Institute:Office of National Coordinator (ONC) Workforce Training Curriculum
Component:The Culture of Health Care
Putting evidence into practice
Slide content:Types of Analysis in a Systematic Review Meta-analysis, which combines results of multiple similar studies, is often used Systematic review meta-analysis Studies may be too heterogeneous in terms of patient characteristics, settings, or other factors, e.g., telemedicine outcomes and diagnosis (Hersh et al., 2001, 2002; Hersh, Hickam, et al., 2006) When meta-analysis is done, summary measures employed usually include odds ratio or weighted mean difference 6
Slide notes:6 What kind of analysis do we perform in a systematic review? Systematic reviews often use meta-analysis, where the results of multiple studies that are appropriately similar are combined. If we have multiple studies that have looked at, for example, the use of a treatment in a disease with a certain patient population, its appropriate to combine these studies in a meta-analysis, which gives us more statistical power. When we have a larger sample size, its easier to achieve statistical significance, and were pooling data from different studies but from studies that are similar. We dont have to do a meta-analysis in a systematic review. In fact, if the studies are too heterogeneous, because there are different patient characteristics, different settings, or other factors, it would be inappropriate to combine them in a meta-analysis. In systematic reviews looking at telemedicine, for example, its difficult to do a meta-analysis when one telemedicine study is a dermatology study, another one is a radiology study, and yet another is a psychiatry study. When systematically reviewing the evidence for improved patient outcomes or improved ability to do diagnosis using any kind of telemedicine, it would be inappropriate to combine all the studies. It would perhaps be possible to combine a few studies in some areas, but in the case of telemedicine, these studies are quite heterogeneous. When we do a meta-analysis, we use a summary measure that gives us an indication of the treatment effect. We use either the odds ratio or the weighted mean difference, which we explain in the next slide.