Background/Purpose:

Psoriatic arthritis is an inflammatory arthritis that causes significant morbidity. While a study from a single research clinic in Canada published in the 1990´s suggested an increased mortality rate compared to that seen in the general population, two recent studies from the UK reported no increased mortality, one based on a single center similar to the Canadian study, and the other based on a sample from the general population. We have performed a study of the mortality rate among all known cases of psoriatic arthritis diagnosed since 1971 in Iceland compared to the general population of the same country.

Methods:

We used a list of all known patients in Iceland with a diagnosis of psoriatic arthritis assembled in 2002-2003 for a cross-sectional study of psoriatic arthritis in Iceland. The list includes both those patients who were still alive in 2002, as well as those who had died before the study began. This list has been validated by examining close to 200 patients, showing that about 85% had active disease in 2003 and more than 80% fulfilled the CASPAR criteria applied post-hoc. Using national identification numbers and the Icelandic national mortality database we were able to determine the year of death for all individuals who died before end of year 2012, making death ascertainment complete. Using data on age- and sex stratified 1-year survival for the Icelandic population available for each year starting in 1971 we were able to compare the survival of patients with psoriatic arthritis to the expected survival of the age- and sex-matched population starting the year that each psoriatic arthritis diagnosis was made.

Results:

The list of psoriatic arthritis patients contained 346 individuals and data on the date of diagnosis of psoriatic arthritis was available for 340. Of these, 293 were diagnosed in 1971 or later and could be used for comparison to the population statistics, with 6747 patient years of follow-up. The mean age at the time of diagnosis was 42.3 years (95%CI 40.1 – 44.4), with 57 diagnosed in the 1970´s, 98 diagnosed in the 1980‘s, 137 diagnosed in the 1990´s and 1 diagnosed in 2001. This is equivalent to an incidence rate of 3.8 (2.9 – 5.0), 5.7 (4.6 – 7.0), and 7.2 (6.1 – 8.6) incident cases per year per 100.000 individuals age 18 or older for each of the three whole decades included in the study.

Out of 107 men with psoriatic arthritis, 28 had died by the end of 2012, and the same was true for 42 of 186 women with psoriatic arthritis. The age- and sex-specific expected number of deaths updated annually based on year of diagnosis was 27 men and 39 women. The age- and sex-standardized mortality ratio of psoriatic arthritis patients compared to the general population was 1.06 (95% CI 0.84-1.13), p=0.64.

Conclusion:

There was no increased death rate among psoriatic arthritis patients compared to the general population.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/psoriatic-arthritis-and-mortality-a-nationwide-study/