The Generalized Data Model for clinical research.

BACKGROUND: Most healthcare data sources store information within their own unique schemas, making reliable and reproducible research challenging. Consequently, researchers have adopted various data models to improve the efficiency of research. Transforming and loading data into these models is a labor-intensive process that can alter the semantics of the original data. Therefore, we created a data model with a hierarchical structure that simplifies the transformation process and minimizes data alteration. METHODS: There were two design goals in constructing the tables and table relationships for the Generalized Data Model (GDM). The first was to focus on clinical codes in their original vocabularies to retain the original semantic representation of the data. The second was to retain hierarchical information present in the original data while retaining provenance. The model was tested by transforming synthetic Medicare data; Surveillance, Epidemiology, and End Results data linked to Medicare claims; and electronic health records from the Clinical Practice Research Datalink. We also tested a subsequent transformation from the GDM into the Sentinel data model. RESULTS: The resulting data model contains 19 tables, with the Clinical Codes, Contexts, and Collections tables serving as the core of the model, and containing most of the clinical, provenance, and hierarchical information. In addition, a Mapping table allows users to apply an arbitrarily complex set of relationships among vocabulary elements to facilitate automated analyses. CONCLUSIONS: The GDM offers researchers a simpler process for transforming data, clear data provenance, and a path for users to transform their data into other data models. The GDM is designed to retain hierarchical relationships among data elements as well as the original semantic representation of the data, ensuring consistency in protocol implementation as part of a complete data pipeline for researchers.

Estimating the Population Benefits and Costs of Rituximab Therapy in the United States from 1998 to 2013 Using Real-World Data.

BACKGROUND: Rituximab was approved in 1997 and is regularly one of the largest drug expenditures for Medicare; however, its benefits and costs have not been estimated from a population perspective. OBJECTIVES: To estimate both the clinical and the economic outcomes of rituximab for its approved hematological uses at the population level. RESEARCH DESIGN: Analyses using cancer registry incidence data from the Surveillance, Epidemiology, and End Results (SEER) program, and outcomes data from SEER data linked with Medicare administrative claims (SEER-Medicare data). These results were incorporated into an epidemiological simulation model of the population over time. SUBJECTS: We modeled all United States patients from 1998 to 2013 diagnosed with diffuse large B-cell lymphoma, follicular lymphoma, or chronic lymphocytic leukemia. MEASURES: Using this model, we estimated the life-years saved, as well as their economic benefit, in the United States population. We also estimated the incremental cost of adding rituximab to chemotherapy. All economic inputs were based on Medicare reimbursed amounts inflated to 2013 dollars. RESULTS: There were 279,704 cumulative life-years saved which were valued at $25.44 billion. The incremental direct medical cost of rituximab was estimated to be $8.92 billion, resulting in an incremental economic gain of $16.52 billion. CONCLUSIONS: These analyses, based on real-world evidence, show that the introduction of rituximab into clinical practice has produced a substantial number of incremental life-years. Importantly, the economic benefit of the life-years gained greatly exceeds the added costs of treatment.

Refining the definition of clinically important mineral and bone disorder in hemodialysis patients.

BACKGROUND: It is important to identify an easily defined subset of patients at increased risk of adverse clinical outcomes associated with mineral and bone disorder (MBD) biomarkers (parathyroid hormone, calcium and phosphate). METHODS: Observational cohort study of 26 221 prevalent hemodialysis patients in Davita clinics as of 31 August 2005 and followed up until 31 December 2006 (16 months). Predictors were 12 possible definitions of 'clinically important' MBD based on all 3 biomarkers, and 18 alternative definitions based on only 1 or 2 biomarkers. Events were death alone and a composite of cardiovascular hospitalization or death. Excess events were calculated based on a multivariate Cox model using 5224 patients in target for all MBD biomarkers and applied to 20 997 patients out of target for at least one biomarker. Excess events attributable to MBD were estimated by subtracting the multivariate model-derived predicted number from the actual number. Outcomes were the proportion of excess events attributable to MBD captured by each definition (threshold ≥70%) and the reduction in the population size considered to have clinically important MBD (threshold ≥30%). The excess fraction was excess events divided by actual events. RESULTS: Patients with more biochemical markers out of target tended to be younger, black and have longer times since starting dialysis. The excess fraction associated with MBD ranged from ∼10 to 26% depending on the clinical endpoint and definition. The only definition to meet the thresholds required at least two of the three MBD biomarkers to be out of target (high or low). It captured 82% of excess composite endpoints and 74% of excess deaths and reduced the at-risk population by 46%. CONCLUSIONS: Patients with at least two of three MBD biomarkers out of target represent a subgroup of patients at elevated risk of adverse clinical events.

Fibroblast growth factor 23 as a risk factor for cardiovascular events and mortality in patients in the EVOLVE trial.

INTRODUCTION: High mortality rates in patients with chronic kidney disease-mineral and bone disorder (CKD-MBD) receiving maintenance hemodialysis are largely due to cardiovascular (CV) events. METHODS: We evaluated associations between MBD parameters, fibroblast growth factor 23 (FGF23) concentrations, and clinically adjudicated CV events from the Evaluation of Cinacalcet Hydrochloride Therapy to Lower Cardiovascular Events (EVOLVE) trial. Patients enrolled in EVOLVE, who had not experienced any study endpoints between randomization and week 20 with evaluable baseline and week 20 values for key laboratory parameters (parathyroid hormone, calcium, phosphate, and FGF23), were assessed. We used adjusted Cox proportional hazards regression models to estimate relative risk of outcomes (primary composite, all-cause mortality, and CV events) based on FGF23 and MBD parameters. Laboratory values were modeled with linear terms and using natural cubic splines with two degrees of freedom. FINDINGS: For the primary endpoint, patients assessed (N = 2309) were followed up over a mean duration of 3.1 years, during which 1037 CV events (497 deaths, 540 nonfatal events) occurred. Adjusted models showed an association between FGF23 and the risk of CV events. Hazard ratio per log unit of FGF23 at week 20 was 1.09 [95% CI: 1.03-1.16], and the hazard ratio per log unit change in FGF23 from week 0 to week 20 was 1.09 [95% CI: 1.00-1.17]. DISCUSSION: Our data highlight FGF23 as an independent CV risk factor and potential biomarker and therapeutic target for patients with CKD-MBD receiving maintenance hemodialysis.

Estimated Life Expectancy and Income of Patients With Sickle Cell Disease Compared With Those Without Sickle Cell Disease.

Importance: Individuals with sickle cell disease (SCD) have reduced life expectancy; however, there are limited data available on lifetime income in patients with SCD. Objective: To estimate life expectancy, quality-adjusted life expectancy, and income differences between a US cohort of patients with SCD and an age-, sex-, and race/ethnicity-matched cohort without SCD. Design, Setting, and Participants: Cohort simulation modeling was used to (1) build a prevalent SCD cohort and a matched non-SCD cohort, (2) identify utility weights for quality-adjusted life expectancy, (3) calculate average expected annual personal income, and (4) model life expectancy, quality-adjusted life expectancy, and lifetime incomes for SCD and matched non-SCD cohorts. Data sources included the Centers for Disease Control and Prevention, National Newborn Screening Information System, and published literature. The target population was individuals with SCD, the time horizon was lifetime, and the perspective was societal. Model data were collected from November 29, 2017, to March 21, 2018, and the analysis was performed from April 28 to December 3, 2018. Main Outcomes and Measures: Life expectancy, quality-adjusted life expectancy, and projected lifetime income. Results: The estimated prevalent population for the SCD cohort was 87 328 (95% uncertainty interval, 79 344-101 398); 998 were male and 952 were female. Projected life expectancy for the SCD cohort was 54 years vs 76 years for the matched non-SCD cohort; quality-adjusted life expectancy was 33 years vs 67 years, respectively. Projected lifetime income was $1 227 000 for an individual with SCD and $1 922 000 for a matched individual without SCD, reflecting a lost income of $695 000 owing to the 22-year difference in life expectancy. One study limitation is that the higher estimates of life expectancy yielded conservative estimates of lost life-years and income. The analysis only considered the value of lost personal income owing to premature mortality and did not consider direct medical costs or other societal costs associated with excess morbidity (eg, lost workdays for disability, time spent in the hospital). The model was most sensitive to changes in income levels and mortality rates. Conclusions and Relevance: In this simulated cohort modeling study, SCD had societal consequences beyond medical costs in terms of reduced life expectancy, quality-adjusted life expectancy, and lifetime earnings. These results underscore the need for disease-modifying therapies to improve the underlying morbidity and mortality associated with SCD.

Quality adjusted life year gains associated with administration of recombinant tissue-type plasminogen activator for treatment of acute ischemic stroke: 1998-2011.

BACKGROUND: Intravenous recombinant tissue-type plasminogen activator (r-tPA) is an approved treatment for select patients with acute ischemic stroke (AIS). Data indicate r-tPA improves functional outcome three months after AIS compared with placebo. This study models the increase in quality adjusted life years (QALYs) associated with r-tPA compared with similar patients not treated with r-tPA. METHODS: Hospital discharge data for AIS and r-tPA were obtained from the Nationwide Inpatient Sample from 1998 to 2011. Discharge location (home, rehabilitation, long-term care, death) was mapped to modified Rankin Scale (mRS) scores based on National Institute of Neurological Disorders and Stroke (NINDS) Study Group Part 1 and 2 clinical studies. The mRS scores were mapped to relative risk of death and QALYs obtained from the literature. The model estimated expected survival and QALYs by age, gender and mRS for patients receiving r-tPA. Life expectancy and QALYs for patients not receiving r-tPA were estimated based on discharge location and mRS for placebo patients in the NINDS study. RESULTS: AIS discharges declined from over 635,000 in 1998 to over 593,000 in 2011. A total of 183,235 patients received r-tPA. Utilization of r-tPA increased from 1% of AIS patients in 1998 to over 4% in 2011. Estimated projections for QALYs gained from utilization of r-tPA to QALYS without r-tPA were just under 240,000 for the 13 years and with no discounting, and just over 165,000 assuming 3% annual discounting. In the most conservative scenario, assuming no difference in proportional discharge status (i.e. patients not treated with r-tPA are discharged in the same manner as r-tPA patients), the estimated life years gained are approximately 35,000 and QALYS gained are approximately 90,000. CONCLUSIONS: r-tPA for AIS has resulted in estimated gains in quality-adjusted life years due to reduction in disability and improvement in functioning since its introduction in 1998.

Cost-effectiveness of denosumab vs zoledronic acid for prevention of skeletal-related events in patients with solid tumors and bone metastases in the United States.

OBJECTIVE: With increasing healthcare resource constraints, it has become important to understand the incremental cost-effectiveness of new medicines. Subcutaneous denosumab is superior to intravenous zoledronic acid (ZA) for the prevention of skeletal-related events (SREs) in patients with advanced solid tumors and bone metastases. This study sought to determine the lifetime cost-effectiveness of denosumab vs ZA in this setting, from a US managed-care perspective. METHODS: A lifetime Markov model was developed, with relative rate reductions in SREs for denosumab vs ZA derived from three pivotal Phase 3 trials involving patients with castration-resistant prostate cancer (CRPC), breast cancer, and non-small-cell lung cancer (NSCLC), and bone metastases. The real-world SRE rates in ZA-treated patients were derived from a large commercial database. SRE and treatment administration quality-adjusted life year (QALY) decrements were estimated with time-trade-off studies. SRE costs were estimated from a nationally representative commercial claims database. Drug, drug administration, and renal monitoring costs were included. Costs and QALYs were discounted at 3% annually. One-way and probabilistic sensitivity analyses were conducted. RESULTS: Across tumor types, denosumab was associated with a reduced number of SREs, increased QALYs, and increased lifetime total costs vs ZA. The costs per QALY gained for denosumab vs ZA in CRPC, breast cancer, and NSCLC were $49,405, $78,915, and $67,931, respectively, commonly considered good value in the US. Costs per SRE avoided were $8567, $13,557, and $10,513, respectively. Results were sensitive to drug costs and SRE rates. LIMITATIONS: Differences in pain severity and analgesic use favoring denosumab over ZA were not captured. Mortality was extrapolated from fitted generalized gamma function beyond the trial duration. CONCLUSION: Denosumab is a cost-effective treatment option for the prevention of SREs in patients with advanced solid tumors and bone metastases compared to ZA. The overall value of denosumab is based on superior efficacy, favorable safety, and more efficient administration.