On The Pulse - 25th May 2012
Statins for primary prevention
The debate about using statins for primary prevention intensified this week, with a meta-analysis in the Lancet of 27 trials in 174,149 participants suggesting that they can reduce the risk of major vascular events by ~20% even in people whose 5-year risk of such events is < 10%, who are not currently considered for statin treatment according to most guidelines. An accompanying Comment discusses the strategy of prescribing statins to everyone aged over 50 to avoid screening costs, but cautions against focusing solely on pharmaceutical remedies for ‘lifestyle-related diseases’.
Induction of labour
Perinatal mortality rises in pregnancies that continue beyond 37 weeks, which seems a good reason to induce labour at term. On the other hand, elective induction could lead to more obstetric intervention, particularly caesarean section. The BMJ has an observational study of over a million singleton births which suggests that the benefits outweigh the harms. Compared with expectant management, elective induction of labour at 37–41 weeks was associated with reduced perinatal mortality, with no reduction in rates of spontaneous vertex delivery. There were however, more admissions to a neonatal unit among babies born after induction.
The NEJM has a large observational study suggesting that drinking six or more cups of coffee a day lowers the risk of death by about 10% in men, and 15% in women. The data are based on a questionnaire completed by ~400,000 members of the American Association of Retired Persons (aged 50–71 years) in 1995-6 and followed subsequently. The protective effect only emerged after controlling for potential confounders (particularly smoking) but was seen across numerous causes of death, and in various subgroups. However, while many closely related variables were included, socioeconomic status does not appear to be explicitly accounted for.
Every doctor wants to give ill people the best possible care, but many studies show that patients often don’t receive all the treatments that the evidence says they should. Using a metaphor from thermodynamics, an article in JAMA explores some of the underlying reasons. The author reckons that something like entropy is at work when error-prone humans try to improve complicated interdependent systems such as healthcare delivery, and despite hard work and good intentions, checklists and care pathways can make things worse rather than better. He does suggest some solutions, but you’ll have to read about them in the article itself.
Dementia in middle-income countries
The cognitive reserve hypothesis essentially posits that dementia can be prevented or delayed by activities that improve cognitive abilities. A paper in the Lancet broadens the evidence base for this theory to middle-income countries: among ~13,000 individuals interviewed in Cuba, the Dominican Republic, Venezuela, Peru, Mexico and China, the incidence of dementia was 18·2–30·4 per 1000 person-years, and independently associated with low education, although not with occupational attainment. An accompanying Comment discusses the connection between education and socioeconomic status, and the problem that countries with very little education do not seem to have the highest incidence of dementia.
Varenicline is a partial agonist of the α4β2 subtype of the nicotinic acetylcholine receptor that reduces cravings for tobacco and decreases the pleasure of smoking. It helps people quit at least as well as nicotine replacement or bupropion, but last year a meta-analysis in the CMAJ raised doubts about safety when it reported a substantial increase in serious cardiovascular events among people who had taken it. A second meta-analysis, this time in the BMJ, which includes more trials but counts only those events that occurred during treatment with varenicline, comes to the opposite conclusion, finding no excess of adverse events.
Sigmoidoscopy for colorectal screening
The best way to screen for colorectal cancer remains debated, but a study in the NEJM adds to the evidence for flexible sigmoidoscopy. The study randomises 154,900 men and women aged 55–74 years to sigmoidoscopy with a repeat screening at 3 or 5 years, or usual care. Screening significantly reduced the incidence of both distal and proximal colorectal cancers, and mortality from distal disease was approximately halved. An accompanying Editorial thinks US physicians are neglecting this approach in favour of colonoscopy, and reminds them that the best screening test is the one the patient will actually agree to.
Improving global health
Global health is JAMA’s theme this week and there are articles on the treatment of acute coronary syndrome in Brazil, inflammatory markers in relation to air pollution in China and micronutrient supplementation for pregnant women in Bangladesh. All worthy enterprises of course, but not of direct relevance to most UK doctors. More interesting are some of the commentaries, including one by Michael Marmot on health equity and social justice, in which he argues that links between social and economic policy and a population’s health are so close that all government ministers, regardless of their actual portfolio, should see themselves as ministers of health.