Is vitiligo associated with comorbidities?

Vitiligo is a relatively common skin disease with a prevalence estimated at 0.5 to 2% worldwide. Its causes are multifaceted, but it is currently classified under the category of autoimmune diseases, meaning that the immune system of those affected by vitiligo mistakenly attacks the melanocytes, which are responsible for the production of melanin. Vitiligo is often associated with other autoimmune diseases, such as Hashimoto's thyroiditis or type 1 diabetes. This can be explained by shared genetic factors that predispose individuals to autoimmune disorders. A study recently published by SPRITZ and his team has indeed highlighted several shared genetic associations between vitiligo and certain autoimmune diseases.

Furthermore, a retrospective study was conducted from 1996 to 2011 via the National Health Insurance research database in Taiwan and showed a strong correlation between vitiligo and several diseases. In total, 14,883 patients with vitiligo and 59,532 individuals without vitiligo were recorded. It was shown that individuals affected by vitiligo had a higher prevalence of multiple comorbidities. Indeed, 14.3% of the vitiligo patients in the study had at least one other autoimmune disease, while only 6% of the "healthy" individuals suffered from at least one autoimmune disease.

In addition to autoimmune diseases, researchers have highlighted an association between vitiligo and certain atopic disorders, this relationship being once again linked to common genetic predispositions. The retrospective study also identified the most frequently associated autoimmune and atopic diseases with vitiligo. Researchers compared their prevalence among patients with vitiligo and those not suffering from this dermatosis, as shown in the table below.

Vitiligo is thus frequently associated with atopic or autoimmune diseases.

It is also suspected that vitiligo may be linked to ocular abnormalities because, in addition to being present in the skin, melanocytes are abundant in the ciliary body, the iris, and the retinal pigment epithelium. They are, in fact, responsible for giving colour to our eyes. Several studies have explored the potential link between vitiligo and ocular disorders, with some indicating a slightly higher tendency for patients suffering from this skin condition to experience dry eyes and suffer from glaucoma, a chronic eye disease caused by damage to the optic nerve. However, the number of participants in these studies was relatively small, preventing any definitive conclusions from being drawn.

Furthermore, scientific literature suggests a possible association between vitiligo and hearing disorders. Indeed, melanocytes are also distributed in the membranous labyrinth of the inner ear and, while their role is not fully understood, it is believed they play a part in hearing. Researchers have therefore investigated whether vitiligo is associated with hearing disorders. Several studies seem to indicate that patients affected by this dermatosis are more likely to develop hearing abnormalities. However, these are once again studies conducted with very small population samples, from which it is difficult to draw solid conclusions.

It is challenging today to assert that there is a connection between vitiligo and visual or auditory diseases.

Vitiligo extends beyond mere cosmetic concern and can have a real impact on patients' psychology due to its conspicuous and stigmatising nature. Indeed, several studies have shown that, compared to the general population, patients with vitiligo tend to have a poorer body image, a lower self-esteem and higher levels of social and psychological distress. It has thus been suspected that the substantial impact of vitiligo on patients' quality of life could be the cause of psychological disorders. To further explore this hypothesis, a retrospective study was conducted between 2000 and 2013. In total, 1432 subjects with vitiligo and 5728 controls were recruited.

After accounting for individuals' psychological disorders and adjusting for sex, age, comorbidity, urbanisation, and the level of care provided by the institution, the adjusted risk ratio for all psychiatric disorders in patients with vitiligo was found to be 2.926. This means that, for the population studied, researchers measured that individuals with vitiligo had nearly 3 times greater risk of suffering from a psychological issue. According to the study, it is primarily obsessive-compulsive disorders that are implicated, with an adjusted risk ratio of 10.790.

The psychosocial burden associated with vitiligo is significant and could explain the observed association with an increased risk of psychiatric disorders. This highlights the importance for doctors to consider the mental health of patients suffering from this disease, in order to provide them with comprehensive care.

• LIU H. & al. Comorbidity profiles in association with vitiligo: a nationwide population-based study in Taiwan. Journal of the European Academy of Dermatology and Venereology (2014).

• BORRADORI L. & al. Dermatologie et infections sexuellement transmissibles. Elsevier Masson (2017).

• THOMSEN S. & al. Comorbidities in vitiligo: comprehensive review. International Journal of Dermatology (2018).

• EZZEDINE K. & al. Vitiligo: A Review. Dermatology (2020).

• HUNG C. & al. Increased risk of psychiatric disorders in adult patients with vitiligo: A nationwide, population-based cohort study in Taiwan. The Journal of Dermatology (2020).

• SPRITZ R. & al. The Genetic Basis of Vitiligo. Journal of Investigative Dermatology (2021).