We have looked at the way NT-proBNP relates to diagnosis and to prognosis, both in the acute setting and in the more chronic setting and in the acute setting, I’ve conducted trials in a New Zealand city and in Singapore and we’ve recruited them according to the same criteria as used for the early studies of NT-proBNP in the emergency department.
And what we find, having studied some 500 over people in New Zealand, and another 600 or more in Singapore, firstly that breathless people are different in these two places. The people in Singapore are younger by quite a margin, more than a decade of life younger, and they tend to have a lower frequency of heart failure.
So, about 1 in 4 of such people will have a diagnosis of heart failure in Singapore; about 1 in 3 of such people have a diagnosis of heart failure in New Zealand. There are other striking differences, which seem to mainly be related to the age difference.
So, atrial fibrillation is a complicating common heart failure rhythm… abnormal rhythm. Kidney function tends to deteriorate with age, so the older New Zealand population has higher levels of natriuretic peptides because they’ve got poorer kidney function.
What this means is that, in the Asian group, the test actually performs rather better at picking out the heart failure cases, because there is less noise from other confounding or interfering conditions to get in the road. So less false positives is the key thing.
Overall accuracy is also a little better – or actually significantly better in Singapore than New Zealand. So if you take all of the positive tests and negative tests that are correct and divide them by all the total number of possible results that gives you accuracy or percent rightness – if you like. Well, percent rightness in New Zealand is about 15 cases less per 100 people tested than it is in Singapore, which is quite a significant difference. And we think this probably can be reasonably extrapolated to a large amount of difference between most of the West and most of Asia. And the reason we say that is the difference in age of presentation seems to be a common factor throughout much of Asia.
We have a registry; it is gathered data from China, Japan, India, and a number – 8 of the Southeast Asian nations. And although Korea and Japan, in particular, tend to have age of presentation with heart failure, which is not too far different from the West, it’s a little younger, it’s still younger. The other countries are much younger.
Therefore, we can be fairly confident NT-proBNP as a diagnostic is going to work well, in fact better, if anything, in Asian centres than it will in Western centres. With respect to chronic follow-up, using NT-proBNP as an ongoing monitoring tool and how it relates to prognosis, we don’t have a lot of evidence of serial guided studies amongst Asian populations.
What we can say though is that we’ve recruited two cohorts for chronic follow-up, one in Singapore of about a thousand heart failure cases, and another in New Zealand of about a thousand. And we’ve related their NT-proBNP levels to their risk of mortality over a 2-year period. And the relationship is very similar; it’s exactly the same in both countries.
So we think that as a signal for risk of bad outcomes, it works equally well in the East and the West. Actually, as a signal for diagnosis in the first place, it actually works rather better in Asia than in the West.
