Severe Mental Illness Among Adults with Atopic Eczema or Psoriasis: Population-Based Matched Cohort Studies within UK Primary Care

Abstract

Background

Existing research exploring associations between atopic eczema (AE) or psoriasis, and severe mental illness (SMI – ie, schizophrenia, bipolar disorder, other psychoses) is limited, with longitudinal evidence particularly scarce. Therefore, temporal directions of associations are unclear. We aimed to investigate associations between AE or psoriasis and incident SMI among adults.

Methods

We conducted matched cohort studies using primary care electronic health records (January 1997 to January 2020) from the UK Clinical Practice Research Datalink GOLD. We identified two cohorts: 1) adults (≥18 years) with and without AE and 2) adults with and without psoriasis. We matched (on age, sex, general practice) adults with AE or psoriasis with up to five adults without. We used Cox regression, stratified by matched set, to estimate hazard ratios (HRs) comparing incident SMI among adults with and without AE or psoriasis.

Results

We identified 1,023,232 adults with AE and 4,908,059 without, and 363,210 with psoriasis and 1,801,875 without. After adjusting for matching variables (age, sex, general practice) and potential confounders (deprivation, calendar period) both AE and psoriasis were associated with at least a 17% increased hazard of SMI (AE: HR=1.17,95% CI=1.12–1.22; psoriasis: HR=1.26,95% CI=1.18–1.35). After additionally adjusting for potential mediators (comorbidity burden, harmful alcohol use, smoking status, body mass index, and, in AE only, sleep problems and high-dose glucocorticoids), associations with SMI did not persist for AE (HR=0.98,95% CI=0.93–1.04), and were attenuated for psoriasis (HR=1.14,95% CI=1.05–1.23).

Conclusion

Our findings suggest adults with AE or psoriasis are at increased risk of SMI compared to matched comparators. After adjusting for potential mediators, associations with SMI did not persist for AE, and were attenuated for psoriasis, suggesting that the increased risk may be explained by mediating factors (eg, sleep problems). Our research highlights the importance of monitoring mental health in adults with AE or psoriasis.

Keywords:

• epidemiology
• dermatology
• psychology

Abbreviations

AE, atopic eczema; BMI, body mass index; CI, confidence interval; CPRD, Clinical Practice Research Datalink, HR, hazard ratio; SMI, severe mental illness.

Declarations

This paper was presented at the Society for Academic Primary Care (SAPC) Annual Scientific Meeting (ASM) 2022 as a short oral presentation. The abstract for the talk can be found on the SAPC ASM 2022 website (doi: https://sapc.ac.uk/doi/10.37361/asm.2022.1.1). This study is based in part on data from the Clinical Practice Research Datalink obtained under license from the UK Medicines and Healthcare products Regulatory Agency. The data are provided by patients and collected by the NHS as part of their care and support. The interpretation and conclusions contained in this study are those of the author/s alone.

Data Sharing Statement

Data may be obtained from a third party and are not publicly available. Data from this study were obtained from the Clinical Practice Research Datalink (CPRD) and to guarantee patient data confidentiality, only the authors have access to the data during the study, and the data cannot be distributed to other parties. Data are available directly from CPRD subject to independent approval.

Ethics Approvals and Patient Consent

This study was approved by the United Kingdom Clinical Practice Research Datalink (CPRD) Independent Scientific Advisory Committee (protocol 20_051) and London School of Hygiene and Tropical Medicine (LSHTM) Research Ethics Committee. This study was performed in line with the principles of the Declaration of Helsinki. Consent is given by GP practices that contribute to CPRD. Individual patient consent is implied. However, patients are offered the right to opt out from the use of their de-identified data.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

JFH has received consultancy fees from Wellcome Trust and juli Health. RM has received consulting fees from AMGEN. CS has received grants from Medical Research Council (MRC) and European Consortium (EC) funded consortia with multiple industry partners (see biomap-eu.im and PSORT.org.uk for details) and SML is also an investigator on BIOMAP but without industry funding and reports grants from Wellcome Trust; CS has received departmental research funding from AbbVie, Novartis, Pfizer, Sanofi, Boehringer Ingelheim, and SOBI. KM has received consultancy fees from AMGEN. The remaining authors declare that they have no relevant conflicts of interest.

Additional information

Funding

EA was funded by a British Skin Foundation (BSF) PhD studentship (Reference: 024/S/18). SML was supported by a Wellcome Trust Senior Research Fellowship in Clinical Science (205039/Z/16/Z). JFH is supported by a UK Research and Innovation (UKRI) grant (Reference: MR/V023373/1), the University College London Hospitals NIHR Biomedical Research Centre and the NIHR North Thames Applied Research Collaboration. This study is funded by the NIHR Research for Patient Benefit programme (Reference: PB-PG-0418-20025). The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care. SML was also supported by Health Data Research UK (Grant number: LOND1), which is funded by the UK Medical Research Council, Engineering and Physical Sciences Research Council, Economic and Social Research Council, Department of Health and Social Care (England), Chief Scientist Office of the Scottish Government Health and Social Care Directorates, Health and Social Care Research and Development Division (Welsh Government), Public Health Agency (Northern Ireland), British Heart Foundation and Wellcome Trust. CS and SML are investigators on the European Union Horizon 2020-funded BIOMAP Consortium (http://www.biomap-imi.eu/). Funders had no role in the study design, collection, analysis, and interpretation of data; in the writing of the report; and in the decision, submit the article for publication. This research was funded in whole or in part by the Wellcome Trust [205039/Z/16/Z]. For the purpose of Open Access, the author has applied a CC BY public copyright licence to any Author Accepted Manuscript (AAM) version arising from this submission.