Influence of Physician Characteristics on the Treatment of Prostate Cancer Public
Quek, Ruben Guang Wei (2013)
Abstract
This dissertation is prepared in light of the ongoing debate about prostate cancer overtreatment, with its attendant implications for patient outcomes and U.S. health care expenditures. Physician characteristics and changes in drug reimbursement rates have been shown to influence practice patterns regardless of clinical guidelines and patient, clinical or sociodemographic factors. This dissertation consists of three essays investigating the effect of physician characteristics on prostate cancer treatment and referral patterns.
The first essay examined the association between urologists' practice affiliations with medical schools and guideline discordant use of primary medical androgen deprivation therapy (ADT) for clinically localized prostate cancer patients, before and after the 2003 Medicare Modernization Act (MMA)'s reductions in ADT reimbursement rates. The odds of patients receiving guideline discordant ADT started to decrease before the MMA. In addition, patients treated by urologists without medical schools affiliations are significantly more likely to receive guideline discordant ADT before and after the passage of the MMA.
The second essay investigated the impact of the urologist on the likelihood that patients with locoregional prostate cancer would consult a radiation oncologist. Patients with locoregional prostate cancer who receive their diagnostic biopsy from urologists practicing in non-institutional settings and/or those who consulted older urologists are significantly more likely to eventually consult a radiation oncologist.
For patients with low-risk clinically localized prostate cancer, the third essay explored the association between patients' clinical, sociodemographic and radiation oncologists' characteristics have on the likelihood that patients received combined external beam radiation therapy and brachytherapy- a treatment regimen at variance with clinical guidelines. Patients' geographic and sociodemographic factors are significantly associated with guideline discordant radiation therapy for patients diagnosed with low-risk clinically localized prostate cancer. Which radiation oncologist a patient consults is important in determining whether they receive combined radiation therapy.
Prostate cancer patients receiving treatments at variance to guidelines and especially those receiving more care than guidelines recommend may be faced with unnecessary health care costs coupled with increased risks for genitourinary and/or gastrointestinal toxicity and decreased quality of life. Efforts directed at reducing guideline discordant treatment and referral patterns among prostate cancer patients are needed.
Table of Contents
Table of Contents
CHAPTER 1 BACKGROUND.. 1
Introduction - Prostate Cancer 1
Prostate Cancer Treatment Modalities. 1
Physicians Influence. 2
Clinical Practice Guidelines. 2
Physician Practice Settings. 3
Physician Financial Incentives. 4
Other Physician Characteristics. 6
Patient Characteristics. 7
CHAPTER 2 CONCEPTUAL MODEL AND HYPOTHESES TESTING.. 12
Conceptual Model 12
Construct Measurement 12
Testable Hypotheses. 15
First Essay. 15
First Essay Hypothesis 1. 15
First Essay Hypothesis 2. 15
Second Essay. 16
Second Essay Hypothesis 1. 16
Third Essay. 16
Third Essay Hypothesis 1. 16
CHAPTER 3 DATA SOURCES.. 26
Surveillance, Epidemiology and End Results - Medicare Database. 26
Surveillance, Epidemiology and End Results Program.. 26
Medicare Data. 27
SEER-Medicare Linkage. 27
Data Limitations. 28
American Medical Association Physician Masterfile. 29
Data Limitations. 30
CHAPTER 4 ANALYTIC STRATEGY.. 34
Χ2 Test of Homogeneity. 34
Expected frequency counts. 34
Test statistic. 34
Hierarchical Generalized Linear Mixed Models. 35
Covariance Structure. 36
Model Building Approach. 36
Intraclass Correlation Coefficient 38
Collinearity Diagnostics. 39
CHAPTER 5 FIRST ESSAY -- REIMBURSEMENT POLICY AND USE OF MEDICAL ANDROGEN DEPRIVATION THERAPY FOR CLINICALLY LOCALIZED PROSTATE CANCER.. 41
Introduction. 41
Methods. 43
Data Sources. 43
Patient Characteristics. 43
Urologist Characteristics. 44
Urologist Medical School Affiliation. 45
Measurement of Treatment and Outcomes. 46
Statistical Analyses. 47
Results. 48
Discussion. 50
References. 64
CHAPTER 6 SECOND ESSAY -- ROLE OF THE UROLOGIST IN WHETHER LOCOREGIONAL PROSTATE CANCER PATIENTS CONSULT A RADIATION ONCOLOGIST. 74
Introduction. 74
Methods. 76
Data Sources. 76
Patient Characteristics. 77
Urologist Characteristics. 78
Urologist Medical School Affiliation. 78
Measurement of Outcomes. 79
Statistical Analyses. 80
Results. 81
Discussion. 84
References. 96
CHAPTER 7 THIRD ESSAY -- DETERMINANTS OF THE COMBINED USE OF EXTERNAL BEAM RADIATION THERAPY AND BRACHYTHERAPY FOR LOW-RISK CLINICALLY LOCALIZED PROSTATE CANCER.. 102
Introduction. 102
Methods. 104
Data Sources. 104
Patient Characteristics. 104
Radiation Oncologist Characteristics. 105
Radiation Oncologists Medical School Affiliation. 106
Measurement of Treatment and Outcomes. 107
Statistical Analyses. 108
Results. 109
Discussion. 112
References. 124
CHAPTER 8 CONCLUSIONS, POLICY IMPLICATIONS AND FUTURE RESEARCH.. 135
Conclusions. 135
Conclusion Regarding First Essay Hypothesis 1. 135
Conclusion Regarding First Essay Hypothesis 2. 135
Conclusion Regarding Second Essay Hypothesis 1. 135
Conclusion Regarding Third Essay Hypothesis 1. 136
Policy Implications and Future Research. 137
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