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Research Briefs

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DeLong, E.R., Nelson, C.L., Wong, J.B., and others (2001). "Tutorial in biostatistics." (AHRQ grants HS08805 and HS06503). Statistics in Medicine 20, pp. 2505-2532.

Observational studies are not as rigorously designed as randomized clinical trails, yet they yield important information about treatment effectiveness. They also have the advantage of providing longer term followup than clinical trials. Thus, observational studies are useful for assessing and comparing patients' long-term prognosis under different treatment strategies. For patients with coronary artery disease, many observational comparisons have focused on medical therapy versus interventional procedures such as coronary artery bypass graft surgery. These authors discuss methodological problems in analyzing longitudinal treatment data—ranging from designation of the therapeutic arms in the presence of early deaths, withdrawals, and treatment cross-overs to site-to-site variability in short-term mortality—and suggest strategies to deal with them, using a coronary artery disease registry as an example.

Gross, P.A., Greenfield, S., Cretin, S., and others (2001). "Optimal methods for guideline implementation." Medical Care 39(8), pp. SII85-92.

Clinical practice guidelines are intended to reduce variations in medical practices as well as actual medical errors. They have not solved these problems, in part because they have not been fully implemented. Clearly, more effort is needed to enhance acceptance of practice guidelines and change the behavior of health care providers. These authors summarize a recent meeting of experts who have studied the problem of guideline implementation in Europe and the United States. They describe the implementation methods studied to date, review the theories of behavioral change, and make recommendations for better implementation of clinical practice guidelines.

Hessol, N.A., Schneider, M., Greenblatt, R.M., and others (2001). "Retention of women enrolled in a prospective study of human immunodeficiency virus infection: Impact of race, unstable housing, and use of human immunodeficiency virus therapy." (AHRQ cooperative agreement and other Federal agencies). American Journal of Epidemiology 154, p. 563-573.

Women and members of racial/ethnic minority groups are typically underrepresented in clinical trials. The good news is that women who have HIV infection or are at risk for it, especially black women, can be successfully recruited and retained in prospective research trials. The researchers describe recruitment and retention of a diverse group of women infected with HIV and at-risk HIV-uninfected women participating in the Women's Interagency HIV Study at six sites across the United States. Over 80 percent of all women were retained during the first 10 study visits, which occurred over a 5-year period. Factors associated with retention were older age, black race, stable housing, HIV-infected serostatus, past experience in studies of HIV/AIDS, and site of enrollment. Only site of enrollment was associated with retention of HIV-uninfected women.

Landrum, M.B., and Becker, M.P. (2001). "A multiple imputation strategy for incomplete longitudinal data." (AHRQ grant HS09183). Statistics in Medicine 20, pp. 2741-2760.

Longitudinal studies are commonly used to analyze processes of change. Because data are collected over time, missing data are pervasive in such studies, and it is difficult to ascertain all the variables. These authors propose a new imputation strategy for completing longitudinal data sets. The proposed method makes use of shrinkage estimators for pooling information across geographic entities and model averaging for pooling predictions across different statistical models.

Macinko, J., and Starfield, B. (2001). "The utility of social capital in research and health determinants." (AHRQ National Research Service Award training grant T32 HS00029). Milbank Quarterly 79(3), pp. 387-427.

These authors systematically reviewed the research literature to examine the utility of social capital in research on health determinants. Social capital is defined in many ways. For some it refers to the capacity of individuals to command scarce resources by virtue of their membership in networks or broad social structures. For others, it refers to features of social organization—such as trust, norms, and networks—that can improve the efficiency of society by facilitating coordinated actions. There is no consensus on the nature of social capital, its appropriate level of analysis, or the appropriate means of measuring it, let alone how it might be related to inequalities in health outcomes, according to the authors. In this article, they explore different definitions of social capital; review how it has been used and interpreted in the sociological, political science, and economic/community development literature; discuss its appearance and use in the health inequalities literature; and suggest further directions for refining the concept for use in explaining health outcomes.

Meenan, R.T., Hornbrook, M.C., Goodman, M.J., and others (2001, August). "Identifying 'high-cost' risks in defined populations." (AHRQ grants HS10688, T32 HS000698, and F32 HS00072). Preventive Medicine in Managed Care 2(4), pp. 179-191.

Integrated programs such as case management and disease management are intended to improve chronic care, an important element of which is early identification of patients at risk of serious clinical and financial sequelae. These authors present a conceptual framework and discuss existing techniques for identifying patients in health maintenance organization (HMO) populations who are at risk for high costs. Using a large multi-HMO database, they compare the ability of three risk-assessment models to distinguish high- and low-cost risks among 1.5 million HMO enrollees. They document that such models have both explanatory and predictive power, but it remains to be seen whether interventions directed by the results of these models will lead to improved health outcomes and lower costs.

Mikulich, Liu, Y.C. Steinfeldt, J., and Schriger, D.L. (2001). "Implementation of clinical guidelines through an electronic medical record: Physician usage, satisfaction, and assessment." (AHRQ grant HS06284). International Journal of Medical Informatics 63, pp. 169-178.

These investigators developed and evaluated the Emergency Department Expert Charting System (EDECS) to provide real-time guidance for emergency department (ED) care of low back pain in adults, fever in children, and occupational exposure to blood and body fluids in health care workers by embedding clinical guidelines within an electronic medical record. They used pre- and post-EDECS use questionnaires to survey 142 ED physicians about their behaviors and attitudes and found that 84 percent of doctors used EDECS at least once. Median session time using EDECS decreased from 12 minutes for session 1, to 5.5 minutes for sessions 16 and above. Doctors generally agreed that care with EDECS was better than standard care, particularly with respect to documentation. These findings highlight both the potential of computer-assisted decisionmaking and the need for context-specific approaches when trying to implement guidelines, conclude the researchers.

Mullan, J.T., and Harrington, C. (2001, September). "Nursing home deficiencies in the United States." (AHRQ grant HS07574). Research on Aging 23(5), pp. 503-531.

Poor quality of care in nursing homes has concerned consumers, professionals, and policymakers for some time. This paper presents a confirmatory factor analysis (CFA) of deficiencies in nursing homes obtained from the On-Line Survey Certification and Reporting system, a national database on nursing home quality maintained by the Centers for Medicare & Medicaid Services (formerly the Health Care Financing Administration). The analysis suggests that there are eight underlying quality of care factors to which State surveyors can respond as they assign deficiencies to nursing homes. The factors are: patient-specific quality of care, including nutrition, personal hygiene, bladder control, and fluid intake, as well as prevention of pressure sores; freedom from abuse such as physical restraints; periodic resident assessment; protection of resident rights; provision of a safe, clean, and comfortable environment; good nutrition; pharmacy quality that sustains few medication errors; and quality administration that includes periodic staff training and performance reviews, proper maintenance of clinical records, and a quality assurance committee.

Patton, L.L., Bonito, A.J., and Shugars, D.A. (2001, August). "A systematic review of the effectiveness of antifungal drugs for the prevention and treatment of oropharyngeal candidiasis in HIV-positive patients." (AHRQ contract 290-97-0011). Oral Surgery, Oral Medicine, Oral Pathology 92, pp. 170-179.

Oral candidiasis is one of the most common, treatable oral mucosal infections seen in people infected with HIV. It can cause frequent and significant discomfort, pain, loss of taste, and aversion to food and may lead to secondary complications such as esophageal candidiasis in some patients. For these reasons, antifungal prophylaxis may be justified in some high-risk patients (CD4 counts less than 200), suggest these researchers. They systematically reviewed clinical trials published between 1966 and 2000 to determine the strength of evidence for the effectiveness of a variety of antifungal drugs to prevent and treat oral candidiasis in HIV-positive patients. The evidence for the prophylactic efficacy of fluconazole was good, although evidence was insufficient to draw conclusions about other antifungals. Evidence for treatment effectiveness was insufficient for amphotericin B but good for nystatin, clotrimazole, fluconazole, ketoconazole, and itraconazole.

Pindzola, R.R., Balzer, J.R., Nemoto, E.M., and others (2001, August). "Cerebrovascular reserve in patients with carotid occlusive disease assessed by stable xenon-enhanced CT cerebral blood flow and transcranial Doppler." (AHRQ grant HS09021). Stroke 32, pp. 1811-1817.

Measurement of cerebrovascular reserve (CVR) by transcranial Doppler ultrasonography (TCD) or quantitative cerebral blood flow (CBF) can identify subgroups of patients at increased risk for stroke. However, TCD is much less sensitive than xenon-enhanced computerized tomography (Xe/CT) CBF for identifying patients with compromised CVR, concludes this study. This may be due to the inability of TCD to identify patients with compromised reserves when their middle cerebral artery blood flow comes from collateral sources. The lack of correlation between TCD and Xe/CT CBF for identifying patients with compromised CVR should be considered when stroke risk assessments are made by TCD, caution the researchers. They compared CVRs before and after acetazolamide administration in 38 patients with occluded carotid arteries.

Shekelle, P.G., Park, R.E., Kahan, J.P., and others (2001). "Sensitivity and specificity of the RAND/UCLA Appropriateness method to identify the overuse and underuse of coronary revascularization and hysterectomy." (AHRQ grant HS07185). Journal of Clinical Epidemiology 54, pp. 1004-1010.

Escalating medical costs have intensified scrutiny of the appropriateness of many medical and surgical procedures. One frequently used method to assess the appropriateness of medical procedures, known as the RAND/UCLA Appropriateness Method, combines expert opinion with scientific evidence. However, this method has been criticized for poor reproducibility and the potential for misclassification, that is, labeling a procedure as inappropriate when it is not. The researchers performed a parallel three-way replication of the appropriateness panel process for each of two procedures, coronary revascularization (all indications) and hysterectomy (for non-emergency, non-oncologic indications). They concluded that past applications of the appropriateness method have overestimated the overuse of hysterectomy, underestimated the overuse of coronary revascularization, and provided true estimates of the underuse of revascularization. Thus, the sensitivity and specificity of the RAND/UCLA appropriateness method vary according to the procedure assessed and appear to estimate the underuse of procedures more accurately than their overuse.

Silber, J.H., Rosenbaum, P.R., Trudeau, M.E., and others (2001). "Multivariate matching and bias reduction in the surgical outcomes study." (AHRQ grant HS09460). Medical Care 39(10), pp. 1-17.

Studies on patient outcomes often need a level of detail that cannot be found in administrative data, thereby requiring abstraction of medical charts. Case-control methods may be used to improve statistical power and reduce abstraction costs, but limitations of exact matching often preclude the use of many covariates. Unlike exact matching, multivariate matching may allow cases to be matched simultaneously on hundreds of covariates. To develop matched case-control pairs in a study of death after surgery in Medicare patients, the researchers used 830 randomly selected patients who died within 60 days from admission and controls who did not die within that time period. Patients were matched on risk of death and other characteristics with up to 173 variables used simultaneously in matching algorithms. Matched controls were far more similar upon admission to patients who died than typical patients. The authors conclude that multivariate matching methods may aid in conducting studies with Medicare claims records by improving the quality of matches.

Wagner, T.H., Hibbard, J.H., Greenlick, M.R., and Kunkel, L. "Does providing consumer health information affect self-reported medical utilization?"; and Wagner, T.H., and Greenlick, M.R. (2001). "When parents are given greater access to health information, does it affect pediatric utilization?" (AHRQ grant HS09997). Medical Care 39(8), pp. 836-847, 848-855.

These researchers conducted a randomized survey of households in Boise, ID, to determine whether providing health information to Boise residents had an effect on their self-reported use of medical services. They mailed questionnaires to the household before and after residents were provided free access to self-care books, telephone advice nurses, and Internet-based health information (via libraries and other places). The first study showed that Boise residents had a higher adjusted odds of entering care (odds ratio 1.27) and 0.1 more doctor visits compared with residents of control cities. However, both effects were small and not significant. A second study analyzed the impact of this health information campaign on parents' use of pediatric care for their children. In this case, the greater access to health information was associated with decreased use of pediatric care, but the significance of the decrease depended on the statistical model used.

Weisman, C.S., Henderson, J.T., Schifrin, E., and others (2001, September). "Gender and patient satisfaction in managed care plans: Analysis of the 1999 HEDIS/CAHPS®." Women's Health Issues 11(4), pp. 401-415.

These researchers investigated differences between men and women in health plan satisfaction and in variables associated with satisfaction, using the Consumer Assessment of Health Plans Study (CAHPS®) adult questionnaire. They analyzed responses representative of nearly 100,000 men and women enrolled in 206 commercial managed care plans nationwide. Mean plan-level differences by sex in satisfaction were small, with no consistent pattern of one sex being more satisfied than the other. Controlling for health plan, member, care use, and selected performance indicators, health plan characteristics accounted for the largest variation in satisfaction. However, not-for-profit plan status and lower turnover of primary care providers were stronger determinants of women's than men's satisfaction. The researchers concluded that analyzing CAHPS® scores by sex may help identify areas for quality improvement in women's care.

Reprints (AHRQ Publication No. 02-R007) are available from the AHRQ Publications Clearinghouse.

Zimmerman, R.K., Silverman, M., Janosky, J.E., and others (2001, August). "A comprehensive investigation of barriers to adult immunization." (AHRQ grant HS09874). Journal of Family Practice 50(8), pp. 703-715.

These investigators developed a multicomponent approach to identify factors that affect adult immunization rates, which are below desired levels among the elderly. They used the PRECEDE-PROCEED framework that allows users to evaluate health problems and design intervention programs and incorporated the Awareness to Adherence physician decisionmaking model and the Triandis consumer decisionmaking model to capture behavioral and educational issues related to health practices. They collected data using focus groups, face-to-face and telephone interviews, self-administered surveys, site visits, participant observation, and medical record review of a broad spectrum of patients from inner-city neighborhood health centers, clinics in Veterans Affairs facilities, rural practices in a network, and urban/suburban practices in a network. The researchers concluded that this approach can be used to identify barriers to immunization in individual practices and develop tailored intervention plans for those practices.

Zou, K.H., and Normand, S.T. (2001). "On determination of sample size in hierarchical binomial models." (AHRQ grant HS09487). Statistics in Medicine 20, pp. 2163-2182.

These researchers summarize the issues involved in determining sample size when interest centers on comparing provider performance, and they describe a new simulation-based approach to solving the problem. The researchers argue that investigators should adopt an estimation framework (as opposed to hypothesis testing) when interest centers on comparing care quality. To do this, they provide a method to determine the number of patients needed per provider in order to estimate a performance measure to within a specified level of precision, when the number of providers (hospitals, physicians, health plans, etc.) is fixed.

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Current as of November 2001
AHRQ Publication No. 02-0007

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