The results of this study do not support the common view that RS values are lower than TTO values , may suggest that TTO biases largely cancel , and support the validity of formulas for correcting SG bias
Background .
A common assertion is that rating scale ( RS ) values are lower than both st and ard gamble ( SG ) and time tradeoff ( TTO ) values .
However , differences among these methods may be due to method specific bias .
Although SG and TTOs suffer systematic bias , RS responses are known to depend on the range and frequency of other health states being evaluated .
Over many diverse studies this effect is predicted to diminish .
Thus , a systematic review and data synthesis of RS-TTO and RS-SG difference scores may better reveal persistent dissimilarities .
The purpose of this study was to establish through systematic review and meta- analysis the net effect of biases that endure over many studies of utilities .
Health values of patients infected with human immunodeficiency virus. Relationship to mental health and physical functioning.
To assess the health values of patients infected with human immunodeficiency virus ( HIV ) and examine the relationships between their health values and health status at two points in time , the authors sought to determine whether patients ' physical and mental health statuses were good predictors of how they valued their current state of health . One hundred thirty-nine patients with various stages of HIV infection were interviewed in a prospect i ve cohort study based in a primary care practice of a community-based teaching hospital . Patients were interviewed twice at 6-month intervals using three  health value measures --the time trade off , rating scale , and Quality of Well-being Scale--  and three health status measures : the  18-item Mental Health Inventory , the Dyspnea-Fatigue Index , and the Medical Outcomes Study SF-36 Health Survey .  The health status of HIV-infected patients was compromised and , with the exception of mental health , generally was worse among patients with more advanced HIV-infection . Rating scale and Quality of Well-being Scale scores were related inversely to disease stage , but time-trade off scores generally were higher regardless of disease stage . Health value measures showed moderate relationships with measures of physical functioning ( r = 0.34 - 0.68 ) but only a fair relationship with mental health ( r = 0.00 - 0.48 ) . The health status of HIV-infected patients who remained asymptomatic or remained symptomatic but without developing acquired immunodeficiency syndrome ( AIDS ) changed little over 6 months , whereas the health status of patients with AIDS and of patients manifesting progression of HIV-infection deteriorated over time . In contrast , health values , particularly time-tradeoff scores , remained stable even in the face of changes in health status and disease progression . With the exception of mental health , the impact of HIV infection on health status tends to parallel the clinical stage of disease . Health values of HIV-infected patients , however , generally are high and correlate better with physical functioning than with mental health
The results of this study do not support the common view that RS values are lower than TTO values , may suggest that TTO biases largely cancel , and support the validity of formulas for correcting SG bias
Background .
A common assertion is that rating scale ( RS ) values are lower than both st and ard gamble ( SG ) and time tradeoff ( TTO ) values .
However , differences among these methods may be due to method specific bias .
Although SG and TTOs suffer systematic bias , RS responses are known to depend on the range and frequency of other health states being evaluated .
Over many diverse studies this effect is predicted to diminish .
Thus , a systematic review and data synthesis of RS-TTO and RS-SG difference scores may better reveal persistent dissimilarities .
The purpose of this study was to establish through systematic review and meta- analysis the net effect of biases that endure over many studies of utilities .