Impact of the Charlson Comorbidity Index score on risk prediction by single-photon emission computed tomography myocardial perfusion imaging following myocardial infarction

Abstract

Background

Comorbidity is common among patients with myocardial infarction (MI). We examined whether comorbidity level modified the single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI)-based prediction of 5-year risk of MI and all-cause death in patients with MI.

Methods

This cohort study included patients with prior MI having a SPECT MPI at Aarhus University Hospital, Denmark, 1999–2011. Using nationwide registries, we obtained information on comorbidity levels (low, moderate, and severe) and outcomes. We computed risk and hazard ratios (HRs) with 95% confidence intervals (CIs) for MI and all-cause death, comparing normal (no defects) versus abnormal scan (reversible and/or fixed defects) using Cox regression adjusting for sex, age, and comorbidity level.

Results

We identified 1,192 patients with MI before SPECT MPI. The 5-year risk for patients with normal versus abnormal scans were 11.7% versus 18.3% for MI, and 8.0% versus 13.2% for all-cause death, respectively. The overall 5-year adjusted HR (aHR) of MI was 1.56 (95% CI: 1.09–2.21), 1.33 (95% CI: 0.82–2.15) with low comorbidity, 1.39 (95% CI: 0.68–2.83) with moderate comorbidity, and 2.53 (95% CI: 1.14–5.62) with severe comorbidity. Similarly, the 5-year aHR for all-cause death was 1.39 (95% CI: 0.90–2.14) overall; 2.33 (95% CI: 0.79–6.84) with low comorbidity, 2.05 (95% CI: 0.69–6.06) with moderate comorbidity, and 1.07 (95% CI: 0.64–1.80) with severe comorbidity.

Conclusion

We conclude that comorbidity level may modify the 5-year risk prediction associated with an abnormal SPECT MPI scan in patients with previous MI.

Keywords:

• comorbidity
• epidemiology
• myocardial infarction
• myocardial perfusion imaging

Supplementary materials

Table S1 Diagnosis codes according to the International Classification of Diseases, 8th (ICD-8) and 10th revision (ICD-10)

Table S2 Diagnosis codes for myocardial infarction according to the International Classification of Diseases, 8th (ICD-8) and 10th (ICD-10) revision

Table S3 Risk and hazard ratio of MI and all-cause death within 5 years following a normal versus abnormal scan

Table S4 Risk and hazard ratio of MI and all-cause death within 5 years following a normal versus abnormal scan.

Acknowledgments

The authors acknowledge Professor Henrik Toft Sørensen from the Department of Clinical Epidemiology, Aarhus University, for providing valuable comments to the manuscript.

Disclosure

The Department of Clinical Epidemiology is involved in studies with funding from various companies as research grants to (and administered by) Aarhus University. The authors report no other conflicts of interest in this work.

Supplementary materials