THE ROLE OF PILOT-STUDIES IN THE ECONOMIC-EVALUATION OF HEALTH TECHNOLOGIES

An increasing number of economic evaluations are being conducted along side clinical trials. While this practice offers the prospect of colle cting comprehensive and accurate cost data, it requires considerable t ime and effort. In the case of clinical data, key analytic decisions s uch as which data to collect and sample size are often made with refer ence to smaller (pilot) trials. However, this approach is not normally followed in the case of economic evaluation. This study was based on a recently completed health technology assessment comparing convention al radiotherapy with continuous hyperfractionated accelerated radiothe rapy (CHART) for patients with head and neck cancer or carcinoma of th e bronchus. In the full health technology assessment, cost data were a vailable for 526 head and neck patients (314 CHART and 212 conventiona l therapy) and 286 bronchus patients (175 CHART and 109 conventional t herapy). In order to simulate a pilot study, data were extracted for t he patients recruited to both trials in the first 3 months. These were then compared with the full data set in order to assess whether such a pilot study would have given useful guidance on: a) the usefulness o f undertaking a full study; b) the sample size required; and c) the im portant resource items for which comprehensive data collection would b e required. Pilot studies can be helpful in determining the likely adv antages of undertaking full economic evaluations and in identifying im portant resource items. Therefore, it is important that clinical resea rchers and research funding bodies create the necessary time window to enable such studies to take place. However, formal sample size calcul ations are more difficult to perform on limited data, since they also require knowledge of the unit cost (or prices) to be attached to the r esource items and the correlation between costs and clinical effects.