Alopecia Areata, Comorbidities, and Age of Onset
Graeme M. Lipper, MD

Comorbidity Profiles Among Patients With Alopecia Areata: The Importance of Onset Age, a Nationwide Population-Based Study
Chu SY, Chen YJ, Tseng WC, et al.
J Am Acad Dermatol. 2011;65:949-956

Study Summary
Alopecia areata (AA) is a common autoimmune-mediated form of nonscarring alopecia that typically presents with sudden-onset hair loss in solitary patches, diffuse bands, or rarely, the full scalp (ie, alopecia totalis) or full body (ie, alopecia universalis). Disease severity correlates with early age of onset, rapid onset of diffuse hair loss, and total alopecia.[1] Although the pathogenesis of AA remains unknown, the disorder occurs in genetically predisposed individuals and is linked to other autoimmune and atopic disorders, including autoimmune thyroid disease (eg, Hashimoto thyroiditis, Graves disease), vitiligo, lupus erythematosus, rheumatoid arthritis, atopic dermatitis, and psoriasis.[1-4]

When diagnosing a patient with AA, clinicians need to consider the possibility of autoimmune comorbidities. It may be prudent to screen for disorders such as hypothyroidism, lupus, or rheumatoid arthritis. To address this important clinical consideration, Chu and colleagues studied comorbidities in a cohort of Taiwanese patients with AA (n = 4334) compared with a cohort of age-matched controls (n = 784,158). Specifically, the authors sought to explore statistical links among AA, atopy, and autoimmune disease, stratified by the age of AA onset.

Key results of this nationwide cohort study were as follows:

Patients with AA were more likely to have comorbid autoimmune disorders (ie, vitiligo, lupus erythematosus, psoriasis, thyroid disease) or atopy (atopic dermatitis more than allergic rhinitis or asthma).
Childhood AA (ie, onset before 10 years of age) was most strongly associated with atopic dermatitis (odds ratio, 3.82) and lupus erythematosus (odds ratio, 9.76).
AA onset during late childhood or teen years (ie, onset at 11-20 years of age) was the only time period associated with psoriasis (odds ratio, 2.43) or rheumatoid arthritis (odds ratio, 2.57).
AA in adults 60 years of age or older correlated strongly with a risk for autoimmune thyroid disease (odds ratio, 2.52).

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Dres. Jana Hercogová, Frederica Ricceri, Lara Tripo, Torello Lotti y Francesca Prignano
Dermatologic Therapy, Vol. 23, 2010, 152–154

La psoriasis en una enfermedad cutánea crónica mediada inmunológicamente que afecta aproximadamente el 1-3% de la población adulta.  La etiología permanece en parte desconocida, pero tanto los factores genéticos como ambientales están implicados en el inicio y curso de la enfermedad.  Se han reconocido varios factores de riesgo asociados con la aparición, progresión y severidad de la enfermedad: cigarrillo, dieta, depresión, traumas físicos repetidos, y eventos de estrés.

Recientemente, existe una fuerte asociación entre el incremento de adiposidad, obesidad y psoriasis.  El índice de masa corporal (BMI) es un índice simple usado comúnmente para clasificar sobrepeso, obesidad y bajo peso en adultos. Se define como el peso en kg dividido la altura en metros al cuadrado (kg/m2), es independiente de la edad y el mismo para ambos sexos.  Mientras existe controversia si la obesidad es consecuencia de la psoriasis, un factor de riesgo para el inicio de la psoriasis, o ambos, varios estudios sugieren relaciones significativas entre BMI y psoriasis.  Naldi y col en un estudio caso-control, encontró que la prevalencia de la psoriasis era dos veces más alta en pacientes con obesidad comparado con el peso normal.

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