New study out in the BMJ, “Delayed antibiotic prescribing strategies for respiratory tract infections in primary care: pragmatic, factorial, randomised controlled trial.”:

Objective To estimate the effectiveness of different strategies involving delayed antibiotic prescription for acute respiratory tract infections. Design Open, pragmatic, parallel group, factorial, randomised controlled trial. Setting Primary care in the United Kingdom. Patients 889 patients aged 3 years and over with acute respiratory tract infection, recruited between 3 March 2010 and 28 March 2012 by 53 health professionals in 25 practices. Interventions Patients judged not to need immediate antibiotics were randomised to undergo four strategies of delayed prescription: recontact for a prescription, post-dated prescription, collection of the prescription, and be given the prescription (patient led). During the trial, a strategy of no antibiotic prescription was added as another randomised comparison. Analysis was intention to treat. Main outcome measures Mean symptom severity (0-6 scale) at days 2-4 (primary outcome), antibiotic use, and patients’ beliefs in the effectiveness of antibiotic use. Secondary analysis included comparison with immediate use of antibiotics.

So they took patients who were being seen for acute respiratory infections, and figured out which “needed” immediate antibiotics and which did not. Those who needed them, were given immediate prescriptions. Those who were judged not to need them immediately were randomized to one of five groups.

No prescription at all Told to recontact the physician for a prescription if needed Given a post-dated prescription if they needed antibiotics later Told to collect the prescription from the clinic later Given an active prescription and told to wait to fill it

Then they checked to see if patients took the antibiotics, and how it changed their symptoms.

Of the five strategies, all resulted in about 40% or less of patients filling the prescriptions. This means that 60% of patients didn’t. That’s good! The fewest patients who took antibiotics were in the “no prescription” group, with 26% eventually getting antibiotics. How or why, I have no idea. Giving no prescription and providing delayed prescriptions offered no improvement in the duration of symptoms. There were also no real differences in satisfaction with the visit.

But here’s the kicker, and this is where I think the BMJ authors buried the lede. Of the people who were felt to “need” antibiotics and who got a prescription immediately, 97% took the antibiotic. About 93% of those patients strongly believed they would help them. But they didn’t. The antibiotics provided no improvements in symptom severity scores, nor the duration of illness.

So giving “needed” antibiotics reinforced their importance, but did no actual good.

Almost all acute respiratory infections have viral causes. Antibiotics are useless. That’s what the study found. Delaying them, or refusing them significantly, reduced the number of patients who eventually got them, but I’m having trouble understanding why anything higher than “none” was considered success.

@aaronecarroll

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