Critical Evaluation of QALY and DALY - Essay Example

Healthcare Economics: Critical evaluation of QALY and DALY Introduction: Researchers and policymakers in the healthcare sector require some measures to evaluate health outcomes of different health care intervention in population. Researchers and policy makers in the healthcare sector want to devise such healthcare programs that would be cost effective and would lead to equitable distribution of health resources. Since health care resources are scarce, researchers and policy makers always want to select those interventions that are capable of using the limited resources in efficient manner. Generally in most of the sector of economy, other than health care section efficiency of any program is evaluated on the basis of the benefits that the program offers or on the basis of value for money. But the thing is quite different in healthcare sector of any economy. In healthcare sector, policymakers are quite reluctant to put a value on life due to a lot of ethical reasons. Until recently there has been huge disagreement on the method of measuring life. Over the years, researchers have tried to measure returns on different heath care interventions or programs using economic analysis framework. In last few decades several indicators have been developed for making economic evaluation of different healthcare interventions. Among those indicators, the two most important and widely used indicators are quality adjusted life years (QALY) and disability adjusted life years (DALY). These two composite indicators are being increasingly used by researchers and policymakers of health care sectors of most of the countries across the world. The paper makes an attempt to critically evaluate each of these composite indicators which are helping policymakers in the healthcare sector to decide which intervention should be made available to the patients. The paper will first discuss the definitions and underlying concepts of each of these two indicators along with their uses, then it will move on to discussing the method of calculation for each of them and examine advantages and disadvantages of them, and finally look into their applications. (Prasad et al. 2009; Morrow and Bryant, 1995; Harron, Burnside and Beauchamp, 1983) Concepts, Definitions and Uses: QALY – One of the most important composite indicators used for assessing the effectiveness of healthcare interventions QALY was devised during the period of 1980s (Hirskyi, 2007) by economists, healthcare researchers and psychologists for conducting cost effectiveness analysis. QALY offers the policymakers of the healthcare sector an economical framework through which they become able to make an efficient allocation of scare health care resources. The QALY is actually based on some arithmetic principles and widely used for measuring the quality of the remaining years of life of the targeted population. Malek defined QALY in the following way: “A QALY is an outcome measure that takes into account both the quantity and the quality of extra life provided by the healthcare intervention. It is the arithmetic product of life expectancy and the quality of remaining life years.” (Hirskyi, 2007, p. 4) This definition clearly implies that one needs to consider quality as well as quantity of the life of a patient. This kind of consideration can be linked to holistic type of patient care. QALY helps in allowing the policymakers to take into account patient’s experience so that a comparison can be made between illness and treatment and hence it would be possible to compare relative value of one particular health state over the other. The invention of QALY represented a very significant breakthrough in conceptualizing the outcomes of healthcare interventions in a ration of cost-effectiveness. Cost-effectiveness ratio is generally defined as “the incremental price of obtaining a unit of health effect from health intervention—be it preventive or curative, population-based, or clinical—when compared with an alternative intervention” (Gold et al. 2002). Very often, playmakers use QALYs for calculating the denominator of the cost-effectiveness ratio. When the ratio of cost effective ness of any healthcare intervention is calculated using QALY in its denominator, the cost effectiveness analysis actually becomes cost utility analysis. While evaluating economic efficiency of different healthcare interventions, a cost utility analysis seems to be apt for those situations where quality of life is considered to be an important outcome of healthcare programs and there is a need of using common unit of measurement while comparing different interventions. Cost utility analysis has widely been conducted in health care sector for around 30 years. Given a particular budget constraint, it is possible to maximize QALY by means of increasing individuals’ utility and the total number of individuals that would come under the purview of a specific healthcare program. Here utility can be defined as the value that people place or the preference that people have for the health outcomes of a program. The magnitude of utility varies between a range of zero to one where the value zero is assigned for death and one is assigned for perfect health. (Brent, 2003) DALY – The term ‘disability adjusted life years’ was first introduced by World Bank in the World Development Report of 1993. It was introduced in that of the report which had presented an investigation in health. Policymakers and researchers in the healthcare sector conceptualize DALY as a measure of quantifying the burden of disease. (Arnesen and Nord, 1999) World Health Organization has defined DALY in the following way: “DALY is a health gap measure that extends the concept of potential years of life lost due to premature death to include equivalent years of ’healthy’ life lost by virtue of being in states of poor health or disability. The DALY combines in one measure the time lived with disability and the time lost due to premature mortality”. (Hirskyi, 2007, pp. 6). DALY was developed with an intention of comparing the extent of burdens of different diseases among different populations. While measuring the burdens of a particular disease DALY takes into account values of social preference along with healthy life. DALY holds immense potential within itself of revolutionizing the process through which the impacts of disease can be measure, the way which should be used for the selection of interventions, and the way through which one would be able to track the success and failure of any healthcare intervention. (Arnesen and Nord, 1999) A striking feature of DALY is that it makes an effort to combine the extent of time lived with disability and the amount of time lost due to premature mortality owing to some disease. The number of years lost are generally measured by taking into account a standardized number of years that people expect to live at each age. On the other hand, to calculate the number of years that are lived with some disability, an equivalent time lost is calculated by using a particular set of weights which reflect the extent of fall in functional capacity due to disease. Higher weights implies greater amount of reduction and vice versa. (Arnesen and Nord, 1999; Anand and Hanson, 1997) Methods of Calculation of QALY and DALY: Any type of composite indicator which is used in cost-effective or cost-utility analysis in health sector is calculated following three main steps – describing health, developing weights for the health condition, and combining the weights of different health conditions with some estimates of life expectancy. Methodological choice for conducting each step varies from one indicator to another. This section will describe each of these three steps for QALY as well as DALY. QALY- Step 1: Traditionally QALYs are estimated using those kinds of weights which are related to individual’s experience of health. These weights are indifferent of type of disease, health condition or nature of disability. Here the weights are mainly based on the values that individuals assign for their own health state or the values that they assign to the health states of others that are known to them. The health states that are assigned values are comprised of “components ‘attributes’, ‘dimensions’ or ‘domains’” (Gold et al., 2002, p. 4). For the calculation of QALYs, health states are first describes along their domains. Measurement of health status in a standardized form necessitates formation of a standard concept regarding the factors that constitute health of an individual. It is widely known fact that there exist numerous types of health states. Measurement of any particular health status has to take into account the complexities of the various types of health states in a manageable way. In past 30 year various types of descriptive systems have been developed that include domains like physical, psychological or social. To build QALYs, the descriptive health status which are commonly used are “Health Utility Index, the Quality of Well-Being Scale (QWB), the EQ-5D (EuroQoL), and the Health and Activity Limitation Index (HALex)” (Gold et al., 2002, p. 5). One thing should be remembered here that different conceptualization of health simply results in variation in the values of health states that are generally terms as HRQL, particularly when the health states are attached to any particular disease form. Step 2: After step one is done, the desirability of the described health condition needs to be valued in a way that makes it possible to combine it with units of life expectancy. For the generation of values a 0 to 1 scale is used for any measure. Since QALYs are a measure of health expectancy, in the health scale the value ‘1’ represents full health, while ‘0’ stands for lowest possible health state, that is death. The health scale is built in such a way that they possesses interval scale properties, that is equal amount of changes anywhere in the scale are equivalent to one another. It simply implies that an improvement of health from point 0.3 to 0.7 would be equivalent to a change in health condition from 05 to 0.9. This kind of feature is essential for a health scale as years of life and HRQL are required to be combined into a single metric so that more QALYs can be affected through changes in life expectancy and health condition. HRQL weights are needed to be devised in such a way that these weights reflect individuals’ preferences for different health conditions. Apart from this, “dimensions of health that can be affected at different levels must ultimately be summarized into scores representing the relative trade-offs in desirability between these different components of health, or impacts of disease” (Gold et al. 2002, p. 7). During the calculation of QALYs, the weights of quality of life are assigned to different states of health on the basis of how individuals “make trade offs between different dimensions of health” (Gold et al. 2002, p 7). For the purpose of generating values while calculating QALYs, a number of techniques are used. The methods which are commonly used include standard gamble, time trade off, and visual analog scale. Under time trade off and standard gamble selected individuals are asked to assign values to health states by making it quite clear what they would be ready to sacrifice to move towards perfect health from the health state they are currently experiencing. On the other hand, in visual analog scales, the individuals are asked to choose a point on the scale that would correspond to their degree of preference for a particular state of health. Since different methods use different valuation techniques, it is quite evident that inconsistency arises in the values of state of health. Apart from this technical issue, another source of variation in the values of health states arises from calculation of values on the basis of responses of different group of individuals. Step 3: Once the values of health states are generated, the next task is to combine these values with life expectancy. In case of QALY, the issue of life expectancy is handled in a more heterogeneous fashion than in any other indicator. In case of QALY, most of the information regarding life expectancy relies on data collected during various observational studies and different clinical trials along with population life tables. To compute QALYs for a particular individual the values of health states, i.e. HRQL are multiplied by the number of years that particular HRQL is expected to prevail. The products of HRQL times the number of years of it would prevail are then added up for a number of given time period. For example suppose, an individual has a life expectancy of 80 years. Along with a number of other assumption s can be made like he might spend first 40 years of his life with HQRL at 0.9, then his HQRL might drop to 0.85 from the age of 40 to 60 and drops further to 0.8 from 60 to 70 and for the remaining 10 years of life his HQRL remains at the level of 0.7. Hence his QALYs will be equal to {[40] (0.90) + [20] (0.85) + [10] (0.8) + [10] (0.7)} = 87.8. Here, for the simplification of calculation and understanding the numbers of years the person actually lives and his life expectancy have been assumed to be same. One thing should be noted here is that decline in the level of HQRL with age can be caused by a variety of reasons, like some specific kind of illness such as hypertension, allergies etc., or some ill defined symptoms, a systematic reduction in ability to function with increasing age and so on. DALY: Step 1: Unlike QALYs, DALYs are calculated by attaching estimates of HRQL to specific diseases rather than to states of heath. For the purpose of describing disease, self assessment system has not given importance for the calculation of DALYs. During the calculation of DALYs, researchers have shown their reliance on secondary data or expert opinion for describing disease. One important thing regarding the computation of DALY is that “Rather than creating a classification scheme of generic health states as is done with all other HRQL measures, DALYs use the conceptualization of nonfatal health outcomes drawn from the International Classification of Impairments, Disabilities, and Handicaps (ICIDH), focusing on disability, or the impact of a disease or condition on the performance of an individual” (Gold, et. Al. 2002, p. 6). Health professionals generate the descriptions of the specific ICIDH disabilities. Step 2: Before discussing the techniques that are employed to generate the values for health and disease, it is required to talk about some general rules of that are followed during the generation of values. First, as DALY is a measure of health gap, in the scale of health the value ‘1’ represents full disability, i.e. death, and ‘0’ stand for no disability, i.e. perfect health. Second, the health scale should have the same interval scale properties that the scale of health for QALY possesses. And third, under DALY, for the purpose of reflecting individuals’ preferences for different diseases or health conditions, a disability weight is assigned to a particular health condition or disease. In case of DALYs, the value for a particular disease or a specific health state is generally obtained by employing an “interactive and deliberative” (Gold et al. 2002, p 8) method that made an attempt to reconcile the differences in the degree of preferences of expert groups with respect to the desirability of several health states and diseases. Valuation of health states in case DALY is mainly based on a “person trade-off (PTO)” (Gold et al. 2002, pp.8) technique. This technique clearly addresses the trade offs between “life and HQRL” (Gold et al. 2002, p.8) for individuals with different kinds of diseases. Step3: Computation of DALY proceeds more or less in the same way as QALYs. But there lies a few differences. In case of DALYs, disability weights are attached to typical time courses of health after beginning of a particular disease. Population burden due to a particular disease is calculated using “these weights, data about the incidence of the disease in the particular population, and average age of onset. Total population disease burden is computed by summing attributable DALYs across diseases” (Gold et al., 2002, p. 13). Advantages and disadvantages of QALYs and DALYs: Both of the two indicators under consideration have several advantages as well as disadvantages. It would be surprising to see that although both of these indicators provide certain advantages to the policymakers for deciding which health care intervention to choose and therefore widely used by policy makers across countries, they suffer from numerous limitations. Most of the limitations are associated with the calculation process of these two indicators. However, before moving on to the discussion of their limitations, it would be better to talk about the advantages they provide to the policy makers. As far as QALY is concerned, the major advantage of this indicator is that it helps policymakers in making efficient distribution of resources by means of estimating the value of health gains of individuals relative to the treatment they receive. The formula of QALY also helps in comparing the effectiveness of different healthcare interventions for the same health related problem. QALY also provides a platform on the basis of which public discussion can take place regarding resource allocation and patient care in health care industry. On the other hand, DALY also has certain advantages. For example, instead of considering mortality alone for the purpose of assessing burden of disease, DALY takes into account time lived with disabilities. Apart from these, unlike other measures, the value choices that are incorporated in DALY are made more clear and consequently “the black box of decision maker’s relative values is then opened for public scrutiny and influence” (Anand and Hanson, 1997, p. 4). These two indicators, however, are subjects to lots of limitation. The disadvantages of QALY and DALY will be discussed one after another. The disadvantages of QALY are as follows. First, when QALY is used, a link is established between patients with particular diseases and declining quality of life. This formula is capable of reducing the extent of autonomy of those patients who have an illness that is intractable and wish to lead a productive life. Generally for diseases like cancer, Alzheimer’s etc., a lower QALY weights are assigned to the health condition. But very often it is found that in practice the people who suffer from cancer or Alzheimer’s do not have lower quality of life than others. In fact, if appropriate treatment and care is available and affordable these people can have potential of a long healthy life. Therefore, low value of QALY does not necessarily mean that the patients will actually have lower quality of life. (Hirskyi, 2007; Brent, 2003) Second, very often QALY is calculated on the basis of a small sample, and therefore it does not reflect the views of the general public. Similarly “if the emphasis of QALYs in areas such as promotion may not reflect the values of society; these may stress the importance of adequate funding for the treatment of patients with chronic illnesses.” (Hirskyi, 2007, p. 5) Third, since QALY is generally perceived as the tool that is used mainly by economists and policy makers in healthcare sector, there is a chance that health professional such as nurses and doctors could not be able to take part in clinical decision making process. Consequently, resource allocation in the health care sector would be determined only by principles of economic efficiency instead of the principles of care. (Hirskyi, 2007) Very often QALY is regarded as a very controversial indicator as there arises a big question regarding whole quality values should be taken into account – “those of members of the public, who may not have experienced illness; or those of doctors and nurses holding the perspective of caregivers” (Hirskyi, 2007, pp. 5). These problems associated with the use of QALY can, however, be solved to some extent if this indicator is used in a little more wise way. For example, it would be much better to seek the views of patient regarding any illness rather than seeking the views of healthy persons as these are these are the people who have already experienced illnesses and consequent treatment procedures and therefore are in a better position to give appropriate views regarding the effects of illnesses and the treatments. (Nord, 1999) The disadvantages of DALY are as follows: First, in case of using DALY for the estimation of the burden of a particular illness, the burden is usually defined as a measure of ill health which is mainly reflected by premature mortality and functional limitation of the patient and this burden is adjusted for age and sex. But the problem is that to have a measure of actual burden, additional information are needed regarding the circumstance of patients, like the support the patient receives from his own income, family, friends and the public healthcare services. Therefore, the calculation DALY considering an information set that only takes into account age and sex is not appropriate. (Arnesen, and Nord, 1999) Second, the incorporation of age in the information set is done in a wrong way during the calculation of DALY. Third, the use of instrumental value for the justification of DALY allocation is similar to the method used in the dialysis of Seattle. This has favored the wage earners and the dependants’ careers. (Persad et al, 2009). Although both of these two indicators suffer from various limitations, they are still used widely by policy makers in a number of areas in the health care sector. For example National Institute of Clinical Excellence situated in Leicester employed QALY for measuring the efficiency of number of healthcare interventions for the prevention and treatment of Influenza A and B. (Turner et al. 2002). On the other hand, DALY was widely employed by organizations like World Bank and WHO for the purpose of measuring global burden of disease. References 1. Gold, M. R., Stevenson, D. and Fryback, D. G. 2002. HALYS AND QALYS AND DALYS, OHMY: Similarities and Differences in Summary Measures of Population Health. Annu. Rev. Public Health, 23: 115-134. 2. Persad,G. Wertheimer, A., and Emanuel, E. J. 2009. Principles for allocation of scarce medical interventions. Lancet 373: 243-31. 3. Turner, D., Wailoo, A., Nicholson, K, Sutton, A.and Abrams, K. 2002. SYSTEMATIC REVIEW AND ECONOMIC DECISION MODELLING FOR THE PREVENTION AND TREATMENT OF INFLUENZA A AND B. University of Sheffield. 4. Anand, S. and Hanson, K. 1997. Disability adjusted life years: a critical review. Journal of Health Economics, 16 : 685-702. 5. Hirskyi, P. 2007. QALY: AN ETHICAL ISSUE THAT DARE NOT SPEAK ITS NAME. London: Sage Publication. 6. Arnesen, T. and Nord, E. 1999. The value of DALY life: problems with ethics and validity of disability adjusted life years. BMJ, 319:1423-1425. 7. Nord E. 1999. Cost-value analysis in health care. Cambridge University Press. 8. Brent R ed. 2003. Cost-benefit analysis and health care evaluations. Edward Elgar. 9. Harron F, Burnside J,and Beauchamp T. 1983. Health and human values. Yale University Press.. 10. Morrow, R. and Bryant, J. H. 1995. Health Policy Approaches to Measuring and Valuing Human Life: Conceptual and Ethical Issues. American Journal of Public Health. 85 (10) : 1356-1360. Read More