Estimating EuroQol EQ-5D scores from Population Healthy Days data.
ABSTRACT Preference-based assessments of population health, which may be used for cost-utility analyses, are lacking for most states and communities. With adequate population data, preference-based values can be estimated from non-preference-based health-related quality of life (HRQOL) data. This study estimates scores on the EuroQol EQ-5D, a preference-based measure, from the Healthy Days
No data set from the US population asks both the Healthy Days and EQ-5D questions for the same respondents. Therefore, estimates for EQ-5D scores were obtained indirectly by matching cumulative distributions of the 2 measures. These distributions were estimated from the 2000- 2002 Behavioral Risk Factor Surveillance System (BRFSS) and the Medical Expenditure Panel Survey (MEPS). The validity of estimates was examined by comparing the mean estimated and observed scores across particular population subgroups. A simulation study was conducted to compare the performance of the proposed method to the regression method.
The overall mean observed EQ-5D index was 0.871 and the mean estimated EQ-5D index was 0.872. In the majority of examined subgroups, the mean scores demonstrated a good match according to sociodemographic variables and health-related conditions and, with the exception of the most impaired health states, the differences tended to be less than 0.04.
This study provided preliminary estimates of EQ-5D scores from the Healthy Days Measures and demonstrated acceptable validity of the estimates. Because the Healthy Days Measures have been included in many state and local surveys, preliminary cost-utility analyses and determination of burden of disease might be able to be conducted at the national, state, and community levels as well as over time.
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- "This study applied a previously constructed algorithm to obtain values for the EuroQol five-dimensional questionnaire index, a preference-based HRQOL measure, for respondents in the BRFSS, based on their age and answers to these four questions  . This algorithm provides valid estimates of EuroQol fivedimensional questionnaire scores of the US population by some demographic subgroups and common health conditions from the BRFSS  , and the bias of estimated QALE from these scores has been estimated to be less than 1% of that using the actual EuroQol five-dimensional questionnaire questions . The BRFSS includes a set of core questions asked in all 50 states and the District of Columbia and a set of modular questions asked in a subset of states. "
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Conference Paper: Path control of a surface ship in restricted waters using sliding mode[Show abstract] [Hide abstract]
ABSTRACT: In this paper, the path control problem is addressed for a ship steering in restricted waters using sliding mode technique. Ship dynamic equations and numerical computation of the bank disturbance forces are briefly introduced. Ship path control systems are revealed, which easily lead to a non-minimum phase system. Therefore, the traditional input-output linearization strategy in geometric control theory is modified to transform the controller design of a fourth-order nonlinear system to that of a second-order linear system. A continuous sliding mode controller is designed to assure the system robustness and better performance. Simulation and experimental studies validate the controller design. The simulation results demonstrate importance to the realistic steering of ships, navigation study and intelligent controller designDecision and Control, 1998. Proceedings of the 37th IEEE Conference on; 02/1998