Values Lower Than Death Jan J. v. Busschbach, Ph.D. –Erasmus University Rotterdam institute for Medical Technology Assessment (iMTA) PO box DR Rotterdam (secretariat) (fax)

Values below the value of death are associated with: In patients with extreme bad health states –Chronic: cancer, pain –Temporary: invasive therapy In patient with extreme high or low arousal –Psychological distress; coma; waiting room, confined to bed Euthanasia

Economic evaluation Acknowledge values lower than death Values lower than death –Heath Utility Index (HUI) Torrance GW. Measurement of health state utilities for economic appraisal. Journal of Health Economics 1986; 5: –EuroQol Brooks R, with the EuroQol Group. EuroQol: the current state of play. Health Policy 1996; 37: –The Rosser & Kind Index Williams A. For Debate... Economics of Coronary Artery Bypass Grafting. British Medical Journal 291: , No values below death –The Quality of Well-being Scale (QWB) Read J., Quinn R., Hoefer M. Measuring overall health: an evaluation of three important approaches. Journal of Chronical Diseases, Vol 40, suppl. 1, pp. 7S-21S, 1987.

Clinical decision making Rarely confronted with values below death because: Patient is already dead –Can not survive a bad health state for long –Euthanasia Patients value their own health states higher –Coping (Medical terminology) –Preference drift (Economical terminology) –Cognitive dissonance reduction (Psychological terminology) Patients are often "Lexicographic" –In a trade-off between quality of life and time, lexicographic patients always chose maximum survival. –They are lexicographic until “Maximum Endurable Time”

Visual Analog scale If death is not the bottom anchor, values below the value of death are possible. V(X) = (X - V(D)) / (V(H) - V(D)) –X is the scale placement –V(X) is the value of X –V(D) is the value of death (often zero) –V(H) is the value of healthy Note: values above “healthy” are also possible: –“Best health state” as top anchor Healthy Death X Healthy Death X Worst health state

Standard Gamble State X Healthy Death P 1-P Below the value of death Healthy Death P 1-P Above the value of death State X Torrance, 1986 Square = choice Circle = chance Above death V(X) = p Below death V(X) = – p / (1 – p)

Time Trade-Off Torrance, 1986 Healthy 1. 0 State X V(X) Healthy 0.0 Time X t Healthy 1. 0 State X V(X) Healthy 0.0 Time X t Above death: V(X) = X / t Below death: V(X) = X / (X – t)

Alternative Time Trade-Off MVH study (York) Healthy 1. 0 State X V(X) Healthy 0.0Time X’ t Below death: V(X’) = (X’ – t) / X’ First choice between above or below dead Time trade-off above death is classic Below death, healthy life is promised after bad state

The problems below death Complicated No lower limit Outliers dominate mean values What can we do….. –Cut-off at zero, – 1, any negative number? –No documented transformation function –If we transform negative values, above and below death become incoparable –Median instead of mean

Can we use negative values? Bizarre political interpretation –In health economics, »Death would implicate additional quality of life »Death would implicate additional QALY’s Bizarre clinical advise –If you die, your life improves…...

Torrance and the rise a fall of values below death 1970 –Does not mention the problem explicitly –Uses good and mild health states 1982 –Introduces negative values –In 3 articles he advises a limit at -1 »Linear transformation (data remains skewed) –No justification 1986 –Limit at -1 –Further work on values below death would be “underway” (reference: Berlin 1984)

Torrance and the rise a fall of values below death 1992 –No more negative values: cut-off at zero –Negative values have no lower limit which “caused some concern” and “requires ad hoc adjustments” –“Negative values may be qualitatively different from positive values” 1996 –Uses “… the current default approach, which is to set negative utility scores worse than death to zero.” –Speaks about “… an upwards bias…” –“…Unfortunately, methodological issues for states worse than death have not as yet been resolved”.

The York Group The MVH-study –N = 3000, general public, 45 EuroQol Health states valued with »(non standard) EuroQol VAS »time trade-off Range from –1.0 to 1.0 –Formula: x/ (x is number of years in full heath) –Transformtion is not linear: also removes skewness VAS – 4 out f 243 health states were negative Time trade-off – 82 out of 243 were negative

The York Group Has a strong opinion that –negative values exits –are useful Arguments for transformation to -1 are –Extreme negative values would have a great impact –Has been done before (Patrick, et al, 1994) »Patrick: “Not longer utilities…. »Torrance: “Not longer utilities, not even for only use below death ––1.0 is mirror vision of + 1.0

Conclusions Psychometric problems –Negative values have no lower limit –Outliers dominate mean values –There is no elegant transformation function Negative values have a difficult interpretation Health states with negative values are –rare –temporary

Negative states There are indeed health states with a negative value –People are prepared to give in life to avoid health state