Browsing by Subject "Propensity score"

Now showing 1 - 4 of 4
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    Comparative risk of severe hypoglycemia among concomitant users of thiazolidinedione antidiabetic agents and antihyperlipidemics
    (Elsevier, 2016-05) Leonard, Charles E.; Han, Xu; Bilker, Warren B.; Flory, James H.; Brensinger, Colleen M.; Flockhart, David A.; Gagne, Joshua J.; Cardillo, Serena; Hennessy, Sean; Department of Medicine, IU School of Medicine
    We conducted high-dimensional propensity score-adjusted cohort studies to examine whether thiazolidinedione use with a statin or fibrate was associated with an increased risk of severe hypoglycemia. We found that concomitant therapy with a thiazolidinedione+fibrate was associated with a generally delayed increased risk of severe hypoglycemia.
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    New statistical methods for the evaluation of effectivenss and safety of a medical intervention in using observational data
    (2016-12-05) Zhan, Jia; Shen, Changyu; Li, Xiaochun; Li, Lingling; Xu, Huiping; Wessel, Jennifer
    Observational studies offer unique advantages over randomized clinical trials (RCTs) in many situations where RCTs are not feasible or suffer from major limitations such as insufficient sample sizes and narrowly focused populations. Because observational data are relatively easy and inexpensive to access, and contain rich and comprehensive demographic and medical information on large and representative populations, they have played a major role in the assessment of the effectiveness and safety of medical interventions. However, observational data also have the challenges of higher rates of missing data and the confounding effect. My proposal is on the development of three statistical methods to address these challenges. The first method is on the refinement and extension of a multiply robust (MR) estimation procedure that simultaneously accounts for the confounding effect and missing covariate process, where we derived the asymptotic variance estimator and extended the method to the scenario where the missing covariate is continuous. The second method focuses on the improvement of estimation precision in an RCT by a historical control cohort. This was achieved through augmenting the conventional effect estimator with an extra mean zero (approximately) term correlated with the conventional effect estimator. In the third method, we calibrated the hidden database bias of an electronic medical records database and utilized an empirical Bayes method to improve the accuracy of the estimation of the risk of acute myocardial infarction associated with a drug by borrowing information from other drugs.
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    Severe hypoglycemia in users of sulfonylurea antidiabetic agents and antihyperlipidemics
    (Wiley, 2016-05) Leonard, Charles E.; Bilker, Warren B.; Brensinger, Colleen M.; Han, Xu; Flory, James H.; Flockhart, David A.; Gagne, Joshua J.; Cardillo, Serena; Hennessy, Sean; Department of Medicine, IU School of Medicine
    Drug-drug interactions causing severe hypoglycemia due to antidiabetic drugs is a major clinical and public health problem. We assessed whether sulfonylurea use with a statin or fibrate was associated with severe hypoglycemia. We conducted cohort studies of users of glyburide, glipizide, and glimepiride plus a statin or fibrate within a Medicaid population. The outcome was a validated, diagnosis-based algorithm for severe hypoglycemia. Among 592,872 persons newly exposed to a sulfonylurea+antihyperlipidemic, the incidence of severe hypoglycemia was 5.8/100 person-years. Adjusted hazard ratios (HRs) for sulfonylurea+statins were consistent with no association. Most overall HRs for sulfonylurea+fibrate were elevated, with sulfonylurea-specific adjusted HRs as large as 1.50 (95% confidence interval (CI): 1.24-1.81) for glyburide+gemfibrozil, 1.37 (95% CI: 1.11-1.69) for glipizide+gemfibrozil, and 1.63 (95% CI: 1.29-2.06) for glimepiride+fenofibrate. Concomitant therapy with a sulfonylurea and fibrate is associated with an often delayed increased rate of severe hypoglycemia.
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    What Are the Benefits of Hip Resurfacing in Appropriate Patients? A Retrospective, Propensity Score-Matched Analysis
    (Sage, 2020-12) McLawhorn, Alexander S.; Buller, Leonard T.; Blevins, Jason L.; Lee, Yuo Yu; Su, Edwin P.; Orthopaedic Surgery, School of Medicine
    Background: Hip arthritis is one of the major causes of disability worldwide. Hip resurfacing arthroplasty (HRA) has emerged in recent years as an alternative to total hip arthroplasty (THA), but complications of HRA have limited the patient population to younger male patients with primary osteoarthritis and large hip anatomy. How the functional benefits of HRA in this population compare with those of THA is not entirely clear. Questions/purposes: The primary aim of this study was to determine whether there were differences in hip disability and patient satisfaction with surgery between these two groups at 2 years after surgery, using patient-reported outcome measures (PROMs) and subjective measures of patient satisfaction. Additionally, we sought to determine whether there were differences in post-operative discharge disposition, revision rates, or adverse events. Methods: We searched an institutional database to identify patients undergoing unilateral HRA or THA between January 2007 and July 2011 who met today's recommended criteria for HRA: younger male patients with large-enough hip anatomy to make surgery viable (a femoral head of at least 48 mm in HRA patients and, in THA patients, an acetabular shell size of 54 mm, the minimum outer shell size that could accommodate a femoral head component of 48 mm; for matching purposes, acetabular shell size in THA was used as a surrogate for the femoral head size used in HRA). We used propensity score matching to control for potentially confounding pre-operative variables and administered the Hip Disability and Osteoarthritis Outcome Score (HOOS) survey, including its subdomains, at the 2-year mark. We also assessed differences between groups in Lower Extremity Activity Scale scores, 12-item Short Form Health Survey results, and answers regarding satisfaction with surgery. We calculated minimal detectable change, minimum clinically important change, and substantial clinical benefit using anchor-based techniques for multiple outcome measures. Results: There were 251 patients in each group. HRA patients scored significantly higher than THA patients on the 2-year HOOS sports and recreation (92 versus 87, respectively) and on rates of overall satisfaction (94% versus 89%, respectively). The HRA group also had a greater chance of achieving minimum clinically important change (18.75 points) in the HOOS sports and recreation subdomains than the THA group (97% versus 91%). No significant difference was found in 6-month adverse event rates. HRA patients also had a significantly shorter mean hospital stay, a higher rate of discharge to home, and a lower incidence of a "significant" limp after surgery. Conclusion: HRA may provide a functional benefit in sports and recreation and greater satisfaction in patients who meet the current criteria for HRA. Because these benefits may be small, pre-operative counseling should focus on balancing the possible functional benefits against the longer-term risks associated with metal-on-metal bearings.