Vitiligo is an acquired, non contagious skin disorder characterised by depigmented patches of skin that may appear in a localised or very generalised distribution, and affecting 0.5-2.0% of the global population.There are however, limited population-based studies on the burden of vitiligo and disparities across people of different ethnicities and deprivation.

The overall purpose of this study is to provide an estimate of the lifetime risk of vitiligo in the population overall and by sociodemographic subgroups. Moreover, to do a subgroup analysis in the vitiligo population to identify health-related disparities across people in different sex, age, deprivation and ethnicity. A detailed understanding of the burden of disease in different sociodemographic groups is vital to plan resource provision.

This study will provide estimate of the cumulative lifetime risk of vitiligo in the population overall, and by important sociodemographic groups, including age, sex, ethnicity and deprivation, which will prevalent key data to show the relative burden of vitiligo across the aforementioned groups. These approaches allow creation of cumulative lifetime risk plots which provide an excellent and accessible way to display the relative disease burden across groups.

The cumulative lifetime risk of vitiligo will be estimated at age 80 years (approximate lifetime expectancy in the UK) using survival models, with age as the timescale and accounting for competing risk of death.

This study will also perform a subgroup analysis in the vitiligo population to identify health-related disparities across people in different deprivation, sex and ethnic groups. The disparities that will be considered are: Mental health conditions; healthcare utilisation; and work impact (time off work and unemployment),

The assessment of any associations with baseline characteristics and the outcome of interest will be used using Cox proportional hazards models (time to event outcomes) and generalised linear models.

Inclusion Criteria:

• The cohort for the endpoint analysis will consist of all adults and adolescents (aged 13+) contributing to OPCRD during the study period (2004-2020).
• The cohort for the lifetime risk analysis will consist of all people contributing to OPCRD during the study period.
• The vitiligo cohort consists of people newly diagnosed with vitiligo at any point during the study period.

Exclusion Criteria:

• People with the alternative non-vitiligo diagnoses (other hypopigmenting conditions).
• People with vitiligo diagnosis within 6 months of practice registration.
• People without vitiligo with less than 1 year of follow up within the dataset.
• People over the age of 95 (for those reaching age 95 during the follow up period follow up was censored at age 95).
• People who have opted out of record sharing.

Incident cases will be defined as people with a first ever diagnosis code of vitiligo during the study period. People with a diagnosis of vitiligo prior to the study period will be excluded. Each case will be assigned an index date at the time of their vitiligo diagnosis. Controls will be matched to people without Vitiligo matched on age, sex, ethnicity and deprivation.

Individual patient data is confidential but can be made available in an anonymised form to bone fide researchers subject to the required data protection training and other requirements. All data will remain behind a firewall and will only be available for access through a secured computer network.

There is no pre-specified time-frame for data availability; this will be considered on an individual basis for each request.

As above.

Deaths, serious adverse events, and nonserious adverse events were not assessed for study participants.