BY: Teh Joo Lin

CLOSE to 100 young men were spared combat training in the past three years after medical tests done before the start of their national service showed they had signs of heart problems.

The 97 pre-enlistees were declared medically unfit for combat duties and assigned jobs in the military such as as clerks or storemen.

Their heart problems showed up during an ECG or electrocardiogram test, which has been added to the routine medical screening for all incoming servicemen since 2000.

In 89 of them, their heart rhythm was abnormal. The other eight had diseases of the heart muscle, a condition known as cardiomyopathy that has been linked to sudden cardiac deaths in young adults.

The details were released to the media this week by the Defence Ministry to explain the types of medical screening national servicemen and regulars are put through.

Parents and some doctors had asked if the SAF's medical screening, especially for heart conditions, was thorough
enough, after two servicemen died within a week last month.

Defence Minister Teo Chee Hean had said the tests, designed by a panel of experts and reviewed every three years, adopted "protocols recommended by the best specialists in Singapore".

He said: "In terms of best practices, structures and systems, I think we are up there with the world's best."

The checks are conducted six to nine months before NS enlistment. About 25,000 youth go through this screening each year at the Medical Classification Centre in Depot Road. It determines how healthy they are and the type of training they can undergo.

Pre-existing conditions like asthma, high blood pressure and heart abnormalities are picked up at this stage. With heart conditions, in particular,explained chief army medical officer Colonel (Dr) Benjamin Seet, SAF doctors will consider, among other things, family history and ECG results.

Should any abnormalities be found, they are sent for further checks. They can also be referred to cardiologists.
Each year, about 550 echocardiograms and 300 treadmill tests are conducted, said Dr Seet.

This was "substantial", he said, keeping in mind the annual incidence of sudden cardiac death among Singaporeans aged 35 and below is very rare, at 1.3 to 1.7 in every 100,000.

Why not make these extra tests mandatory like the ECG, as some doctors have suggested? Dr Terrance Chua, chairman of the SAF's cardiac screening advisory panel and deputy director of the National Heart Centre, said: "I think we want to emphasise that for the SAF, cost is not an issue."

But not every condition can be picked up and in rare medical conditions, some tests are also limited in accuracy.
"We know no test is perfectly accurate. We will have some occasions where the test is normal but the person has a condition. This may give the false assurance that there's nothing there," Dr Chua said.

The reverse is also true, since inaccurate tests produce false positives - where patients who are actually well are shown to be suffering from a condition. The number of "false positives" can be sizeable if large cohorts are tested.

"Let's say you test 10,000 people who are relatively well...the false positive rate is about 1 per cent, but that's still over 100. You'll have a substantial number of people with false positives," he said.

These people - even though they are well - will require further testing, which exposes them to unnecessary health risks, however slight, that come with the tests. For example, CT scans expose patients to small doses of radiation.

"At some point, you need to balance the benefit of picking up the (few) individuals with that small but definite risk of adverse consequences for screening a well population," said Dr Chua.

EVALUATING EVERY TEST

"For every test, I think it's a very natural impulse to want to do more. Within the expert panel, we have to carefully
evaluate... every test that's being offered and make sure of its value. We don't want to end up with unintended consequences."

DR TERRANCE CHUA, chairman of the SAF's cardiac screening advisory panel and deputy director of the National Heart Centre

SPECIALISTS' INPUT

"We do not devise our medical protocols in isolation. We consult a panel of the best specialists that we have in
Singapore and we go by what they recommend is the most appropriate for the SAF."

DEFENCE MINISTER TEO CHEE HEAN in an interview to mark SAF Day on Tuesday, July 1

This article was first published in The Straits Times on July 4, 2008.