Of smokers, enthusiasts, and bedbugs

People have been surveying smokers for years, and as a result there's a wealth of information still capable of yielding new insights or settling old scores. Two examples appear in this week's BMJ.

On p 1097 Richard Doll and colleagues use data from the British doctors cohort to lay to rest the suggestion that smoking might protect against dementia. Richard Doll has been studying the smoking habits of doctors since 1951, and data from the cohort were influential in prompting doctors to be one of the earliest groups to abandon smoking. In this they were the vanguard of a phenomenon outlined by A E J M Cavelaars and colleagues (p 1102): in the early phases of the “smoking epidemic” smoking is taken up by high socioeconomic groups, then spreads widely throughout society before staring to fall, again led by higher socioeconomic groups, so that by the final stage smoking is progressively more a habit of lower socioeconomic groups. Cavelaars et al use this pattern to explain their observation that higher rates of current and ever smoking are found among groups with lower educational levels only in northern Europe; in southern Europe, at an earlier stage in the epidemic, men and (particularly) women with higher levels of education smoke more. The authors also predict that socioeconomic inequalities in morbidity and mortality related to smoking are likely to increase in future because social gradients in smoking are steeper in younger than in older people

In contrast to these mega-studies is the story, told by Toby Lipman and Dawn Price, about how they tried to implement a change in their general practice and failed. In the first place the evidence on which they based their decision turned out not to be very sound (though later they discovered better evidence); they thought for a time that their change might have produced worse outcomes for patients (though it didn't); and, although all the GPs had agreed to implement the change, in fact they did so only patchily. As Trisha Greenhalgh says in her commentary, we are left “on a cliffhanger in which our humbled [enthusiasts] have sensibly abandoned their efforts to table clinical epidemiology as ‘any other business’ ”. I won't give away the plot—it's on p 1114.

A final detective story is provided in the letters column by John Paul and Janice Bates, who think that bedbug infestations may be on the increase in Britain (p 1141). In each of four recent reported infestations there was circumstantial evidence that the bedbugs had travelled in luggage or furnishings, in three cases from abroad. If patients present with nocturnally acquired bites or itchy rashes without obvious cause, say the authors, then bedbugs should be considered.