Burden of atrial fibrillation

ABSTRACT

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia seen in clinical practice and has attracted much attention due to its association with a substantial mortality and morbidity, particularly from stroke, thromboembolism and heart failure. This Editorial Commentary provides a brief overview of the clinical, economic and epidemiological burden of AF, particularly in the context of hospital readmission of patients with AF.

It concludes that further studies on identifying factors and reasons for readmission in AF patients are therefore warranted. Understanding the patterns and factors that are responsible for readmission would help clinicians optimise the treatment strategies for AF patients and in turn improve quality of care and potentially lessen the large burden of AF on healthcare systems.

Key words: :

• Atrial fibrillation
• Burden of illness
• Epidemiology
• Hospital readmissions

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia seen in clinical practice. AF has attracted much attention due to its association with a substantial mortality and morbidity, particularly from stroke, thromboembolism and heart failure. Indeed, nearly 1% of the UK NHS costs can be attributed to AF1, an economic burden which has also been reported in other countries2.

What do epidemiological studies on AF tell us of the ‘burden’ of this arrhythmia? They tell us that this is a common problem and increasingly so. The incidence and prevalence of AF is increasing with age, leading to a substantial public health and economic burden3. Indeed, there has been a rise of AF by 13% over the past 2 decades and it has been estimated that 15.9 million people in the USA will have AF by 2050, if a continuous rise in the incidence of AF continues3.

In the Framingham Heart Study, the overall prevalence of AF was 6%, and the lifetime risk for both men and women aged 40 and above to develop AF was 1 in 44. Of those who had developed AF without prior or concurrent congestive heart failure or myocardial infarction, lifetime risks for AF were still approximately 16%. A similar prevalence was reported in the Rotterdam study5, which found an overall prevalence of 5.5%, rising from 0.7% for patients aged 50–59 years to 17.8% in those who aged 85 years and above. In another population-based study in West Scotland – the Renfrew–Paisley study6 – the prevalence of AF in patients aged 45–64 years old was 6.5%. The largest screening study for AF in recent literature is the Screening for Atrial Fibrillation in the Elderly (SAFE) study7 which showed a baseline prevalence of 7%, with an increased prevalence of 10% for patients aged 75 years and older. The incidence of AF also follows a similar pattern and appears to be rising. In the Renfrew–Paisley study, the incidence of AF was 2.1 cases per 1000 person-years in men and 1.7 cases per 1000 person-years in women. The Framingham study4 and the Manitoba study8 also reported a similar overall incidence rate of two cases per 1000 person-years.

What are the clinical implications of the increasing epidemiological burden of AF? Population-based studies have shown an increased risk of all-cause mortality and death from cardiovascular causes in AF patients6,8. The risk of stroke or thromboembolism is 4–5-fold across all age groups9. Patients with stroke and AF generally have poorer outcome, greater disability and longer inpatient stays10. As well as stroke, AF has also been shown to be associated with heart failure, and in both the Manitoba study and Renfrew–Paisley study, there was a 3–4-fold increase in risk of heart failure6,8.

Despite improvements in healthcare, the prognosis related to AF does not seem to be improving and, if anything, mortality and hospitalisations related to AF seem to be increasing. One study showed that the proportion of subjects aged 45 and older with AF reported as the underlying cause of death rose from 8.3% in 1980 to 11.6% in 199811. Wattigney et al.12 also reported that the hospitalisation rate for AF in the United States had increased 2–3-fold between 1985 and 1999. Meanwhile, the number of male and female patients discharged home decreased from 77 to 63% and 72 to 56%, respectively, over the same period of time. In a study from Olmsted County, MN, USA, Miyasaka et al.13 reported that the mortality risk for newly diagnosed AF patients was high, particularly within the first 4 months of diagnosis.

This increasing burden of AF may be a reflection of improved survival post-myocardial infarction14, as well as the increasing age of the general population. Indeed, AF increases with increasing age, with an overall prevalence of 0.9% in some studies, which steadily increases to 10% or higher in people over 80 years of age15.

As mentioned above, many studies also indicate an increase in the number of hospitalisations for AF over the last 25 years 12,16–18. This can be attributed to the rise in prevalence and incidence due to the ageing population, as well as the associated mortality and morbidity of AF. More importantly, hospitalisations related to AF tend to be associated with greater healthcare costs and longer inpatient stays, with a lower rate of discharge to their own homes.

In the current issue of the Current Medical Research and Opinion, Kim et al.19 evaluated the incidence and temporal pattern of readmission in 4174 AF patients from January 2003 to June 2006. In this retrospective, cohort analysis based on the Integrated Healthcare Information Systems National Managed Care Benchmark Database, 12.5% of chronic AF patients were readmitted for AF with a mean time to readmission of 142.5 days. As for the newly-diagnosed AF patients, 10.1% were readmitted for AF with a mean time to readmission of 133.8 days. The readmission mostly occurred within the first 6 months of the index hospitalisation for both chronic AF (65.8%) and newly-diagnosed AF (67.2%) patients. Furthermore, a high proportion (22.7%) of newly-diagnosed AF patients had readmission within the first month. This registry analysis has re-emphasised the fact that AF is associated with hospital readmission. The factors or reasons for readmission were not identified due to the lack of clinical details on the database. Surely this increased readmission into hospital poses an economic burden on the modern healthcare system.

A large survey of the National Health Service (NHS) expenditure in the UK showed that the cost of managing AF had increased from 0.6–1.2% in 1995 to 0.9–2.4% in 20001. A similar report in the United States showed that 73% of the US$6.65 billion treatment costs for AF were related to inpatient care20. Indeed, spending on hospitalised AF patients was much greater when compared with a matched group without AF21. It is clear that with the increase in mortality and morbidity in AF patients, hospitalisation rates will become higher and the expenditure on the management of AF patients will also increase.

AF is closely related to various comorbidities, and the presence of age, gender, body mass index, systolic blood pressure, treatment for hypertension, PR interval, cardiac murmurs and heart failure have been used to predict the development of AF22. Another study has linked AF, heart failure and risk of death in diabetic patients23. In the study by Du et al.23, AF patients with diabetes had a 61% increased risk of developing heart failure or other cerebrovascular problems when compared with diabetic patients who did not have AF. This increased risk of heart failure in AF patients would no doubt increase rate of hospitalisation which in turn would increase the burden on the healthcare system.

Thus, AF confers a substantial burden – both clinically, epidemiologically and economically – and things can only improve. One analysis of the trends in warfarin use and overall ischaemic and haemorrhagic strokes among prevalent patients with AF has shown that the burden of ischaemic stroke is reducing with increased rates of anticoagulation, with no appreciable rise in haemorrhagic stoke24. Further studies on identifying factors and reasons for readmission in AF patients are therefore warranted. Understanding the patterns and factors responsible for readmission would help clinician optimise the treatment strategies for AF patients. This in turn would improve quality of care for AF patients and might potentially lessen the large burden of AF on healthcare systems.

Acknowledgement

Declaration of interest: This editorial was independently commissioned by CMRO journal editors and no external funding or contributor fees are associated with it.

G.Y.H.L. has received funding for research, educational symposia, consultancy and lecturing from different manufacturers of drugs used for the treatment of atrial fibrillation. He was Clinical Adviser to the Guideline Development Group writing the United Kingdom National Institute for Health and Clinical Excellence (NICE) Guidelines on atrial fibrillation management (www.nice.org.uk), and is on the writing committee for the American College of Chest Physicians Guidelines on Antithrombotic Therapy for Atrial Fibrillation. C.W.K has no interests of a declarable nature. No funding was received from any pharmaceutical company for the preparation of this article.