Human costs of tobacco-related diseases *

1. Human costs of tobacco-related diseases* Marco Vannotti, France Priez, Claude Jeanrenaud, Jean-Pierre ZellwegerInstitut de recherches économiques et régionales, Université de Neuchâtel et Policlinique médicale universitaire de Lausanne*Commissioned by the Swiss Federal Office of Public Health, contract V 8057 Background Economics offer various methods to value health. Smoking-related diseases have adverse effects on the quality of life of patients and of their relatives. The loss of wellbeing due to deterioration in quality of life may be estimated in monetary units using appropriate methodology (expressed or revealed preferences). In this study, human costs correspond to the monetary value attached by the general population to the existential damage caused by diseases. • Aim • The aim of this Swiss study, conducted by physicians and economists, was to estimate the value of the reduction in quality of life and life expectancy due to six tobacco-related diseases: lung cancer, chronic bronchitis, angina, stroke, non-fatal heart attack and fatal heart attack. These diseases were chosen according to two criteria: • the high number of cases attributable to smoking. According to Frei (1998), attributable fractions of the selected diseases are between 0.39 (for angina) and 0.88 (for lung cancer); • the number of new cases diagnosed each year is over 2,000 per disease (incidence data). Method Contingent valuation method In health economics, this is a widespread approach (Diener, 1998). A sample of the general population is surveyed by means of a questionnaire in order to establish the value people attribute to quality of life. • Interviewees are asked to indicate: • the maximum amount of their income they are willing to sacrifice to reduce their own risk of contracting one of the selected diseases. • To obtain this information, a hypothetical market - called contingent market - is presented to respondents. The good provided is a reduction in their probability of contracting a disease. The price they are prepared to pay for this risk reduction - their willingness-to-pay (WTP) - reveals the value they attribute to their own quality of life. • Before they express their WTP, three types of information are presented in a didactic way : • Main risk factors of the disease; • Average risks in the general population by gender; • Impact of the disease on quality of life. Impact of a disease on quality of life Results MWTP depend on some characteristics of respondents such as smoking status, linguistic region or frequency of physical activities. Ex-ante approach Potential victims are surveyed: the target population is the Swiss population. Quota sampling Respondents’ represen-tativeness of the Swiss population is based on area of residence (urban or rural), age, sex and social stratum. Survey 868 individuals 18-years old and over were interviewed in May 1998 in the three linguistic regions of Switzerland. Regression analysis The internal validity of the contingent valuation is assessed. For this purpose, respondents’ characteristics and other relevant variables are compared with their WTP to reduce their risk by 1 in 100,000 (marginal WTP). A semi-logarithmic model provides the best estimation of the marginal WTP. Influence of smoking habits on MWTP Influence of linguistic region on MWTP From MWTP to human costs Human costs (HC) of the disease i are obtained by multiplying the estimated marginal WTP (MWTP) by 100,000 : HCi = MWTPi* 100,000 HCi corresponds to the estimated value attributed by interviewees to the impact on the quality of life of one statistical case of the disease i. MWTP of smokers, occasional smokers or non-smokers, is divided by MWTP of non-smokers, where both have the same characteristics otherwise. Smokers are willing to pay between 6 to 9.7 times more than non-smokers are to reduce their own risk of contracting lung cancer, fatal heart attack or chronic bronchitis. Occasional smokers have higher MWTP than non-smokers regarding lung cancer only. MWTP of Swiss-Germans is divided by that of the Swiss-French and the Swiss-Italians. Swiss-Germans seem to have a different risk perception and a different degree of risk aversion because they are less willing to pay than the Swiss-French and the Swiss-Italians. Conclusion ResultsLung cancer is considered as generating the most serious impact on quality of life with human costs exceeding 500,000 Swiss francs per patient. This is twice the value attributed to fatal heart attack. People attribute a lower value to the risk of sudden death, estimated as human costs of fatal heart attack, than to the risk of lung cancer or stroke with their serious impact on quality of life. Usefulness Human costs are a useful indicator for economists and health care providers: They can contribute to a better understanding of behaviour and beliefs of smokers and of the general population regarding tobacco- related diseases. Thus, medical strategies for smoking cessation and prevention could be improved.  Quantification of quality of life in economic terms constitutes an analytic tool allowing integration of human suffering in the economic considerations of public health policies. Human costs partly reveal the advantages for society, which would result from reinforcing smoking prevention. Further research In order to compare these results with other estimations of quality of life and to examine whether the results converge, it would be useful to analyse in detail single cases and to survey people suffering from these diseases - ex-post approach - to get an estimation of their human costs. Influence of physical activities on MWTP Human costs of tobacco-related diseases, per case in thousandsof Swiss francs, 1995 MWTP of sedentary individuals is divided by that of individuals practising sport. It reveals that sedentary individuals are willing to pay between 1.7 to 2.5 times more than others are for the three diseases. Each new case of lung cancer causes a loss of wellbeing, due to lower quality of lifeand shorter life expectancy which is valued higher than the other diseases.