Til Stürmer
Biographic Data
| ID | 5535056 |
|---|---|
| NAME | Til Stürmer |
| GIVEN NAMES | Til |
| FAMILY NAME | Stürmer |
| SIGNATURE | STÜRMER T |
| AFFILIATIONS | University of North Carolina at Chapel Hill |
| ORCID | 0000-0002-9204-7177 |
| VERIFIED | Yes |
| TOTAL WORKS | 22 |
| TOTAL CITATIONS | 0 |
| WORKS AS AUTHOR | 22 |
| WORKS AS EDITOR | 0 |
| FIRST PUBLICATION YEAR | 2006 |
| LATEST PUBLICATION YEAR | 2026 |
| H-INDEX | 0 |
Differences in the Measurement of Comorbidities Based on ICD-10-CM Coding Definitions Using Medicare Advantage Encounter Data and Fee-For-Service Claims
BACKGROUND: Medicare Advantage (MA) encounter data became available for research in 2019; data quality concerns remain. OBJECTIVES: We evaluated the consistency of ICD-10-CM comorbidity coding between MA and Fee-For-Service (FFS) data. METHODS: We used round 7 (2017) of the National Health and Aging Trends Study (NHATS) linked to Medicare enrollment, MA encounter, and FFS claims (2016-2017). We included participants continuously enrolled in MA or…
Ethno-Racial Differences in Age and Symptom Severity Among Pre-Menopausal Women Commencing Treatment for Benign Gynecological Conditions with a Levonorgestrel-Releasing Intrauterine Device
Introduction: Levonorgestrel-releasing intrauterine devices (LNG-IUDs) can be effective treatments for benign gynecological conditions, but there may be ethno-racial differences in how patients receive treatment. Methods: Data were from a health care system in the U.S. South (April 2014-September 2019). We identified 783 female patients aged 18-44 years with an LNG-IUD for a benign gynecological condition (455 White, 208 Black, and 120 Hispanic p…
Beyond Bleeding
Objectives: Black patients have the highest mortality rate from endometrial cancer (EC), and yet remain underrepresented in EC research. Thus, currently published symptom patterns may not be comprehensive for this population. The purpose of this study is to analyze symptomatology among Black patients with EC in the Guidelines for Ultrasound in the Detection of Early Endometrial Cancer study and to compare with those undergoing benign hysterectomy…
Multiple cardiovascular risk factor care in 55 low- and middle-income countries
The prevalence of multiple age-related cardiovascular disease (CVD) risk factors is high among individuals living in low- and middle-income countries. We described receipt of healthcare services for and management of hypertension and diabetes among individuals living with these conditions using individual-level data from 55 nationally representative population-based surveys (2009–2019) with measured blood pressure (BP) and diabetes biomarker. We …
Performance of a Claims-Based Frailty Proxy Using Varying Frailty Ascertainment Lookback Windows
BACKGROUND: Frailty is an aging-related syndrome of reduced physiological reserve to maintain homeostasis. The Faurot frailty index has been validated as a Medicare claims-based proxy for predicting frailty using billing information from a user-specified ascertainment window. OBJECTIVES: We assessed the validity of the Faurot frailty index as a predictor of the frailty phenotype and 1-year mortality using varying frailty ascertainment windows. RE…
Impacts of Initial Prescription Length and Prescribing Limits on Risk of Prolonged Postsurgical Opioid Use
BACKGROUND: In response to concerns about opioid addiction following surgery, many states have implemented laws capping the days supplied for initial postoperative prescriptions. However, few studies have examined changes in the risk of prolonged opioid use associated with the initial amount prescribed. OBJECTIVE: The objective of this study was to estimate the risk of prolonged opioid use associated with the length of initial opioid prescribed a…
Single-arm Trials With External Comparators and Confounder Misclassification
BACKGROUND: "Single-arm trials" with external comparators that contrast outcomes in those on experimental therapy to real-world patients have been used to evaluate efficacy and safety of experimental drugs in rare and severe diseases. Regulatory agencies are considering expanding the role these studies can play; guidance thus far has explicitly considered outcome misclassification with little discussion of misclassification of confounding variabl…
Comparison of Medicare Claims-based Proxy Measures of Poor Function and Associations With Treatment Receipt and Mortality in Older Colon Cancer Patients
BACKGROUND: Multiple claims-based proxy measures of poor function have been developed to address confounding in observational studies of drug effects in older adults. We evaluated agreement between these measures and their associations with treatment receipt and mortality in a cohort of older colon cancer patients. METHODS: Medicare beneficiaries age 66+ diagnosed with stage II-III colon cancer were identified in the Surveillance, Epidemiology, a…
Examining Parental Medication Adherence as a Predictor of Child Medication Adherence in Pediatric Anxiety Disorders
BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) are the recommended first-line pharmacotherapy for pediatric anxiety disorders but adherence remains difficult to predict. OBJECTIVES: To estimate SSRI adherence in children with anxiety disorders and determine if prior parental medication adherence is predictive of child high SSRI adherence. METHODS: We identified children (3-17 y) initiating SSRI treatment after an anxiety disorder dia…
Approaches to Address Premature Death of Patients When Assessing Patterns of Use of Health Care Services After an Index Event
BACKGROUND: Studies of the use of health care after the onset of disease are important for assessing quality of care, treatment disparities, and guideline compliance. Cohort definition and analysis method are important considerations for the generalizability and validity of study results. We compared different approaches for cohort definition (restriction by survival time vs. comorbidity score) and analysis method [Kaplan-Meier (KM) vs. competing…
Using Procedure Codes to Define Radiation Toxicity in Administrative Data
BACKGROUND: Systematic coding systems are used to define clinically meaningful outcomes when leveraging administrative claims data for research. How and when these codes are applied within a research study can have implications for the study validity and their specificity can vary significantly depending on treatment received. SUBJECTS: Data are from the Surveillance, Epidemiology, and End Results-Medicare linked dataset. STUDY DESIGN: We use pro…
Validation of Medicaid Claims-based Diagnosis of Myocardial Infarction Using an HIV Clinical Cohort
BACKGROUND: In nonexperimental comparative effectiveness research using health care databases, outcome measurements must be validated to evaluate and potentially adjust for misclassification bias. We aimed to validate claims-based myocardial infarction (MI) algorithms in a Medicaid population using an HIV clinical cohort as the gold standard. METHODS: Medicaid administrative data were obtained for the years 2002-2008 and linked to the UNC CFAR HI…
Assessing the Impact of Propensity Score Estimation and Implementation on Covariate Balance and Confounding Control Within and Across Important Subgroups in Comparative Effectiveness Research
PURPOSE: Researchers are often interested in estimating treatment effects in subgroups controlling for confounding based on a propensity score (PS) estimated in the overall study population. OBJECTIVE: To evaluate covariate balance and confounding control in sulfonylurea versus metformin initiators within subgroups defined by cardiovascular disease (CVD) history comparing an overall PS with subgroup-specific PSs implemented by 1:1 matching and st…
Evidence of Sample Use Among New Users of Statins
BACKGROUND: Epidemiologic studies of prescription medications increasingly rely on large administrative health care databases. These data do not capture patients' use of medication samples. This could potentially bias studies of short-term effects where date of initiation may be inaccurate. OBJECTIVES: To assess the extent of sample use among patients initiating statin therapy. RESEARCH DESIGN: Retrospective cohort of patients who filled a first …
Hospitalization and Skilled Nursing Care are Predictors of Influenza Vaccination Among Patients on Hemodialysis
BACKGROUND: Observational studies of preventive medications, such as vaccinations, can suffer from the healthy-user bias because vaccinated patients may be healthier than unvaccinated patients. Indicators of health status and frailty suitable for attenuating this bias could be identified in administrative data. OBJECTIVE: To examine the association of baseline variables and time-dependent hospitalization and skilled nursing care with the receipt …
Identifying Specific Chemotherapeutic Agents in Medicare Data
BACKGROUND: Large health care databases are increasingly used to examine the dissemination and benefits and harms of chemotherapy treatment in routine practice, particularly among patients excluded from trials (eg, the elderly). Misclassification of chemotherapy could bias estimates of frequency and association, warranting an updated assessment. METHODS: We evaluated the validity of Medicare claims to identify receipt of chemotherapy and specific…
Doubly Robust Estimation of Causal Effects
Doubly robust estimation combines a form of outcome regression with a model for the exposure (i.e., the propensity score) to estimate the causal effect of an exposure on an outcome. When used individually to estimate a causal effect, both outcome regression and propensity score methods are unbiased only if the statistical model is correctly specified. The doubly robust estimator combines these 2 approaches such that only 1 of the 2 models need be…
Depressive Symptoms, Social Support, and Risk of Adult Asthma in a Population-Based Cohort Study
OBJECTIVE: To investigate the association between depressive symptoms, social support, and prevalent as well as incident asthma. Depressive symptoms and social support may affect the development of asthma. This relationship could be mediated by health behaviors and/or inflammatory processes. Evidence from prospective cohort studies on depressive symptoms and social support in relation to asthma risk in adults remains sparse. METHODS: Between 1992…
Confounding Control in Healthcare Database Research
Epidemiologic studies are increasingly used to investigate the safety and effectiveness of medical products and interventions. Appropriate adjustment for confounding in such studies is challenging because exposure is determined by a complex interaction of patient, physician, and healthcare system factors. The challenges of confounding control are particularly acute in studies using healthcare utilization databases where information on many potent…
Increasing Levels of Restriction in Pharmacoepidemiologic Database Studies of Elderly and Comparison With Randomized Trial Results
BACKGROUND: The goal of restricting study populations is to make patients more homogeneous regarding potential confounding factors and treatment effects and thereby achieve less biased effect estimates. OBJECTIVES: This article describes increasing levels of restrictions for use in pharmacoepidemiology and examines to what extent they change rate ratio estimates and reduce bias in a study of statin treatment and 1-year mortality. METHODS: : The s…
Adjustments for Unmeasured Confounders in Pharmacoepidemiologic Database Studies Using External Information
BACKGROUND: Nonexperimental studies of drug effects in large automated databases can provide timely assessment of real-life drug use, but are prone to confounding by variables that are not contained in these databases and thus cannot be controlled. OBJECTIVES: To describe how information on additional confounders from validation studies can help address the problem of unmeasured confounding in the main study. RESEARCH DESIGN: Review types of vali…
Variable Selection for Propensity Score Models
Despite the growing popularity of propensity score (PS) methods in epidemiology, relatively little has been written in the epidemiologic literature about the problem of variable selection for PS models. The authors present the results of two simulation studies designed to help epidemiologists gain insight into the variable selection problem in a PS analysis. The simulation studies illustrate how the choice of variables that are included in a PS m…
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Variable Selection for Propensity Score Models
Despite the growing popularity of propensity score (PS) methods in epidemiology, relatively little has been written in the epidemiologic literature about the problem of variable selection for PS models. The authors present the results of two simulation studies designed to help epidemiologists gain insight into the variable selection problem in a PS analysis. The simulation studies illustrate how the choice of variables that are included in a PS m…
Increasing Levels of Restriction in Pharmacoepidemiologic Database Studies of Elderly and Comparison With Randomized Trial Results
BACKGROUND: The goal of restricting study populations is to make patients more homogeneous regarding potential confounding factors and treatment effects and thereby achieve less biased effect estimates. OBJECTIVES: This article describes increasing levels of restrictions for use in pharmacoepidemiology and examines to what extent they change rate ratio estimates and reduce bias in a study of statin treatment and 1-year mortality. METHODS: : The s…
Adjustments for Unmeasured Confounders in Pharmacoepidemiologic Database Studies Using External Information
BACKGROUND: Nonexperimental studies of drug effects in large automated databases can provide timely assessment of real-life drug use, but are prone to confounding by variables that are not contained in these databases and thus cannot be controlled. OBJECTIVES: To describe how information on additional confounders from validation studies can help address the problem of unmeasured confounding in the main study. RESEARCH DESIGN: Review types of vali…
Depressive Symptoms, Social Support, and Risk of Adult Asthma in a Population-Based Cohort Study
OBJECTIVE: To investigate the association between depressive symptoms, social support, and prevalent as well as incident asthma. Depressive symptoms and social support may affect the development of asthma. This relationship could be mediated by health behaviors and/or inflammatory processes. Evidence from prospective cohort studies on depressive symptoms and social support in relation to asthma risk in adults remains sparse. METHODS: Between 1992…
Confounding Control in Healthcare Database Research
Epidemiologic studies are increasingly used to investigate the safety and effectiveness of medical products and interventions. Appropriate adjustment for confounding in such studies is challenging because exposure is determined by a complex interaction of patient, physician, and healthcare system factors. The challenges of confounding control are particularly acute in studies using healthcare utilization databases where information on many potent…
Doubly Robust Estimation of Causal Effects
Doubly robust estimation combines a form of outcome regression with a model for the exposure (i.e., the propensity score) to estimate the causal effect of an exposure on an outcome. When used individually to estimate a causal effect, both outcome regression and propensity score methods are unbiased only if the statistical model is correctly specified. The doubly robust estimator combines these 2 approaches such that only 1 of the 2 models need be…
Hospitalization and Skilled Nursing Care are Predictors of Influenza Vaccination Among Patients on Hemodialysis
BACKGROUND: Observational studies of preventive medications, such as vaccinations, can suffer from the healthy-user bias because vaccinated patients may be healthier than unvaccinated patients. Indicators of health status and frailty suitable for attenuating this bias could be identified in administrative data. OBJECTIVE: To examine the association of baseline variables and time-dependent hospitalization and skilled nursing care with the receipt …
Identifying Specific Chemotherapeutic Agents in Medicare Data
BACKGROUND: Large health care databases are increasingly used to examine the dissemination and benefits and harms of chemotherapy treatment in routine practice, particularly among patients excluded from trials (eg, the elderly). Misclassification of chemotherapy could bias estimates of frequency and association, warranting an updated assessment. METHODS: We evaluated the validity of Medicare claims to identify receipt of chemotherapy and specific…
Assessing the Impact of Propensity Score Estimation and Implementation on Covariate Balance and Confounding Control Within and Across Important Subgroups in Comparative Effectiveness Research
PURPOSE: Researchers are often interested in estimating treatment effects in subgroups controlling for confounding based on a propensity score (PS) estimated in the overall study population. OBJECTIVE: To evaluate covariate balance and confounding control in sulfonylurea versus metformin initiators within subgroups defined by cardiovascular disease (CVD) history comparing an overall PS with subgroup-specific PSs implemented by 1:1 matching and st…
Evidence of Sample Use Among New Users of Statins
BACKGROUND: Epidemiologic studies of prescription medications increasingly rely on large administrative health care databases. These data do not capture patients' use of medication samples. This could potentially bias studies of short-term effects where date of initiation may be inaccurate. OBJECTIVES: To assess the extent of sample use among patients initiating statin therapy. RESEARCH DESIGN: Retrospective cohort of patients who filled a first …
Validation of Medicaid Claims-based Diagnosis of Myocardial Infarction Using an HIV Clinical Cohort
BACKGROUND: In nonexperimental comparative effectiveness research using health care databases, outcome measurements must be validated to evaluate and potentially adjust for misclassification bias. We aimed to validate claims-based myocardial infarction (MI) algorithms in a Medicaid population using an HIV clinical cohort as the gold standard. METHODS: Medicaid administrative data were obtained for the years 2002-2008 and linked to the UNC CFAR HI…
Using Procedure Codes to Define Radiation Toxicity in Administrative Data
BACKGROUND: Systematic coding systems are used to define clinically meaningful outcomes when leveraging administrative claims data for research. How and when these codes are applied within a research study can have implications for the study validity and their specificity can vary significantly depending on treatment received. SUBJECTS: Data are from the Surveillance, Epidemiology, and End Results-Medicare linked dataset. STUDY DESIGN: We use pro…
Examining Parental Medication Adherence as a Predictor of Child Medication Adherence in Pediatric Anxiety Disorders
BACKGROUND: Selective serotonin reuptake inhibitors (SSRIs) are the recommended first-line pharmacotherapy for pediatric anxiety disorders but adherence remains difficult to predict. OBJECTIVES: To estimate SSRI adherence in children with anxiety disorders and determine if prior parental medication adherence is predictive of child high SSRI adherence. METHODS: We identified children (3-17 y) initiating SSRI treatment after an anxiety disorder dia…
Approaches to Address Premature Death of Patients When Assessing Patterns of Use of Health Care Services After an Index Event
BACKGROUND: Studies of the use of health care after the onset of disease are important for assessing quality of care, treatment disparities, and guideline compliance. Cohort definition and analysis method are important considerations for the generalizability and validity of study results. We compared different approaches for cohort definition (restriction by survival time vs. comorbidity score) and analysis method [Kaplan-Meier (KM) vs. competing…
Comparison of Medicare Claims-based Proxy Measures of Poor Function and Associations With Treatment Receipt and Mortality in Older Colon Cancer Patients
BACKGROUND: Multiple claims-based proxy measures of poor function have been developed to address confounding in observational studies of drug effects in older adults. We evaluated agreement between these measures and their associations with treatment receipt and mortality in a cohort of older colon cancer patients. METHODS: Medicare beneficiaries age 66+ diagnosed with stage II-III colon cancer were identified in the Surveillance, Epidemiology, a…
Single-arm Trials With External Comparators and Confounder Misclassification
BACKGROUND: "Single-arm trials" with external comparators that contrast outcomes in those on experimental therapy to real-world patients have been used to evaluate efficacy and safety of experimental drugs in rare and severe diseases. Regulatory agencies are considering expanding the role these studies can play; guidance thus far has explicitly considered outcome misclassification with little discussion of misclassification of confounding variabl…
Impacts of Initial Prescription Length and Prescribing Limits on Risk of Prolonged Postsurgical Opioid Use
BACKGROUND: In response to concerns about opioid addiction following surgery, many states have implemented laws capping the days supplied for initial postoperative prescriptions. However, few studies have examined changes in the risk of prolonged opioid use associated with the initial amount prescribed. OBJECTIVE: The objective of this study was to estimate the risk of prolonged opioid use associated with the length of initial opioid prescribed a…
Multiple cardiovascular risk factor care in 55 low- and middle-income countries
The prevalence of multiple age-related cardiovascular disease (CVD) risk factors is high among individuals living in low- and middle-income countries. We described receipt of healthcare services for and management of hypertension and diabetes among individuals living with these conditions using individual-level data from 55 nationally representative population-based surveys (2009–2019) with measured blood pressure (BP) and diabetes biomarker. We …
Performance of a Claims-Based Frailty Proxy Using Varying Frailty Ascertainment Lookback Windows
BACKGROUND: Frailty is an aging-related syndrome of reduced physiological reserve to maintain homeostasis. The Faurot frailty index has been validated as a Medicare claims-based proxy for predicting frailty using billing information from a user-specified ascertainment window. OBJECTIVES: We assessed the validity of the Faurot frailty index as a predictor of the frailty phenotype and 1-year mortality using varying frailty ascertainment windows. RE…
Ethno-Racial Differences in Age and Symptom Severity Among Pre-Menopausal Women Commencing Treatment for Benign Gynecological Conditions with a Levonorgestrel-Releasing Intrauterine Device
Introduction: Levonorgestrel-releasing intrauterine devices (LNG-IUDs) can be effective treatments for benign gynecological conditions, but there may be ethno-racial differences in how patients receive treatment. Methods: Data were from a health care system in the U.S. South (April 2014-September 2019). We identified 783 female patients aged 18-44 years with an LNG-IUD for a benign gynecological condition (455 White, 208 Black, and 120 Hispanic p…
Beyond Bleeding
Objectives: Black patients have the highest mortality rate from endometrial cancer (EC), and yet remain underrepresented in EC research. Thus, currently published symptom patterns may not be comprehensive for this population. The purpose of this study is to analyze symptomatology among Black patients with EC in the Guidelines for Ultrasound in the Detection of Early Endometrial Cancer study and to compare with those undergoing benign hysterectomy…
Differences in the Measurement of Comorbidities Based on ICD-10-CM Coding Definitions Using Medicare Advantage Encounter Data and Fee-For-Service Claims
BACKGROUND: Medicare Advantage (MA) encounter data became available for research in 2019; data quality concerns remain. OBJECTIVES: We evaluated the consistency of ICD-10-CM comorbidity coding between MA and Fee-For-Service (FFS) data. METHODS: We used round 7 (2017) of the National Health and Aging Trends Study (NHATS) linked to Medicare enrollment, MA encounter, and FFS claims (2016-2017). We included participants continuously enrolled in MA or…
Medicine (17 works) · Internal Medicine (13 works) · Advanced Causal Inference Techniques (12 works) · Internal Medicine (12 works) · Confounding (8 works) · Population (7 works) · Statistics (7 works) · Confidence interval (6 works) · Health Systems, Economic Evaluations, Quality of Life (6 works) · MEDLINE (6 works)