A National Estimate of the Health and Cost Burden of Escherichia coli Bacteraemia in the Hospital Setting: The Importance of Antibiotic Resistance

<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Antibiotic resistance poses a threat to public health and a burden to healthcare systems. <jats:italic>Escherichia coli</jats:italic> causes more bacteraemia cases in England than any other bacterial species, these infections, in part due to their high incidence, also pose a significant antibiotic resistance burden. The main aim of this study was to estimate the impact of <jats:italic>E. coli</jats:italic> bacteraemia on patient in-hospital mortality and length of stay. Secondarily, this study also aimed to estimate the effect of antibiotic resistance on these outcomes.</jats:p></jats:sec><jats:sec><jats:title>Methods and Findings</jats:title><jats:p>Case patients were adult <jats:italic>E. coli</jats:italic> bacteraemia patients infected between July 2011 and June 2012, as reported in an English national mandatory surveillance database, with susceptibility data taken from a national laboratory surveillance database. Control patients were all non-case, adult patients with an English hospital admission record. Case and control patient characteristics and admission information were taken from NHS Digital Datasets. ‘Resistance’ was defined as non-susceptible and intermediate isolates, whilst ‘susceptible’ was defined as susceptible and non-tested isolates. Time to in-hospital mortality and discharge was investigated through Cox proportional hazards models. To acquire estimates of excess length of stay, multistate models were constructed, with a unit bed day cost applied to estimate cost burden. The total number of case and control hospital spells was 14,051 and 8,919,275 respectively. Acquisition of <jats:italic>E. coli</jats:italic> bacteraemia was associated with a statistically significant increased daily risk of in-hospital mortality, especially for the first eight days of someone’s hospital admission [Hazard Ratio = 2.77 (95% confidence interval; 2.61-2.94)]. Antibiotic resistance did not seem to significantly increase this risk further, though did significantly reduce risk of experiencing a discharge event (dead or alive). <jats:italic>E.coli</jats:italic> bacteraemia was estimated to cost £14,340,900 over the study period (rounded to the nearest £100), with resistance associated with excess costs per infection of £220 - £420 dependent on resistance type, for those where a significant impact was found (rounded to the nearest £10).</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p><jats:italic>E. coli</jats:italic> bacteraemia places a significant burden on patient health and on the hospital sector in England. Resistance is an important factor on length of stay with regards to such infections.</jats:p></jats:sec>