Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


The Risk of Myocardial Infarction among Patients with Psoriatic Arthritis.

Love1,  Thorvardur J., Solomon3,  Daniel Hal, Karlson2,  Elizabeth W.

Brigham and Women's Hospital, Boston, MA
Brigham and Womens Hosp, Boston, MA
Brigham and Womens Hospital, Boston, MA

Background:

Severe psoriasis is associated with an increased risk of myocardial infarction (MI). A recent study found a standardized prevalence ratio of 2.51 for MI among psoriatic arthritis (PsA) patients compared to individuals from a telephone survey of the general population. We examined data from a hospital-based PsA repository, a population based survey, and medical records of patients without PsA to evaluate the risk of MI.

Methods:

We performed two matched cohort analyses, using a single group of validated cases of PsA from a psoriatic arthritis patient repository seen at a tertiary care teaching hospital between 1995 and 2008, with each PsA case matched 2:1 on birth year, gender, and race to two separate comparison groups: non-PsA patients drawn from the same hospital population, and participants in the NHANES 2005–2008 population survey. The first documented diagnosis of PsA marked the beginning of follow up. The start of follow up for the hospital non-PsA group was the visit date closest in time to the diagnosis of the matched PsA case. Incident MI was determined by the presence of an ICD9 code in medical records, or self report in the NHANES cohort. Each individual was followed from either the onset of PsA or the matched index date, until they had an MI or follow-up ended. We excluded anyone with less than 12 months of follow up, and those with pre-existing cardiovascular conditions.

Results:

We successfully matched 1404 BWH non-PsA patients to 702 PsA cases found in our repository. From NHANES we found two matched controls for each of 734 PsA cases. Cumulative follow up time in the three arms of the study was 21,509 person years. There were 33 incident cases of MI in the PsA-group, 67 in the BWH non-PsA group, and 18 in the NHANES group. The incidence rate (IR) for MI per 10,000 patient years was 72 [50– 101], 80 [62–102], and 21 [12–33] per 10,000 patient years at risk in the three groups, respectively. The crude incidence rate ratio for MI in PsA was 0.93 [0.60–1.44] and 3.46 [1.89–6.52] compared to the hospital and NHANES groups. Table 1 shows the results of the multivariate Cox proportional hazards analysis adjusted for age, calendar year, diabetes, hypertension, and hyperlipidemia for the risk of MI.

Table 1. Cox proportional hazard analysis of the risk of MI associated with psoriatic arthritis, adjusted for age, calendar year, diabetes, hypertension, and hyperlipidemia.

 Hospital comparisonNHANES comparison
 HR[95% CI]HR[95% CI]
Psoriatic arthritis0.990.941.041.181.081.28
Age1.041.021.051.051.031.08
Calendar year1.020.951.101.060.941.19
Diabetes1.941.282.942.341.294.24
Hypertension4.922.519.633.251.497.06
Hyperlipidemia2.821.664.802.141.134.06

Conclusion:

We did not find any difference in the risk of MI in the PsA group when comparing to a non-PsA group drawn from the same hospital based source population. We replicated a previously demonstrated association between PsA and MI when comparing cases of PsA to individuals from the general population. Furthermore, we quantified the risk by estimating the IR, the IRR, and the adjusted HR. This suggests that the choice of control population affects the results of analyses of MI risk in PsA. Studies of PsA cases drawn from the general population are needed to support the hypothesis that PsA increases the risk of MI in the general population.

To cite this abstract, please use the following information:
Love, Thorvardur J., Solomon, Daniel Hal, Karlson, Elizabeth W.; The Risk of Myocardial Infarction among Patients with Psoriatic Arthritis. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :793
DOI: 10.1002/art.28561

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