title: Robust modeling in screening studies: estimation of sensitivity and preclinical sojourn time distribution.
abstract: In early-detection clinical trials, quantities such as the sensitivity of the screening modality and the preclinical duration of the disease are important to describe the natural history of the disease and its interaction with a screening program. Assume that the schedule of a screening program is periodic and that the sojourn time in the preclinical state has a piecewise density function. Modeling the preclinical sojourn time distribution as a piecewise density function results in robust estimation of the distribution function. Our aim is to estimate the piecewise density function and the examination sensitivity using both generalized least squares and maximum likelihood methods. We carried out extensive simulations to evaluate the performance of the methods of estimation. The different estimation methods provide complimentary tools to obtain the unknown parameters. The methods are applied to three breast cancer early-detection trials.
authors.affiliation: Department of Biostatistics and Applied Mathematics, M. D. Anderson Cancer Center, University of Texas, Houston, TX 77030, USA. yshen@mdanderson.org
authors.forename: Yu
authors.initials: Y
authors.lastname: Shen
authors.forename: Marvin
authors.initials: M
authors.lastname: Zelen
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000175:diagnosis; D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D016018:Least-Squares Analysis; D016013:Likelihood Functions; D008327:Mammography; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D015233:Models, Statistical; D016032:Randomized Controlled Trials as Topic; D012680:Sensitivity and Specificity; D013269:Stochastic Processes