The measurement of health is central to the evaluation of health care. Until the first part of the 20th century, health was defined as the absence of disease and was measured in terms of morbidity and mortality. This simple approach to health status was rejected in 1948 with the expansion of the concept of health by the World Health Organization (WHO), which defined health as “A state of complete physical, mental and social wellbeing and not merely the absence of disease or infirmity.”1 This definition reflected the multidimensionality of health and considered not only biologic markers but also the ability to perform physically, psychologically, and socially in the everyday environment.
This change in the definition of health gave rise to the current outcomes movement. Other factors, such as the reversal of the proportion of care rendered for acute illnesses versus chronic diseases, technological advancements in health care, rising health care costs, the emerging concept of quality of care, and increased recognition of the importance of patients’ views about their care and health, have further fostered the growth of this movement. Conscientious health care providers use both individual clinical expertise and the best available objective, external evidence for treatment. The best available external evidence for treatment is defined as clinically relevant research, often from the basic sciences of medicine but especially from patient-based clinical research into the accuracy and precision of diagnostic tests (including the clinical examination); the power of prognostic markers; and the efficacy and safety of therapeutic, rehabilitative, and preventive regimens.2 The integration of clinical expertise and best available external evidence for treatment is the practice of evidence-based medicine. With the plethora of current and relevant literature, it is impossible for most clinical care providers to keep abreast of the latest developments in their field. Because of this problem, structured approaches to literature synthesis, such as that organized by the Cochrane Collaboration, have arisen to summarize, with the least possible bias, the best available research on a specific topic (see later discussion). The goal is to make relevant information widely available and evidence-based practice unencumbered for all health care providers.
This chapter focuses on common terminology used in outcomes assessment and on outcomes measurement tools used in research on and treatment of patients with chronic noncancer pain because they are part of the foundation of what will become evidence-based practice and perhaps eventually guidelines for treatment. Although the comprehensiveness and validity of outcome measures for the treatment of all types of pain lag behind those of equally high-impact conditions that affect the public's health, this lag is even more pronounced for cancer pain than for noncancer pain.3 Much more research has addressed functional assessment, and how pain management influences function, in patients with acute or chronic noncancer pain than in those whose pain results from malignancy.4