“Research highlights” is a weekly round-up of research papers appearing in the print BMJ. We start off with this week’s research questions, before providing more detail on some individual research papers and accompanying articles.

• How does continuous positive airway pressure affect blood pressure in patients with systemic hypertension and obstructive sleep apnoea?
• Which bedside test is best for detecting inadvertent endobronchial intubation?
• How is age associated with functional outcomes in patients with acute ischaemic stroke undergoing thrombolysis?
• How do alcohol consumption patterns relate to incidence of ischaemic heart disease in two countries with contrasting lifestyles?
• Does retirement change the risk of incident chronic disease, depressive symptoms, and fatigue?

Could CPAP be used to treat hypertension?
In Joaquín Durán-Cantolla and colleagues’ multicentre trial in Spain patients with hypertension and at least moderate sleep apnoea were randomised to continuous positive airway pressure (CPAP) or sham CPAP for three months. This was a trial with a great research question and with methods that should prove generalisable, given that the participants were snorers recruited from primary care whose hypertension had been diagnosed recently by their general practitioners.

Mean 24 hour ambulatory blood pressures (systolic, diastolic, and night time) fell by around 1.5-2 mm Hg in the CPAP group. But what do these statistically significant primary outcomes mean for clinical practice? In an accompanying video the authors and Domhnall MacAuley, BMJ primary care editor, discuss the trial and ponder its clinical implications.

R&R: rest and retirement
Many of us look to retirement as an opportunity to put our feet up and see out our twilight years free from the stress and hassles of the workplace. But does all this relaxation have any tangible benefit on physical or mental health, or would we be better off staying in the office?

Hugo Westerlund and colleagues’ 15 year prospective study of 14,000 French men and women before and after retirement found that retirement reduced the prevalence of mental fatigue, physical fatigue, and depression. However, retirement had no effect on self reported respiratory disease, diabetes, and coronary heart disease and stroke, which cumulatively increased with age without showing any change in trend around retirement.

Writing in a linked editorial, Alex Burdorf reports that the gap between the common retirement age at 65 and life expectancy at that age has increased substantially in the Netherlands from 6.4 to 13.3 years in the past 50 years. Whether retiring or continuing to work is best for the health of over 65s is an important question for governments to consider given the increasing longevity of Western populations.

Drinking patterns and ischaemic heart disease
The relation between alcohol consumption and heart disease is a complicated one, with news reports lurching between saying that alcohol, usually red wine, is good for your heart and that drinking is bad for cardiovascular health.

Jean-Bernard Ruidavets and colleagues have probed this topic by comparing the drinking habits of two countries with contrasting lifestyles: Northern Ireland and France. They found that although middle aged men in France were more likely to be drinkers than those in Belfast, and they drank more alcohol a week, the incidence of myocardial infarction and coronary death was higher in Belfast.

Looking closer, the authors discovered that in Belfast most men’s alcohol intake was concentrated on one day of the weekend and that binge drinkers were almost 20 times more common in Belfast than in France. Given that binge drinkers were almost twice as likely to develop ischaemic heart disease as those who drank more regularly, the authors suggest that the high prevalence of binge drinking in Belfast might explain some of the higher risk of heart disease in the city.

And, of course, wine drinking was associated with a lower risk of coronary events, irrespective of the country. These analyses were adjusted for classic cardiovascular risk factors.

Childhood adiposity and cardiovascular risk in adolescence
Cross sectional studies in childhood show associations between body mass index (BMI) and cardiovascular risk factors, but few prospective studies have been published. It’s been said that BMI is a poor measure of adiposity, particularly in childhood, and that the magnitude of its association with risk factors might underestimate the true adverse effect of greater adiposity in this age group. In a prospective cohort study of over 5000 children in the UK, Debbie Lawlor and colleagues found that BMI, waist circumference, and total fat mass assessed at age 9-12 were positively associated with cardiovascular risk factors at age 15-16. The size of the associations was similar for all measures of adiposity. Girls who lost weight between childhood and adolescence had cardiovascular risk profiles broadly similar to those who were normal weight at both time points. Boys who lost weight, however, had risk factor profiles that were intermediate between those of boys who were normal weight at both ages and boys who were overweight at both ages.