Chapter 15

Clinical Significance

Celia C. Kamath, Jeffrey A. Sloan, and Joseph C. Cappelleri

15.1 Introduction

The field of patient-reported outcomes, particularly health-related quality of life (QOL), has burgeoned in the last few years [1,2]. The importance assigned to the study of these outcomes has been attributed to the aging of the population and consequently higher prevalence of chronic diseases, along with the reality that medical treatment often fails to cure the disease but may affect QOL [3]. Health-related quality of life has gained attention in research and clinical trial settings [3,4].

The increasingly important role assigned by patients and clinicians to QOL’s role in medical decision-making has resulted in greater attention paid to the interpretation of QOL scores, particularly as it relates to clinical significance [5–7]. Clinical significance relates to the clinical meaningfulness of inter-subject or intra-subject changes in QOL scores. Clinical significance has been difficult to determine, in part because of the development of a myriad of QOL instruments over the past decade [8,9]. Some of these developments have had little or no psychometric [1,2,0,10,11] or clinical validation [9,12]. Moreover, relative to traditional clinical endpoints like survival and systolic blood pressure, QOL as a clinical endpoint is relatively unfamiliar, especially in regard to interpretation and relevance of changes in QOL scores [13].

Why is clinical significance of QOL scores ...

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