Reporting the cost-effectiveness of interventions with nonsignificant effect differences: example from a trial of secondary prevention of coronary heart disease.
OBJECTIVE
This study reports the cost-effectiveness of interventions with nonsignificant differences in effect, and considers reporting of cost-effectiveness in situations where nonsignificant differences arise in some but not all end points.


METHODS
Data on costs and effects associated with three end points (adequate assessment, risk factors, and life-years) were derived from a trial of methods to promote secondary prevention of coronary heart disease. Incremental cost per life-year gained figures were calculated, and the uncertainty around these was displayed on cost-effectiveness planes in the form of ellipses.


RESULTS
There was a significant difference in one of the intermediate end points (adequate assessment) but nonsignificant differences in the other intermediate end point (risk factors) and the final end point (life-years). Estimation of cost per life-year figures revealed the cost-effectiveness of the interventions to be unfavorable.


CONCLUSIONS
Cost-effectiveness ratios based on final end points should be calculated even in situations where nonsignificant differences in life-years arise, to avoid publication bias and to provide decision makers with useful information. Uncertainty in the incremental cost-effectiveness ratios should be estimated and presented graphically.
Johnston
Katharine
K
Health Economics Research Centre, University of Oxford, Institute of Health Sciences, Headington, UK.
Gray
Alastair
A
Moher
Michael
M
Yudkin
Patricia
P
Wright
Lucy
L
Mant
David
D
D000368:Aged; D003327:Coronary Disease / Q000175:diagnosis / Q000191:economics / Q000517:prevention & control*; D017281:Cost of Illness; D003362:Cost-Benefit Analysis / Q000706:statistics & numerical data*; D003627:Data Interpretation, Statistical; D005260:Female; D006302:Health Services Research; D006801:Humans; D008297:Male; D008875:Middle Aged; D011314:Preventive Health Services / Q000191:economics*; D019057:Quality-Adjusted Life Years; D012307:Risk Factors; D006113:United Kingdom