Insights Into Breast Cancer Screening: A Computer Simulation of Two Contemporary Screening Strategies.

OBJECTIVE: The debate over the value of screening mammography is rekindled with each new published study or guideline. Central to the discussion are the uncertainties about screening benefits and harms and the criteria used to assess them. Today, the magnitude of benefits for a population is less certain, and the evolving concept of harm has come to encompass false-positives (FPs), unnecessary biopsies, overdiagnosis, and overtreatment. This study uses a Monte Carlo computer simulation to study the balance of benefits and harms of mammographic breast cancer screening for average-risk women. MATERIALS AND METHODS: This investigation compares the American Cancer Society's 2015 mixed annual-biennial guideline with the U.S. Preventive Services Task Force's 2016 fixed biennial guideline. Screening strategies are compared using cost-effectiveness acceptability curves, an economic analysis describing uncertainty in evaluating costs and health outcomes. Strategy preference is examined under changing assumptions of willingness to pay for a quality-adjusted life-year. Additionally, comparative effectiveness analysis is performed using FP screens and unnecessary biopsies per life-year gained. Alternative scenarios are compared assuming a reduced mortality benefit of screening. RESULTS: In general, results using both cost-effectiveness and clinical measures indicate that American Cancer Society's 2015 mixed annual-biennial guideline is preferred. Assuming decreases in the mortality benefit of mammography, no screening may be reasonable. CONCLUSION: The use of a mixed annual-biennial strategy for population screening takes advantage of the nonuniformity of occurrence of mammography benefits and harms over the duration of screening. This approach represents a step toward improving guidelines by exploiting age dependencies at which benefits and harms accrue.

A method for evaluating breast cancer screening strategies using screen-preventable loss of life.

The objective of this study is to describe how screen-preventable loss of life (screen-PLL) can be used to analyze the distribution of life savings with mammographic screening. The determination of screen-PLL with mammography is possible using a natural history model of breast cancer that simulates clinical and pathologic events of this disease. This investigation uses a Monte Carlo Markov model with data from the Surveillance, Epidemiology, and End Results Program; American Cancer Society; and National Vital Statistics System. Populations of one million women per screening strategy are simulated over a lifetime with mammographic screening based on current guidelines of the American Cancer Society (ACS), United States Preventive Services Task Force (USPSTF), triennial screening from age 50-70, and no screening. Screen-PLL curves are generated and show guideline performance over a lifetime. The screen-PLL curve with no screening is determined by tumor discovery through clinical awareness and has the highest values of screen-PLL. The ACS and USPSTF strategies demonstrate screen-PLL curves favoring the elderly. The curve for triennial screening is more uniform than the ACS or USPSTF curves but could be improved by adding screen(s) at either end of the 50-70 age range. This study introduces the use of screen-PLL as a tool to improve the understanding of screening guidelines and allowing a more balanced allocation of life savings across an aging population. The method presented shows how screen-PLL can be used to analyze and potentially improve breast cancer screening guidelines.

Sources of Error in Office Blood Pressure Measurement.

PURPOSES: To evaluate 2 commonly overlooked sources of error in measuring blood pressure (BP) in the office, improper patient positioning and frequency of terminal digit bias (TDB) using manual and automated (BP) devices. METHODS: BPs recorded by 3 nurses using manual and automated devices were analyzed for TDB. In the next part of the study, 294 patients were recruited and tested with each patient's BP measured twice in the table position and compared with BP measured in the chair position. To eliminate concern for position sequence, a randomized controlled trial was initially conducted. RESULTS: Significant TDB for the digit zero was identified in BPs measured by all nurses using a manual device. No such bias was identified for any nurse when measuring BP with an automated device. For the positional study, the randomized controlled study showed no significant sequencing effect therefore the sequence of table then chair BP measurements was adopted. Significant BP lowering was observed in 128 patients (42.7%) in the chair compared with the table position. Misclassification of prehypertension and hypertension would have occurred in 15.3% and 16% of patients, respectively, when BP was recorded in the table instead of the chair position. CONCLUSIONS: Significant TDB was identified for all nurses when using a manual but not an automated device. Patient positioning on the examination table resulted in elevations of systolic and diastolic BPs.

Getting the hypertension Dx right: Patient positioning matters.

Taking blood pressure with the patient seated on the edge of an exam table led to misclassification of prehypertension or hypertension in 13.2% of patients.

The relation of breast cancer staging to screening protocol compliance: a computer simulation study.

A computer model based on relational database techniques was used to analyze the relationship between staging and population compliance to a breast cancer screening protocol. Stage distribution data permitted estimates of compliance to the protocol. This relationship followed the equation y=5.83e-2.44x where y was compliance and x was disease stage. Application of this equation to SEER and NCDB data estimated that the levels of compliance never exceeded 16 percent. Results indicated increasing clinical Stage IV disease as population compliance decreased. As the clinical staging increased there was increased sub-clinical Stage IV disease. With regular screening, simulation suggested that mortality would decrease.

A computer model for the study of breast cancer.

A computer model was designed as a relational database to assess breast cancer screening in a cohort of women where the growth and development of breast cancer originates with the first malignant cell. The concepts of thresholds for growth, axillary spread, and distant sites are integrated. With tumor diagnosis, staging was performed that includes clinical and sub-clinical states. The model was parameterized to have staging characteristics similar to data published by the Surveillance, Epidemiology, and End-Results (SEER) Program. Validation was accomplished by comparing simulated staging results with non-SEER sources, and simulated survival with independent clinical survival data.

Impact of cervical spine management brain injury on functional survival outcomes in comatose, blunt trauma patients with extremity movement and negative cervical spine CT: application of the Monte Carlo simulation.

Cervical spine (CS) magnetic resonance imaging (MRI) and collar use may prevent quadriplegia, yet create brain injury. We developed a computer model to assess the effect of CS management strategies on outcomes in comatose, blunt trauma patients with extremity movement and a negative CS CT scan. Strategies include early collar removal (ECR), ECR & MRI, late collar removal (LCR), and LCR & MRI. MRI risks include hypoxia, hypotension, increased intracranial pressure (↑ICP), and ventilator-associated pneumonia (VAP). LCR risks include ↑ICP, VAP, and delirium. Model elements include Quadriplegia and Primary, Secondary, LCR, and MRI Brain Injury. The Monte Carlo simulation determines health outcomes (Functional Survival versus Quadriplegia, Severe Brain Disability, or Dead). Utility values are Functional Survival 0.90, Quadriplegia 0.20, Severe Brain Disability 0.10, and Dead 0.00. Years of life expectancy are Functional Survival 39.5, Quadriplegia 20.0, Severe Brain Disability 20.0, and Dead 0.0. Unstable CS rate 2.5%: Functional Survival/1,000: Unstable Patients: ECR 384, LCR 350, LCR & MRI 332, ECR & MRI 331; High-Risk Patients: ECR 161, LCR 151, LCR & MRI 140, ECR & MRI 153; Stable Patients: ECR 596, LCR 587, LCR & MRI 573, ECR & MRI 595. Quality-Adjusted Life Months for Unstable, High-Risk, and Stable Patients are greater with ECR; Stable Patient ECR and ECR & MRI are similar. Unstable CS rate 0.5%: Functional Survival/1000: Unstable Patients: ECR 394, LCR 352, LCR & MRI 332, ECR & MRI 332; High-Risk Patients: ECR 164, LCR 151, LCR & MRI 140, ECR & MRI 152; Stable Patients: ECR 611, LCR 592, LCR & MRI 576, ECR & MRI 598. Quality-Adjusted Life Months for Unstable, High-Risk, and Stable Patients are greater with ECR. LCR and MRI brain injury results in losses of functional survivorship that exceed those from quadriplegia. Model results suggest that early collar removal without cervical spine MRI is a reasonable, and likely the preferable, cervical spine management strategy for comatose, blunt trauma patients with extremity movement and a negative cervical spine CT scan.

Comparative analysis of cervical spine management in a subset of severe traumatic brain injury cases using computer simulation.

BACKGROUND: No randomized control trial to date has studied the use of cervical spine management strategies in cases of severe traumatic brain injury (TBI) at risk for cervical spine instability solely due to damaged ligaments. A computer algorithm is used to decide between four cervical spine management strategies. A model assumption is that the emergency room evaluation shows no spinal deficit and a computerized tomogram of the cervical spine excludes the possibility of fracture of cervical vertebrae. The study's goal is to determine cervical spine management strategies that maximize brain injury functional survival while minimizing quadriplegia. METHODS/FINDINGS: The severity of TBI is categorized as unstable, high risk and stable based on intracranial hypertension, hypoxemia, hypotension, early ventilator associated pneumonia, admission Glasgow Coma Scale (GCS) and age. Complications resulting from cervical spine management are simulated using three decision trees. Each case starts with an amount of primary and secondary brain injury and ends as a functional survivor, severely brain injured, quadriplegic or dead. Cervical spine instability is studied with one-way and two-way sensitivity analyses providing rankings of cervical spine management strategies for probabilities of management complications based on QALYs. Early collar removal received more QALYs than the alternative strategies in most arrangements of these comparisons. A limitation of the model is the absence of testing against an independent data set. CONCLUSIONS: When clinical logic and components of cervical spine management are systematically altered, changes that improve health outcomes are identified. In the absence of controlled clinical studies, the results of this comparative computer assessment show that early collar removal is preferred over a wide range of realistic inputs for this subset of traumatic brain injury. Future research is needed on identifying factors in projecting awakening from coma and the role of delirium in these cases.

Simulation of begin and end ages for mammography screening.

This article is designed to assist healthcare professionals in identifying begin and end ages for annual breast cancer mammography screening through the use of cost-effectiveness and computer modeling. With a limit of acceptability of $50,000 per life-year saved, the ages of screening were found to be 35 to 85. The present study identifies the end age for screening more clearly than currently available evidence while meeting the societal limits of $50,000 per life-year saved and equitable spending for the young and old alike.

Simulation of breast cancer screening: quality assessment of two protocols.

Healthcare professionals must make breast cancer screening decisions without the help of clear answers in current medical knowledge. This study used computer simulation to evaluate two screening protocols. The American Cancer Society (ACS) protocol comprising self-breast examination, professional breast examination and annual mammography was evaluated versus annual mammography alone. The effective frequency of mammography and the cost in the ACS protocol doubles the cost of mammography alone. Breast self-examination and clinical breast examination contributes to increased cost without any added health effects. These study results could be applied by healthcare professionals to assist their decision making for breast cancer screening.