Editor's Choice

Less is better—sometimes

BMJ 2015; 350 doi: https://doi.org/10.1136/bmj.h2158 (Published 23 April 2015) Cite this as: BMJ 2015;350:h2158
  1. Elizabeth Loder, acting head of research, The BMJ
  1. eloder{at}bmj.com

Global cigarette sales are going down. In most rich countries the proportion of adults who smoke is falling. So why aren’t antitobacco activists celebrating? Our feature this week by Jonathan Gornall (doi:10.1136/bmj.h2052) is the first in a series of articles that describe the efforts of the tobacco industry to regain credibility and influence public policy. Many experts say that the hard won successes of the war against tobacco are in danger of being undone. Population growth will be concentrated in countries with poor tobacco control, and population expansion will exceed any decrease in prevalence. Furthermore, tobacco company profits continue to rise, in part because of expansion into a variety of alternative tobacco and nicotine products, particularly electronic cigarettes (doi:10.1136/bmj.h2133).

It is not yet clear whether the harm reduction attributed to e-cigarettes outweighs their potential to normalise and encourage smoking behaviour (doi:10.1136/bmj.h2110; doi:10.1136/bmj.g5484). No matter, though: the fact that they might be an improvement on regular cigarettes allows the tobacco industry to position itself “as a player in the public health debate,” says Gornall. This manoeuvre, along with other legal and tactical strategies, means that the tobacco industry is far from vanquished and that “there is no tobacco farmer or manufacturer who need worry about their job,” says one expert quoted by Gornall. In a timely reminder of the burden of tobacco related illness, Mons and colleagues use data from 25 large cohort studies to quantify the dangers of smoking in older adults, an age group in which the harms of smoking have been understudied (doi:10.1136/bmj.h1551). Smokers had roughly twice the risk of cardiovascular mortality and acute coronary events as non-smokers. Less was better, though: risks were lower in those who smoked less or quit.

Meanwhile Tang and colleagues try to identify an age at which screening for colorectal cancer with flexible sigmoidoscopy might no longer be appropriate (doi:10.1136/bmj.h1662). Using data from a meta-analysis of randomised controlled trials, they conclude that reductions in cancer specific mortality take about a decade to become apparent, so less screening, or none at all, might be better in people with limited life expectancy. In a linked editorial, however, Brenner argues that this conclusion rests on the “questionable assumption” that absolute improvements in colorectal cancer mortality in older adults are similar to those in middle aged adults (doi:10.1136/bmj.h2029); in fact, the risk of such mortality increases sharply in older age, with a corresponding increase in the benefits of screening. The time to benefit from screening “might be substantially shorter” than the study estimates, especially for adults who have not previously been screened. So less screening is not necessarily better for everyone.

There is much interest in the therapeutic potential of transcranial direct current stimulation of the brain, mostly to treat various painful conditions. The technique delivers electrical current to a target area of the brain through electrodes applied to the overlying scalp. It is postulated to work by altering pain processing activity. This all sounds good, especially since the procedure is non-invasive and safe. The only problem is that enthusiasm has outstripped evidence: previous studies were low quality and underpowered. The final nail in the coffin is Luedtke and colleagues’ trial of the technique for chronic back pain (doi:10.1136/bmj.h1640). Their study, which randomised participants to receive real or sham stimulation prior to a rehabilitation programme, found no benefits of stimulation. A linked editorial describes this trial as “convincingly negative” and says that the technique cannot be recommended for treatment of chronic pain (doi:10.1136/bmj.h1774). The editorialists note that the technique has generated “considerable hype,” yet “evidence of benefit gets weaker as trials get stronger.” Clearly, less hype and more real help would make things better for patients with chronic pain.

Notes

Cite this as: BMJ 2015;350:h2158

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