Translational Research: The Study of Community Effectiveness in Digestive and Liver Disorders
Article Outline
Hashem B. El-Serag, MD, MPH
Figure 1.
Community effectiveness model offers a conceptual framework for translating efficacy to effectiveness.
Translational research refers to the effort made toward bridging the gap between discoveries made at “the bench” with basic research—in which scientists study disease at a molecular or cellular level—and the clinical level, or the patient’s “bedside.” However, translational research also encompasses bridging the gap between clinical trials of therapeutic and diagnostic modalities and their proper application at the bedside in patient care. The benefits of therapies and diagnostic tests are often reduced once they are implemented in clinical practice compared with the benefit reported in clinical trials. Efficacy is the extent to which a specific intervention produces a beneficial effect under ideal conditions, usually clinical trials. Effectiveness is the extent to which an intervention is beneficial when deployed in a community-based practice setting. Efficacy is largely determined by the biological effects of a therapy, but effectiveness takes into account external factors, such as individual patient characteristics, health system features, or societal influences. These effects are not evaluated easily in clinical trial settings. In addition to pharmacologic and physiologic effects, other issues must be considered for an intervention to be effective. These include (1) availability of the intervention to patients who can obtain maximum benefit, (2) identification of patients who are appropriate for the intervention, (3) recommendation of the intervention by providers, (4) acceptance of intervention by patients, and (5) adherence to treatment at the recommended dosing for therapeutic coverage to achieve fully the benefits of therapy. Effectiveness can be viewed from a patient or consumer perspective: If I receive the treatment as prescribed, will I benefit? Effectiveness is also viewed from a societal perspective: Are the benefits of this therapy reaching all those with the targeted condition? This commentary deals mostly with the societal perspective.
The concept of community effectiveness illustrates the impact on health related to the health care system and human behavior (Figure 2). Community effectiveness is calculated by multiplying the probabilities of these parameters. Once all factors are considered, the overall community effectiveness of a therapy is typically much lower than its efficacy. Models of community effectiveness can be operationalized to evaluate therapeutic (eg, treatment of viral hepatitis) and diagnostic (eg, colorectal screening) effectiveness in the community at large.
Figure 2.
Underutilization and disparity, a model. Modified from McGuire et al.2
For example in Table 1, under an optimistic scenario of a 50% efficacy for current hepatitis C therapy (therapy A) for achieving sustained viral response in genotype 1, the overall effectiveness can be <17% given relatively small decrements in the rates of access, diagnosis, recommendation, acceptance, and adherence. If a new therapy (B) is developed with increased efficacy (70%), overall effectiveness increases to 24%, if all other parameters remained unchanged. However, if the less efficacious therapy A becomes more available, accepted, recommended, and adhered to, then the overall effectiveness might become greater than that of the more efficacious therapy B.
Table 1. How Several Factors Related to the Health Care System and Human Behavior Affect the Translation of Efficacy Into Effectiveness
| Therapy | Efficacy (%) | Access (%) | Correct diagnosis (%) | Recommendation (%) | Acceptance (%) | Adherence (%) | Community effectiveness (%) |
|---|---|---|---|---|---|---|---|
| A | 50 | 80 | 85 | 85 | 85 | 70 | 17 |
| B | 70 | 80 | 85 | 85 | 85 | 70 | 24 |
| A, with modifications | 50 | 90 | 90 | 90 | 90 | 80 | 26 |
As this illustrates, the efficacy observed in clinical trials may not be easily replicated in the community; therefore, it is imperative to conduct studies to evaluate the effectiveness of interventions, identify the reasons for poor effectiveness, and develop interventions to counter these factors. Such studies should consider several factors shown in Figure 2. Effectiveness (including outcomes) studies have methodologic constraints that require attention to study design, accounting for potential biases, and adjusting for confounding factors. In addition, it is imperative that the investigators have rigorous training in epidemiologic and statistical methods to ensure methodologic robustness and study validity.
The first step in evaluating effectiveness is to examine the extent and variations of utilization in the therapeutic or diagnostic modality of interest. Variations in the utilization of health services can be a consequence of over- or underutilization of recommended care as well as disparities in care (eg, related to race or gender; Figure 2).2 Variations may be appropriate if they could be explained by disease related factors (eg, presence of known contraindications) or patient preferences (eg, patients refusing a certain therapy).3 Variation that cannot be explained by these 2 factors may be related to the health care system (eg, differential access to care) and/or provider misinformation or bias (eg, lack of knowledge or training, discrimination).2, 4 Variation among different racial/ethnic groups that is not explained by underlying health condition or treatment preferences of patients is conventionally described as disparity.5 Access to care is often cited as a major element in disparities in health care. It is well recognized that patients without adequate insurance have difficulties accessing effective care. Even in populations with more equitable access to care (eg, Medicare and veteran populations), a number of studies have shown that health services utilization patterns and outcomes are unfavorable to black patients as compared with whites.6, 7 Providers’ knowledge and attitudes toward therapeutic or diagnostic procedures can be a major explanation of inappropriate utilization or disparity. Finally, the interaction dynamics between patients and health care providers should also be considered. For example, it has been shown that physicians provide less information and do not encourage as much participation in black compared with white patients.8
Effectiveness studies of therapeutic and diagnostic interventions used for digestive and liver disorders remain scarce. Exceptions include studies of the effectiveness of colorectal screening and treatment.9, 10 A Focused Study Group held recently in the 2006 Annual Meeting for the American Association for the Study of Liver Diseases highlighted the chasm between efficacy and effectiveness of several practices, including hepatitis C antiviral therapy for preventing hepatocellular carcinoma, screening for hepatocellular carcinoma, and treatment of hepatocellular carcinoma. Where present, the evidence indicated marked underutilization of these interventions.11 Of even more concern, underutilization seems to follow some disturbing patterns in relation to ethnicity, poverty, and gender.6 However, perhaps most striking was the dearth of studies to examine most of the important links mediating efficacy to effectiveness (Figure 1).
Although the development of new therapies has traditionally received considerable attention and resources, enhancing the potential benefits of what we already have as well as the importance of nonmedical or health system factors is often forgotten. Both aspects are crucial in our quest to improve the health of patients. It is clear that information on variables other than efficacy cannot be easily obtained from clinical trials, and that studies of practice patterns have a major role in the assessment of the overall effectiveness of therapeutic or diagnostic modalities, identifying the reasons for poor effectiveness, and developing interventions to counter these factors. These studies provide insight into the effectiveness of new therapies in the context of usual practice in the community and should complement clinical trials as a necessary component of evidence-based medicine. More studies are required to evaluate and improve community effectiveness for a variety of established therapeutic and diagnostic procedures that are used in digestive and liver disorders.
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PII: S0016-5085(06)02518-2
doi:10.1053/j.gastro.2006.11.038
© 2007 AGA Institute. Published by Elsevier Inc. All rights reserved.
