Effect of implementing a heart failure admission care bundle on hospital readmission and mortality rates: interrupted time series study

Abstract

This study aimed to evaluate the impact of developing and implementing a care bundle intervention to improve care for patients with acute heart failure admitted to a large London hospital. The intervention comprised three elements, targeted within 24 hours of admission: N-terminal pro-B-type natriuretic peptide (NT-proBNP) test, transthoracic Doppler two-dimensional echocardiography and specialist review by cardiology team. The SHIFT-Evidence approach to quality improvement was used. During implementation, July 2015-July 2017, 1169 patients received the intervention. An interrupted time series design was used to evaluate impact on patient outcomes, including 15 618 admissions for 8951 patients. Mixed-effects multiple Poisson and log-linear regression models were fitted for count and continuous outcomes, respectively. Effect sizes are slope change ratios pre-intervention and post-intervention. The intervention was associated with reductions in emergency readmissions between 7 and 90 days (0.98, 95% CI 0.97 to 1.00), although not readmissions between 0 and 7 days post-discharge. Improvements were seen in in-hospital mortality (0.96, 95% CI 0.95 to 0.98), and there was no change in trend for hospital length of stay. Care process changes were also evaluated. Compliance with NT-proBNP testing was already high in 2014/2015 (162 of 163, 99.4%) and decreased slightly, with increased numbers audited, to 2016/2017 (1082 of 1101, 98.2%). Over this period, rates of echocardiography (84.7-98.9%) and specialist input (51.6-90.4%) improved. Care quality and outcomes can be improved for patients with acute heart failure using a care bundle approach. A systematic approach to quality improvement, and robust evaluation design, can be beneficial in supporting successful improvement and learning.

Keywords: Evaluation methodology; Healthcare quality improvement; Implementation science.

Figure 1

Number of care bundles administered per month, intervention site, June 2015–July 2017.

Figure 2

Interrupted time series analysis of heart failure admission outcomes. Time series with continuous time trends pre-intervention and post-intervention (heart failure care bundle) for control and intervention hospital sites. Circular markers for each month denote the aggregated measure for that month: in the case of readmissions and mortality, the proportion, in the case of length of stay, the geometric mean. The solid light blue line shows the fitted result of each model, on each site, with all covariates averaged over the entire study period; thus, this line is guaranteed to be continuous at the interruption by the use of linear splines. The solid dark blue line shows the fitted result for the pre-intervention and post-intervention periods, on each site, with all covariates averaged within each period (pre-intervention and post-intervention). This line is not necessarily continuous across the interruption, since these average values differ between the two periods. The solid grey line shows the fitted result with covariates averaged over each month. Fitted results shown by these three solid lines were marginalised over random effects.