Patient, clinician, and population perspectives on determining the clinical significance of quality-of-life scores

Despite the success of screening and treatment of major cancers in the United States, cancer remains a chronic condition dominated by symptoms and treatment-related adverse effects. Because of these often taxing symptoms and adverse effects, numerous studies have been conducted to document the effects of cancer diagnosis and treatment on the quality of life (QOL) of patients. But there has been limited investigation of the clinical significance of QOL scores. This article examines the clinical significance of QOL scores from 3 key perspectives: patients, clinicians, and the general population. The patient's perspective includes an evaluation of the size of difference in scores that individual patients can detect and regard as important. The clinician perspective relies on whether the clinician believes the patient's condition has stayed the same vs whether changes have occurred (decline or improvement). The population perspective represents a democratic process in which the input or votes of a community of people are used to determine if health state A is clinically significantly different from health state B. While many clinicians and researchers advocate for QOL to be defined from the patient's perspective, the reality is that QOL is often defined by clinicians in terms of observable events. Even when measures are used in which the patient identifies how his or her life has been affected, it is often the clinician who interprets the clinical importance of this information. The clinician's perspective has value in framing an experience within the context of what is usual for a group of individuals, and the population perspective provides inputs as to how society may use limited resources. However, we conclude that a more prominent role for the patient's QOL perspective is needed.