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Measuring the Cost-Effectiveness of Cancer Care

Measuring the Cost-Effectiveness of Cancer Care

ABSTRACT: Historically, new therapeutic strategies for cancer have been evaluated on the basis of safety and clinical efficacy. However, the current national emphasis on efficiency of resource allocation has led to the inclusion of economic assessments in oncology studies. Economic assessments measure patients' health status and resource consumption associated with a therapeutic strategy, and combine these in a cost-effectiveness analysis. Study design can include prospective analysis of clinical trials, retrospective analysis of a clinical trial or administrative databases, or a decision analytic model. Economic analysis is being used increasingly in oncology and will continue to provide meaningful data to assist clinicians in determining the optimal treatment strategies for cancer patients and to help inform health policy decision-makers about the importance of specific cancer therapeutic strategies. [ONCOLOGY 9(6):523-538, 1995]

Introduction

Traditionally, the assessment of new therapeutic strategies for
cancer has relied almost solely on safety and clinical efficacy.
Recent concerns over escalating US health-care expenditures and
with optimizing patient outcomes have led to increased interest
in the economic assessment of cancer therapies as a secondary
objective in the evaluation of such treatments. In particular,
attention has focused on the efficiency of resource allocation
in health-care delivery. New economic measures are increasingly
being integrated into cancer clinical trials to assess the cost-effectiveness
of therapy and patients' quality of life after treatment. These
measures will improve the assessment of both the costs and benefits
of cancer treatment strategies.

Given the growing recognition by clinicians, patients, and health-care
financing organizations of resource constraints on the provision
of health-care services, economic evaluation of new drugs and
new technologies has taken on greater importance [1-3]. Economic
evaluation is being used to help guide clinical practice by informing
clinicians and patients about specific screening and treatment
strategies. These assessments are often performed by hospital
or health maintenance organization formulary committees as part
of the selection process for preferred treatments within these
organizations [4-6]. They are also being used increasingly by
health policy decision-makers at the national level in Canada
and Australia to help make funding decisions for their national
health insurance systems [4,5], as well as in the United States
through consensus treatment and screening recommendations [7-15].

Economic Concepts

Economic evaluation includes an assessment of both the costs and
benefits of cancer therapies. The costs of care may fall into
four categories:

Direct medical costs, which are the costs of medical services

Direct nonmedical costs, which are the costs incurred in receiving
medical care (such as transportation to and from a bone marrow
transplant center)

Indirect costs, which are the costs of morbidity and mortality
due to illness

Intangible costs, which are the costs of pain and suffering related
to illness.

An economic assessment of cancer treatment may include any or
all of these categories of costs.

Costs may be calculated from different perspectives. Costs of
medical care can be computed from the viewpoint of the patient,
caregiver, physician, payor, or society. The calculation of societal
costs represents the total costs of the transaction, whereas the
calculation of costs from the other perspectives may include only
those costs relevant to that specific party. For example, a patient
whose insurance requires a 20% copayment incurs a $1,000 hospitalization
cost. Thus, the insurer would pay $800 and the patient would pay
$200. The costs of that hospitalization episode viewed from the
perspectives of the insurer, patient, and society are $800, $200,
and $1,000, respectively. An economic evaluation can measure costs
from a single perspective or multiple perspectives.

Quality-Of-Life Assessments

Increasingly, investigators are interested in assessing quality
of life or patients' perceptions of their health status as primary
or secondary end points for cancer clinical trials [16-59]. This
type of assessment is a relatively new area for cancer clinical
studies. Inclusion of quality-of-life end points in clinical studies
reflects the growing recognition that traditional clinical trial
end points may not adequately capture the impact of cancer and
cancer treatment on patients' lives. In broad terms, quality of
life can be measured within clinical trials using two different
measurement constructs: functional status and patient preference.

Functional Status

Functional status instruments are used to quantify the ability
or limitation of patients across specific areas of functioning
related to health. These areas, called "domains," generally
include physical, emotional, and social functioning. Functional
status instruments compare patients to standardized levels of
functioning, the results of which are then quantified into a quality-of-life
score. Functional status measures are further divided into global
and disease-specific functional status measures.

Global assessment measures, such as the Sickness Impact Profile
(SIP) [60], the Medical Outcomes Study Short Form (MOS-SF-36)
[61], and the Nottingham Health Profile (NHP) [62], have been
widely used, and may be generalizable across populations of patients
with different clinical conditions. However, global measures may
not be sensitive to small changes in health status within therapeutic
categories.

Disease-specific measures typically include some of the same elements
measured by global assessments but are designed to be more responsive
to the illness being evaluated.Various cancer-specific functional
status instruments have been developed to focus on conditions
experienced by cancer patients and on the adverse side effects
of cancer therapies [16-59].

Patient Preference

In contrast to functional status instruments, which evaluate patient
health status against standardized levels of functioning, patient
preference assessments measure patients' interpretation of their
health states [63-65]. Patient preference measures include developed
instruments as well as specific techniques to elicit these data.

The most common instruments used to assess patient preference
are the EuroQol© [66], the Quality of Well Being (QWB) scale
[67], and the Mark Health Utilities Index (Mark HUI-III) [30,31,65].
Both the QWB and Mark HUI-III evaluate functional status across
specific domains and then combine these measures into a single
preference or utility score based on a predetermined population
preference assessment for each component of the different health
states described by the instrument. The EuroQol© asks patients
to evaluate their current health state using a 0 to 100 scale,
where 0 is the worst imaginable health state and 100 is the best
imaginable state.

Preference elicitation techniques are interview methods that use
risk or uncertainty explicitly to elicit patient preferences for
their health states. The standard gamble[64,65] and the time tradeoff
[68,69], for example, offer the patient the choice between a health
state of defined impairment and an option requiring patients to
take a risk on their health outcomes offering a probability of
perfect health and the reciprocal probability of death. Patient
preference for a given health state is calculated from the point
of indifference between the two options. The economic outcome
measure, quality-adjusted life-years (QALYS), is calculated using
both survival and patient preference information [65].

Cost-Effectiveness Analysis

Different outcome measures can be used to assess the clinical
benefits of therapy for an economic evaluation. These outcome
measures are intermediate clinical end points, such as complete
or partial response to treatment, and final end points, such as
a change in survival. The final end points are more generalizable
across all the study populations within an economic evaluation.

Interpretation of economic studies in the assessment of cancer
screening or treatment strategies is based on the relationship
between the costs and benefits of the strategy being assessed.
As depicted in Figure 1, an economic study can have four potential
results: An improvement in clinical outcome at a reduced cost
of medical services (+/+, upper left box) would be considered
a dominant strategy and would be adopted. A strategy that resulted
in an increase in the cost of medical services while yielding
a reduction in clinical outcomes (-/-, bottom right box) would
be considered to be dominated and would be rejected.

The other two potential results (the shaded boxes, +/- and -/+)
are ambiguous, and their interpretation depends on both the magnitude
of the change in cost and the clinical outcome, as compared with
the base-case strategy. To make a treatment decision in these
ambiguous cases, cost-effectiveness analysis would be used to
compare the costs of the medical services provided relative to
the clinical outcome.

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