Why carry out this study? |
Given the emergence of new treatment options, information on the occurrence of alopecia areata (AA) and its subtypes in various populations and care settings is of greater interest. |
This study evaluated the incidence rates and prevalence of hospital-treated AA and its subtypes in Denmark, as well as patients’ demographic and clinical characteristics. |
What was learned from this study? |
In 1995–2016, there were 2778 patients with incident hospital-treated AA in Denmark. A majority of patients were female and < 50 years of age, and prevalence of hospital-treated comorbidities was low. |
The overall incidence rate of AA was 2.62 per 100,000 person-years, and the overall prevalence in 2016 was 71.7 per 100,000 persons. Incidence rate and prevalence of AA increased over time. |
Hospital-treated patients with AA are likely to represent a more severe spectrum of disease than patients with AA treated outside the hospital. |
Introduction
Methods
Setting and Data Sources
Study Population
Statistical Analyses
Ethical Approval
Results
Incidence Rate and Prevalence of Hospital-Treated AA
Any AA | Incidence rate per 100,000 person-years (95% CI) | Prevalence per 100,000 persons (95% CI) |
---|---|---|
All | 4.04 (3.51–4.64) | 71.7 (69.4–74.1) |
Age 12–17 years | 5.88 (3.82–9.10) | 66.8 (58.6–76.0) |
Age 18–50 years | 4.81 (4.02–5.76) | 75.5 (72.1–79.0) |
Age ≥ 51 years | 2.85 (2.21–3.66) | 68.2 (64.7–71.8) |
Female | 5.09 (4.28–6.06) | 89.7 (86.0–93.5) |
Male | 3.00 (2.36–3.74) | 53.4 (50.6–56.4) |
AT/AU | ||
All | 0.41 (0.27–0.63) | 19.6 (18.4–20.9) |
Age 12–17 years | 0.00 (0.00–1.09) | 12.7 (9.4–17.0) |
Age 18–50 years | 0.37 (0.20–0.70) | 17.5 (15.9–19.2) |
Age ≥ 51 years | 0.52 (0.29–0.93) | 23.3 (21.3–25.4) |
Female | 0.57 (0.34–0.95) | 23.9 (22.1–25.9) |
Male | 0.25 (0.12–0.54) | 15.3 (13.8–16.9) |
Non-AT/AU | ||
All | 3.63 (3.14–4.21) | 62.0 (59.8–64.2) |
Age 12–17 years | 5.88 (3.82–9.09) | 60.0 (52.3–68.8) |
Age 18–50 years | 4.45 (3.69–5.36) | 66.1 (6.0–69.4) |
Age ≥ 51 years | 2.32 (1.76–3.07) | 57.5 (54.4–60.9) |
Female | 4.52 (3.76–5.44) | 78.7 (75.3–82.3) |
Male | 2.72 (2.14–3.46) | 45.0 (42.4–47.7) |
Characteristics of Patients with Hospital-Treated AA
AT/AU vs. Non-AT/AU
Incident AA cohort | |||
---|---|---|---|
All (n = 2778) | AT/AU (n = 472) | Non-AT/AU (n = 2306) | |
Calendar period at diagnosis, n (%) | |||
1995–1999 | 463 (16.7) | 96 (20.3) | 367 (15.9) |
2000–2004 | 492 (17.7) | 93 (19.7) | 399 (17.3) |
2005–2009 | 601 (21.6) | 111 (23.5) | 490 (21.2) |
2010–2014 | 845 (30.4) | 125 (26.5) | 720 (31.2) |
2015–2016 | 377 (15.6) | 47 (10.0) | 330 (14.3) |
Sex, n (%) | |||
Female | 1753 (63.1) | 271 (57.4) | 1482 (64.3) |
Male | 1025 (36.9) | 201 (42.6) | 824 (35.7) |
Age at diagnosis, n (%) | |||
Median (IQR), years | 39 (27–52) | 42 (28–56) | 39 (27–51) |
> 18 years | 2476 (89.1) | 426 (90.3) | 2050 (88.9) |
12–17 years | 302 (10.9) | 46 (9.7) | 256 (11.1) |
18–50 years | 1679 (60.4) | 261 (55.3) | 1418 (61.5) |
> 50 years | 797 (28.7) | 165 (35.0) | 632 (27.4) |
Autoimmune and atopic diseases, n (%) | |||
Autoimmune thyroiditis | 18 (0.7) | ||
Atopic dermatitis | 142 (5.1) | ||
Systemic lupus erythematosus | 36 (1.3) | ||
Psoriasis | 66 (2.4) | ||
Vitiligo | 44 (1.6) | ||
Rheumatoid arthritis | 41 (1.5) | ||
Celiac disease | 13 (0.5) | ||
Type 1 diabetes | 22 (0.8) | ||
Ulcerative colitis | 48 (1.7) | ||
Crohn’s disease | 37 (1.3) | ||
Psoriatic arthritis | 10 (0.4) | ||
Allergic rhinitis | 49 (1.8) | ||
Asthma | 189 (6.8) | ||
Multiple sclerosis | 9 (0.3) | ||
Comorbidities, n (%) | |||
Chronic obstructive pulmonary disorder | 54 (1.9) | 10 (2.1) | 44 (1.9) |
Diabetes (type 1 or type 2) | 108 (3.9) | 16 (3.4) | 92 (4.0) |
Hearing loss (at hospital encounter) | 88 (3.2) | 25 (5.3) | 63 (2.7) |
Hyperlipidemia | 46 (1.7) | < 5 | Masked |
Hypertension | 156 (5.6) | 21 (4.4) | 135 (5.9) |
Hysterectomy, salpingectomy, or oophorectomy | 48 (1.7) | < 5 | Masked |
Substance abuse | 68 (2.4) | 11 (2.3) | 57 (2.5) |
Surgery in the last 6 months | 92 (3.3) | 9 (1.9) | 83 (3.6) |
Any cancer (except BCC/SCC) | 140 (5.0) | 29 (6.1) | 111 (4.8) |
Basal cell carcinoma | 38 (1.4) | < 5 | Masked |
Squamous cell carcinoma | 41 (1.5) | < 5 | Masked |
Malignant melanoma | 10 (0.4) | < 5 | Masked |
Lymphoma | 10 (0.4) | < 5 | Masked |
Breast cancer | 47 (1.7) | 11 (2.3) | 36 (1.6) |
Cervical carcinoma in situ | 16 (0.6) | < 5 | Masked |
Acute MI | 24 (0.9) | < 5 | Masked |
Any ischemic heart disease | 70 (2.5) | 12 (2.5) | 58 (2.5) |
Any stroke | < 5 | 0 (0.0) | < 5 |
CABG | 8 (0.3) | 0 (0.0) | 8 (0.3) |
Hemorrhagic stroke | 7 (0.3) | 0 (0.0) | 7 (0.3) |
Hospitalization due to HF | 31 (1.1) | < 5 | Masked |
Ischemic stroke | 30 (1.1) | 8 (1.7) | 22 (1.0) |
PCI | 12 (0.4) | 0 (0.0) | 12 (0.5) |
Unstable angina | 6 (0.2) | 0 (0.0) | 6 (0.3) |
DVT, PE, or ATE | 43 (1.5) | < 5 | Masked |
Medication use, n (%) | |||
Antidiabetic agents | 91 (3.3) | 12 (2.5) | 79 (3.4) |
Antihypertensive agents | 474 (17.1) | 87 (18.4) | 387 (16.8) |
Drugs used in dermatologya | 31 (1.1) | < 5 | Masked |
Hormone replacement therapy | 97 (3.5) | 13 (2.8) | 84 (3.6) |
Immunosuppressants | 121 (4.4) | 15 (3.2) | 106 (4.6) |
Janus kinase inhibitors | < 5 | < 5 | 0 (0.0) |
Lipid-modifying agents | 166 (6.0) | 19 (4.0) | 147 (6.4) |
Oral contraceptives | 26 (0.9) | < 5 | Masked |
Systemic steroids | 408 (14.7) | 64 (13.6) | 344 (14.9) |
Charlson comorbidity index score, n (%) | |||
Low (0) | 2126 (76.5) | 360 (76.3) | 1766 (76.6) |
Medium (1–2) | 532 (19.2) | 95 (20.1) | 437 (19.0) |
High (≥ 3) | 120 (4.3) | 17 (3.6) | 103 (4.5) |