Clinical endpoints measurement scales

It is important when choosing a particular measurement scale to answer a number of questions. Is the choice that is made of clinical relevance How is the endpoint to be measured Can we measure the clinical endpoint directly, or must we choose an indirect approach Is the choice that is made sensitive enough to measure real treatment effects Having collected the information how are we to analyse it Some of these issues are illustrated in the following sections. 

The application of NIR for predicting the endpoint of clinical or production scale batches based on the NIR calibration models developed in the laboratory may prove to be very important to the pharmaceutical manufacturer. When drugloading or polymer-coating efficiencies vary, as they do, from lab scale equipment to the larger equipment used for manufacturing, the availability of a rapid on-line or at-line measurement for prediction of process endpoint may save many millions of dollars in time and materials. Although the standard error of prediction may not match the values obtained when... 

Quality of life Measured by validated scales and patient interviews to determine the effect of therapy on a patient s lifestyle. An improvement in quality of life may be an endpoint in clinical trials. 

Optimization and then selection of final formulations, doses, regimens, and efficacy endpoints for larger scale, multicenter studies. Efficacy endpoints should be able to be measured reliably and should quantitatively reflect clinically relevant changes in the disease or condition of interest. 

To calculate QALY, we need to estimate the life years of the patient population based on clinical trial data and the health states and their durations during the life years. Health states are usually related to the study endpoints, for example, disease progression or deaths. Multistate analysis can be used to make these estimates. Once the health states are determined, the value or QoL (Q) associated with each state can be established using expert opinion, QoL data collected in the clinical studies, or direct or indirect research. The most frequently used method in practice is direct or indirect research by way of preference survey of health providers and patients. Time trade-off, standard gamble, and rating scale are among the ways to assess the preference of specific health state. As an alternative, indirect research uses questionnaires for health state in several health domains or attributes (e.g., EQ5D) and then to construct a multiattribute utility as a summary measure that reflects preferences both within and across health domains. 

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