BP treatment needs to be adjusted in winter
By Lilian Anekwe
Blood pressure levels vary seasonally in hypertensive patients, by enough to warrant a different treatment strategy in winter months, a major new study concludes.
Results of research by a leading US cardiologist suggest that blood pressure levels in as many as 60% of patients show ‘marked, periodic and regular seasonality'.
When treated in the winter, 7.8% fewer hypertensive patients had their blood pressure levels reduced to normal than during summer months.
Researchers analysed the electronic health records of more than one million patients, and identified 443,632 patients in 15 US cities with high blood pressure – defined by a blood pressure reading of ?140/80mmHg on three separate days.
Regardless of city, age, race or altitude, fewer patients returned to a normal blood pressure when treated in winter compared with those treated during the summer months.
The research was presented at the American Heart Association annual scientific conference this week.
Study leader Dr Ross Fletcher, chief of staff at the VA Medical Center in Washington DC, said the effect was likely to be a result of a combination of factors – including weight gain, dietary changes in winter and circadian differences. He insisted the differences were large enough, and seen in large enough numbers of patients, to justify altering treatment in the winter.
‘The effect isn't seen in all patients, but where it is seen the effect is very striking. Between 50% and 60% of hypertensive patients show this seasonality.
‘We will incorporate this into our treatment strategies, and I'd advise UK GPs to do the same – there's really no reason to assume the effects we saw in 15 cities wouldn't be seen elsewhere.
‘I'd advise doctors to examine their patients, and if their winter readings are elevated beyond the summer's I'd recommend increasing the medication.'
Dr Daniel Jones, dean of the school of medicine at the University of Mississippi medical center, said the results were ‘fascinating'.
‘What Dr Fletcher and his colleagues have achieved will resonate with doctors everywhere. By identifying and adjusting for seasonality, they've achieved blood pressure control in more than 85% of patients. That's remarkable and shows the clinical impact of accounting for these differences.'