Presentation of relative effects regarding pain will facilitate interpretation of treatment effects
OBJECTIVE Pain is a patient-important outcome , but current reporting in r and omized controlled trials and systematic review s is often suboptimal , impeding clinical interpretation and decision making .
Basic statistics for clinicians: 3. Assessing the effects of treatment: measures of association.
In the third of a series of four articles the authors show the calculation of measures of association and discuss their usefulness in clinical decision making . From the rates of death or other " events " in experimental and control groups in a clinical trial , we can calculate the relative risk ( RR ) of the event after the experimental treatment , expressed as a percentage of the risk without such treatment . The absolute risk reduction ( ARR ) is the difference in the risk of an event between the groups . The relative risk reduction is the percentage of the baseline risk ( the risk of an event in the control patients ) removed as a result of therapy . The odds ratio ( OR ) , which is the measure of choice in case-control studies , gives the ratio of the odds of an event in the experimental group to those in the control group . The OR and the RR provide limited information in reporting the results of prospect i ve trials because they do not reflect changes in the baseline risk . The ARR and the number needed to treat , which tells the clinician how many patients need to be treated to prevent one event , reflect both the baseline risk and the relative risk reduction . If the timing of events is important -- to determine whether treatment extends life , for example -- survival curves are used to show when events occur over time
Presentation of relative effects regarding pain will facilitate interpretation of treatment effects
OBJECTIVE Pain is a patient-important outcome , but current reporting in r and omized controlled trials and systematic review s is often suboptimal , impeding clinical interpretation and decision making .