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New tool better at predicting the prognosis of acute cough, study finds

A new tool for predicting the course of an acute cough in primary care could help reduce antibiotic prescriptions, researchers have found.

The newly developed RISSC85 tool outperforms other tools for predicting the outcome of acute cough, which could be useful for helping to cut down on antibiotic prescribing, they claimed.

Public Health England announced ambitions to cut the amount of antibiotics prescribed in general practice over the next two years after it found that one in five antibiotic prescriptions was ‘inappropriate’.

The study, carried out by researchers in the UK and Belgium, looked at data from a European database for just over 2,600 patients who had presented to primary care with an acute cough. Around 20% of these patients experienced a poor outcome, defined as re-consultation or hospital admission.

The authors used modelling to look for variables that were significant in predicting a poor outcome and included them in the tool.

They found that although the performance of RISSC85 was suboptimal, with a positive predictive value of 27%, it still performed better than existing prognostic prediction tools, such as the PSI and CRB65 tools, at separating patients who were and were not at risk of poor outcome.

The variables they included in the tool were baseline risk of poor outcome, how much the cough was interfering with daily activities, number of years since the patient had stopped smoking, severity of sputum as assessed by the patient, presence of crackles, and blood pressure. Adding factors such as CRP levels, blood nitrogen urea levels and chest X-ray findings did not significantly improve the performance of the tool.

They authors also suggested that as the tool had a negative predictive value of 86%, it could be useful for reassuring patients that their cough was not clinically significant and for reducing antibiotic prescriptions.

They said in the paper that practice nurses and GPs could use the simplified RISSC85 to 'differentiate between patients where a "wait and see approach" is appropriate, and careful reassurance is the preferred treatment strategy, and those more at risk for poor outcome, who could then be more explicitly advised about key symptoms and signs that require re-consultation, and possibly offered a delayed prescription.'

Br J Gen Pract 2017; available online 9 April