Modifiable healthcare factors affecting 28-day survival in bloodstream infection: a prospective cohort study

Abstract

Background: Bloodstream infection is common in the UK and has significant mortality depending on the pathogen involved, site of infection and other patient factors. Healthcare staffing and ward activity may also impact on outcomes in a range of conditions, however there is little specific National Health Service (NHS) data on the impact for patients with bloodstream infection. Bloodstream Infections-Focus on Outcomes is a multicentre cohort study with the primary aim of identifying modifiable risk factors for 28-day mortality in patients with bloodstream infection due to one of six key pathogens. Methods: Adults under the care of five NHS Trusts in England and Wales between November 2010 and May 2012 were included. Multivariable Cox regression was used to quantify the association between modifiable risk factors, including staffing levels and timing of appropriate therapy, and 28-day mortality, after adjusting for non-modifiable risk factors such as patient demographics and long-term comorbidities. Results: A total of 1676 patients were included in the analysis population. Overall, 348/1676 (20.8%) died within 28 days. Modifiable factors associated with 28-day mortality were ward speciality, ward activity (admissions and discharges), movement within ward speciality, movement from critical care, and time to receipt of appropriate antimicrobial therapy in the first 7 days. For each additional admission or discharge per 10 beds, the hazard increased by 4% (95% CI 1 to 6%) in medical wards and 11% (95% CI 4 to 19%) in critical care. Patients who had moved wards within speciality or who had moved out of a critical care ward had a reduction in hazard of mortality. In the first 7 days, hazard of death increased with increasing time to receipt of appropriate antimicrobial therapy. Conclusion: This study underlines the importance of appropriate antimicrobials within the first 7 days, and the potential for ward activity and ward movements to impact on survival in bloodstream infection.

Analytical challenges in estimating the effect of exposures that are bounded by follow-up time: experiences from the Blood Stream Infection—Focus on Outcomes study

“…A summary of missing data is given in Supplementary Table 1, Additional file 1 and the model used to derive the risk score is shown in Supplementary Table 2, Additional file 1 . After adjustment for organism and the risk score representing the non-modifiable risk factors, modifiable risk factors that were associated with mortality within 28 days were ward speciality, ward activity, cumulative count of ward movements within speciality, cumulative count of movements from critical care, and time to receipt of appropriate therapy [ 13 ]. Inclusion of time to receipt of appropriate antimicrobial therapy violated the proportional hazards assumption, therefore the effect of time to receipt of appropriate antimicrobial therapy was estimated separately within each of three intervals: days 0–6, days 7–13, and day14 onwards.…”

“…The primary aim of the study was to quantify the effect of modifiable factors on all-cause 28-day mortality (including deaths after hospital discharge). The results of the study have been published elsewhere [ 13 ].…”

“…Antimicrobial therapy was defined as ‘appropriate’ if the organism was susceptible to the antimicrobial prescribed and the therapy was continued for at least 36 hours [ 13 , 14 ]. Consecutive appropriate antimicrobials were treated as a single period of appropriate therapy, provided that the subsequent therapy began within 24 h of the last dose of the previous therapy [ 13 ].…”

“…Bloodstream Infections – Focus on Outcomes (BSI-FOO) was a multicentre, prospective cohort study with the primary objective of identifying modifiable risk factors associated with all-cause mortality in patients with a BSI. The study has been described in detail previously [ 13 ].…”

Bacterial genotypic and patient risk factors for adverse outcomes in Escherichia coli bloodstream infections: a prospective molecular-epidemiological study

“…Most have identified the importance of comorbidity and age on mortality. Some have identified factors that are amendable to intervention such as timing of effective antibiotics [22,23]. Only two have examined the role of bacterial sequence type, but failed to identify an association with adverse outcome such as mortality [16,24].…”