Standard blood pressure tests are likely to be inaccurate in up to 20 per cent of cases, but there is a reluctance to use newer methods.
THE FAMILIAR blood pressure test that all of us have at some stage is a testament to the conservative nature of the medical profession. The basic test was developed in 1896 by the Italian, Scipione Riva-Rocci. The practice of also listening for sounds with a stethoscope was added in 1905 by the Russian Nikolai Korotkoff.
And in the 103 years since, with all their leaps in technology and medical knowledge, nothing has changed.
As my case shows, the test is not particularly accurate. "It showed your blood pressure to be perfectly normal," says Eoin O'Brien. "Indeed, had we been not doing this exercise, you wouldn't have had the 24-hour monitor at all."
In fact, it is inaccurate in two distinct ways. The first is the one that applies in my case a normal reading that conceals masked hypertension. But the other is the complete opposite - high blood pressure being diagnosed when it does not in fact exist. This is the phenomenon of white coat hypertension - a person's pressure being raised simply by the fact of having it measured by a doctor.
In the first category, at least 10 per cent of standard tests are likely to be wrong. In the second, the figure is 20 per cent. It follows, says O'Brien, that hypertension is being misdiagnosed in as many as a third of all patients attending for routine blood pressure measurements.
This degree of inaccuracy quite rightly would not be tolerated in any laboratory test but we accept it in clinical practice, why? O'Brien himself pioneered the 24-hour ABPM test as long ago as 1979, when he adapted technology from NASA, and as a result Ireland is better placed in this regard than the US or the UK.
Well over half of GPs here are now using the ABPM machines, which are recommended both for anyone who has had heart problems or a stroke, and for anyone who is being diagnosed with hypertension on the basis of the old test.
But there is still a significant degree of reluctance to use the new methods. Particularly for GPs with public patients, the cost of investing in the technology and carrying out tests for which they will not be paid is an obvious disincentive.
There's a message, says O'Brien, to GPs who have resisted ABPM and stayed with the old technique, despite the evidence. But there's also a message for the Government to say this should be everywhere and we should pay for it.
The devices themselves cost about €2,500 each, though O'Brien believes it should be possible to create cheaper and simpler machines. Each test costs about €40 in the public health system, though patients going privately can be charged up to €200.