Keep a weather eye on blood pressure
medwireNews: Some people's blood pressure (BP) may fluctuate in line with changes in the weather, say researchers.
"Knowing a patient's BP response to weather can help reduce unnecessary antihypertensive treatment modification, which may in turn increase BPV [variability] and, thus, risk," say lead researcher Sandosh Padmanabhan (University of Glasgow, UK) and co-workers.
The team assessed repeat BP measurements from 16,010 patients attending a single hypertension clinic in the west of Scotland in relation to the prevailing weather in the area at the time. If the weather was similar between two clinic visits, then patients' BP tended to fall by about 2%, on average.
However, if temperature fell from the top to the bottom quartile between visits, then patients' BP rose by an average of 2.1%, and the same was true for a reduction in sunshine, at a 2.3% increase. Reductions in air frost and rainfall did not affect patients' BP, but increases in these parameters from the bottom to top quartiles was associated with respective 1.4% and 0.8% rises in BP.
"We also show that the effect of temperature on BP varies between individuals and, based on response, patients can be classified as either temperature sensitive or temperature nonsensitive," write the researchers in Hypertension.
Moreover, BP outcomes varied according to whether patients were sensitive or nonsensitive to a fall in temperature. During the first 5 years of follow up, BP in the whole cohort declined by an average of 4/2 mmHg per year. Temperature-sensitive patients, however, had an average 2.68/1.84 mmHg increase in BP, relative to nonsensitive patients, after accounting for confounders.
The detrimental effect of temperature sensitivity also extended to survival, with temperature-sensitive patients a significant 35% more likely to die over the long term than those who did not respond to reductions in temperature.
"It remains to be established whether BP response to temperature or BPV is the causal determinant of increased risk, or whether it is the underlying autonomic function status of the individual that is causal and BPV is just a reflection of this," says the team.
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Eleanor McDermid, Senior medwireNews Reporter