Increased risk of acute myocardial infarction and mortality in patients with systemic lupus erythematosus: Two nationwide retrospective cohort studies

https://doi.org/10.1016/j.ijcard.2014.08.006Get rights and content

Highlights

  • We reported increased risk of AMI among SLE patients compared with non-SLE cohort.

  • The association between SLE and AMI risk was more significant in women than in men.

  • Patients with SLE had higher post-AMI mortality when undergoing cardiac surgeries.

Abstract

Background

This study evaluated the risk of acute myocardial infarction (AMI) and mortality among patients with systemic lupus erythematosus (SLE) in two nationwide retrospective cohort studies.

Methods

Using Taiwan's National Health Insurance Research Database, we conducted a retrospective cohort study and identified 1207 adults newly diagnosed with SLE in 2000–2004. Non-SLE cohort consisted of 9656 adults without SLE, frequency-matched for age and sex and randomly selected from the same data set. Events of AMI were considered as outcome during the follow-up period between 2000 and 2008. Another nested cohort study of 6900 patients with AMI receiving cardiac surgeries was conducted to analyze the impact of SLE on post-AMI mortality.

Results

During the follow-up period, there were 52 newly diagnosed AMI cases. The incidences of AMI for SLE cohort and non-SLE cohort were 2.10 and 0.49 per 1000 person-years, respectively, with an adjusted hazard ratio (HR) of 5.11 (95% confidence interval [CI] 2.63–9.92). For females, the adjusted HR of AMI associated with SLE was as high as 6.28 (95% CI 2.67–14.7). Further analyses in the nested cohort showed that SLE was significantly associated with post-AMI mortality (odds ratio, 2.60; 95% CI 1.09–6.19).

Conclusion

Patients with SLE had higher risk of AMI compared with non-SLE control, and this risk was more significant in females. In addition, SLE is an independent risk factor for post-AMI mortality.

Introduction

Systemic lupus erythematosus (SLE) is a chronic autoimmune connective tissue disorder with a broad range of clinical presentations that mainly affect women of childbearing age [1]. It represents a substantial global disease burden, with one United States estimate of prevalence finding 143.7 cases per 100,000 people [2]. Although the epidemiology, complications and treatment of SLE are well studied [1], [2], [3], poor quality of life and increased mortality from SLE are serious problems of global concern [4].

Over the past thirty years, many studies have provided clinical evidence regarding management of acute myocardial infarction (AMI) [5]. Although reductions in incidence and mortality of AMI have been investigated [6], [7], the high cost and social burden associated with this condition remain important issues [8], [9]. Epidemiological studies have documented that more than 90% of AMI cases are attributable to modifiable risk factors such as smoking, dyslipidemia, hypertension, abdominal obesity, and diabetes [10]. However, specific risk factors for AMI still need to be validated.

People with SLE have shown a higher prevalence of atherosclerosis, which is a traditional risk factor for cardiovascular diseases [11]. The significantly increased risk of cardiovascular diseases in patients with SLE also has been investigated [12], [13], [14], [15], [16], [17], [18], [19], [20]. Previous studies reported that people with SLE had higher risk of AMI compared with those without SLE [12], [13], [14], [15], [16]. However, these studies were limited by small sample size [15], focusing on specific populations [12], [14], [16], poor study design [13], [14], and inadequate adjustment for potential confounding factors [12], [15].

Using Taiwan's National Health Insurance Research Database, we conducted a retrospective cohort study to investigate the association between SLE and AMI with longitudinal design, a nationwide sample, and multivariate adjustment. We also performed a nested retrospective cohort study to verify the potentially higher risk of post-AMI adverse outcomes in patients with SLE when receiving cardiac surgery.

Section snippets

Data sources

The research data used in this study was obtained from reimbursement claims of Taiwan's National Health Insurance Program, which was implemented in 1995 and which covers more than 99% of 22.6 million Taiwan residents. The National Health Research Institutes established a National Health Insurance Research Database recording all beneficiaries' medical services, including inpatient and outpatient demographics, primary and secondary diagnoses, procedures, prescriptions and medical expenditures.

Results

Compared with non-SLE cohort (Table 1), cohort with SLE had higher proportions of living in very urbanized areas (27.9% vs. 23.5%, p = 0.0004), low income (3.3% vs. 2.1%, p = 0.0093), trauma (74.2% vs. 66.9%, p < 0.0001), mental disorders (34.1% vs. 24.8%, p < 0.0001), hyperlipidemia (12.7% vs. 10.2%, p = 0.0073), atherosclerosis (6.9% vs. 3.6%, p < 0.0001), liver cirrhosis (5.6% vs. 4.2%, p = 0.0293), and renal dialysis (2.7% vs. 0.5%, p < 0.0001). Patients with SLE had used more medication than non-SLE

Discussion

This nationwide retrospective cohort study reported increased risk of AMI among SLE patients compared with non-SLE cohort. The association was more significant in women than in men. We further investigated the impacts of emergency visit and hospital inpatient services among SLE patients having higher risk for AMI. A further retrospective cohort study found SLE patients after AMI had higher 30-day in-hospital postoperative mortality than non-SLE cohort when undergoing cardiac surgeries.

In the

Funding

This study was supported in part by a grant from the National Science Council Taiwan (NSC102-2314-B-038-021-MY3).

Competing interests

The authors report no relationships that could be construed as a conflict of interest.

Author contribution

All authors were involved in drafting the article, interpreting the data or revising it critically for important intellectual content, and all authors approved the final version to be published. Dr. Chen had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Acknowledgments

This study is based on data from the National Health Insurance Research Database provided by the National Health Research Institutes. The interpretation and conclusions contained herein do not represent those of the National Health Research Institutes.

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    Chiao-Yi Lin and Ta-Liang Chen contributed equally to this work.

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