Physical Trauma Increases Risk for PsA Development in Psoriasis Patients

Data from a prospective, longitudinal, population-based cohort study suggest that a history of bone and joint trauma is an independent risk factor for psoriatic arthritis (PsA) development in patients with psoriasis.¹  This same association was not found for patients with rheumatoid arthritis (RA). These results were recently reported in Annals of the Rheumatic Diseases.

PsA, thought to develop when environmental factors trigger inflammatory processes in genetically susceptible individuals, occurs in approximately one-third of patients with psoriasis.²  Identifying accurate risk factors for PsA development allows clinicians to risk-stratify patients, with a goal of providing earlier treatment if symptoms do occur.  Stefán Már Thorarensen, MD, MPH, University of Iceland, and colleagues sought to evaluate if joint trauma was one of the risk factors for the development of incident PsA in patients with psoriasis.

Patient data and long-term health outcomes was gathered from UK The Health Improvement Network (THIN) database between the years of 1995 and 2013, a registry that includes >550 general practices. The READ diagnostic system coding for medical diagnoses was used to identify clinical information. 

Researchers identified patients with psoriasis with and without exposure to prior trauma, and stratified these groups according to age, gender, psoriasis disease duration, and date of entry into the patient database.  

Trauma exposure was gauged utilizing READ diagnostic codes, and classified into joint, bone, nerve, and skin trauma.  Researchers identified the following potential confounders: gender, age, body mass index, smoking status, alcohol consumption, psoriasis disease duration, and number of outpatient clinician visits.

A total of 70 646 patients with psoriasis were pulled from the registry for a combined total follow-up of 425 120 person-years (PYs). In this group, 15 416 of these patients had a history of prior trauma and 55 230 did not.  During the study follow-up period, 1010 cases of incident PsA were identified that corresponded with an incidence rate (IR) of 23.8 (95% CI 22.3 to 25.3) per 10 000 PYs.

Patients with psoriasis and a prior history of trauma were found to have an increased risk of developing PsA as compared with matched controls (hazard ratio [HR] 1.32 95% CI 1.13 to 1.54).  When comparing specific causes of trauma, bone traumas was associated with a multivariate HR of 1.46 (95% CI 1.04 to 2.04), while joint trauma was associated with a multivariate HR of 1.50 (95% CI 1.19 to 1.90).  This association did not persist between nerve and skin trauma and the development of PsA.

When other patients with no psoriasis from the THIN database were analyzed, no association was found between prior history of trauma and the development of rheumatoid arthritis (RA). 

“The deep Koebner response provides a potential explanation for the increased risk. In the context of the synovio-entheseal complex, innate immunity activation due to physical trauma may result in pro-inflammatory molecules accessing the synovium to trigger and perpetuate inflammation to cause synovitis,” the authors hypothesized. 

Summary and Clinical Applicability

Bone and joint trauma were found to be independently associated with increased risk of PsA development in patients with psoriasis in a prospective, population-based cohort study. 

“Ultimately, most incident cases of PsA present long after an initial diagnosis of psoriasis and should preventative strategies and therapies become available, a risk profile would help identify patients most likely to benefit from risk modification,” the researchers concluded.

Limitations and Disclosures

• Adjustments for potential confounders such as smoking and alcohol consumption were not possible in all patients due to lack of data
• Identification of a relatively small number patients with history of nerve trauma may have limited conclusions on whether it was as related to development of PsA

Reference

1. Thorarensen SM, Na L, Ogdie A, et al. Physical trauma recorded in primary care is associated with the onset of psoriatic arthritis among patients with psoriasis. Ann Rheum Dis 2016 Jul 25. doi:10.1136/annrheumdis-2016-209334 [Epub ahead of print]
2. Ogdie A, Langan S, Love T, et al Prevalence and treatment patterns of psoriatic arthritis in the UK. Rheumatology (Oxford) 2013;52:568–75. doi:10.1093/rheumatology/kes324