Selecting a Quality of Life Instrument

It is always important to select an instrument that has adequate reliability and validity. Although many instruments have been published, many of these have little supporting validation. Another sources of information include the Medical Outcomes Trust (2001), www.outcomes-trust.org. Some instruments, such as the MOS-SF-36, a generic QOC instrument, seem to be gaining popularity, and it is tempting to routinely incorporate them into clinical studies. Many experts in the field recommend that both a disease-specific and generic instrument should be used in each study, in order to capture the broadest QOL information. Yet, excess burden on patients can defeat the accuracy and completeness of what is collected. Generally, if resources or patient burden threatens, then most experts would argue for retention of a disease-specific instrument when it is only possible to use a single measure.

The handling and analysis of pharmacoeco-nomic data should be along the lines familiar to those observing good clinical practices (GCP) for other purposes. Data collection instruments need to be selected, or created and incorporated into case report forms, just as for any other end-point. Data analysis plans should be created prospect-ively. The statistical analysis plan should be prospective, and should help put the pharmacoe-conomic measures in the context of other properties of the test medication (Table 19.3). Are they included to test a hypothesis or is this a hypothesis-generating study for the pharmacoeconomic measures? Is the goal to evaluate patients, discriminate between patients, or predict how patients might act? The type of data collected should drive the level of analysis (continuous vs. categorical data). If there is an investigators' meeting for the study, the pharmacoeconomic components should be presented at the meeting so the investigators and/ or the study coordinators fully understand their role in data collection. As the study is ongoing, appropriate levels of monitoring should be conducted. Queries that arise during the study and reconciliation of the data afterwards should be handled in the same manner in which clinical queries and data reconciliation are handled. Standard operating procedures and quality analysis should be a part of every study in which the company invests money to collect end-points, be they traditional or pharmacoeconomic endpoints.

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