Browsing by Author "Narayan, KM Venkat"

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    Changes in Health State Utilities With Changes in Body Mass in the Diabetes Prevention Program
    (2009-12) Ackermann, Ronald T.; Edelstein, Sharon L.; Narayan, KM Venkat; Zhang, Ping; Engelgau, Michael M.; Herman, William H.; Marrero, David G.
    Health utilities are measures of health-related quality of life (HRQL) used in cost-effectiveness research. We evaluated whether changes in body weight were associated with changes in health utilities in the Diabetes Prevention Program (DPP) and whether associations differed by treatment assignment (lifestyle intervention, metformin, placebo) or baseline obesity severity. We constructed physical (PCS-36) and mental component summary (MCS-36) subscales and short-form-6D (SF-6D) health utility index for all DPP participants completing a baseline 36-item short form (SF-36) HRQL assessment (N = 3,064). We used linear regression to test associations between changes in body weight and changes in HRQL indicators, while adjusting for other demographic and behavioral variables. Overall differences in HRQL between treatment groups were highly statistically significant but clinically small after 1 year. In multivariable models, weight change was independently associated with change in SF-6D score (increase of 0.007 for every 5 kg weight loss; P < 0.001), but treatment effects independent of weight loss were not. We found no significant interaction between baseline obesity severity and changes in SF-6D with changes in body weight. However, increases in physical function (PCS-36) with weight loss were greater in persons with higher baseline obesity severity. In summary, improvements in HRQL are associated with weight loss but not with other effects of obesity treatments that are unrelated to weight loss. Although improvements in the SF-6D did not exceed commonly reported thresholds for a minimally important difference (0.04), these changes, if causal, could still have a significant impact on clinical cost-effectiveness estimates if sustained over multiple years.
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    Referral management and the care of patients with diabetes: the Translating Research Into Action for Diabetes (TRIAD) study.
    (2004-02) Kim, Catherine; Williamson, David F.; Herman, William H.; Safford, Monika M.; Selby, Joseph V.; Marrero, David G.; Curb, David; Thompson, Theodore J.; Narayan, KM Venkat; Mangione, Carol M.
    OBJECTIVE: To examine the effect of referral management on diabetes care. STUDY DESIGN: Cross-sectional analysis. PATIENTS AND METHODS: Translating Research Into Action for Diabetes (TRIAD) is a multicenter study of managed care enrollees with diabetes. Prospective referral management was defined as "gatekeeping" and mandatory preauthorization from a utilization management office, and retrospective referral management as referral profiling and appropriateness reviews. Outcomes included dilated eye exam; self-reported visit to specialists; and perception of difficulty in getting referrals. Hierarchical models adjusted for clustering and patient age, gender, race, ethnicity, type and duration of diabetes treatment, education, income, health status, and comorbidity. RESULTS: Referral management was commonly used by health plans (55%) and provider groups (52%). In adjusted analyses, we found no association between any referral management strategies and any of the outcome measures. CONCLUSIONS: Referral management does not appear to have an impact on referrals or perception of referrals related to diabetes care.
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    Value of Urinary Albumin-to-Creatinine Ratio as a Predictor of Type 2 Diabetes in Pre-Diabetic Individuals
    (2008-12) Friedman, Allon; Marrero, David G.; Ma, Yong; Ackermann, Ronald; Narayan, KM Venkat; Barrett-Connor, Elizabeth; Watson, Karol; Knowler, William C.; Horton, Edward S.
    OBJECTIVE: The albumin-to-creatinine ratio (ACR) reflects urinary albumin excretion and is increasingly being accepted as an important clinical outcome predictor. Because of the great public health need for a simple and inexpensive test to identify individuals at high risk for developing type 2 diabetes, it has been suggested that the ACR might serve this purpose. We therefore determined whether the ACR could predict incident diabetes in a well-characterized cohort of pre-diabetic Americans. RESEARCH DESIGN AND METHODS: A total of 3,188 Diabetes Prevention Program (DPP) participants with a mean BMI of 34 kg/m(2) and elevated fasting glucose, impaired glucose tolerance, and baseline urinary albumin excretion measurements were followed for incident diabetes over a mean of 3.2 years. RESULTS: Of the participants, 94% manifested ACR levels below the microalbuminuria range and 21% ultimately developed diabetes during follow-up. Quartiles of ACR (median [range] within quartiles: 1, 3.0 [0.7-3.7]; 2, 4.6 [3.7-5.5]; 3, 7.1 [5.5-9.7]; and 4, 16.5 [9.7-1,578]) were positively associated with age, markers of adiposity and insulin secretion and resistance, blood pressure, and use of antihypertensive agents with antiproteinuric effects and inversely related to male sex and serum creatinine. An elevated hazard rate for developing diabetes with doubling of ACR disappeared after adjustment for covariates. Within the DPP intervention groups (placebo, lifestyle, and metformin), we found no consistent trend in incident diabetes by quartile or decile of ACR. CONCLUSIONS: An ACR at levels below the microalbuminuria range does not independently predict incident diabetes in adults at high risk of developing type 2 diabetes.