Screening people over 65 years of age for atrial fibrillation increases the rate of detection

Background

Atrial fibrillation is a common cardiac arrhythmia that makes the heart beat rapidly and irregularly. This can occur for brief episodes or may be continuous. Symptoms of the disease include heart palpitations, chest pain, shortness of breath, light-headedness and fatigue. The condition is rare in those younger than 40 years of age but is more common as people age. Not everyone with atrial fibrillation experiences symptoms, so some people are unaware that they have it; others may experience mild symptoms that they do not attribute to the disease. Atrial fibrillation hinders efficient flow of blood through the heart, resulting in increased risk of clot formation. If these clots leave the heart, they can block the vessels supplying blood to the brain, causing a stroke. Treatment with anticoagulant medication is designed to prevent the formation of blood clots and can reduce the risk of stroke by over 60%.

Review question

For a screening programme for atrial fibrillation to be worthwhile, it needs to increase the rate of detection and to benefit those identified to have the problem through screening. The aim of this review was to examine the first part of this question - to find out whether screening increases the number of new diagnoses of atrial fibrillation compared with normal practice, in which people are diagnosed when they consult a health professional with symptoms or risk factors that would lead to testing. This review also examined the safety and rate of uptake of screening, as well as the costs involved.

Results

The evidence is current to November 2015. This review identified one study that met the inclusion criteria. This study examined systematic screening, whereby everyone over 65 years of age was offered an electrocardiogram (ECG) test, and opportunistic screening, in which those over 65 years of age had their pulse taken when they visited their general practitioner (GP) for any reason and were offered an ECG because an irregular pulse was found. Moderate-quality evidence showed that both of these screening programmes increased the rate of detection of new cases of atrial fibrillation compared with normal practice. Screening appeared to be more effective in men than women, but no information about its effectiveness in different ethnic or socioeconomic groups was provided. As only one study was found, it was not possible to compare the effectiveness of screening in different settings. Uptake of screening was higher for systematic screening than for opportunistic screening, and within both interventions, uptake was higher for men and for the 65 to 74 year age group than for people over 75 years old. No safety issues or complications were reported. From the point of view of the health service provider, systematic screening was more costly than opportunistic screening. However, because all results are based on a single study, one needs to be cautious about applying them outside of the setting (UK primary care) and patient population (over 65 years of age) in which this study was carried out.

Authors' conclusions: 

Evidence suggests that systematic screening and opportunistic screening for AF increase the rate of detection of new cases compared with routine practice. Although these approaches have comparable effects on the overall AF diagnosis rate, the cost of systematic screening is significantly greater than the cost of opportunistic screening from the perspective of the health service provider. Few studies have investigated effects of screening in other health systems and in younger age groups; therefore, caution needs to be exercised in relation to transferability of these results beyond the setting and population in which the included study was conducted.

Additional research is needed to examine the effectiveness of alternative screening strategies and to investigate the effects of the intervention on risk of stroke for screened versus non-screened populations.

Read the full abstract...
Background: 

Atrial fibrillation (AF), the most common arrhythmia in clinical practice, is a leading cause of morbidity and mortality. Screening for AF in asymptomatic patients has been proposed as a way of reducing the burden of the disease by detecting people who would benefit from prophylactic anticoagulation therapy before the onset of symptoms. However, for screening to be an effective intervention, it must improve the detection of AF and provide benefit for those detected earlier as a result of screening.

Objectives: 

This review aims to answer the following questions.

Does systematic screening increase the detection of AF compared with routine practice? Which combination of screening population, strategy and test is most effective for detecting AF compared with routine practice? What safety issues and adverse events may be associated with individual screening programmes? How acceptable is the intervention to the target population? What costs are associated with systematic screening for AF?

Search strategy: 

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid) and EMBASE (Ovid) up to 11 November 2015. We searched other relevant research databases, trials registries and websites up to December 2015. We also searched reference lists of identified studies for potentially relevant studies, and we contacted corresponding authors for information about additional published or unpublished studies that may be relevant. We applied no language restrictions.

Selection criteria: 

Randomised controlled trials comparing screening for AF with routine practice in people 40 years of age and older were eligible. Two review authors (PM and CT) independently selected trials for inclusion.

Data collection and analysis: 

Two review authors (PM and CT) independently assessed risk of bias and extracted data. We used odds ratios (ORs) and 95% confidence intervals (CIs) to present results for the primary outcome, which is a dichotomous variable. As we identified only one study for inclusion, we performed no meta-analysis. We used the GRADE (Grades of Recommendation, Assessment, Development and Evaluation Working Group) method to assess the quality of the evidence and GRADEPro to create a 'Summary of findings' table.

Main results: 

One cluster-randomised controlled trial met the inclusion criteria for this review. This study compared systematic screening (by invitation to have an electrocardiogram (ECG)) and opportunistic screening (pulse palpation during a general practitioner (GP) consultation for any reason, followed by an ECG if pulse was irregular) versus routine practice (normal case finding on the basis of clinical presentation) in people 65 years of age or older.

Results show that both systematic screening and opportunistic screening of people over 65 years of age are more effective than routine practice (OR 1.57, 95% CI 1.08 to 2.26; and OR 1.58, 95% CI 1.10 to 2.29, respectively; both moderate-quality evidence). We found no difference in the effectiveness of systematic screening and opportunistic screening (OR 0.99, 95% CI 0.72 to 1.37; low-quality evidence). A subgroup analysis found that systematic screening and opportunistic screening were more effective in men (OR 2.68, 95% CI 1.51 to 4.76; and OR 2.33, 95% CI 1.29 to 4.19, respectively) than in women (OR 0.98, 95% CI 0.59 to 1.62; and OR 1.2, 95% CI 0.74 to 1.93, respectively). No adverse events associated with screening were reported.

The incremental cost per additional case detected by opportunistic screening was GBP 337, compared with GBP 1514 for systematic screening. All cost estimates were based on data from the single included trial, which was conducted in the UK between 2001 and 2003.

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