Highlights

Diagnosing streptococcal pharyngitis

Existing clinical prediction rules for identifying group A streptococcal infection in children with pharyngitis lack sufficient accuracy and fail to select use of rapid antigen detection testing efficiently. This study used a systematic review to identify eight clinical prediction rules published between 1975 and 2010 and newly validated them in a prospective multicentre cohort of 678 consecutive children recruited from 17 outpatient pediatric practices in France from 2010–2011. In the absence of better rules, it may be reasonable for clinicians to perform rapid antigen detection testing in all children presenting with pharyngitis, suggest the authors. See Research, page 23

Canadian guidelines are sorely needed to achieve a cost-effective, universal approach to microbiological testing and treatment for acute pediatric pharyngitis, say the authors of this commentary. See Commentary, page 13

Harms associated with amoxicillin

A systematic review of randomized placebo-controlled trials found that amoxicillin–clavulanic acid was commonly associated with diarrhea, and both amoxicillin and amoxicillin–clavulanic acid were associated with candidiasis. Of 45 trials included in the review, only 25 provided data suitable for assessment of harms, which suggested under-reporting. Still, these results can contribute to better-informed decisions about the benefit–harm trade-off for these antibiotics, say the authors. See Research, page E21

Absence of evidence of harm should not be construed as evidence of absence of harm, warn Loke and Mattishent. Their commentary laments the poor monitoring of harms in clinical trials and calls for unrestricted access to complete trial datasets for both beneficial and adverse effects. See Commentary, page 15

Birth-weight curves by world region

The authors used 10 years’ of data for more than 1 million live births in Ontario to construct world region–specific birth-weight curves. The impact of applying these new curves could be assessed by estimating the cost savings from sparing newborns prolonged hospital stays, special care or referral to specialists, say the authors. See Research, page E32

Drug interactions in comorbid HIV

Many antiretroviral drugs are prone to pharmacokinetic drug–drug interactions because they are substrates for, as well as inhibitors or inducers of, various CYP450 isoenzymes. This is important when patients who are receiving antiretroviral treatment require medication for comorbid diseases, something that is becoming increasingly common as AIDS-related mortality declines. Hughes and colleagues discuss how to manage this problem. See Review, page 36

A 62-year-old woman with syncope

A patient loses consciousness after straining on the toilet. What diagnoses should be considered? Does she require neuroimaging or other investigations? Soong and coauthors discuss these and other questions in this installment of the Choosing Wisely Canada series in CMAJ. See Decisions, page 48

A patient with recurrent rheumatic fever

A 39-year-old man with a history of rheumatic fever presented with a three-day history of fever, headache, and muscle and joint pain. Despite the patient receiving penicillin injections every four weeks, recurrent rheumatic fever was diagnosed. Bagnall and colleagues explain why. See Cases, page 50

Venous thrombosis in inflammatory bowel disease

A 41-year-old woman with a flare-up of ulcerative colitis developed multifocal venous thromboses, including in the cerebral and intra-abdominal veins. Anticoagulant thromboprophylaxis is strongly recommended in patients admitted to hospital with moderate to severe IBD flare-ups without severe bleeding, stress Mian and Lawlor. See Clinical images, page 55