Background/Purpose: Conflicting reports of the mortality risk among patients with psoriatic arthritis (PsA) exist in the literature, however excess mortality has been presumed given the elevated mortality rates in rheumatoid arthritis and psoriasis.  Previous studies have been small, lacked internal comparison groups, and were mostly performed in rheumatology clinics rather than the general population.  The objective of this study was to examine the risk of mortality in patients with PsA as compared to matched controls as well as patients with psoriasis and rheumatoid arthritis (RA). 

Methods: A longitudinal cohort study was performed.  Patients aged 18-89 were selected from The Health Improvement Network (THIN), a large primary care medical record database in the United Kingdom, if they had a diagnosis of PsA, RA, or psoriasis.  PsA and psoriasis diagnoses have been validated in THIN (positive predictive value 85% and 90% respectively).  Up to 10 unexposed controls were matched on practice and start date within the practice for each patient with PsA.  Data from 1994-2010 were included.  Hazard ratios (HRs) were calculated using Cox proportional hazards models.  A priori we hypothesized an interaction between disease status and Disease Modifying Antirheumatic Drug (DMARD) use.  We used a purposeful selection modeling approach, including in the final model only confounders which changed the main effects by >15% and had a p-value of <0.1.

Results: Patients with PsA (N=8,706), RA (N=41,752), psoriasis (N=138,424) and controls (N=82,258) had mean age 50.7, 61.4, 47.6, and 49.9 years respectively.  The average follow up time was 5.3 years, and 1,442,357 person-years were observed during which 21,825 deaths occurred.  There was a significant interaction between disease and DMARD use and thus, stratified results are presented.  Compared with population controls, patients with PsA did not have an increased risk of mortality after adjusting for age and sex and did not significantly differ by DMARD use (DMARD users: HR 0.94, 95%CI: 0.80-1.10, DMARD non-users: HR 1.06, 95%CI: 0.94-1.19). RA patients had increased mortality when compared to population controls (DMARD users HR 1.59, 95%CI: 1.52-1.66, DMARD non-users HR 1.54, 95%CI: 1.47-1.60).  Similarly, patients with psoriasis who have not been prescribed a DMARD had a small increased risk of mortality compared to population controls (HR 1.08, 95%CI: 1.04-1.12) while those who had been prescribed a DMARD had greater risk (HR 1.75, 95%CI: 1.56-1.95).  These findings were unchanged after adjustment for baseline comorbidities including Charlson comorbidity index, cardiovascular disease, renal disease, diabetes, body mass index, depression and smoking status.  Adjusting for start year in the cohort did not change the results.

Conclusion: Patients with RA and psoriasis had increased mortality compared to the general population, a finding corroborated by previous studies. Despite increased mortality in these related conditions, however, patients with PsA did not have a statistically significant increased risk of mortality in this study.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/mortality-in-patients-with-psoriatic-arthritis-compared-to-patients-with-rheumatoid-arthritis-psoriasis-alone-and-the-general-population/