Biomedical subjects

Elena B Elkin

Publications and source records attributed to Elena B Elkin.

11 recordsLinked to original sources

PubMed2006

Radiation therapy facilities in the United States.

PURPOSE: About half of all cancer patients in the United States receive radiation therapy as a part of their cancer treatment. Little is known, however, about the facilities that currently deliver external beam radiation. Our goal was to construct a comprehensive database of all radiation therapy facilities in the United States that can be used for future health services research in radiation oncology. METHODS AND MATERIALS: From each state's health department we obtained a list of all facilities that have a linear accelerator or provide radiation therapy. We merged these state lists with information from the American Hospital Association (AHA), as well as 2 organizations that audit the accuracy of radiation machines: the Radiologic Physics Center (RPC) and the Radiation Dosimetry Services (RDS). The comprehensive database included all unique facilities listed in 1 or more of the 4 sources. RESULTS: We identified 2,246 radiation therapy facilities operating in the United States as of 2004-2005. Of these, 448 (20%) facilities were identified through state health department records alone and were not listed in any other data source. CONCLUSIONS: Determining the location of the 2,246 radiation facilities in the United States is a first step in providing important information to radiation oncologists and policymakers concerned with access to radiation therapy services, the distribution of health care resources, and the quality of cancer care.

Health Services Accessibility↗

PubMed2006

Adjuvant chemotherapy and survival in older women with hormone receptor-negative breast cancer: assessing outcome in a population-based, observational cohort.

PURPOSE: For older breast cancer patients, there is limited evidence of the efficacy of adjuvant chemotherapy from randomized clinical trials. Our goal was to assess the relationship between adjuvant chemotherapy use and survival in a large, population-based cohort of older women with hormone receptor (HR) -negative breast cancer. METHODS: We identified women age 66 and older diagnosed with HR-negative, nonmetastatic breast cancer from 1992 to 1999 in the Surveillance, Epidemiology and End Results (SEER) cancer registries. Chemotherapy use was identified in Medicare claims linked to SEER records. Clinical and sociodemographic predictors of chemotherapy use were identified using logistic regression. The effect of chemotherapy on survival was evaluated using propensity score methods and multivariable proportional hazards regression. RESULTS: A total of 1,711 (34%) of 5,081 women with HR-negative breast cancer received chemotherapy within 6 months of cancer diagnosis. Chemotherapy use decreased with increasing age and comorbidity, and increased with year of diagnosis, tumor size, number of positive lymph nodes, and higher tumor grade. Adjuvant chemotherapy was associated with a mortality reduction of approximately 15% whether analyzed using propensity scores or standard multivariable methods. The greatest overall survival benefit was observed in patients with node-positive disease and in the node-negative patients most likely to receive chemotherapy. CONCLUSION: This analysis suggests a survival benefit from adjuvant chemotherapy in older women with HR-negative breast cancer. The benefit of chemotherapy is most pronounced in the patients most likely to be selected for treatment, including those with involved lymph nodes or other high-risk disease characteristics.

Aged↗

PubMed2006

Primer: using decision analysis to improve clinical decision making in urology.

Many clinical decisions in urology involve uncertainty about the course of disease or the effectiveness of treatment. Many decisions also involve trade-offs; for example, an improvement in patient survival at the cost of an increased risk of treatment-related adverse effects. Decision analysis is a formal, quantitative method for systematically comparing the benefits and harms of alternative clinical strategies under circumstances of uncertainty. The basic steps in performing a decision analysis are to define the clinical scenario or problem, identify the clinical strategies to be considered in the decision, enumerate all of the important sequelae of each strategy and their associated probabilities, define the outcome of interest, and assign a value to each possible outcome. Health outcomes can be defined in a number of ways, including quality-adjusted survival. A key aspect of decision analysis is allowing the values of particular health outcomes to vary from patient to patient, depending on individual preferences. Decision analysis has already been used to assess a variety of prevention, screening and treatment decisions in urology, and there is much potential for its future application. Greater incorporation of decision-analytic techniques into urology research and clinical practice might improve decision making, and thereby improve patient outcomes.

Decision Making↗

PubMed2005

Trends in survival from primary central nervous system lymphoma, 1975-1999: a population-based analysis.

BACKGROUND: The age-adjusted incidence of primary central nervous system lymphoma (PCNSL) has increased since the 1970s, and treatment for this disease has evolved considerably. The objective of this study was to examine time trends in overall survival and disease-specific mortality in a population-based cohort of patients with PCNSL. METHODS: We identified patients diagnosed with PCNSL from 1975-1999 in the Surveillance, Epidemiology, and End Results (SEER) cancer registries. To assess time trends, year of diagnosis was classified in 5-year intervals: 1975-1980, 1981-1985, 1986-1990, 1991-1995, and 1996-1999. Overall survival distributions were estimated via Kaplan-Meier methodology and a competing risk analysis was used to assess PCNSL-specific mortality. We used information on underlying cause of death to distinguish likely immunocompetent patients from those whose PCNSL was related to human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS). We also examined survival stratified by age at diagnosis. RESULTS: From 1975-1999, 2462 patients were diagnosed with PCNSL in SEER. Median survival was 4 months (95% CI 4, 5) for the entire cohort and 9 months (95% CI 8, 11) for the immunocompetent cohort (n = 1565). In the immunocompetent cohort, 965 of 1323 (73%) deaths were attributed to PCNSL. No significant time trend was observed in either overall or PCNSL-specific survival. CONCLUSIONS: Overall survival for patients with PCNSL has not improved consistently in the past three decades despite important therapeutic advances during this time. Although results from clinical trials suggest progress in the treatment of PCNSL, survival improvements are not reflected in this population-based cohort.

Acquired Immunodeficiency Syndrome↗

PubMed2005

The effect of changes in tumor size on breast carcinoma survival in the U.S.: 1975-1999.

BACKGROUND: Temporal comparisons of case survival are commonly used to assess improvement in cancer treatment at the population level. However, such comparisons may be confounded by secular trends in disease prognosis, even within conventional stage categories. The objective of the current study was to characterize within-stage migration of tumor size in breast carcinoma, and to estimate the effect of this shift on reported breast carcinoma survival. METHODS: Population-based Surveillance, Epidemiology, and End Results (SEER) cancer registry data were used to evaluate secular trends in tumor size at the time of diagnosis and relative survival among localized and regional invasive breast carcinoma patients diagnosed between 1975-1999. Outcomes were stage-specific tumor size distribution, 5-year relative survival, relative survival standardized to the tumor size distribution of the cohort diagnosed between 1975-1979, and the percentage of improvement in relative survival attributable to shifts in tumor size distribution. RESULTS: Within each stage category, the proportion of smaller tumors increased significantly over time. Comparing patients diagnosed between 1995-1999 with those diagnosed between 1975-1979, within-stage migration of tumor size accounted for 61% and 28%, respectively, of the relative survival increases noted in localized and regional breast carcinoma. CONCLUSIONS: The tumor size distribution of incident breast carcinomas in SEER has shifted toward smaller tumors. A substantial fraction of the improvement in breast carcinoma survival noted since 1975 may be attributable to within-stage migration of tumor size.

Age Factors↗

PubMed2005

Adjuvant ovarian suppression versus chemotherapy for premenopausal, hormone-responsive breast cancer: quality of life and efficacy tradeoffs.

PURPOSE: Recent clinical trials suggest that adjuvant ovarian suppression may be an equally effective and less toxic alternative to systemic chemotherapy in premenopausal women with hormone-responsive breast cancer. We used a decision-analytic framework to evaluate tradeoffs between efficacy and quality of life in the choice between these treatments. PATIENTS AND METHODS: We used a Markov state-transition model to simulate clinical practice in a cohort of 40-year-old premenopausal women with newly diagnosed, hormone-responsive early breast cancer. We assessed three adjuvant treatments: chemotherapy, surgical ovarian suppression, and medical ovarian suppression. Outcomes were recurrence-free, overall, and quality-adjusted survival. Quality-adjusted survival reflected effects of cancer, treatment-related side effects, and menopausal symptoms. RESULTS: Assuming equal efficacy, ovarian suppression was superior to chemotherapy when the relative utility of chemotherapy side effects compared with ovarian suppression side effects was less than 0.95. Results were sensitive to assumptions about the likelihood, duration and consequences of treatment-induced menopause. Treatment choice was affected by a 7% proportional increase in the efficacy of one therapy relative to the others, independent of other factors. CONCLUSION: If adjuvant chemotherapy and ovarian suppression have similar efficacy, then there may be a subgroup of women for whom quality-of-life considerations dominate the choice of treatment. However, small differences in the relative efficacy of these therapies have a substantial impact on treatment choice, regardless of side effects and menopausal transitions.

Breast Neoplasms↗

PubMed2004

HER-2 testing and trastuzumab therapy for metastatic breast cancer: a cost-effectiveness analysis.

PURPOSE: Trastuzumab therapy has been shown to benefit metastatic breast cancer patients whose tumors exhibit HER-2 protein overexpression or gene amplification. Several tests of varying accuracy and cost are available to identify candidates for trastuzumab. We estimated the cost-effectiveness of alternative HER-2 testing and trastuzumab treatment strategies. PATIENTS AND METHODS: We performed a decision analysis using a state-transition model to simulate clinical practice in a hypothetical cohort of 65-year-old metastatic breast cancer patients. Outcomes were quality-adjusted life-years (QALYs), lifetime cost, and incremental cost-effectiveness ratio (ICER). Interventions included testing with the HercepTest (DAKO, Carpinteria, CA) immunohistochemical assay alone, fluorescence in situ hybridization (FISH) alone, and both tests, followed by trastuzumab and chemotherapy for patients with positive test results and chemotherapy alone for patients with negative test results. RESULTS: In the base case, initial HercepTest with FISH confirmation of all positive results had an ICER of $125,000 per QALY gained. The incremental cost-effectiveness of initial FISH was $145,000 per QALY gained. Other strategies yielded the same or poorer effectiveness at a higher cost, or lower effectiveness at a lower cost, but with a less favorable ICER. These findings persisted under a range of assumptions, and only changes in test characteristics substantially altered results. CONCLUSION: It is more cost-effective to use FISH alone or as confirmation of all positive HercepTest results, rather than using FISH to confirm only weakly positive results or using HercepTest alone. When multiple tests are available to identify treatment candidates, test characteristics may have a substantial impact on the aggregate costs and effectiveness of treatment.

Aged↗

PubMed2004

Should older women have antepartum testing to prevent unexplained stillbirth?

OBJECTIVE: Older women are at an increased risk for unexplained stillbirth late in pregnancy. The purpose of this study was to compare 3 strategies for the prevention of unexplained fetal death in women aged 35 years and older. We compared usual care (no antepartum testing or induction before 41 weeks), weekly testing at 37 weeks with induction after a positive test, and no testing with induction at 41 weeks. METHOD: We used a Markov model to quantify the risks and benefits of each strategy in terms of the number of antepartum tests, inductions, and additional cesarean deliveries per fetal death averted. Probability data used in the model were derived from obstetrical databases and the literature. RESULTS: Without a strategy of antepartum surveillance between 37 and 41 weeks, women aged 35 years and older would experience 5.2 unexplained fetal deaths per 1,000 pregnancies. For nulliparous women 35 and older, weekly antepartum testing initiated at 37 weeks would avert 3.9 fetal deaths per 1,000 pregnancies but would require 863 antepartum tests, 71 inductions, and 14 additional cesarean deliveries per fetal death averted. A strategy of no testing but induction at 41 weeks would avert 0.9 fetal deaths per 1,000 pregnancies and require 469 inductions and 219 additional cesareans per fetal death averted. CONCLUSION: A strategy of antepartum testing in older women would reduce the number of unexplained stillbirths at term and would result in fewer inductions and cesareans per fetal death averted than a strategy of no antepartum testing but induction at 41 weeks.

Cesarean Section↗

PubMed2004

Benchmarking lung cancer mortality rates in current and former smokers.

STUDY OBJECTIVES: To develop and validate a model for estimating the risk of lung cancer death in current and former smokers. The model is intended for use in analyzing a population of subjects who are undergoing lung cancer screening or receiving lung cancer chemoprevention, to determine whether the intervention has altered lung cancer mortality. DESIGN/SETTING/PATIENTS: Model derivation was based on analyses of the placebo arm of the Carotene and Retinol Efficacy Trial. Model validation was based on analyses of three other longitudinal cohorts. MEASUREMENTS: Observed and predicted number of deaths due to lung cancer. RESULTS: In internal validation, the model was highly concordant and well calibrated. In external validation, the model predictions were similar to what was observed in all of the validation analyses. The predicted and observed deaths within 6 years were very similar when assessed in the Johns Hopkins Hospital trial of chest radiography and sputum cytology screening (176 predicted, 184 observed, p = 0.53), the Memorial Sloan-Kettering Cancer Center trial of chest radiography and sputum cytology screening (108 predicted, 114 observed, p = 0.57), and the National Health and Nutrition Evaluation Survey part I (24 predicted, 21 observed, p = 0.52). CONCLUSIONS: The number of lung cancer deaths in a population of current or former smokers can be accurately predicted, making model-based evaluations of prevention and early detection interventions a useful adjunct to definitive randomized trials. We illustrate this potential use with a small example.

Adult↗

PubMedDate not supplied

Preference assessment method affects decision-analytic recommendations: a prostate cancer treatment example.

PURPOSE: To evaluate the effect of preference assessment method on treatment recommended by an individualized decision-analytic model for early prostate cancer. METHODS: Health state preferences were elicited by time tradeoff, rating scale, and a power transformation of the rating scale from 63 men ages 55 to 75. The authors used these values in a Markov model to determine whether radical prostatectomy or watchful waiting yielded the greater quality-adjusted life expectancy. RESULTS: Time tradeoff and transformed rating scale recommendations differed widely. Time tradeoff and transformed rating scale utilities differed in their treatment recommendation for 21% to 52% of men, and the mean difference in quality-adjusted life years varied from less than 0.5 to greater than 1.0. CONCLUSIONS: Treatment recommendations from the prostate cancer decision model were sensitive to the method of preference assessment. If decision analysis is used to counsel individual patients, careful consideration must be given to the method of preference elicitation.

Aged↗

PubMedDate not supplied

Decision curve analysis: a novel method for evaluating prediction models.

BACKGROUND: Diagnostic and prognostic models are typically evaluated with measures of accuracy that do not address clinical consequences. Decision-analytic techniques allow assessment of clinical outcomes but often require collection of additional information and may be cumbersome to apply to models that yield a continuous result. The authors sought a method for evaluating and comparing prediction models that incorporates clinical consequences,requires only the data set on which the models are tested,and can be applied to models that have either continuous or dichotomous results. METHOD: The authors describe decision curve analysis, a simple, novel method of evaluating predictive models. They start by assuming that the threshold probability of a disease or event at which a patient would opt for treatment is informative of how the patient weighs the relative harms of a false-positive and a false-negative prediction. This theoretical relationship is then used to derive the net benefit of the model across different threshold probabilities. Plotting net benefit against threshold probability yields the "decision curve." The authors apply the method to models for the prediction of seminal vesicle invasion in prostate cancer patients. Decision curve analysis identified the range of threshold probabilities in which a model was of value, the magnitude of benefit, and which of several models was optimal. CONCLUSION: Decision curve analysis is a suitable method for evaluating alternative diagnostic and prognostic strategies that has advantages over other commonly used measures and techniques.

Decision Support Techniques↗