High blood pressure increases heart attack and stroke risk
High blood pressure is picked up less often in people who smoke, despite them being at higher risk of heart disease, research suggests.
A study of more than 20,000 men and women in England found smokers were less likely to be aware that they had high blood pressure than non-smokers.
The University College London team said spotting the condition was particularly important in those who smoke.
Being diagnosed can also prompt people to quit, heart experts said.
Smoking and high blood pressure, also known as hypertension, are both key causes of early death, the researchers wrote in the European Journal of Cardiovascular Prevention and Rehabilitation.
National guidelines advocate that doctors encourage those with high blood pressure to stop smoking and that greater effort should be made to look for signs of the condition in those who smoke.
The study, which took data from the Health Survey for England in 2003 and 2006, found improvements over time in the proportion of people who knew they had high blood pressure.
But it was being detected less frequently in people who smoked compared with those who did not, or those who used to smoke but had quit.
Among those smokers who had been diagnosed with the condition, they were more likely to have been told by a health professional to stop smoking than those who did not know they had hypertension, and were more likely to have quit.
One reason for the lack of diagnosis could be that smokers in the study tended to be thinner than those who did not smoke.
The researchers, who were funded by Cancer Research UK, said that GPs may be more likely to test blood pressure in people who were overweight.
Since 2004, GPs have been paid an incentive to test blood pressure and to record whether someone is a smoker.
Study author Dr Jennifer Mindell said it was disappointing to find smokers with high blood pressure were not being diagnosed.
"It's important to pick up high blood pressure in everybody but it's particularly important in somebody who already has a higher than average risk of heart disease or stroke, including those who smoke.
"And anything that gives people additional motivation to quit must be a good thing.
"It is a reminder for GPs that measuring blood pressure in smokers, even if they are thin, is important."
June Davison, a cardiac nurse from the British Heart Foundation, said: "It is crucial that smokers are aware of their blood pressure as smoking and high blood pressure are among the most common risk factors for cardiovascular disease.
"This study also highlights that if smokers are made aware of their high blood pressure, it can increase their motivation to stop smoking.
She added that smokers over the age of 40 should go for a health check where their blood pressure will be measured and advice on quitting smoking can be given.