Chest
Volume 137, Issue 5, May 2010, Pages 1091-1097
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ORIGINAL RESEARCH
COPD
Increased Risk of Myocardial Infarction and Stroke Following Exacerbation of COPD

https://doi.org/10.1378/chest.09-2029Get rights and content

Objective

Patients with COPD are at risk for cardiovascular events. This is attributed to increased systemic inflammation. The course of COPD is punctuated by exacerbations, which further increase systemic inflammation, but the risk of vascular events in the postexacerbation period has never been defined.

Methods

We analyzed data from 25,857 patients with COPD entered in The Health Improvement Network database over a 2-year period. Exacerbations were defined using a health-care use definition of prescription of oral corticosteroids > 20 mg/d and/or selected oral antibiotics. The risk of myocardial infarction (MI) and stroke in the postexacerbation period was calculated relative to the patient's baseline risk using the self-controlled case series approach.

Results

We identified 524 MIs in 426 patients and 633 ischemic strokes in 482 patients. The incidence rates of MI and stroke were 1.1 and 1.4 per 100 patient-years, respectively. There was a 2.27-fold (95% CI, 1.1–4.7; P = .03) increased risk of MI 1 to 5 days after exacerbation (defined by prescription of both steroids and antibiotics). This relative risk diminished progressively with time and was not significantly different from the baseline MI risk at any other postexacerbation time interval. One in 2,513 exacerbations was associated with MI within 1 to 5 days. There was a 1.26-fold (95% CI, 1.0–1.6; P = .05) increased risk of stroke 1 to 49 days after exacerbation.

Conclusion

The results suggest that exacerbations of COPD increase the risk of MI and stroke. This may have implications for therapy in both stable and exacerbated COPD.

Section snippets

Materials and Methods

We examined The Health Improvement Network (THIN) database, which contains anonymized medical records of primary care practices in England and Wales. The database is comparable to the General Practice Research Database (GPRD)21 and the prevalence, demographics, smoking habits, and mortality of patients with COPD in THIN match other national data.22 The study had approval from the Nottingham Research Ethics committee.

The main analysis used the self-controlled case series approach. This involved

MI and Stroke Incidence Rates

Table 1 reports the total number of patients with COPD and the number experiencing an MI or stroke. There were 25,857 patients with COPD in 277 practices at the start of the observation period. Over the subsequent 2 years, these patients were alive and in contributing practices for 16,874,379 days (average 1.79 years per patient). For all patients with COPD, the incidence rate of MI events was 1.1 per 100 patient-years and for stroke events, 1.4 per 100 patient-years.

Number and Annual Rates of Exacerbations

Table 2 shows the number

Discussion

This study has for the first time, to our knowledge, shown that exacerbation of COPD is associated with a small, but statistically significant, 2.27-fold increased relative risk of MI during a short 5-day period and of a stroke during the 1- to 49-day period immediately following an exacerbation. There are a number of strengths of our study. We examined a large population of patients with COPD. Although the diagnosis of COPD could not be confirmed with spirometry in all patients, we found a

Acknowledgments

Author contributions: Dr Donaldson had full access to all the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Dr Donaldson: contributed to the original idea for the study, performed the statistical analysis, wrote the initial draft of the paper, edited the paper, and approved the final version.

Dr Hurst: contributed to the original idea for the study, decided which Read codes to use for definitions, wrote the initial draft of the

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Funding/Support: This study was funded by the British Lung Foundation.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestpubs.org/site/misc/reprints.xhtml).

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