Economic evaluations and randomized trials in spinal disorders: principles and methods.
STUDY DESIGN: Descriptive methodologic recommendations. OBJECTIVE: To help researchers designing, conducting, and reporting economic evaluations in the field of back and neck pain. SUMMARY OF BACKGROUND DATA: Economic evaluations of both existing and new therapeutic interventions are becoming increasingly important. There is a need to improve the methods of economic evaluations in the field of spinal disorders. MATERIALS AND METHODS: To improve the methods of economic evaluations in the field of spinal disorders, this article describes the various steps in an economic evaluation, using as example a study on the cost-effectiveness of manual therapy, physiotherapy, and usual care provided by the general practitioner for patients with neck pain. RESULTS: An economic evaluation is a study in which two or more interventions are systematically compared with regard to both costs and effects. There are four types of economic evaluations, based on analysis of: (1) cost-effectiveness, (2) cost-utility, (3) cost-minimization, and (4) cost-benefit. The cost-utility analysis is a special case of cost-effectiveness analysis. The first step in all these economic evaluations is to identify the perspective of the study. The choice of the perspective will have consequences for the identification of costs and effects. Secondly, the alternatives that will be compared should be identified. Thirdly, the relevant costs and effects should be identified. Economic evaluations are usually performed from a societal perspective and include consequently direct health care costs, direct nonhealth care costs, and indirect costs. Fourthly, effect data are collected by means of questionnaires or interviews, and relevant cost data with regard to effect measures and health care utilization, work absenteeism, travel expenses, use of over-the-counter medication, and help from family and friends, are collected by means of cost diaries, questionnaires, or (telephone) interviews. Fifthly, real costs are calculated, or the costs are estimated on the basis of real costs, guideline prices, or tariffs. Finally, in the statistical analysis the mean direct, indirect, and total costs of the alternatives are compared, using bootstrapping techniques. Incremental cost-effectiveness ratios are graphically presented on a cost-effectiveness plane and acceptability curves are calculated. CONCLUSION: Economic evaluations require specific methods. These recommendations may be helpful in improving the quality of economic evaluations of new and existing therapeutic interventions in the field of spinal disorders.