Revisiting United States valuation of EQ-5D states

In the original US valuation study of EQ-5D states, all worse-than-dead time trade-off responses (26% of the sample) were divided by 39 to increase the QALY estimates. This transformation has no theoretical justification and motivates this re-examination. Using the publically available dataset, we compared three alternative random utility models: instant (IRUM), angular (ARUM), and episodic (ERUM) models. Each leads to a distinct econometric estimator: mean ratio, ratio of means, and coefficient, respectively. IRUM suggests that 203 of the 243 EQ-5D states are worse-than-dead, which has little face validity compared to ARUM and ERUM (42 and 3 WTD states). ARUM and ERUM estimates are proportionally related such that losses in QALYs are approximately 37% larger under ARUM than ERUM. Compared to ERUM, economic evaluations using ARUM estimates emphasize quality of life, and this difference may influence policy decisions. Either ERUM or ARUM values sets are recommended over the original, transformed set.

Toward a more universal approach in health valuation

By polling individual responses to hypothetical scenarios, valuation studies estimate population preferences toward health on a quality-adjusted life year (QALY) scale. The scenarios typically involve trade-offs in time (time trade-off (TTO)), risk (standard gamble (SG)), or number of persons affected (person trade-off (PTO)). This paper revisits the QALY assumptions and provides a coherent health econometric approach that unites TTO, SG, and PTO techniques under a common estimator. The proposed approach avoids the use of ratio statistics in QALY estimation and the common convention of arbitrarily changing trade-off responses. As an example, 34% of the TTO responses from the seminal Measurement and Valuation of Health study were changed in the original UK analysis, which led to substantially lower QALY estimates. As a general rule, if the original estimate is less than 0.5 QALYs, add 0.25 QALYs to get the new estimates.

Validity of the time trade-off and standard gamble methods of utility assessment in retinal patients

AIM

To assess the validity of the time trade-off (TTO) and standard reference gamble (SRG) techniques of utility assessment in patients with retinal disease. A cross section of eligible patients was studied and validity was determined through their relation with two logical constructs, visual acuity and scores from the Visual Function 14 (VF-14) index.

METHODS

The study consisted of eligible patients presenting to a tertiary retinal facility who completed an interview. All patients had best corrected vision of 20/40 or worse in at least one eye. TTO and SRG utilities, as well as a VF-14 questionnaire, were administered through a standardised interview. Demographic and clinical (including Snellen visual acuity) information was also collected.

RESULTS

323 patients met these study criteria. Significant predictors of TTO utilities in the multivariate analysis were vision in the better seeing eye (p<0.01) and VF-14 scores (p<0.01). Significant predictors of standard gamble utilities were also vision in the better seeing eye (p<0.01) and VF-14 scores (p<0.05).

CONCLUSION

Both the standard gamble and TTO methods demonstrate strong validity when evaluated against visual acuity in the better seeing eye and the VF-14 score.

Utilities measured by rating scale, time trade-off, and standard gamble: review and reference for health care professionals

Utility is a simple expression of health-related quality of life in individuals with different states of health. A number of studies on utility measurements were conducted and published in the past. We retrieved 164 English-language articles which appeared in 1966 through 1999 for a systematic review. The number of reports has been increasing at an accelerating pace, especially during the past decade. The most widely used method of utility measurement was time trade-off, TTO (40%), followed by rating scale, RS (31%) and standard gamble, SG (29%). The utility of chronic health status was more frequently reported as compared with acute health status (907 vs 86). Accordingly, frequently explored clinical categories were cardiology, neurology, nephrology, and gastroenterology. Specifically, coronary heart disease (52 utilities), physical disability due to neurological diseases (45 utilities), chronic renal failure (74 utilities), and colorectal cancer (29 utilities) were subject to utility measurement. Mental or social dysfunctioning accounted for only a small proportion (48 utilities). There is a strong tendency for RS to yield the lowest and SG to yield the highest values. We compiled an extensive list of the results of studies on utility as a reference for health care professionals in this field.