Screening asymptomatic people with diabetes for silent ischaemia: still no outcome gain

Design

Systematic review and random-effects meta-analysis of randomised trials; not prospectively registered

Population

3,315 asymptomatic adults with diabetes and no known coronary artery disease (5 trials)

Primary outcome

Major adverse cardiovascular events, cardiovascular mortality and all-cause mortality

Effect

Pooled HR/RR 0.76 (95% CI 0.48 to 1.19) across four trials

This systematic review pooled randomised trials that compared systematic screening for silent myocardial ischaemia or occult coronary disease with usual care in adults with diabetes and no known coronary disease. Five trials with 3,315 participants qualified (DIAD, DYNAMIT, FACTOR-64, DADDY-D and a small pilot). Four could be pooled, and the combined estimate for major cardiovascular outcomes was 0.76 (95% CI 0.48 to 1.19). The interval includes no effect.

Screening did find occult ischaemia or atherosclerosis. What it did not show was fewer events or deaths compared with the medical management used in those trials. Reporting of false positives and procedure-related harm was patchy, so the cost side of the ledger is poorly measured. The review was not prospectively registered, and the trials date from an era of less intensive prevention than today.

In practice this supports the existing reluctance to test everyone. A positive stress or imaging result in an asymptomatic patient mostly leads to more testing, and the useful actions (statin, blood pressure, glucose, kidney-protective therapy) apply regardless of the result. Test when the answer would change what you do, for example before a high-risk procedure or when there are atypical symptoms such as unexplained breathlessness or exercise intolerance.

• Do not order routine stress testing or coronary imaging in asymptomatic patients with diabetes just because they have diabetes.
• Ask about atypical symptoms (exertional breathlessness, fatigue, jaw or arm discomfort); these are a reason to test.
• Put the effort into risk-factor treatment: lipids, blood pressure, glucose and kidney-protective drugs where indicated.
• If testing is planned, decide beforehand what a positive result would change.
• Record autonomic neuropathy when present, since it can mute ischaemic symptoms.

Why it matters

It questions the habit of treating a diabetes diagnosis as a reason to look for coronary disease that has not declared itself.

Don't overread it

The trials used older usual-care strategies, and the pooled interval is wide; this does not rule out benefit in selected high-risk patients.

The statistics, in plain English

A pooled ratio of 0.76 would mean a 24% lower rate if it were real, but the interval runs from 0.48 to 1.19, so the data are compatible with a large benefit, no benefit or a modest harm. That is why the finding is read as 'not shown' rather than 'shown not to work'. Four of five trials were pooled; the fifth could not be combined because its primary composite differed.

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