Misinformation about common cold treatments
In the old days, physicians were patriarchal and made decisions for their patients. That was before the EBM movement. One important part of EBM is to discuss the sizes of the treatment effects. Thereby the patients can themselves consider whether a treatment makes sense or not.
Margaret McCartney wrote that common cold treatments "only slightly reduced duration" of colds. However, "slightly" is a subjective word and it would be much more informative to readers to describe what the actual estimates of effect are.
According to meta-analyses, high-dose zinc acetate lozenges can shorten colds by 40% [1,2]. In absolute terms, the effect is some 3 days reduction in common cold duration from the placebo group duration of 7 days . Margaret McCartney has the right to consider that a 40% reduction in common cold duration is a “slight” effect. However, some physicians and patients might disagree. Therefore reporting the actual estimate of effect is important since it allows readers to consider the facts themselves.
McCartney referred to Allan and Arroll's review on common cold treatments in CMAJ. In an eLetter, I pointed out some of the problems in that review . As to zinc and the common cold, they referred to the meta-analysis by Dr Science et al. (2012), which had a number of problems [5,6]; and to the Cochrane review (2011) by Singh and Das, which also had problems. The latter problems were not corrected in the Cochrane (2013) update, and that update had new problems including unattributed copying of data . Therefore the Cochrane (2013) update was withdrawn . Thus, Allan and Arroll were not critical when reading and citing the literature on zinc and the common cold.
McCartney wrote that "a cold will go away by itself. It doesn't need treatment for resolution". I work as a GP and I consider that that kind of attitude towards patients is not reasonable. Patients have lots of short term problems, but "short term" does not imply that physicians should not try to help their patients. For example, patients have pains because of accidents etc. and I prescribe pain killers so that they can sleep better. “Pain will go away by itself and it does not need treatment for resolution” is not a valid counterargument for treating such patients.
Furthermore, it has been know for decades that the common cold is a common cause for asthma exacerbations . When my patients have a cough that disturbs their sleep, associated with the common cold, wheezing or low PEF value are not very infrequent. Such a problem will go away by itself, but I can help those patients.
So far, evidence indicates that zinc acetate lozenges should be started within a day after the onset of the common cold [1-3], and most common cold patients come too late in that respect. However, if the patient sees a pharmacist, and if the pharmacist is properly educated, the patient might benefit from an early initiation of zinc acetate lozenge treatment.
Competing interests: No competing interests