Browsing by Author "Kim, Woohyeon"

Now showing 1 - 4 of 4
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    Follow-up Colonoscopies: Referral Patterns and Outcomes in Colorectal Cancer Survivors
    (James A. Baker III Institute for Public Policy, 2019) Kim, Woohyeon; Mac Gregor, Mariana Chavez; Ho, Vivian; James A. Baker III Institute for Public Policy
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    Health Reform Monitoring Survey-Texas, Issue Brief #10: Marketplace Plans: Premiums, Network Size and Market Competition
    (James A. Baker III Institute for Public Policy;Episcopal Health Foundation, 2014) Kim, Woohyeon; Marks, Elena M.; Short, Marah Noel; Crowe, Hannah; Ho, Vivian; James A. Baker III Institute for Public Policy
    Since late 2013, individuals have been able to shop for and purchase private health insurance through the Marketplace via Healthcare.gov. Through the Marketplace, Texans can learn what plans are available to them, examine the features of the plans, determine whether they qualify for tax credits to lower their premiums, and purchase the plan that is best suited to their needs. During the first year of the Affordable Care Act’s Health Insurance Marketplace, consumers learned that many plans offered limited provider networks. This issue brief examines the availability of Marketplace plans in Texas, the number of in-network hospitals in the plans, and other plan characteristics influencing premiums. Our analysis focuses on Marketplace Silver plans, because they provide the benchmark by which premium-reducing tax credits are determined and because the majority of Texans who purchased Marketplace plans chose a Silver plan.
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    Measuring the Volume-Outcome Relation for Complex Hospital Surgery
    (Springer, 2016) Kim, Woohyeon; Wolff, Stephen; Ho, Vivian; James A. Baker III Institute for Public Policy
    Background: Prominent studies continue to measure the hospital volume-outcome relation using simple logistic or random-effects models. These regression models may not appropriately account for unobserved differences across hospitals (such as differences in organizational effectiveness) which could be mistaken for a volume outcome relation. Objective: To explore alternative estimation methods for measuring the volume-outcome relation for six major cancer operations, and to determine which estimation method is most appropriate. Methods: We analyzed patient-level hospital discharge data from three USA states and data from the American Hospital Association Annual Survey of Hospitals from 2000 to 2011. We studied six major cancer operations using three regression frameworks (logistic, fixed-effects, and random-effects) to determine the correlation between patient outcome (mortality) and hospital volume. Results: For our data, logistic and random-effects models suggest a non-zero volume effect, whereas fixed-effects models do not. Model-specification tests support the fixed-effects or random-effects model, depending on the surgical procedure; the basic logistic model is always rejected. Esophagectomy and rectal resection do not exhibit significant volume effects, whereas colectomy, pancreatic resection, pneumonectomy, and pulmonary lobectomy do.
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    Three Essays on the Efficiency of Medical Providers
    (2016-04-22) Kim, Woohyeon; Ho, Vivian
    Physicians use colonoscopy to detect recurrent colorectal cancer for patients who have had colorectal cancer surgery. Clinical studies show both underuse and overuse of this test among survivors of colorectal cancer in relation to guideline recommendations. Yet few studies have examined referrals and test findings. To identify determinants of colonoscopy referral for colorectal cancer survivors and ex-post test outcome, Chapter 1 examines Texas cancer registry data linked with Medicare claims from 2000 to 2009 for colorectal cancer survivors with a history of resection surgery. Risk-adjusted regression analyses are used to measure the association of patient, referring physician and clinical factors with referrals and test results. Intestinal symptoms, the timing of referrals, and referring physician specialty are associated with referral decisions and test results. Gastroenterologists are more likely to refer patients for colonoscopy than oncologists, surgeons or primary care physicians, but their rates of positive test results are the lowest. The discrepancy between referral decisions and test results suggests suboptimal test use. Chapter 2 studies referral patterns for colonoscopies and applies cost-benefit analysis to examine whether this test has been overused or underused among patients with a cancer history. A key aspect of the analysis is that the ex post value of colonoscopy is partially observable in insurance claims records based on whether the test identifies recurrent cancer. Estimating the physician-specific parameter representing physicians' practice styles, I find that referral patterns exhibit physician-level heterogeneity. The percentage of physicians who overuse colonoscopy varies with physician specialty: A significant number of gastroenterologists overuse colonoscopy, whereas a much lower portion of oncologists and primary care doctors overuse it. These findings illustrate the need for well-targeted health care policies to curb growing health care costs. Chapter 3 measures the relationship between hospital volume and patient mortality for six cancer operations (colectomy, esophagectomy, pancreatic resection, pneumonectomy, pulmonary lobectomy, and rectal resection). Analyzing hospital discharge data from Florida, New Jersey, and New York for the 12 years 2000 to 2011, we find that the statistical significance of hospital volume depends critically on the regression model used: for the data, logistic and random-effects models suggest that higher volume is associated with lower mortality, but fixed-effects models do not. Model-specification tests support either the fixed-effects or random-effects model, depending on the surgical procedure; the basic logistic model is always rejected. These findings illustrate the importance of testing alternative model specifications, especially when drawing policy conclusions about promoting high-volume facilities.