This week in the BMJ
Volume 331, Number 7522, Issue of 22 Oct 2005Obesity begins in infancy
blockers for elderly surgical patients
Obesity begins in infancy
Heavy infants and those who grow rapidly are at increased risk of being obese later in life. In a systematic review, Baird and colleagues (p 929) found 22 cohort studies and two case-control studies that assessed the association between infant size or growth and subsequent obesity. Obese infants were up to nine times more likely than non-obese infants to become obese adults, and infants who grew rapidly were up to five times more likely to become obese adults compared with other infants. Strategies for preventing obesity may need to address factors during or before infancy, say the authors.
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Choose long acting 
blockers for elderly surgical patients
Patients older than 65 who undergo elective surgery are less likely to have a myocardial infarction or die if they receive atenolol rather than metoprolol. The effect extends to other long acting and short acting blockers. A population based, retrospective cohort study by Redelmeier and colleagues (p 932) included more than 37 000 consecutive elderly patients undergoing surgery in acute care hospitals in Ontario, Canada over a decade. The results suggest that switching from short acting to long acting blockers may prevent one myocardial infarction or death for every 165 patients, with no increase in other common perioperative complications.
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Ethics may lead to bias: recruitment
Ethical committees increasingly require participant recruitment to be done by the "opt-in" approach (with potential participants asked to actively signal willingness to participate in research). But this seems to result in lower response rates and a biased sample compared with the "opt-out" approach (which assumes willingness to participate unless potential participants actively signal their unwillingness). Junghans and colleagues (p 940) randomised 510 patients with angina to either method when recruiting for an observational study. Compared with those in the opt-out arm, patients in the opt-in arm had significantly fewer risk factors (44% v 60%), less treatment for angina (69% v 82%), and less functional impairment (9% v 20%).
Ethics may lead to bias: consent
Adults who consent to participate in observational research differ from those who do not or cannot consent. This can bias disease registers, epidemiological studies, and health services research. Al-Shahi and colleagues (p 942) analysed the differences in a prospective, population based cohort study of all adults with newly diagnosed brain arteriovenous malformation over a three year period. When non-consenters (those who didn't give explicit consent, or refused to participate in the study) were excluded from the analysis, the important finding that initial presentation with intracranial haemorrhage conferred a significantly higher risk of subsequent haemorrhage during follow-up was lost.
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Who is to blame for high prices of US drugs?
The United States government and the pharmaceutical industry have been blaming the high prices of drugs in the US on lower prices in other rich countries, which—they argue—don't pay their share of investment into research and development of new drugs. On page 958, Light and Lexchin challenge this foreign rip-off theory and present and discuss the evidence that disputes it. They say that the "free riding" argument is an economic artefact and suggest that the US cuts the prices of drugs rather than trying to force other rich countries to raise them.
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