Hospital admissions for stroke and bleeding in Hounslow following a quality improvement initiative

Abstract

Objective: Atrial fibrillation (AF) is the most common arrhythmia. Undiagnosed and poorly managed AF increases risk of stroke. The Hounslow AF quality improvement (QI) initiative was associated with improved quality of care for patients with AF through increased detection of AF and appropriate anticoagulation. This study aimed to evaluate whether there has been a change in stroke and bleeding rates in the Hounslow population following the QI initiative.

Methods: Using hospital admissions data from January 2011 to August 2018, interrupted time series analysis was performed to investigate the changes in standardised rates of admission with stroke and bleeding, following the start of the QI initiative in October 2014.

Results: There was a 17% decrease in the rate of admission with stroke as primary diagnosis (incidence rate ratio (IRR) 0.83; 95% CI 0.712 to 0.963; p<0.014). There was an even larger yet not statistically significant decrease in admission with stroke as primary diagnosis and AF as secondary diagnosis (IRR 0.75; 95% CI 0.550 to 1.025; p<0.071). No significant changes were observed in bleeding admissions. For each outcome, an additional regression model including both the level change and an interaction term for slope change was created. In all cases, the slope change was small and not statistically significant.

Conclusion: Reduction in stroke admissions may be associated with the AF QI initiative. However, the immediate level change and non-significant slope change suggests a lack of effect of the intervention over time and that the decrease observed may be attributable to other events.

Keywords: atrial fibrillation; electrocardiography; quality of health care; stroke; translational medical research.

Figure 1

Proposed impact model with a level change for the ITS analysis. Red solid line=preintervention trend; red dashed line=counterfactual; blue line=postintervention trend; β0=intercept representing starting level of outcome variable; β1=slope prior to intervention; β2=change in level after intervention; T=time since start of the study; X=intervention. ITS, interrupted time series.

Figure 2

Seasonality adjusted ITS regression showing age-sex-standardised rate of admission with stroke as primary diagnosis in Hounslow CCG from January 2011 to August 2018. Grey vertical line: Intervention time point. Level change in relation to intervention variable: IRR 0.83; 95% CI 0.721 to 0.963; p<0.014. AF, atrial fibrillation; CCG, Clinical Commissioning Group; IRR, incidence rate ratio; ITS, interrupted time series.

Figure 3

Seasonality adjusted ITS regression showing age-sex-standardised rate of admission with stroke as primary diagnosis and AF as secondary diagnosis in Hounslow CCG from January 2011 to August 2018. Grey vertical line: Intervention time point. Level change in relation to intervention variable: IRR 0.75; 95% CI 0.550 to 1.025; p<0.071. AF, atrial fibrillation; CCG, Clinical Commissioning Group; IRR, incidence rate ratio; ITS, interrupted time series.

Figure 4

Seasonality adjusted ITS regression showing age-sex-standardised rate of admission with bleeding as primary diagnosis and AF in any position of diagnosis in Hounslow CCG from January 2011 to August 2018. Grey vertical line: Intervention time point. Level change in relation to intervention variable: IRR 0.93; 95% CI 0.597 to 1.449; p<0.749. AF, atrial fibrillation; CCG, Clinical Commissioning Group; IRR, incidence rate ratio; ITS, interrupted time series.

Figure 5

Seasonality adjusted ITS regression showing age-sex-standardised rate of admission with bleeding as primary diagnosis and use of OAC as secondary diagnosis in Hounslow CCG from January 2011 to August 2018. Grey vertical line: intervention time point. Level change in relation to intervention variable: IRR 0.92; 95% CI 0.520 to 1.621; p<0.769. CCG, Clinical Commissioning Group; IRR, incidence rate ratio; ITS, interrupted time series; OAC, oral anticoagulation.