Characterising the natural history and risk factors for the development of psoriatic arthritis in a UK population

Date of ISAC Approval: 
31/07/2015
Lay Summary: 
Psoriatic arthritis (PsA) is an inflammatory arthritis, which affects approximately 1 in 3 people with psoriasis and up to 400,000 people in England. PsA causes pain, swelling and joint stiffness and is accompanied by chronic disfiguring skin disease. Screening patients with psoriasis for PsA has revealed a high prevalence of undiagnosed disease and there is emerging evidence that delay in diagnosis results in worse outcome. This study forms part of an NIHR funded Programme Grant on the impact of early diagnosis of PsA. The study aims to describe the incidence, prevalence and evolution of musculoskeletal symptoms reported by people with psoriasis in UK primary care and investigate predictors of the development of PsA in people with psoriasis, such as obesity and smoking. Additionally, co-morbidity in PsA and the utilisation of primary health care resources before/after PsA diagnosis will be described. This study will quantify the association between modifiable risk factors and the development of PsA in patients with psoriasis and will help to describe the diagnostic pathway and identify potential causes of diagnostic delay in PsA. It will also inform clinical recommendations on the most effective screening strategies, such as identifying specific patient groups at highest risk of developing PsA.
Technical Summary: 
This study forms part of a wider NIHR funded Programme Grant (RP-PG-1212-20007) on the impact of early diagnosis of PsA. The proposed study aims to describe the incidence, prevalence and evolution of musculoskeletal symptoms reported to general practitioners by people with psoriasis in UK primary care and investigate predictors of the development of PsA in people with psoriasis, such as obesity and smoking. The study will follow a cohort study design and identify cases of psoriasis and PsA in the Clinical Practice Research Datalink, between 01/01/1998 and 31/12/2014, and follow them prospectively until the end of the study period or the time they leave the database. The incidence and prevalence of musculoskeletal symptoms will be calculated for each year after entry into the study period stratified by age, sex and psoriasis disease severity and survival rates from musculoskeletal symptom presentation to PsA diagnosis will be calculated. Generalised linear models with time varying covariates will be used to investigate factors associated with the development of PsA. Additionally, co-morbidity in PsA and the utilisation of primary health care resources before and after PsA diagnosis will be described to inform the cost-effectiveness component of the wider Programme Grant.
Health Outcomes to be Measured: 
Cases of PsA will be identified within the base population between 1-Jan-1998 and 31-Dec-2014, based on Read codes previously validated in a study by Ogdie et al. using data from THIN
Collaborators: 

Dr Alison Nightingale - Chief Investigator - University of Bath
Dr Alison Nightingale - Corresponding Applicant - University of Bath
Professor Gavin Shaddick - Researcher - University of Bath
Professor Neil McHugh - Researcher - University of Bath
Dr Rachel Charlton - Researcher - University of Bath