Measuring the Benefits of Healthcare: DALYs and QALYs – Does the Choice of Measure Matter? A Case Study of Two Preventive Interventions

Document Type : Original Article

Authors

1 Institute for Clinical Effectiveness and Health Policy (IECS-CONICET), Buenos Aires, Argentina

2 University of Alabama at Birmingham, Birmingham, AL, USA

3 Cardiff University, Cardiff, UK

4 Facultad de Medicina, Universidad San Sebastian, Santiago, Chile

5 Pharmerit, Rotterdam, The Netherlands

6 University of Leeds, Leeds, UK

Abstract

Background
The measurement of health benefits is a key issue in health economic evaluations. There is very scarce empirical literature exploring the differences of using quality-adjusted life years (QALYs) or disability-adjusted life years (DALYs) as benefit metrics and their potential impact in decision-making.

 
Methods
Two previously published models delivering outputs in QALYs, were adapted to estimate DALYs: a Markov model for human papilloma virus (HPV) vaccination, and a pneumococcal vaccination deterministic model (PNEUMO). Argentina, Chile, and the United Kingdom studies were used, where local EQ-5D social value weights were available to provide local QALY weights. A primary study with descriptive vignettes was done (n = 73) to obtain EQ-5D data for all health states included in both models. Several scenario analyses were carried-out to evaluate the relative importance of using different metrics (DALYS or QALYs) to estimate health benefits on these economic evaluations.

 
Results
QALY gains were larger than DALYs avoided in all countries for HPV, leading to more favorable decisions using the former. With discounting and age-weighting – scenario with greatest differences in all countries – incremental DALYs avoided represented the 75%, 68%, and 43% of the QALYs gained in Argentina, Chile, and United Kingdom respectively. Differences using QALYs or DALYs were less consistent and sometimes in the opposite direction for PNEUMO. These differences, similar to other widely used assumptions, could directly influence decision-making using usual gross domestic products (GDPs) per capita per DALY or QALY thresholds.

 
Conclusion
We did not find evidence that contradicts current practice of many researchers and decision-makers of using QALYs or DALYs interchangeably. Differences attributed to the choice of metric could influence final decisions, but similarly to other frequently used assumptions.

Keywords

Main Subjects


  1. Drummond KF, Sculpher MJ, Torrance GW, O’Brien BJ, Stoddart GL. Methods for the Economic Evaluation of Health Care Programmes. Oxford: Oxford University Press; 2005. 
  2. Debicki D, Ferko N, Demarteau N, et al. Comparison of detailed and succinct cohort modelling approaches in a multi-regional evaluation of cervical cancer vaccination. Vaccine. 2008;26(suppl 5):F16-28. doi:10.1016/j.vaccine.2008.02.040 
  3. De Wals P, Black S, Borrow R, Pearce D. Modeling the impact of a new vaccine on pneumococcal and nontypable Haemophilus influenzae diseases: a new simulation model. Clin Ther. 2009;31(10):2152-2169. doi:10.1016/j.clinthera.2009.10.014
  4. Marti SG, Colantonio L, Bardach A, et al. A cost-effectiveness analysis of a 10-valent pneumococcal conjugate vaccine in children in six Latin American countries. Cost Eff Resour Alloc. 2013;11(1):21. doi:10.1186/1478-7547-11-21
  5. Colantonio L, Gomez JA, Demarteau N, Standaert B, Pichon-Riviere A, Augustovski F. Cost-effectiveness analysis of a cervical cancer vaccine in five Latin American countries. Vaccine. 2009;27(40):5519-5529. doi:10.1016/j.vaccine.2009.06.097 
  6. Augustovski F, Irazola V, Velazquez A, Gibbons L, Craig B. Argentine valuation of the EQ-5D health states. Value Health. 2009;12(4):587-596. 
  7. Dolan P. Modeling valuations for EuroQol health states. Medical Care. 1997;35(11):1095-1108. 
  8. Zarate V, Kind P, Valenzuela P, Vignau A, Olivares-Tirado P, Munoz A. Social valuation of EQ-5D health states: the Chilean case. Value Health. 2011;14(8):1135-1141. doi:10.1016/j.jval.2011.09.002
  9. Galante J, Augustovski F, Colantonio L, et al. Estimation and comparison of EQ-5D health states' utility weights for pneumococcal and human papillomavirus diseases in Argentina, Chile, and the United Kingdom. Value Health. 2011;14(5 suppl 1):S60-S64. doi:10.1016/j.jval.2011.05.007
  10. Primera Encuesta Nacional de Factores de Riesgo. 1st ed. Buenos Aires: Ministerio de Salud y Ambiente de la Nación; 2006. http://www.msal.gov.ar. Accessed June 29, 2013. 
  11. Health Survey for England. http://www.archive.official-documents.co.uk/document/doh/survey96/tab5-29.htm. Published 1996. 
  12. Global Burden of Disease 2004 update: disability weights for diseases and conditions. Geneva: World Health Organization; 2004: http://www.who.int/healthinfo/global_burden_disease/GBD2004_DisabilityWeights.pdf. 
  13. Fox-Rushby JA, Hanson K. Calculating and presenting disability adjusted life years (DALYs) in cost-effectiveness analysis. Health Policy Plan. 2001;16(3):326-331. 
  14. Murray CJL, Lopez AD. The Global Burden of Disease: A Comprehensive Assessment of Mortality and Disability From Diseases, Injuries, and Risk Factors in 1990 and Projected to 2020. Cambridge, MA: Harvard University Press; 1996. 
  15. Stouthard M, Essink-Bot M, Bonsel G, Barendregt J, Kramers P. Disability Weights for Diseases in the Netherlands. Rotterdam: Department of Public Health, Erasmus University; 1997. 
  16. Salomon JA, Vos T, Hogan DR, et al. Common values in assessing health outcomes from disease and injury: disability weights measurement study for the Global Burden of Disease Study 2010. Lancet. 2012;380(9859):2129-2143. doi:10.1016/s0140-6736(12)61680-8
  17. Sachs JD. Macroeconomics and health: Investing in health for economic development. Report of the Commission on Macroeconomics and Health. World Health Organization; 2001. http://whqlibdoc.who.int/publications/2001/924154550x.pdf. 
  18. Principal Global Indicators. International Monetary Fund website. http://www.principalglobalindicators.org/Pages/Default.aspx. Accessed June 20, 2013. 
  19. Gandjour A. Drug pricing and control of health expenditures: a comparison between a proportional decision rule and a cost-per-QALY rule. Int J Health Plann Manage. 2015;30(4):395-402. doi:10.1002/hpm.2247
  20. Hjelmgren J, Berggren F, Andersson F. Health economic guidelines--similarities, differences and some implications. Value Health. 2001;4(3):225-250. doi:10.1046/j.1524-4733.2001.43040.x
  21. Augustovski F, Garay OU, Pichon-Riviere A, Rubinstein A, Caporale JE. Economic evaluation guidelines in Latin America: a current snapshot. Expert Rev Pharmacoecon Outcomes Res. 2010;10(5):525-537. doi:10.1586/erp.10.56
  22. Briggs AH, Weinstein MC, Fenwick EA, et al. Model parameter estimation and uncertainty: a report of the ISPOR-SMDM Modeling Good Research Practices Task Force--6. Value Health. 2012;15(6):835-842. doi:10.1016/j.jval.2012.04.014
  23. Arnesen T, Kapiriri L. Can the value choices in DALYs influence global priority-setting? Health Policy. 2004;70(2):137-149. doi:10.1016/j.healthpol.2003.08.004
  24. Arnesen T, Nord E. The value of DALY life: problems with ethics and validity of disability adjusted life years. BMJ. 1999;319(7222):1423-1425. 
  25. Dimoliatis ID. Standardised QALYs and DALYs are more understandable, avoid misleading units of measurement, and permit comparisons. J Epidemiol Community Health. 2004;58(4):354. 
  26. Richardson G, Manca A. Calculation of quality adjusted life years in the published literature: a review of methodology and transparency. Health Econ. 2004;13(12):1203-1210. doi:10.1002/hec.901
  27. Zarate V. DALYs and QALYs in developing countries. Health Aff (Millwood). 2007;26(4):1197-1198. 
  28. Diel R, Lampenius N. Cost-effectiveness analysis of interventions for tuberculosis control: DALYs versus QALYs. Pharmacoeconomics. 2014;32(7):617-626. doi:10.1007/s40273-014-0159-5
  29. Airoldi M, Morton A. Adjusting life for quality or disability: stylistic difference or substantial dispute? Health Econ. 2009;18(11):1237-1247. doi:10.1002/hec.1424
  30. Tan-Torres Edejer T, Baltussen R, Adam T, et al. Making Choices in Health: WHO Guide to Cost-Effectiveness Analysis. Geneva: World Health Organization; 2003.
  • Receive Date: 09 May 2016
  • Revise Date: 09 January 2017
  • Accept Date: 10 April 2017
  • First Publish Date: 01 February 2018