Scandinavian Journal of Public Health, 2008; 36: 850–856 ORIGINAL ARTICLE Costs of heart disease and risk behaviour: Implications for expenditure on prevention MARIE KRUSE1, MICHAEL DAVIDSEN1, METTE MADSEN2, DORTE GYRD-HANSEN3 & JAN SØRENSEN4 1 National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark, 2Institute of Public Health, University of Copenhagen, Copenhagen, Denmark, 3Institute of Public Health, University of Southern Denmark, Odense Denmark and Danish Institute for Health Services Research, Copenhagen, Denmark, and 4Centre for Applied Health Services Research and Technology Assessment, University of Southern Denmark, Odense, Denmark Abstract Aims: The objective of this paper is firstly to estimate the healthcare costs attributable to heart disease in Denmark using recently available data for 2002–05. Secondly, to estimate the attributable healthcare costs of lifestyle risk factors among heart patients, in order to inform decision making about prevention programmes specifically targeting patients with heart disease. Methods: For a cohort consisting of participants in a national representative health interview survey, register-based information about hospital diagnosis was used to identify patients with heart disease. Healthcare consumption during 2002– 05 among individuals developing heart disease during 2002–05 was compared with individuals free of heart disease. Healthcare costs attributable to heart disease were estimated by linear regression with adjustment for confounding factors. The attributable costs of excess drinking, physical inactivity and smoking among future heart patients were estimated with the same method. Results: Individuals with heart disease cost the healthcare system on average J3195 (pv0.0001) per person-year more than individuals without heart disease. The attributable cost of unhealthy lifestyle factors among individuals at risk of heart disease was about 11%–16% of the attributable cost of heart disease. Conclusions: Heart disease incurs significant additional costs to the healthcare sector, and more so if heart patients have a history of leading an unhealthy life. Consequently, strategies to prevent or cease unhealthy lifestyle may not only result in cost savings due to avoided heart disease. Additional cost savings may be obtained because heart patients who prior to the disease led a more healthy life consume fewer healthcare resources. Key Words: Attributable costs, excess drinking, heart disease, physical inactivity, prospective cohort analysis, smoking Background Heart disease is a major cause of death and hospitalization throughout the world. With expensive treatment procedures and high prevalence, the disease incurs high costs to the healthcare sector [1–5]. The costs of heart disease represent potential savings to the healthcare sector if successful preventive programmes targeting lifestyle changes can be implemented. However, improving the lifestyle of individuals at risk of heart disease may also affect the course of the heart disease should it occur. Consequently, there may be an economic effect of prevention in addition to the cost savings associated with avoiding heart disease in terms of less expensive treatments being needed among heart patients who have a history of a more healthy lifestyle. In order to quantify this effect, it is necessary to assess the costs of heart disease and the impact of lifestyle risk behaviour before disease debut on healthcare costs of heart disease. A few European studies have assessed the attributable costs of heart disease in terms of the average additional cost of heart patients in comparison with Correspondence: Marie Kruse, National Institute of Public Health, University of Southern Denmark, Øster Farimagsgade 5A, DK-1399 Copenhagen, Denmark. Tel: +45 3920 7777. Fax: +45 3920 8010. E-mail: [email protected] (Accepted 1 July 2008) # 2008 the Nordic Societies of Public Health DOI: 10.1177/1403494808095955 Downloaded from sjp.sagepub.com at PENNSYLVANIA STATE UNIV on March 6, 2016 Costs of heart disease non-heart patients. Taylor et al. (2007) estimated the attributable healthcare costs for patients suffering from acute coronary syndrome in 2004 in a number of European countries. They found the average annual attributable healthcare costs to be J7000 in the UK and J8000–10,000 in France, Germany and Spain [6]. For Sweden, Zethraeus et al. (1999) estimated the attributable cost of coronary heart disease to be J4400 per patient per year [7]. A number of studies have quantified population attributable fractions (PAF), that is, the share of the disease burden attributable to a certain risk factor, for example physical inactivity in relation to heart disease [8–10]. A few studies assessed PAF for excess drinking in relation to heart disease [11–13]. However no studies were found to analyse the cost attributable fraction to lifestyle risk factors, that is, the healthcare costs attributable to physical inactivity or excess drinking in patients with heart disease. However, it has been shown that smoking has an unambiguous negative impact on health as well as on healthcare costs [14–16]. The smoking attributable fraction (SAF) of healthcare costs, defined as the fraction of healthcare costs due to heart disease, which is attributable to smoking, was found to be 6%–8% in a general population [15,16]. Higher cost estimates were found in studies that focus on heart patients specifically, although there is great variation across studies. Lightwood (2003) found the cost SAF for heart disease to be about 20% [17], while ReynalesShigematsu et al. (2006) estimated the cost SAF for myocardial infarction to be 56% [18] and Martiniuk et al. (2006) found in a comparative study for the Asia-Pacific region the cost SAF to be 13%–33% for male heart patients and v1%–28% for female heart patients [19]. Aim With the aim of informing decision making about prevention programmes specifically targeted towards patients at risk of heart disease, the objective of this paper is firstly to estimate the healthcare costs attributable to heart disease in Denmark using recently available data for 2002–05, and secondly, to estimate the attributable healthcare costs of lifestyle risk factors amongst future heart patients. In a register-based cohort, we identified a sample of patients aged over 50 years who were diagnosed with heart disease for the first time during 2002–05 and compared their annual healthcare cost with a similar population of individuals without heart disease. For the heart patients we estimated attributable costs of 851 their excess drinking, physical inactivity and smoking before disease debut. To adjust for differences in social factors and lifestyle we employed multiple regression analysis. Data and methods We used data from the Danish National Cohort Study (DANCOS) [20]. DANCOS includes individuals who participated in the Danish nationally representative health interview surveys (NHIS). In addition to the survey data, DANCOS holds data on the participants’ use of healthcare resources obtained through linkage to several national registers. In this study we included the cohort who completed the personal interview in the 2000 NHIS. The 2000 cohort was based on a geographical stratified sample of 22,486 individuals aged 16 and older of which 74.2%, or 16,688 individuals, agreed to participate [21]. In Table I the cohort used for this study is described. From the sample of 16,688 individuals, we excluded respondents under 50 years of age (n59,559), respondents with missing information relating to social or lifestyle variables (n515) and individuals who prior to 2002 had been admitted to hospitals with a diagnosis of heart disease (n5958). The final cohort comprised 6171 individuals aged 50+ years and no hospital contact with a heart disease diagnosis at the start of 2002. Three hundred and eight, or 5%, of those individuals were diagnosed with heart disease during the study period 2002-05. For each individual in the cohort we obtained selfreported data on length of education and lifestyle (smoking, alcohol consumption, physical activity, body mass index, stress) from the 2000 NHIS; and date of death or migration (if any) from the Centralised Civil Register. The survey questions on lifestyle are displayed in Table II. The survey was completed in 2000, i.e. the lifestyle factors relate to the period before the disease debut. Table I. Characteristics of participants in the national representative health survey. Heart Non-heart patients* patients Population before exclusion Excluded due to age under 50 Excluded due to heart disease before 2002 Excluded due to missing information Study population 1483 216 958 1 308 15,205 9343 – 14 5848 *Defined as individuals with a hospital contact with a primary diagnosis of heart disease during 2002-05 Downloaded from sjp.sagepub.com at PENNSYLVANIA STATE UNIV on March 6, 2016 852 M. Kruse et al. Table II. Characteristics of heart patients before disease debut, and non-heart patients, in the 2000 NHIS. Definition in the analysis Mean age Percentage men Percentage smokers Percentage without education or training Percentage physical inactive Percentage with body mass index w30 Percentage who often or occasionally feel stressed Percentage alcohol abstainers Age at the interview was divided into 10-year intervals Gender, male/female Based on the survey question: Do you smoke? (‘‘Yes’’, ‘‘Yes but on some days I don’t smoke’’, ‘‘No’’). In this study, respondents who smoke occasionally are considered smokers. Smoking therefore has two categories. Based on the survey question: ‘‘Have you completed any kind of vocational training or education? If yes, which?’’ (The survey question has nine categories, here divided into three: no education, short or vocational training, tertiary education.) Based on the survey question ‘‘If we look back on the past year, what would you say best describes your spare time activities? (1: Heavy training and competitive sports regularly and several times a week; 2: Exercise or heavy gardening at least 4 hours a week; 3: Walk, bike or other easy exercise at least 4 hours a week (include Sunday excursions, light gardening and biking/ walking to work); 4: Read, watch TV or other sedentary occupation)’’ BMI was based on self-reported height and weight and divided into three categories: less than 25 (underweight or normal), 25–30 (overweight), more than 30 (obese). Based on the survey question: ‘Do you suffer from stress in your everyday life?’ (The response has three categories: ‘‘often’’, ‘‘sometimes’’, ‘‘rarely or never’’) Based on the survey question: ‘‘How many alcoholic drinks did you have each day last week? We’ll start with yesterday and take one day at a time (1 drink512 grams of alcohol).’’ The respondent is asked to state a number of drinks for each of the 7 previous days. In this study we divided alcohol consumption into three categories: abstainers (one drink or less per week), moderate drinkers (two to 14 drinks per week for women and two to 21 drinks per week for men); and excess drinkers (15 or more drinks per week for women and 22 or more drinks per week for men) Data on the utilization of healthcare services were obtained for each individual through the National Patient Register (hospital services) and the National Health Insurance Register (primary healthcare services). The cost of hospital services was defined through the Danish system of diagnostic related groups (DRG) that includes an average cost per inpatient admission or outpatient visit. For primary healthcare services the cost was defined as the activity-based remunerations. Per capita payment to general practitioners was disregarded, as were all non-variable costs in the hospital sector. We conducted a prospective cohort analysis where cases were identified as heart patients and compared with similar individuals without heart disease. Heart patients were identified through inspection of the hospital records during 2002–05. The first hospital contact (inpatient or outpatient) with a heart disease diagnosis identified the time of disease debut and the individual was thereafter classified as a patient with heart disease. Prior to the disease debut, Heart patients n5308 Non-heart patients n55,848 t-test for equality of means 69.1 59.6 36.4 62.8 45.9 34.4 pv0.0001 pv0.0001 NS 42.1 34.1 p50.002 27.5 19.6 p50.0002 15.2 11.1 pv0.001 20.1 28.1 p50.001 43.8 35.2 P50.005 the individual was categorized as a non-heart patient. The relevant ICD-10 diagnostic codes were: DI00–DI25 and DI30–DI52 (thus including acquired heart disease and excluding congenital heart disease). Patients with other diseases who had heart disease as a secondary diagnosis as well as individuals taking prescription medicines for heart disease but who had never been admitted to hospital with a heart disease diagnosis, were considered nonheart patients, in order to maintain operational definitions. The healthcare cost per individual was calculated as the total costs registered in the observation period divided by the number of 6-month periods the individual was observed (i.e. adjusting for death and migration during the observation period). For patients who were diagnosed with heart disease, the costs were estimated separately for the period without and with heart disease. We tested whether there were significant differences between heart patients and non-heart patients Downloaded from sjp.sagepub.com at PENNSYLVANIA STATE UNIV on March 6, 2016 Costs of heart disease in social and lifestyle characteristics using t-test for equality of means. On the basis of these results we chose to adjust the cost analysis for differences in age, gender, socioeconomic grouping, education, smoking, excess drinking, physical activity, body mass index and perceived stress. Costs attributable to heart disease were obtained by a multiple linear regression analysis. The log-transformation of total costs was considered the dependent variable. Unadjusted attributable costs were obtained as the parameter estimate of heart disease (yes/no) in a regression analysis that included this single variable. Similarly, adjusted estimates were obtained using multiple regression controlling for age, gender, socioeconomic grouping, education, smoking, excess drinking, physical activity, body mass index and perceived stress. Costs attributable to not adhering to lifestyle recommendations prior to heart disease were obtained as the parameter estimate for each lifestyle variable in a multiple regression conducted for heart patients only. The resulting parameter estimate is interpreted as the costs attributable to a history of smoking among heart patients. For the group of heart patients who smoked, were physically inactive and excess drinkers simultaneously, we computed attributable costs of their risk behaviour, compared with all other heart patients. The average costs per 6 months were logtransformed because preliminary examination showed a skewed distribution with a long right hand tail, as is frequently observed for healthcare cost data. Before log-transformation, observations with zero costs were assigned a value of J0.1. The transformation normalized the distribution of residuals. The logged costs were transformed to nominal costs using a smearing technique [22,23] where the logged cost means were exponentiated 853 and multiplied by a smearing factor, compiled as the difference between the parameter estimate and the mean. SASH v. 9.1 was used for all computations. All costs were adjusted to 2007 price level using the net price index. 2007 costs were converted from Danish Kroner to Euros using the exchange rate J157.50 DKK. Net present values were estimated using a discount rate of 3%. Results Table II shows the characteristics of included heart patients in 2000. The cohort with heart disease included more men and was older than the cohort without heart disease. There were more heart patients with no or short education, they were more likely to be overweight and less likely to be stressed compared to non-heart patients. There was no significant difference between the two groups in smoking behaviour. In Table III, total and attributable cost estimates are shown. The total mean healthcare cost for heart patients was J4285 and J876 for the control group. The unadjusted regression result for attributable cost was J3409 per person year – almost five times the cost of the control group. When adjusting for age, gender, socioeconomic group, education and lifestyle, the average cost attributable to heart disease reduced to J3195 per person year. Table III also reports the regression results for the attributable costs of an unhealthy lifestyle. High intake of alcohol among heart patients was associated with an attributable cost of J503 per person year, or 15.7% of costs attributable to heart disease. Physical inactivity was associated with an attributable cost of J362 or 11.3 %, and smoking was associated with an attributable cost of J474 or 14.8%. A lifestyle including all three risk factors simultaneously was associated with an attributable cost of J890 or 27.9%. Table III. Estimated attributable costs (NPV 2007-EURO) Costs per person year 95 % CI 4285 876 3409 3223 3195 585 503 503 362 384 474 890 4109–4461 859–893 3326–3492 3139–3307 3112–3670 406–765 309–697 334–671 185–541 256–512 338–609 47–1734 Total healthcare costs, heart patients Total healthcare costs, non-heart patients Costs attributable to heart disease, unadjusted Costs attributable to heart disease, adjusted for age and gender Costs attributable to heart disease, adjusted for sociodemographic variables and lifestyle Costs attributable to excess drinking among heart patients, not adjusted Costs attributable to excess drinking among heart patients, adjusted Costs attributable to lack of physical exercise among heart patients, not adjusted Costs attributable to lack of physical exercise among heart patients, adjusted Costs attributable to smoking among heart patients, not adjusted Costs attributable to smoking among heart patients, adjusted Costs attributable to excess drinking, physical inactivity and smoking among heart patients Downloaded from sjp.sagepub.com at PENNSYLVANIA STATE UNIV on March 6, 2016 854 M. Kruse et al. The attributable cost of unhealthy lifestyles was higher when no adjustment was made for age, gender, socioeconomic group, education, body mass index and perceived stress, although the cost associated with smoking was lower. Discussion The linkage of survey data and administrative registers at individual level provided a data set with an accurate description of the resource use and enabled us to analyse usage of health services in relation to self-reported lifestyle. As the cohort is based on a nationally representative sample the external validity of the results is high. All healthcare costs were related to the heart patients’ group or the non-heart patients’ group by half person years. This may potentially cause a minor bias as some non-heart disease related costs could be wrongly categorized as heart disease related costs. Healthcare costs were estimated on basis of register-based information on DRG prices, and charges. These may not accurately reflect the opportunity costs that ideally should be used. However DRG prices and charges are the best available proxies for opportunity costs. The present study included healthcare costs for a maximum period of 4 years subsequent to heart disease diagnosis. The short follow-up period was chosen since a longer-term analysis of costs of lifestyle in relation to heart disease has some caveats. In particular, non-smokers live longer than smokers [24–26] and are thus likely to incur more healthcare costs during their lifetime than smokers. The same applies, to a lesser extent, to other lifestyle components [26]. Also, applying a long run perspective would have required more information on lifestyle changes over time in order to adjust for changes relative to the status in the year 2000. With the available information it was considered inappropriate to extrapolate the results to a lifetime perspective. Adherers to lifestyle recommendations and nonadherers are likely to differ on other characteristics than their adherence to prevention. Although we have made an effort at controlling for confounders such as age, gender, education and other lifestyle components, we cannot exclude the possibility that other explanatory factors may to some extent drive the cost difference we observed. Our results confirm earlier observations that individuals with heart disease impose higher costs on the healthcare system than individuals without heart disease. The level of the estimated attributable costs correspond to about three quarters of the Zethraeus et al. (1999) result of J4400 per coronary heart disease patient per year [7]. Compared to the findings of Taylor et al. (2007), our estimate is even less, about half of the estimated attributable costs of acute coronary syndrome in the UK [6]. We applied a broader definition of heart disease than these earlier studies, as we also included nonacute admissions, e.g. those due to heart failure or heart valve disease. This may, to some extent, explain our results being lower than other studies. Smoking and excess drinking are associated with additional healthcare costs for patients with heart disease. We also found higher costs attributable to physical inactivity in relation to heart disease. The share of attributable costs for a given risk factor is not related to the population attributable fraction. The population attributable fraction for excess drinking and physical inactivity [9,11–13] pertains to the higher risk of developing the disease, whereas the higher costs might arise from higher treatment costs for excess drinkers and physical inactivity. Thus, risks and treatment costs are unrelated. In the field of smoking, cost attributable fractions have been estimated [17–19]. The estimated costs of smoking is less than the cost SAF of 20% estimated by Lightwood (2003) [17]. The result, however, falls within the cost SAF range of 13%–33% for men and v1%–28% for women established by Martiniuk et al. (2006) [19]. It is likely that the differences between our results and Lightwood’s have methodological grounds, as Lightwood’s estimate is based on a top-down analysis and not on individual data. The estimate for attributable costs of all three risk factors together is rather uncertain as only about 3% of heart patients adopted all three risk factors simultaneously. The attributable costs of three risk factors in combination were not much less than the sum of attributable costs for the individual risk factors. This relates to the other risk factors being adjusted for in the analysis of the individual risk factor attributable cost figures. Unadjusted attributable costs of heart disease were not substantially higher than adjusted attributable costs. Adjusting for age, gender, education and lifestyle seems to somewhat reduce the cost difference between heart patients and non-heart patients while not considerably altering the overall result. While sociodemographic variables differ between heart patients and non-heart patients, they only have a minor impact on costs of heart disease. Downloaded from sjp.sagepub.com at PENNSYLVANIA STATE UNIV on March 6, 2016 Costs of heart disease Estimates of costs due to heart disease – or other diseases – may be interpreted as potential savings that could be harvested if heart disease was eradicated. While it remains unrealistic for heart disease to be eradicated, some interventions may succeed in bringing down the incidence. A feasible interpretation of the result is that a potential saving to society might emerge if the incidence of heart disease can be reduced through a targeted prevention effort. Prevention of heart disease may take many forms. In this study we chose to assess the impact on healthcare costs of preventing heart disease and of preventing risk behaviour before disease debut among heart patients. We considered the costs of heart disease and analysed the share of these costs attributable to patients’ lifestyle prior to disease debut. We found that about one sixth of the attributable costs of heart disease could be attributed to these lifestyle components, after adjusting for covariates. The benefit of prevention of lifestyle risk factors would be of equal magnitude. This result, which focuses on the longer-term consequences of lifestyle, points to the relevance and importance of prevention programmes aimed at patients who are at risk of heart disease. Moreover, a healthy lifestyle is likely to yield savings for other diseases in a similar manner as described for heart disease in this paper. Non-adherence to lifestyle recommendations renders heart disease more costly. More healthcare expenditure is channelled towards treatment of these patients; these resources could be used elsewhere in the healthcare sector, if non-adherers change their behaviour. Conclusion We found that heart disease is associated with attributable healthcare costs of J3195 per person year; these costs are higher for individuals not adhering to lifestyle recommendations. An unhealthy lifestyle increases healthcare costs associated with heart disease significantly, which impacts negatively on the entire budget for health care, and consequently on expenditure on other patient groups. Therefore an increased spending on effective prevention programmes could have wide-ranging beneficial effects. Acknowledgments We wish to thank the NHIS respondents for taking part in the survey. There are no competing interests. The source of funding for this work is an 855 unrestricted PhD grant from the Danish Heart Foundation. References [1] Russell MW, Huse DM, Drowns S, Hamel EC, Hartz SC. 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