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Research Briefs

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Cohen, S.B., Machlin, S.R., and Branscome, J.M. (2000). "Patterns of survey attrition and reluctant response in the 1996 Medical Expenditure Panel Survey." Health Services & Outcomes Research Methodology 1(2), pp. 131-148.

When researchers conduct national household health care surveys, they often allocate a significant amount of survey resources to obtain participation from people who initially decline to participate. This is necessary in order to complete the target of sampled households. This study describes a way to identify the characteristics that distinguish survey participants across survey rounds from the part-year respondents. It also identifies factors that distinguish the cooperative respondents, the reluctant respondents, and the part-year respondents to better inform the data collection of the Agency for Healthcare Research and Quality's Medical Expenditure Panel Survey (MEPS). The AHRQ researchers found that reluctant respondents in the first round of the survey were significantly more likely to become nonrespondents in the second round. If no effort had been made to convert reluctant participants, the precision of the MEPS estimates would have declined but not substantially.

Reprints (AHRQ Publication No. 00-R052) are available from the AHRQ Publications Clearinghouse.

Engels, E.A., Terrin, N., Barza, M., and Lau, J. (2000). "Meta-analysis of diagnostic tests for acute sinusitis." (AHRQ Contract No. 290-97-0019). Journal of Clinical Epidemiology 53, pp. 852-862.

The most accurate and cost-effective methods for diagnosing acute sinusitis remain uncertain. This meta-analysis of diagnostic tests for acute sinusitis concluded that many studies were of poor quality, with inadequately described test methods and unblinded test interpretation. Based on sinus puncture/aspiration (considered most accurate), 49 to 83 percent of symptomatic patients had acute sinusitis. Compared with puncture/aspiration, radiography offered moderate ability to diagnose sinusitis. Studies evaluating ultrasonography revealed substantial variation in test performance. The clinical evaluation, including medical history and physical examination findings, had moderate ability to identify patients with positive radiographs. The authors conclude that radiography and clinical evaluation provide useful information for diagnosis of sinusitis.

Editor's Note: This article is drawn from an evidence report prepared for AHRQ by the New England Medical Center Evidence-based Practice Center. Copies of the full report, Diagnosis and Treatment of Acute Bacterial Rhinosinusitis, (AHRQ Publication No. 99-E016) and a summary (AHRQ Publication No. 99-E015) are available from the AHRQ Publications Clearinghouse.

Freiman, M.P., and Zuvekas, S.H. (2000). "Determinants of ambulatory treatment mode for mental illness." Health Economics 9, pp. 423-434.

These authors analyze the determinants of the use of outpatient treatment from the specialty mental health sector along with the determinants of use of psychotropic drugs for mental conditions for a nationally representative sample of U.S. households. They found significant differences in treatment choice by education, sex, race, and ethnicity, while controlling for several aspects of self-reported mental health and treatment attitudes. For example, although women were more likely than men to use the specialty mental health sector and more likely to take psychotropic medications, this difference between men and women was much greater for psychotropic medications. The authors discuss how the estimated differences may reflect traditional patient preferences and may also reflect biases and misperceptions on the part of patients and providers. They also discuss how results relate to some findings and policies in the general health care sector.

Reprints (AHRQ Publication No. 00-R048) are available from the AHRQ Publications Clearinghouse.

Grembowski, D.E., Diehr, P., Novak, L.C., and others (2000, August). "Measuring the 'managedness' and covered benefits of health plans." (AHRQ grant HS06833). Health Services Research 35(3), pp. 707-734.

These researchers constructed managed care and benefit variables through analysis of health insurance information for 189 insurance product lines and 755 products in the Seattle area, and linked the variables with data on over 2,000 primary care patients. From the managed care variables, they constructed three provider-oriented indexes for the financial, utilization management, and network domains of health plans. From these, they constructed a single "managedness index," which correlated as expected with the individual measures, domain indexes, plan type, and independent assessments of local experts, as well as with patients' attitudes about their health insurance. The researchers also constructed an in-network benefits index and out-of-network benefits index, which they correlated with the "managedness" index. The authors discuss the potential uses of the "managedness" and benefit indexes, which were associated with the personal characteristics and health status of the study patients.

Health Outcomes Methodology Symposium Proceedings.

In September 1999, the Agency for Healthcare Research and Quality and the National Cancer Institute jointly sponsored a conference on health outcomes research methodology. The commissioned papers and other presentations from the conference were published recently in a special supplement to Medical Care. Four papers supported by AHRQ grants are summarized here. Nearly 20 other papers are contained in the proceedings.

See Medical Care, 38(9, Suppl II), September 2000.

Hays, R.D., Morales, L.S., and Reise, S.P. (2000). "Item response theory and health outcomes measurement in the 21st century." (AHRQ grant HS08578). Medical Care 38(9), pp. SII28-42.

This authors of this article compared classical test theory (CTT) and item response theory (IRT), two statistical techniques for measuring health outcomes. They found that IRT is superior and is ideally suited for implementing computer adaptive testing. In addition, IRT can be helpful in developing better health outcomes measures and in assessing change over time.

Patrick, D.L., and Chiang, Y-P. (2000). "Measurement of health outcomes in treatment effectiveness evaluations: Conceptual and methodological challenges." Medical Care 38(9), pp. SII14-25.

Evaluating the effectiveness of medical treatment often incorporates a wide variety of outcomes, such as physical measures, observational measures by clinicians, and patient or self-reports. This paper addresses the conceptual and methodological challenges to valid measurement of health outcomes. The authors point out that modern test theory offers the potential for individualized, comparable assessments and for the careful examination and application of different measurement models. Selection and critique of measures should be based on the intended application and accumulated evidence for that application. Also, validity in use is the most important measurement characteristic for treatment effectiveness. An evaluation of the validity of preference-based measures is particularly important for the interpretation and comparability of outcomes in cost-effectiveness evaluations. The researchers note that the successful translation of research into policy and practice is limited by the extent to which these critical issues are addressed in actual treatment evaluations.

Reprints (AHRQ Publication No. 00-R053) are available from the AHRQ Publications Clearinghouse.

Tsevat, J. (2000). "What do utilities measure?" (AHRQ grant HS09103). Medical Care 38(9), pp. SII160-164.

This paper examines utility measures, which assess the value or desirability of a state of health against an external metric. The most common instruments are the standard reference gamble, time tradeoff, and rating scale. The standard gamble determines the risk of (usually) death that one would be willing to take to improve a state of health. The time tradeoff technique asks how many months or years of life one would be willing to give up in exchange for a better health state. Scores on the standard gamble and time tradeoff can range from 0 to 1.0, where 0 usually represents death and 1 represents excellent or perfect health. The rating scale, perhaps the simplest of the 3, asks the patient to rate his or her health on a scale from 1 to 100. The author describes other utilities as well. The lack of a 1-to-1 relationship between health status and utilities does not compromise their validity when used as quality weights for quality-adjusted life years, according to the authors.

Wu, A.W. (2000). "Quality-of-life assessment in clinical research: Application in diverse populations." (AHRQ grant HS07824). Medical Care 38(9), pp. SII130-135.

This paper addresses the application of quality-of-life assessment in clinical research to diverse populations. These include groups that differ in terms of language, culture, age, sex, education, privilege, and resources, including but not restricted to so-called vulnerable populations. The author reviews common research designs that incorporate measures of health-related quality of life, suggests tests for the equivalence of measures using clinical data, and describes problems that may be encountered in applications to diverse populations. The author also examines several assumptions necessary to achieve "universality" of a measure, and explores whether this is attainable by examining research on differences in treatment effectiveness related to race and sex.

Jarvik, J.G., and Deyo, R.A. (2000, September). "Cementing the evidence: Time for a randomized trial of vertebroplasty." (AHRQ grants HS08194 and HS09499). American Journal of Neuroradiology 21(8), pp. 1373-1374.

Percutaneous vertebroplasty is a technique for treating low back pain that is gaining popularity in the United States. However, there still are no randomized controlled trials that compare the long-term outcomes of this procedure with a control therapy. This type of plastic surgery to prevent further collapse of the vertebrae, or even possibly restore height, might reduce the pain associated with osteoporotic compression fractures. However, this remains to be proven, according to the authors, who argue for controlled clinical trials of the procedure. They point out that vertebroplasty may well be an effective and even cost-effective method for treating low back pain. If the technique is as good as its promoters suggest, then it should be straightforward to demonstrate its efficacy in a well-designed trial that addresses if and when vertebroplasty should be done.

Yan, Y., Moore, R.D., and Hoover, D.R. (2000). "Competing risk adjustment reduces overestimation of opportunistic infection rates in AIDS." (AHRQ grant HS07809). Journal of Clinical Epidemiology 53, pp. 817-822.

To illustrate the importance of adjusting the estimates of cumulative incidence of AIDS-related illnesses for competing risk of other causes of death, these researchers compared unadjusted and adjusted (for competing events) incidence estimates for four AIDS-related illnesses: Pneumocystis carinii pneumonia (PCP), Mycobacterium avium complex (MAC), cytomegalovirus (CMV), and esophageal candidiasis, among patients with HIV disease at one hospital between 1989 and 1995. Ratios of 4-year unadjusted incidence estimates to 4-year adjusted incidence estimates for the four diseases ranged from 1.38 to 1.86, corresponding to cumulative death rates of 61 to 69 percent. For CMV, the ratios of 4-year unadjusted to adjusted incidence estimates for five groups of patients ranged from 1.5 to 2.33, corresponding to cumulative death rates of 48 to 78 percent. The researchers conclude that ignoring the competing risk of death can result in substantial overestimation of disease occurrence.

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Current as of November 2000
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