@article {981,
	title = {Age-specific prevalence and years of healthy life in a system with three health states.},
	journal = {Stat Med},
	volume = {27},
	year = {2008},
	month = {2008 Apr 30},
	pages = {1371-86},
	abstract = {<p>Consider a 3-state system with one absorbing state, such as Healthy, Sick, and Dead. Over time, the prevalence of the Healthy state will approach an {\textquoteright}equilibrium{\textquoteright} value that is independent of the initial conditions. We derived this equilibrium prevalence (Prev:Equil) as a function of the local transition probabilities. We then used Prev:Equil to estimate the expected number of years spent in the healthy state over time. This estimate is similar to the one calculated by multi-state life table methods, and has the advantage of having an associated standard error. In longitudinal data for older adults, the standard error was accurate when a valid survival table was known from other sources, or when the available data set was sufficient to estimate survival accurately. Performance was better with fewer waves of data. If validated in other situations, these estimates of prevalence and years of healthy life (YHL) and their standard errors may be useful when the goal is to compare YHL for different populations.</p>},
	keywords = {Age Factors, Biometry, Health Status, Humans, Life Tables, Longitudinal Studies, Middle Aged, Models, Statistical, Probability, Quality-Adjusted Life Years},
	issn = {0277-6715},
	doi = {10.1002/sim.3056},
	author = {Diehr, Paula and Yanez, David and Derleth, Ann and Newman, Anne B}
}
@article {1050,
	title = {Evaluation of a method for fitting a semi-Markov process model in the presence of left-censored spells using the Cardiovascular Health Study.},
	journal = {Stat Med},
	volume = {27},
	year = {2008},
	month = {2008 Nov 20},
	pages = {5509-24},
	abstract = {<p>We used a longitudinal data set covering 13 years from the Cardiovascular Health Study to evaluate the properties of a recently developed approach to deal with left censoring that fits a semi-Markov process (SMP) model by using an analog to the stochastic EM algorithm--the SMP-EM approach. It appears that the SMP-EM approach gives estimates of duration-dependent probabilities of health changes similar to those obtained by using SMP models that have the advantage of actual duration data. SMP-EM estimates of duration-dependent transition probabilities also appear more accurate and less variable than multi-state life table estimates.</p>},
	keywords = {Activities of Daily Living, Aged, Aged, 80 and over, Cardiovascular Diseases, Cardiovascular System, Data Interpretation, Statistical, Disease Progression, Female, Humans, Longitudinal Studies, Male, Markov Chains, Models, Statistical, Stochastic Processes, Time Factors},
	issn = {0277-6715},
	doi = {10.1002/sim.3382},
	author = {Cai, Liming and Schenker, Nathaniel and Lubitz, James and Diehr, Paula and Arnold, Alice and Fried, Linda P}
}
