Doctors within the NHS are confronting major changes at work. While we endeavour to improve the quality of health care, junior doctors' hours have been reduced and the emphasis on continuing medical education has increased. We are confronted by a growing body of information, much of it invalid or irrelevant to clinical practice. This article discusses evidence based medicine, a process of turning clinical problems into questions and then systematically locating, appraising, and using contemporaneous research findings as the basis for clinical decisions. The computerisation of bibliographies and the development of software that permits the rapid location of relevant evidence have made it easier for busy clinicians to make best use of the published literature. Critical appraisal can be used to determine the validity and applicability of the evidence, which is then used to inform clinical decisions. Evidence based medicine can be taught to, and practised by, clinicians at all levels of seniority and can be used to close the gulf between good clinical research and clinical practice. In addition it can help to promote self directed learning and teamwork and produce faster and better doctors.

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Evidence based medicine: an approach to clinical problem-solving

BACKGROUND Although structural heart disease is often present in patients with nonrheumatic atrial fibrillation, the echocardiographic precursors of atrial fibrillation have not been reported previously. In this elderly, population-based cohort, our objective was to examine prospectively the echocardiographic predictors of nonrheumatic atrial fibrillation. METHODS AND RESULTS Subjects in the Framingham Heart Study were routinely evaluated with M-mode echocardiography; 1924 subjects, ranging in age from 59 to 90 years, comprised the population at risk. Cox proportional hazards modeling was used to analyze the association of selected echocardiographic features with atrial fibrillation risk after adjustment for age, sex, hypertension, coronary heart disease, congestive heart failure, diabetes, and valvular heart disease. During a mean follow-up interval of 7.2 years, 154 subjects (8.0%) developed atrial fibrillation. Multivariable stepwise analysis identified left atrial size (hazard ratio [HR] per 5-mm increment, 1.39; 95% confidence interval [CI], 1.14 to 1.68), left ventricular fractional shortening (HR per 5% decrement, 1.34; 95% CI, 1.08 to 1.66), and sum of septal and left ventricular posterior wall thickness (HR per 4-mm increment, 1.28; 95% CI, 1.03 to 1.60) as independent echocardiographic predictors of atrial fibrillation. For each of the echocardiographic predictors, risk increased progressively over successive quartiles. Moreover, risk increased markedly when highest-risk-quartile measurements for these features were present in combination; the cumulative 8-year age-adjusted atrial fibrillation rates were 7.3% and 17.0%, respectively, when one and two or more highest-risk-quartile features were present, compared with 3.7% when none was present. CONCLUSIONS In this elderly, population-based sample, left atrial enlargement, increased left ventricular wall thickness, and reduced left ventricular fractional shortening were predictive of risk for nonrheumatic atrial fibrillation. These echocardiographic precursors offer prognostic information beyond that provided by traditional clinical atrial fibrillation risk factors.

Echocardiographic predictors of nonrheumatic atrial fibrillation. The Framingham Heart Study.

http://www.macoalition.org/documents/ACCP_8_published.pdf

Antithrombotic Therapy in Atrial Fibrillation: American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition)

ContextPatients with nonvalvular atrial fibrillation (AF) have an increased
risk of stroke and other vascular events.ObjectiveTo compare the risk of vascular and bleeding events in patients with
nonvalvular AF treated with vitamin K –inhibiting oral anticoagulants
or acetylsalicylic acid (aspirin).DesignPooled analysis of patient-level data from 6 published, randomized clinical
trials.PatientsA total of 4052 patients with AF randomly assigned to receive therapeutic
doses of oral anticoagulant or aspirin with or without low-dose oral anticoagulants.Main Outcome MeasuresIschemic and hemorrhagic stroke, other cardiovascular events, all-cause
death, and major bleeding events. Person-year incidence rates were calculated
to provide crude comparisons. Relative efficacy was assessed using proportional
hazards modeling stratified by study. The variation of the oral anticoagulant's
relative effect by pertinent patient factors was explored with interaction
terms. All analyses were conducted using the intention-to-treat principle.ResultsPatients receiving oral anticoagulant and aspirin were balanced for
important prognostic factors. There was no significant heterogeneity between
trials in the relative efficacy of oral anticoagulant vs aspirin for any outcome.
Patients receiving oral anticoagulant were significantly less likely to experience
any stroke (2.4 vs 4.5 events per 100 patient-years; hazard ratio [HR], 0.55;
95% confidence interval [CI], 0.43-0.71), ischemic stroke (HR, 0.48; 95% CI,
0.37-0.63), or cardiovascular events (HR, 0.71; 95% CI, 0.59-0.85) but were
more likely to experience major bleeding (2.2 vs 1.3 events per 100 patient-years;
HR, 1.71; 95% CI, 1.21-2.41). The reduction in ischemic stroke risk was similar
in patients with paroxysmal AF (1.5 vs 4.7 events per 100 patient-years; HR,
0.32; 95% CI, 0.16-0.61; P<.001). Treating 1000
patients with AF for 1 year with oral anticoagulant rather than aspirin would
prevent 23 ischemic strokes while causing 9 additional major bleeds. Overall
all-cause survival did not differ but appeared to improve for oral anticoagulant
patients 3 years after therapy was started.ConclusionsCompared with aspirin, oral anticoagulant significantly decreases the
risk of all strokes, ischemic strokes, and cardiovascular events for patients
with nonvalvular chronic or paroxysmal AF but modestly increases the absolute
risk of major bleeding. The balance of benefits and risks varies by patient
subgroup.

https://jamanetwork.com/journals/jama/articlepdf/195518/jcc20007.pdf

Oral anticoagulants vs aspirin in nonvalvular atrial fibrillation: an individual patient meta-analysis.

Cardiovascular disease, which includes myocardial infarction, stroke, and peripheral vascular diseases, is the leading cause of death in the United States and most developed countries, accounting for more than 900 000 deaths annually in the United States alone. Aspirin can reduce risks of occlusive vascular events by inhibiting platelet aggregation,1 but uncertainty among healthcare providers remains regarding its appropriate use in different categories of patients. This concise review of current knowledge, an update of an earlier AHA statement,2 is intended to provide clinicians with guidelines for the use of aspirin in the treatment and prevention of cardiovascular disease.

Aspirin therapy confers conclusive net benefits in the acute phase of evolving myocardial infarction (MI) and should be administered routinely to virtually all patients with evolving acute MI. In the Second International Study of Infarct Survival (ISIS-2),3 more than 17 000 men and women within 24 hours of onset of symptoms of suspected MI were randomly assigned to 162 mg of aspirin or placebo daily for 30 days. After 5 weeks patients allocated to receive aspirin had statistically significant reductions in risk of vascular mortality (23%), nonfatal reinfarction (49%), and nonfatal stroke (46%). There was no increase in hemorrhagic stroke or gastrointestinal bleeding in the treated group and only a small increase in minor bleeding. Thus, aspirin has perhaps the best benefit-to-risk ratio of any proven therapy for acute MI. The benefits of aspirin on risk of subsequent MI, stroke, or vascular death are substantial and the risks of serious bleeding and sensitivity reactions low as well as amenable to treatment in an acute care setting, even with a history of bleeding or other sensitivity to aspirin. Thus, contraindications to use of aspirin in acute MI are relative, not absolute.

To achieve an immediate clinical antithrombotic effect, an initial …

K. E. James

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Warfarin in the prevention of stroke associated with nonrheumatic atrial fibrillation. authors reply