Family Practice Vol. 17, No. 4, 337-339
© Oxford University Press 2000
Detected atrial fibrillation in North Italy: rates, calculated stroke risk and proportion of patients receiving thrombo-prophylaxis
a Family Physician, S.I.M.G. (Italian Society of General Practice), via. S. Francesco 14, 24050 Mozzanica,
b Family Physician, S.I.M.G., via della Pace 44, 25035 Ospitaletto and
c Family Physician, S.I.M.G., via S. Giorgio 14 24058 Romano di Lombardia, Italy.
Alessandro Filippi.
Filippi A, Bettoncelli G and Zaninelli A. Detected atrial fibrillation in North Italy: rates, calculated stroke risk and proportion of patients receiving thrombo-prophylaxis. Family Practice 2000; 17: 337–339.
Received 4 November 1999; Revised 10 March 2000; Accepted 13 March 2000.
Abstract
Background. Atrial fibrillation (AF) is a major risk factor in the development of ischaemic stroke. The rate of embolic events can be reduced significantly by appropriate therapy. Epidemiological data and information about the attitude of physicians towards prophylaxis of thromboembolism are crucial to determine future strategies to decrease strokes in patients with AF. Unfortunately, these data are unknown in Italy.
Objectives.The aims of this study were to study the prevalence of diagnosed AF in northern Italy, to estimate the percentage of high, moderate and low risk patients and to investigate the pattern of embolic prophylaxis among GPs.
Methods.Fifty-one GPs reviewed all the clinical records of subjects aged 
40 years and identified those patients with chronic or paroxysmal AF.
Results. Among 41 050 patients, 719 [1.75%; 95% confidence interval (CI) 1.59–1.91] had AF (70% chronic, 30% paroxysmal). Only 4% were at low risk for ischaemic stroke, whereas 32% were at moderate and 64% at high risk. Contraindications to antiplatelet or anticoagulant therapy were present in 11% of AF patients. Antithrombotic prophylaxis was underused among the 51 GPs.
Conclusions.Detection of AF could be 30–40% lower than real prevalence and, therefore, adequate evaluation and treatment aimed at avoiding ischaemic stroke could be denied to a great number of Italian patients. AF detection and prophylaxis of thromboembolic risk can be improved among GPs in northern Italy.
Keywords. Atrial fibrillation, prevalence, risk stratification.
Introduction
Atrial fibrillation (AF) is a major risk factor in the development of ischaemic stroke. The rate of embolic events can be reduced significantly by appropriate therapy. Epidemiological data and information about the attitude of physicians towards prophylaxis of thromboembolism are crucial to determine future strategies aimed at decreasing strokes in patients with AF. Unfortunately these data are unknown in Italy. The aims of this study were: (i) to study the prevalence of diagnosed AF in Northern Italy; (ii) to estimate the percentage of high, moderate and low risk patients; and (iii) to investigate the pattern of embolic prophylaxis among GPs.
Methods
As there is a low prevalence of AF among younger patients, only the population over 40 years of age was examined. We estimated that ~40 000 subjects were needed to achieve epidemiologically acceptable results. Accordingly, we asked 51 GPs to participate. The following criteria were used to contact them: personal knowledge, previous reliable participation in simple research, use of computerized records and geographical location of the practice. They were required to review all their clinical records to identify patients with chronic or paroxysmal AF. It was a computer search and the GPs were instructed to use ‘atrial fibrillation’, ‘fibrillation’, ‘AF’, ‘digoxin’ or any other appropriate personal diagnosis or abbreviation to find subjects who could be affected by this arrhythmia. The records were then examined by the GP in charge of the patient to confirm the diagnosis and to fill in the research form. The data collected for every patient were: age and gender, presence of risk factors for ischaemic stroke, current use of oral anticoagulants or antiplatelet agents, and contraindications to the use of oral anticoagulants or antiplatelet agents. When echocardiography was available, atrial enlargement was reported.
Paroxysmal AF was defined as more than one documented episode of AF in a patient's life (post-operative and post-acute myocardial infarction AF were excluded). Risk factors for ischaemic stroke were: hypertension, previous stroke, previous transient ischaemic attack (TIA), diabetes, heart failure, mitral valve disease, history of ischaemic heart disease, thyroid disease and peripheral arterial disease.
The GPs used the following checklist to identify patients who could not be treated with oral anticoagulants and/or antiplatelet agents. Contraindications to oral anticoagulants were: poor compliance (including alcohol misuse and limited understanding of anticoagulation by patient and family), gastrointestinal ulcer, uncontrolled hypertension, liver failure, coagulation disorders, high risk vascular malformation, serious cancer, pregnancy and previous major bleeding during warfarin therapy. Contraindications to antiplatelet agents were: coagulation disorders, active gastrointestinal ulcer and major adverse reactions. There was no validation of data or review of records by the authors.
According to Lip's criteria,1 stroke risk was considered to be low (annual risk 1%), moderate (annual risk 4%) or high (annual risk 8–12%). Following collection of the case records, we determined the personal risk of the patients.
Results
A population sample of 41 050 subjects 40 years of age was examined. AF was diagnosed in 719 patients [1.75%; 95% confidence interval (CI) 1.59–1.91%], 48.5% male and 51.5% female, mean age 73 ± 10.35 years. A total of 214 had paroxysmal AF (29.8%) and 505 chronic AF (70.2%). Thirty-one subjects were at low risk for stroke (4%), 232 were at moderate risk (32%) and 456 were at high risk (64%). A total of 611 patients (85%) had no contraindications to oral anticoagulants or antiplatelet agents. No prophylactic therapy had been given to 15 (48.4%) of low risk, to 64 (31.7%) of moderate risk and to 54 (13.3%) of high risk patients without contraindications to these drugs. Nine low-risk subjects were inappropriately on warfarin.
Antiplatelet drugs were used in seven (22.6%) low risk, in 75 (37.1%) moderate risk and in 265 (65.1%) high risk patients. Oral anticoagulants were used in nine (29%) low risk, in 29 (14.3%) moderate risk and in 93 (22.8%) high risk patients.
Discussion
In our population 40 years of age, the prevalence of diagnosed AF was 1.75%. This arrhythmia was chronic in 70% of cases. Studies that used active electrocardiography (ECG) screening in older subjects2–4 have reported a prevalence of chronic AF ~2% (absolute value) higher than in our study (when comparing the same age groups), but are unable to provide data about paroxysmal AF. A UK5 study conducted in general practice using record review methods showed a prevalence of chronic and paroxysmal AF similar to ours: 2.4%. The difference in prevalence can be explained by the higher risk of AF in a population older (>50 years) than that examined in our study. It is probable that AF is not detected in clinical practice in some patients, possibly because they are not checked regularly and because pulse examination lacks 100% sensitivity for AF.6 The prevalence of diagnosed AF in northern Italy and in the UK seems to be similar According to these data, 30–40% of patients with chronic AF could be unaware of this arrhythmia.
Only 4% of our patients with AF were at low risk for thromboembolic stroke, 32% were at moderate risk and 64% at high risk. Contraindications to warfarin or antiplatelet agents were considered to be present in only 15%, less than previously reported in other studies.3,7
We do not know the risk profile of undiagnosed AF, but even if a lower percentage of patients were at moderate and high risk, still a great number of eligible subjects would not be treated.
Despite the absence of contraindications, almost 20% of patients in the high and moderate risk groups were not treated. The favourite drugs seem to be antiplatelet agents, particularly aspirin, in both moderate and high risk subjects. According to international guidelines and considering the low number of patients without contraindications, warfarin is underused, particularly in high risk subjects.
Conclusion
The prevalence of diagnosed atrial fibrillation in northern Italy is ~1.75% among patients 40 years of age, ~30–40% lower than that reported in British studies examining chronic AF.
Only 4% of our patients were at low embolic risk, the great majority being at high (64%) and moderate (32%) risk. A relevant percentage of eligible patients were not given prophylactic therapy. It is therefore obvious that AF detection and prophylaxis of thromboembolic risk can be improved among GPs in northern Italy.
References
1 Lip GYH. Thromboprophylaxis for atrial fibrillation. Lancet 1999; 353: 4–6.[Web of Science][Medline]
2
Wheeldon NM, Tayler DI, Anagnostou E, Cook D, Wales C, Oakley GD. Screening for atrial fibrillation in primary care. Heart 1998; 79: 50–55.
3 Sudlow M, Thomson R, Thwaites B, Rodgers H, Kenny RA. Prevalence of atrial fibrillation and elegibility for anticoagulants in the community. Lancet 1998; 352: 1167–1171.[Web of Science][Medline]
4
Langenberg M, Hellemons BSP, van Ree JW et al. Atrial fibrillation in elderly patients: prevalence and comorbidity in general practice. Br Med J 1996; 313: 1534.
5 Lip GY, Golding DJ, Nazir M, Beevers DG, Child DL, Fletcher RI. A survey of atrial fibrillation in general practice: the West Birmingham Atrial Fibrillation Project. Br J Gen Pract 1997; 47: 285–289.[Web of Science][Medline]
6
Sudlow M, Rodgers H, Kenny RA, Thomson R. Identification of patients with atrial fibrillation in general practice: a study of screening methods. Br Med J 1998; 317: 327–328.
7 Fahey T, Rimmer J, Godfrey P. Risk stratification in the management of atrial fibrillation in the community. Br J Gen Pract 1999; 49: 295–296.[Web of Science][Medline]
CiteULike 
Connotea 
Del.icio.us What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||