set sampling identified patients without a CISD. Patient follow-up lasted until the first of the following occurred: VTE, death, disenrollment, or end of data stream.

Exposures

Patients with vs without CISD.

Main Outcomes and Measures

Venous thromboembolism events were identified with validated algorithms. Incidence rates were computed before and after 1:1 propensity-score matching to account for VTE risk factors. Hazard ratios were estimated to compare the incidence of VTE in the CISD vs non-CISD cohorts.

Results

A total of 158 123 patients were identified with CISD: with psoriasis (n = 96 138), atopic dermatitis (n = 30 418), alopecia areata (n = 17 889), vitiligo (n = 7735), or HS (n = 5934); 9 patients had 2 of these conditions. A total of 1 570 387 patients were without a CISD. The median follow-up time was 1.9 years (interquartile range, 0.8-4.0 years) in patients with CISD. The incidence rate (per 1000 person-years) of outpatient or inpatient VTE was 1.57 in psoriasis, 1.83 in atopic dermatitis, 0.94 in alopecia areata, 0.93 in vitiligo, 1.65 in HS and 1.53 in CISD overall, compared with 1.76 in patients without a CISD. Incidence rates increased in patients aged 50 years or older (2.3 per 1000 person-years) and decreased in those aged 18 to 49 years (0.8 per 1000 person-years). After propensity-score matching to patients without a CISD, the hazard ratio (HR) of VTE was 0.86 (95% CI, 0.75-0.99) in psoriasis, 1.19 (95% CI, 0.95-1.48) in atopic dermatitis, 0.97 (95% CI, 0.65-1.46) in alopecia areata, 0.90 (95% CI, 0.49-1.65) in vitiligo, 1.64 (95% CI, 0.82-3.27) in hidradenitis suppurativa, and 0.94 (95% CI, 0.84-1.05) in CISD overall.

Conclusions and Relevance

In this large-scale cohort study, CISDs were not associated with an increased incidence of VTE after controlling for relevant VTE risk factors in a representative dermatology patient population.

Association Between Alopecia Areata and Natural Hair Color Among White Individuals

IMPORTANCE

Alopecia areata (AA) is a complex immune-mediated disorder that causes nonscarring hair loss. Previous reports have documented preferential targeting of pigmented hair follicles with sparing of gray, nonpigmented hair follicles in alopecia lesions. Thus, immune targeting of melanogenesis-associated proteins in melanocytes and keratinocytes represents a potential mechanism for the inflammation that targets anagen hairs in alopecia areata.

OBJECTIVE

To investigate the association of alopecia areata with hair color among White residents of the UK.

DESIGN, SETTING, AND PARTICIPANTS

This matched, case-control study conducted in October 2020 used a large prospectively acquired cohort and included data that were collected from the UK Biobank, a large-scale prospective resource designed to study phenotypic and genotypic determinants in adults. A total of 502 510 UK Biobank participants were reviewed for inclusion. Among these individuals, 1673 cases of alopecia areata with reported hair color were captured and matched by age and sex to 6692 controls without alopecia areata using 1:4 matching.

MAIN OUTCOMES AND MEASURES

Conditional logistic regression analysis was performed, in which the outcome variable was alopecia areata and the main predictor was natural hair color before graying. The variables considered included diabetes, hypothyroidism, hyperthyroidism, and vitiligo.

RESULTS

Of 464 353 participants, 254 505 (54.8%) were women, and the mean (SD) age for those with alopecia areata was 46.9 (16.5) years. Alopecia areata was significantly more common in individuals with black (adjusted odds ratio [aOR], 2.97; 95% CI, 2.38-3.71) and dark brown hair (aOR, 1.26; 95% CI, 1.11-1.42) compared with light brown hair. In contrast, blond individuals exhibited significantly decreased alopecia areata compared with those with light brown hair (aOR, 0.69; 95% CI, 0.56-0.85). Red hair color was not significantly different from light brown hair.

CONCLUSIONS AND RELEVANCE

The findings of this matched case-control study seem to indicate that alopecia areata is modulated by natural hair color, preferentially targeting darker hair. Our results support a previously proposed model of alopecia areata in which immunity is directed against melanogenesis-associated proteins in the anagen hair follicles. However, further study is needed to more precisely understand the immunopathogenic association between alopecia areata and hair color.