Problems and solutions in calculating quality-adjusted life years (QALYs).
Health Qual Life Outcomes
; 1: 80, 2003 Dec 19.
Article
em En
| MEDLINE
| ID: mdl-14687421
The quality-adjusted life-year (QALY) is a measure of the value of health outcomes. Since health is a function of length of life and quality of life, the QALY was developed as an attempt to combine the value of these attributes into a single index number. The QALY calculation is simple: the change in utility value induced by the treatment is multiplied by the duration of the treatment effect to provide the number of QALYs gained. QALYs can then be incorporated with medical costs to arrive at a final common denominator of cost/QALY. This parameter can be used to compare the cost-effectiveness of any treatment. Nevertheless, QALYs have been criticised on technical and ethical grounds. A salient problem relies on the numerical nature of its constituent parts. The appropriateness of the QALY arithmetical operation is compromised by the essence of the utility scale: while life-years are expressed in a ratio scale with a true zero, the utility is an interval scale where 0 is an arbitrary value for death. In order to be able to obtain coherent results, both scales would have to be expressed in the same units of measurement. The different nature of these two factors jeopardises the meaning and interpretation of QALYs. A simple general linear transformation of the utility scale suffices to demonstrate that the results of the multiplication are not invariant. Mathematically, the solution to these limitations happens through an alternative calculation of QALYs by means of operations with complex numbers rooted in the well known Pythagorean theorem. Through a series of examples, the new calculation arithmetic is introduced and discussed.
Texto completo:
1
Temas:
ECOS
/
Aspectos_gerais
Bases de dados:
MEDLINE
Assunto principal:
Anos de Vida Ajustados por Qualidade de Vida
/
Modelos Teóricos
Tipo de estudo:
Prognostic_studies
Aspecto:
Ethics
/
Patient_preference
Limite:
Humans
Idioma:
En
Revista:
Health Qual Life Outcomes
Assunto da revista:
SAUDE PUBLICA
Ano de publicação:
2003
Tipo de documento:
Article
País de afiliação:
Espanha