Seminar - Modelling step-wedge designs using interrupted time series/segmented regression
6 July 2012
Full title: Modelling step-wedge designs using interrupted time series/segmented regression to evaluate prevention and control of infection in hospital units
Presenter: Professor Val Gebski, NHMRC Clinical Trials Centre
Common methods for evaluating interventions to reduce the rate of new Staphylococcus aureus (MRSA) infections in hospitals use segmented regression or interrupted time-series analysis. Approaches to evaluating interventions introduced in different healthcare units at different times are developed. We compare fitting a segmented Poisson regression in each hospital unit with pooling the individual estimates by inverse variance. An extension of this approach to accommodate potential heterogeneity allows estimates to be calculated from a single statistical model: a 'stacked' model. It can be used to ascertain whether transmission rates before the intervention have the same slope in all units, whether the immediate impact of the intervention is the same in all units, and whether transmission rates have the same slope after the intervention.
The methods are illustrated by analyses of data from a study at a Veterans Affairs hospital. Both approaches yielded consistent results. The methods presented are easily implemented in standard statistical packages and yield measures of effect which are clinically interpretable by health care professionals.
About the speaker: Val Gebski is the Professor of Biostatistics & Research Methodology at the NHMRC Clinical Trials Centre where he leads a team of 12 biostatisticians of aspects of clinical trials design, conduct, analysis and interpretation. He is the Group statistician for 4 collaborative cancer trials groups (ANZBCTG, AGITG, ANZUP and TROG) as well as co-directing the Masters of Clinical Trials course at Univ. of Sydney. He is a fellow of the Royal Australian & New Zealand College of Radiologists.
Hosted by The George Institute for International Health
Location: Level 10, King George V Building, Royal Prince Alfred Hospital
Contact: Serigne Lo
Phone: 02 9657 0329