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Food and Nutrition
Article
Health care and lost productivity costs of overweight and obesity in New Zealand Anita Lal, Marj Moodie
Abstract Objective: To estimate the costs of health care and lost productivity attributable to overweight and obesity in New Zealand
Deakin Health Economics, Population Health Strategic Research Centre, Deakin University, Victoria
Toni Ashton
(NZ) in 2006.
National Institute for Health Innovation, School of Population Health, University of Auckland, New Zealand
Methods: A prevalence-based approach to costing was used in which costs were calculated for all cases of disease in the year 2006. Population attributable fractions (PAFs) were calculated based on the
Mohammad Siahpush Department of Health Promotion, Social and Behavioral Health, College of Public Health, University of Nebraska Medical Center, United States
relative risks obtained from large cohort studies and the prevalence of overweight and obesity. For each disease, the PAF was multiplied by the total health care cost. The costs of lost productivity associated with premature mortality were estimated
Boyd Swinburn WHO Collaborating Centre for Obesity Prevention, Population Health Strategic Research Centre, Deakin University, Victoria
using both the Human Capital approach (HCA) and Friction Cost approach (FCA). Results: Health care costs attributable to overweight and obesity were estimated to be NZ$624m or 4.4% of New Zealand’s total health care expenditure in 2006. The costs of lost productivity using the FCA were estimated to be NZ$98m and NZ$225m using the HCA. The combined costs of health care and lost productivity using the FCA were $722m and $849m using the HCA. Conclusion: The cost burden of overweight and obesity in NZ is considerable. Implications: Policies and interventions are urgently needed to reduce the prevalence of obesity thereby decreasing these substantial costs. Key words: obesity, health care costs, lost productivity costs Aust NZ J Public Health. 2012; 36:550-6 doi: 10.1111/j.1753-6405.2012.00931.x
O
besity is at epidemic levels worldwide. In New Zealand (NZ) in 2007, an estimated 35% of the population aged 15 and over (1.2 million people) were overweight and 25.4% (850,000 people) were obese.1 The prevalence of overweight for Māori (31.7%) and Pacific (24.5%) populations was lower, however the prevalence of obesity was much higher for the Māori (43.2%) and Pacific (65.1%) populations.1 These ethnic groups comprise approximately 14.6% and 6.9% of the NZ population respectively.2 Ethnic differences in obesity may originate from genetic factors, different patterns of eating and physical activity or low socioeconomic status. Obesity has been well established as a key risk factor for major chronic illnesses such as cardiovascular diseases,3-6 type 2 diabetes7,8 and some cancers.9 Because of the growing demand for limited health care resources, it is important to assess the cost burden of obesity in order to inform resource allocation. Cost of illness studies help to demonstrate the adverse effects of diseases in monetary terms.10 This information, along with cost-effectiveness Submitted: August 2011
studies, can then be used by policy makers to prioritise areas in terms of the allocation of resources to prevention, treatment and research. Cost of obesity studies carried out in other western countries have estimated the health care costs to be between 2% and 7.6% of national health care expenditures. Australia had the highest proportion at 7.6%, 11,12 followed by the US (6.8%),13 Canada (4.1%),14 The Netherlands (4%),15 the UK (2.3%),16 Sweden and France (2%).17,18 However, these proportions are for different years and jurisdictions, and are calculated using different methodologies, including the actual costs included. A previous study estimated the health care costs of obesity in NZ to be 2.5% of total health care expenditure or $135m in 1991 NZ dollars.19 The NZ estimate requires revision using new and updated evidence. The prevalence of obesity has increased by over 10 percentage points since the last published estimate1 and additional diseases have been identified as being attributable to obesity.20 This previous study also included only the health care costs, which is just one aspect of
Revision requested: November 2011
Accepted: February 2012
Correspondence to: Anita Lal, Deakin Health Economics, Poulation Health Strategic Research Centre, Deakin University, 221 Burwood Highway, Burwood VIC 3125; e-mail:
[email protected]
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AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH © 2012 The Authors. ANZJPH © 2012 Public Health Association of Australia
2012 vol. 36 no. 5
Food and Nutrition
Costs of obesity in New Zealand
the financial cost of overweight and obesity. The purpose of this study is to estimate the health care and lost productivity cost burden that was attributable to overweight and obesity in NZ in 2006. There have been very few published studies that include productivity losses in the cost of obesity. Productivity losses are the costs associated with lost or impaired ability to work due to health status.21 Time off work can be permanent or temporary and due to morbidity or premature death. There are two main techniques which have been used in economic evaluations to measure and value productivity gains and losses: the Human Capital Approach (HCA) and the Friction Cost Approach (FCA). The HCA estimates the value of potential lost production from death until retirement age, assuming full employment.22 Alternatively, the FCA assumes that individuals on long-term sick leave can be replaced by someone currently unemployed after a ‘friction’ period.22 Given the debate surrounding which method is appropriate, both methods will be used. An Australian study estimated productivity losses using the HCA at 44% of the total financial costs of obesity.23
Methods and Procedures Obesity and overweight co-morbidities The prevalence of overweight and obesity is usually assessed by body mass index (BMI), defined as the weight in kilograms divided by the square of the height in metres (kg/m2). A BMI of 25-29.9 kg/ m2 is defined as overweight, and a BMI of over 30 kg/m2 as obese.24 Our analysis included diseases for which associations found between BMI and disease outcomes satisfy the widely accepted criteria for causal relationships20: type 2 diabetes,7,8 stroke,25 ischemic heart disease (IHD),3-6 hypertension which leads to hypertensive heart disease,26,27 osteoarthritis,28 colorectal cancer, postmenopausal breast cancer, uterine cancer and kidney cancer.9 Population attributable fractions (PAFs) were used to calculate the proportion of each disease attributable to overweight and obesity. They were derived using the formula: PAF=
P1(RR1 – 1)+ P2 (RR2-1) 1+ P1(RR1 – 1)+ P2 (RR2-1)
where ‘P1’ is the prevalence of overweight , P2 is the prevalence of obesity, ‘RR1’ is the relative risk for the disease for an overweight person and RR2 is the relative risk for the disease for an obese person.29 The relative risks associated with overweight and obesity were obtained from meta-analyses and reviews detailed in Mathers et al.7 and James et al.20 and are presented in Table 1 along with the PAFs. Separate PAFs were calculated for Māori and Pacific populations using the age standardised prevalence figures outlined in Figure 1.
Health care costs Cost of Illness
Health care costs included both private and public sector costs and were estimated under the following categories: hospital costs (inpatient and outpatient), allied health professional costs, general practitioner visits, residential/aged care, pharmaceuticals and 2012 vol. 36 no. 6
laboratory tests. A prevalence-based approach to costing was used, such that costs were calculated for all cases of disease in the year 2006. A combination of ‘bottom-up’ and ‘top-down’ approaches to the estimation of costs was used depending on the type and level of data available. The ‘bottom-up’ approach uses patient level data to calculate costs whereas ‘top-down’ uses aggregated data. All costs are expressed in NZ dollars for the 2006 reference year. Where costs were not available for the reference year (such as private hospital admissions where the most recent available data were for 2004), costs were inflated to 2006 prices based on the NZ health care price index.30 In 2006, NZ$1.00 was equivalent to US$0.65.31 Hospital inpatient costs
A bottom-up approach was used for the costing of inpatient services, based on hospital admissions extracted from public and private hospital inpatient data obtained from the NZ Health Information Service (NZHIS). Patients with obesity-related diseases were identified based on the International Classification of Diseases codes ICD-10 set out in Supplementary Table 1.24 For simplicity, and to avoid double counting, the costing was based on principal diagnosis only. Cost weights and cost weight multipliers were provided by the NZHIS to calculate the total costs for hospital inpatients for each discharge.32 The cost weight for each stay takes account of length of stay as well as other issues related to the cost complexity of admissions. The cost-weight multiplier converts the cost-weight to a dollar amount.32 In the absence of information for private hospital admissions, the same costing methodology was used. Hospital outpatients costs
Disease-specific outpatient costs were available for diabetes. An average cost per person by age group was provided by the NZ Ministry of Health based on all people (about 190,000) diagnosed or treated for type 1 and 2 diabetes.33 These costs were then multiplied by the number of incident cases of type 2 diabetes.33 For all other diseases, the only data available were from the national Non-Admitted Patient Collection from the NZHIS which contains only the number of events, with no data on diagnosis or costs. Since clinical practice at the secondary care level in NZ is similar to Australia,34 estimations based on the ratio of outpatient to inpatient costs from the Australian Institute of Health and Welfare (AIHW) were used.34,35 The relevant proportion was then applied to total NZ costs to give the cost of allied health services for each disease. Pharmaceutical and laboratory test costs
Pharmaceutical and laboratory test resource use and costs were provided by the NZ Ministry of Health (MOH).36 Patients with cancers and chronic conditions using pharmaceuticals and laboratory tests were identified using cancer registry data and public hospital patient data. As well as diabetes patients identified from the primary care pharmaceutical collections, the MOH identified some diabetes patients from outpatient data records. General Practitioner costs
A GP visit was costed at $50 based on a report by PHARMAC Pharmaceutical Management Agency.37 The mean number of visits
AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH © 2012 The Authors. ANZJPH © 2012 Public Health Association of Australia
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Table 1: Relative risks and population attributable fractions (PAF) for overweight and obese and the Pacific and Māori population. Overweight Relative Risk
Obesity Relative Risk
Men
Men
Women
PAF* (%)
Women
Men
Women
PAF* Pacific (%) Men
PAF* Māori (%)
Women
Men
Women
diabetes type 2
1.80
1.80
3.20
3.20
46.6
44.7
62.1
62.0
55.1
54.2
stroke
