Systemic Sclerosis As a Risk Factor of Acute Myocardial Infarction: A Us Population Based Study

Background:

Select studies in the past have described significantly increased risk of acute myocardial infarction (AMI) in patients with systemic sclerosis (SSc). Increased atherosclerosis as well as microvascular involvement with recurrent focal ischemia and subsequent fibrosis are the proposed mechanisms. Our study aims to shed further light on SSc as an independent risk factor for development of acute myocardial infarction using a large US inpatient database

Methods: We selected SSc (ICD-9-CM code 710.1) related hospitalizations of adults ≥ 18 years using the Nationwide Inpatient Sample (NIS) database from 2009-2011 sponsored by the Agency for Healthcare Research and Quality as a part of Healthcare Cost and Utilization Project. Two mutually exclusive cohorts (patients with and without AMI) were identified among the selected. ICD-9-CM codes were used to identify the known risk factors for AMI (including age, sex, chronic kidney disease, diabetes mellitus, smoking, peripheral vascular disease, hypertension and hyperlipidemia) and population with concomitant diagnosis of SLE and RA were excluded to reduce confounding. STATA version 13.0 (College Station, TX) was used to do univariate and multivariate logistic regression to determine the odds of association between the SSc and AMI.

Results: We included 16,353(weighted N= 80,412) adults with SSc and 23,223,297 (weighted N= 96,700,380) controls without SSc in our analysis. The incidence of AMI was 3.06% in SSc group versus 2.96 % in the control group (adjusted p = 0.485). While univariate analysis revealed a statistically insignificant increased risk of AMI in SSc population (OR = 1.04, CI = 0.934 – 1.14, p = 0.479), multivariate analysis after controlling for confounders mentioned above showed statistically significant increased risk of AMI (OR = 1.29, CI = 1.17 – 1.43, p < 0.0001) (Table 1). 

Conclusions:

In line with the prior studies, we found that SSc is an independent risk factor for occurrence of AMI.  Aggressive treatment of SSc could potentially prevent such fatal outcome.  Assessing such a possibility is a matter of further study.