More than half or 58 per cent of the 2,890 male patients and nearly three-quarters of the 2,217 female patients hospitalised between Dec 17 and Jan 31 turned down the test when asked if they wanted it.

CGH started the tests on Dec 17, following a study last year of leftover blood samples belonging to public hospital patients, none of whom was known to be HIV positive. Tests done found one in 350 to be infected.

A CGH spokesman said the hospital understands the sensitivity of the routine test, and it is studying the reasons patients opted out.

Mr Lionel Lee, executive director of Action for Aids (AFA), confirmed that privacy is a major factor. He pointed out that in Kelantan Lane, where one can take the test anonymously, the number of those tested went up 14 per cent - from 6,046 in 2006 to 6,903 last year.

He said those who test positive are counselled and advised to register at the Communicable Disease Centre for treatment.

'It is a choice they have to make themselves,' he said.

However, if an individual tests positive in a hospital setting, it is no longer a private affair. The hospital is requiredby law to inform the Ministry of Health (MOH).

CGH is the first public hospital to offer the test to all adult in-patients. Those who take it pay between $6 and $23, depending on the class of ward.

CGH declined to reveal how many of those who were tested turned out to be HIV positive.

KK Women's and Children's Hospital, which began testing all its expectant mothers for HIV on an opt-out basis since 2004, extended the test to the few young males in its adolescence medicine wards in January. Singapore General Hospital starts HIV testing next month.

The rationale for these tests is that early detection means timely treatment - and longer, improved quality of life - for the patient.

A check with MOH found that 356 new cases of HIV were reported here in the first 10 months of last year, compared to 357 in the whole of 2006.

A CGH spokesman said that, despite the disappointing take-up rate for the test, the hospital will continue to encourage its patients to take it.

AFA's Mr Lee also hopes testing in hospitals will catch on.

'I believe, with time and education, people will no longer opt out,' he said.

juditht@sph.com.sg