Background Psoriasis is a common inflammatory skin disease affecting 2–4% of the population and of these a subset will develop an associated inflammatory arthritis (psoriatic arthritis - PsA). An increased risk of osteoporosis has previously been reported in psoriasis patients but the risk of fracture in patients with both psoriasis and PsA has not been established.
Objectives To estimate the effect of psoriasis, and PsA, on the risk of fracture using a large electronic primary health care database.
Methods A matched cohort study was conducted utilizing data from the Clinical Practice Research Datalink, a large UK database of primary care medical records. The exposed population was defined as psoriasis patients aged over 40 years with an incident diagnosis between 1990–2004, who were followed up until 2015. Four unexposed patients were matched to each exposed based on age, sex and general practice. The incidence rate of fracture were calculated as the number of incident diagnoses per 10,000 person-years, stratified by sex. Hazard ratios (HR) and 95% confidence intervals were estimated using a Cox proportional hazards model to compare the hazard rate between the exposed and unexposed, adjusting for BMI, alcohol consumption, smoking status, Charlson comorbidity index and steroid use. Fracture risk was estimated for patients with both psoriasis and PsA, identified as patients with an incident diagnosis of psoriasis and a diagnosis of PsA between 1990–2004.
Results 24,219 patients with psoriasis and 94,820 controls were included in the study. The mean age was 59 years at study entry and just over half (51%) of the patients were male. The incidence rate of fracture was 58.4 (95% CI:55.6–61.3) and 53.1 (51.7–54.5) per 10,000 person-years for the exposed and unexposed, respectively. After adjusting for confounding factors, patients with psoriasis had 12% increased risk of fracture (HR: 1.12; 95% CI: 1.06–1.19) compared to the matched unexposed group. The risk was slightly higher in males (1.22 (1.09–1.36)) than females (1.09 (1.03–1.17)). Among those with psoriasis, 4.1% were also diagnosed with PsA. An increased risk of 45% was found in those exposed to both psoriasis and PsA compared to the unexposed group (1.45 (1.09–1.94)).
Conclusions This study reports for the first time, an increase in fracture risk in patients with psoriasis. A higher risk was found in males than females and the risk was further increased if the patient also had PsA. These findings suggest that fracture risk assessment needs to be considered for individuals with psoriasis and PsA.
Acknowledgements This study was funded by the National Institute for Health Research School for Primary Care Research (NIHR SPCR). CDM is funded by the National Institute for Health Research (NIHR) Collaborations for Leadership in Applied Health Research and Care West Midlands, the NIHR School for Primary Care Research and a NIHR Research Professorship in General Practice (NIHR-RP-2014–04–026). TH is funded by an NIHR Clinical Lectureship in General Practice. AAS is funded by an NIHR Postdoctoral Fellowship. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health.
Disclosure of Interest None declared