Background/Purpose:

An increased risk of premature atherosclerosis has been well described in patients with rheumatoid arthritis and systemic lupus erythematosus. However, there is limited data on the risk of atherosclerotic diseases, myocardial infarction (MI) in patients with Systemic Sclerosis (SSc). Moreover, the scarce information has come from selected populations.  To fill this knowledge gap, we estimated the risk of newly recorded MI events among incident cases with SSc compared to controls from the general population using physician billing and hospitalization databases that cover the entire population from our province (~ 5 million). 

Methods:

Our data included all visits to health professionals and hospital admissions covered by the comprehensive provincial medical services plan (from Jan1990 until Dec 2010) and all dispensed medication (from Sept 1995 to Dec 2010); for all individuals >= 18 years of age.  We conducted a matched cohort analysis among patients satisfying at least one of the following criteria: a) diagnosis of SSc on at least two visits within a two-year period between Jan 1996 and Dec 2010 by a non-rheumatologist physician; b) diagnosis of SSc on at least one visit by a rheumatologist or from a hospital. To increase specificity we excluded cases that were not confirmed by a rheumatologist if they were seen at a later point. Ten controls matched by birth year, sex and calendar year of follow-up were selected from the general population for each case. Newly recorded MI events from hospital or death certificate were recorded as an outcome. We estimated relative risks (RRs) comparing SSc with age-, sex- and entry time-matched comparison cohorts, adjusting for potential cardiovascular risk factors.

Results:

Among 1,208 individuals with incident SSc (84% female, mean age of 56 yrs [SD 15.0]), 90 developed MI (incidence rate= 20.2 per 1000 person years) (Table 1). Compared with non-SSc individuals (N= 12,080), the age-, sex-, and entry-time-matched RR for MI was 3.8 (95% CI, 2.9 to 4.8). The risk was 9 times greater within the first year after the disease onset and progressively decreases over time. After further adjustment for angina, COPD, obesity, cardiovascular disease, diabetes, hormone replacement therapy, dyslipidemia, non steroidal anti-inflammatory drugs, Cox-2 inhibitors, number of hospitalizations and Charlson’s comorbidity index at baseline; the RR remained similar (4.0, 95% CI, 3.1 to 5.3).   These results persisted among men, women and different age groups (Table 1).

Conclusion:

This large population-based study indicates an increased risk of MI in patients with SSc, especially within the first year of disease diagnosis.  These findings support increased monitoring of MI complication and risk factors in those with SSc, particularly during the early phase of SSc diagnosis.

Table 1.  Relative risk of incident MI according to Systemic Sclerosis status.