Mental illness is more common in people with inflammatory skin diseases like atopic eczema and psoriasis, but we do not know why. Possible causes include socioeconomic deprivation, poor sleep quality, poor lifestyle choices or the inflammatory process itself. Identifying those most at risk of mental illness would enable targeted screening to identify mental health issues. Both mental illness and atopic eczema/psoriasis are common, so any link could have far reaching consequences.
Our study will follow very large numbers of people with and without atopic eczema/psoriasis over time to see whether they develop mental illnesses. We will determine how much higher the risk of mental illness is in those with atopic eczema/psoriasis compared to people without skin disease, and whether people with atopic eczema/psoriasis have different risk factors for mental illness. By establishing the size of the problem of mental illness in people with atopic eczema/psoriasis, we will offer a call to arms for clinicians, researchers and policy makers. We will highlight the importance of identifying mental illness in those with visible and potentially stigmatising skin disease, and potentially offer opportunities for identifying modifiable risk factors for mental illness, and people who would particularly benefit from targeted mental illness screening. This knowledge will help us identify mental illness in people with skin disease earlier and manage it better, limiting their impact and cost, promoting a holistic approach to managing skin disease, and potentially improving skin disease treatment in those with mental illness.
The overall aim of the study is to explore the relationship between atopic eczema/psoriasis and mental illness (common mental disorders: depression and anxiety; and severe mental illness: schizophrenia, bipolar disorder, and other psychotic illness).
We will identify two matched cohorts: one including people with and without atopic eczema, and one including people with and without psoriasis. Each cohort will include those with skin disease (including incident and prevalent cases of atopic eczema/psoriasis) and an age, sex and GP-practice matched cohort of individuals without skin disease (i.e. the comparison group will include those without atopic eczema for the atopic eczema cohort, and those without psoriasis for the psoriasis cohort) during the same period (from 1997 to latest data available). Follow-up of people without skin disease will start on the same date as that of their matched skin disease cases (i.e. for those with skin disease follow up starts on the latest of: atopic eczema/psoriasis diagnosis, GP registration plus one year, study start, 18th birthday, or date practice met CPRD quality control standards).
We will use Cox regression (fully-adjusted for potential confounders and accounting for matching) to estimate hazard ratios comparing the risk of severe mental illness and common mental health conditions in those with and without either atopic eczema or psoriasis. Potential risk factors considered will include: comorbidities (e.g. asthma, psoriatic arthropathy), ethnicity, lifestyle factors (e.g. smoking, alcohol intake, and body mass index), and socioeconomic deprivation. We will construct crude models including just the main exposure variable (atopic eczema or psoriasis) followed by sequential models adjusting for other potential explanatory variables (such as comorbidities and lifestyle factors). We will then restrict to cohorts with skin disease only to construct predictive logistic regression models to identify subgroups at risk of mental illness.
Primary outcomes: 1) Common mental disorders (depression and anxiety); 2) Severe mental illness (schizophrenia, bipolar disorder, and other psychotic illness).
Secondary outcomes: Where power permits we will also explore specific subtypes of our primary outcomes including: 1) depression; 2) anxiety; 3) schizophrenia; 4) bipolar disorder; 5) other psychoses.
Sinead Langan - Chief Investigator - London School of Hygiene & Tropical Medicine ( LSHTM )
Kathryn Mansfield - Corresponding Applicant - London School of Hygiene & Tropical Medicine ( LSHTM )
Alasdair Henderson - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Amy Mulick - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Catherine Smith - Collaborator - King's College London (KCL)
Elizabeth Adesanya - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Joseph Hayes - Collaborator - University College London ( UCL )
Lauren Rayner - Collaborator - King's College London (KCL)
Liam Smeeth - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Lynnette Mukasa - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
Rohini Mathur - Collaborator - London School of Hygiene & Tropical Medicine ( LSHTM )
2011 Rural-Urban Classification at LSOA level;HES Admitted Patient Care;Patient Level Carstairs Index for 2011 Census;Practice Level Carstairs Index for 2011 Census (Excluding Northern Ireland)