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Central to the evaluation of health care is the measurement of
health. Until the first part of the twentieth 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 well
being 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.
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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. Outcomes research seeks to
define which treatments are effective, at which point in the natural
history of medical conditions these interventions should be provided,
for which patients, and at what cost, thus providing objective evidence
to guide treatment.
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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.
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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, as 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 lags 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, ...