The Importance of Intraclass Correlation Coefficient for Clinical Pathways

Cluster randomized trials (CRT) are increasingly being used in healthcare evaluation to show the effectiveness of a clinical pathways. In CRTs, patients are nested within clusters such as hospitals and interventions are applied at cluster levels but outcomes are measured at the individual level. It is expected that individuals in the same cluster e.g. hospital, would have more similarities compared to individuals in different clusters. Intraclass correlation coefficient (ICC) is used to determine the degree of within-cluster dependence and it plays an important role in estimating sample size for cluster randomized trials. ICC takes value between 0 and 1. Higher ICC means higher within group similarities compared to between groups similarities. To perform a well-designed cluster randomized trial, the ICC should be available before conducting a trial to estimate the required sample size. The degree of the increase in sample size is a function of both ICC and cluster sizes where generally a greater ICC requires enrollment of a greater number of patients in the trial. In recent years, the need to have published ICCs from different CRTs was put forward to help planning future studies. We are happy to inform you that the first study to present ICC estimates for a cluster randomized trial of care pathway are recently available1.
1 Kul S, Vanhaecht K, Panella M. Intraclass correlation coefficients for cluster randomized trials in care pathways and usual care: hospital treatment for heart failure.BMC Health Serv Res. 2014 Feb 24;14(1):84. [Epub ahead of print]

Assoc. Prof. Dr. Seval Kul
Gaziantep University Faculty of Medicine, Department of Biostatistics, Gaziantep, Turkey

Care Pathways for Acute Coronary Syndrome

A quality improvement research project

Cardiovascular diseases are the leading cause of death globally. In Europe, half of the acute myocardial infarctions hospitalizations are due to ST elevated myocardial Infarction (STEMI). Optimal treatment for STEMI has been published and disseminated through decades of (inter)national guidelines. Despite the availability of these guidelines, adherence to evidence on STEMI care varies greatly between hospitals, systems of care and time.

The Care Pathways for Acute Coronary Syndrome (CP4ACS) Quality Improvement Research Project was set up by the European Pathway Association to evaluate and improve the care process and the quality of care for adult patients with STEMI in 16 Belgian hospitals. The project started in May 2013 as a collaboration between the European Pathway Association, the Health Services Research Group of the Department of Public Health & Primary Care, KU Leuven and the Department of Cardiology of the University Hospitals Leuven. The 3-year project is funded by an unrestricted Grant from Astra Zeneca.

CP4ACS uses an interrupted time series design with one retrospective and two prospective measurements on quality of care (both on patient as hospital level). Providing feedback on the actual organization of the care process, informing the teams on the available evidence, enhancing the teamwork and using quality improvement strategies are used as a complex intervention in the participating hospitals. Variables were selected by a RAND modified Delphi method and cover under-, over- and misuse of care. Specific attention to STEMI process improvement will be on time intervals (i.e. door to balloon time) and life style changes (i.e. smoking cessation, nutritional advice and activity level).

ImageProf. dr. Peter Sinnaeve (Department of Cardiology, University Hospitals Leuven): “CP4ACS succeeded to set up a bottom – up research project which enables STEMI teams to improve quality of care by providing evidence, benchmarking and tailored quality improvement interventions. As such it prepares STEMI teams for public reporting.”

Dr. Kris Vanhaecht ( together with prof. dr. Peter Sinnaeve ( are the principal investigators of the CP4ACS project. The project builds on previous EPA research experience on care pathways for hip fracture and COPD.

Daan Aeyels ( or +32 475298377) is the dedicated research fellow and Phd student for the CP4ACS project.

Dr. Kris Vanhaecht, secretary general, E-P-A