Methodology Score: 2.5/5               
Usefulness Score:  2.5/5

Little P, et al. BMJ. 2017 May 22;357:j2148.

Editorial: Controlling antibiotic prescribing for lower respiratory tract infections Scott AM et al. BMJ. 2017 May 22;357:j2398. doi: 10.1136/bmj.j2398.

Question and Methods: This is a large, prospective, observational study of ambulatory patients with acute cough treated with no, immediate or delayed antibiotics that compared rates of re-consultation, admission and death in each group.

Findings: There was no change in admission or death with antibiotics, but re-consultation for new, worsening, or non-resolving symptoms decreased with delayed antibiotics (RR 0.64, 95% CI 0.57 to 0.72, P<0.001).

Limitations: Limitations include lack of randomization, non-standardized antibiotic regimes, no blinding to treatment, no discussion of antibiotic associated adverse events, and rates of compliance were not measured.

Interpretation: In patients presenting with a cough without signs of pneumonia if you are considering prescribing antibiotics, use a delayed prescription to decrease rates of re-consultation.
By: Dr. Erica Lee

Epi Lesson

Impact of Clusters in Analyses

Most statistical analyses assume that all observations (data) are independent from each other. On occasion, groups share similarities (for e.g. patients of a same physician) which makes the contribution of each patient slightly less valuable or different from the others. The amount of similarity within a group is called “intra-class correlation” and can be measured statistically. This can be used to calculate a slightly larger required sample size, or to adjust analyses accordingly.
By: Dr. Christian Vaillancourt


  • Hans Rosenberg

    Dr. Rosenberg is an emergency physician at the Ottawa Hospital, assistant professor at the University of Ottawa, and Director of the Digital Scholarship and Knowledge Dissemination Program.

    View all posts