Clare Collins , Alexis Hure , Tracy Burrows , and Amanda Patterson
Key Points
• Limited studies have determined the relationship between diet quality and health care costs. The current analysis investigates the relationship between Medicare health care costs and claims in Australia with diet quality, in a nationally representative sample of mid- aged Australian women over the 10-year period from 2001 to 2010. Health care utiliza- tion data was obtained from Medicare and diet quality was calculated using the Australian Recommended Food Score (ARFS). The ARFS is derived from Food Frequency Questionnaire (FFQ) responses to foods that are consistent with national recommendations detailed in the Dietary Guidelines for Australian Adults.
• It was found that consuming a greater variety of vegetables predicted lower 10-year cumulative Medicare Charges, Benefi t, Gap and a lower number of claims. However, for fruit, dairy and healthy fats component scores this relationship was in the opposite direction. Further evalua- tions in other studies are needed and will provide the basis for model- ling future cost savings and may help to identify appropriate dietary targets associated with reduced health care costs.
Abbreviations
AIHW Australian Institute of Health and Welfare
ALSWH Australian Longitudinal Study on Women’s Health
ARFS Australian Recommended Food Score DALY Disability-adjusted life years DQES Dietary Questionnaire for Epidemio-
logical Studies DQI Diet Quality Index DQS Diet Quality Score EPC Enhanced Primary Care FFQ Food Frequency Questionnaire HDI Healthy Diet Indicator HEI Healthy Eating Index HFI Healthy Food Index
HMO Health Maintenance Organization MDS Mediterranean Diet Score RFS Recommended Food Score
SENECA Survey in Europe on Nutrition and the Elderly; a Concerted Action
Introduction
Surprisingly, only limited studies have examined the relationship between diet quality and the health care costs to government or to individuals.
Additionally, very few studies have examined whether diet quality is able to predict future health care costs.
Optimal dietary quality in the context of this review has been defi ned as eating patterns that refl ect greater adherence to national dietary rec- ommendations. Diet quality can be measured by diet quality or diet index scores. There are over 25 indexes to date that have been developed to assess overall diet quality and/or variety. Wirt and Collins [ 1 ] reviewed these in 2009 and found that the major indexes included the Healthy
Eating Index (HEI) [ 2 ], the Healthy Diet Indicator (HDI) [ 3 ], the Healthy Food Index (HFI) [ 4 ], the Recommended Food Score (RFS) [ 5 ], the Diet Quality Index (DQI) [ 6 ], the Diet Quality Score (DQS) [ 7 ], and the Mediterranean Diet Score (MDS) [ 8 ]. Construction of these diet quality indexes follows three major scoring approaches:
(1) based on food groups or specifi c foods, (2) based on nutrient intakes or (3) derived from combinations of foods and nutrient intakes [ 9 ].
A review of the relationship between these diet quality scores and health-related outcomes demonstrated that higher quality eating patterns were associated with lower self-reported indices of health care usage and lower morbidity and mortality from chronic disease [ 1 , 10 , 11 ].
However, whether higher diet quality trans- lates into lower health care costs over time has rarely been examined. One key Australian report evaluated the relationship between fruit and veg- etable intake (as a measure of diet quality) and burden of disease. This Australian Institute of Health and Welfare report (AIHW-2003) esti- mated that 2.1 % of the total burden of disease could be attributed to inadequate fruit and vegeta- ble consumption, making it seventh in a ranking of 14 risk factors studied [ 12 ], which together explained 32.2 % of the total burden of disease and injury. Eating an adequate amount of fruits and vegetables has been shown to prevent chronic diseases such as cardiovascular disease, type 2 diabetes and some cancers [ 12 ]. The AIHW report found that 69 % of the burden from low fruit and vegetable consumption was due to ischaemic heart disease and that two-thirds of this was expe- rienced by males. Further, the report estimated that 81 % of the burden from low fruit and vegeta- ble consumption was due to mortality, and that the absolute burden from low consumption peaked between 60 and 80 years of age [ 12 ].
We previously reported the results of the relationship between diet quality and health Keywords
Diet index • Diet quality • Diet score • Health costs • Health service usage • Medicare • Nutrition survey
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service use in a cross-sectional analysis of the Australian Longitudinal Study on Women’s Health (ALSWH) for over 9,000 mid-aged women [ 13 ]. Among these women, a higher Australian Recommended Food Score (ARFS, the index of diet quality used) was associated with better self- reported health status (excellent, very good, good or fair/poor), a lower number of visits to a general medical practitioner in the previous year and fewer consultations with a specialist medical practitioner in the previous year. Those with a higher ARFS also had higher intakes of micronutrients and a lower percentage of energy from total or saturated fat [ 13 ].
Kant and Schatzkin [ 11 ] examined the 10-year association between diet quality (measured by nutrient intakes) with self-reported doctor- advised chronic medical conditions, for a nation- ally representative sample of adults (>25 years, n = 7,207) in the Continuing Survey of Food Intakes. A greater number of self-reported medi- cal conditions were associated with an increased risk of not consuming 100 % of the Recommended Dietary Allowance (RDA) for some nutrients (vitamins E, B12 and calcium, zinc and iron, P < 0.05). Women were more likely to report poor nutrient intakes than men [ 11 ].
In the SENECA (Survey in Europe on Nutrition and the Elderly; a Concerted Action) study on older persons from seven European countries, Haveman-Nies et al. [ 14 ] examined the health status and lifestyle behaviours of 216 men and 264 women born between 1913 and 1918, for the 10-year period (1988–1999). Self-rated health and self-care ability declined in men and women with both healthy and unhealthy lifestyle habits during follow-up. There was no relationship between having a healthy, Mediterranean-style diet and deterioration in health status. Inactive and smoking persons did have an increased risk for a decline in health status, compared with active and non-smoking people, and the authors concluded that both physical activity and being a non-smoking delayed deterioration in health status for older people.
Cost-effectiveness studies have modelled the potential cost savings of implementing strategies to promote healthful eating patterns and prevent dis-
ease development. Cobiac et al. [ 15 ] evaluated the cost-effectiveness of interventions to promote fruit and vegetable consumption to assess the degree to which promotion strategies could potentially reduce population disease burden. They identifi ed 23 interventions that promoted fruit and vegetable intake in adults that also had suffi cient information to model the health impacts in disability-adjusted life years (DALY). They modelled the intervention costs and potential cost savings from averting dis- ease treatment, and the cost-effectiveness over the population’s lifetime, from a health sector perspec- tive. They found that only fi ve of the 23 interven- tions had less than a $50,000 per DALY cost-effectiveness threshold and that the most effective intervention could avert only 5 % of the disease burden attributed to insuffi cient fruit and vegetable intake. They concluded that further eval- uation of population level interventions was needed. While observational studies and modelling estimates do provide a clear rationale for trialling interventions to improve diet quality as a strategy to reduce health care and medical costs, evaluation in real-life settings and databases provides impor- tant data in relation to true health care costs.
Others have assessed the cost-effectiveness of interventions to improve diet in specifi c at risk populations groups. Patrick et al. [ 16 ] random- ized about 5,000 health maintenance organiza- tion (HMO) older Medicare benefi ciaries to receive a 2-year preventive service benefi t pack- age that included one component aimed at improving diet quality, as measured by percent- age energy from fat and grams from daily fi bre intakes, or to usual care. At the 2- and 4-year follow-ups, the treatment group reportedly par- ticipated in more exercise and reduced their per- centage fat intake more than the control group.
Although they observed an unexpected greater number of deaths in the treatment group, which they attributed to more individuals over the age of 75 years being randomized to the intervention group, the surviving treatment group participants reported higher satisfaction with health, less decline in self-rated health status, and fewer depressive symptoms than surviving control par- ticipants. However, the intervention did not yield a lower cost per quality adjusted life year.
4 Diet Quality and Its Potential Cost Savings
Wolf et al. [ 17 ] evaluated, in a 12-month randomized controlled trial, the costs associated with provision of a lifestyle intervention pro- gramme on health care expenditure in a high-risk obese population ( n = 147) with type 2 diabetes.
The intervention group received individual and group education, support and referrals to regis- tered dietitians, while the usual-care group received educational materials only. The net cost of the intervention was $328 per person per year, but the overall mean health plan costs (including the $328) was $3,586 lower in intervention group compared to the usual care group (95 % CI −$8,036 to −$25, P < 0.05). The difference was driven by group differences in medical costs (−$3,316, 95 % CI −$7,829 to −$320, P < 0.05), with signifi cantly fewer inpatient admissions for the intervention group (prevalence 2.8 % in the intervention group vs. 22.5 % in controls, P < 0.001). Authors con- cluded that adding a modest-cost, registered dieti- tian-led lifestyle case-management intervention to usual medical care did not increase health care costs, but resulted in modest cost savings for obese patients with type 2 diabetes.
Pavlovich et al. conducted a systematic review of randomized controlled trials on the cost- effectiveness of the provision of outpatient nutri- tion services [ 18 ]. Of the 13 studies included there was relatively consistent support for the cost- effectiveness of nutrition services. Provision of nutrition services was cost-effective in reducing serum cholesterol levels (for example, $20–1,268/
mmol/L decrease in serum low-density lipoprotein level), for weight loss ($2.40–10 per pound lost), and in reducing blood glucose ($5/mmol/L decrease). This was evident in target populations with diabetes mellitus and hypercholesterolemia as well as for those without such diagnoses. The authors noted that due to limitations in trial quality and differences in cost perspectives though, that more randomized controlled trials addressing these omissions were needed.
While these approaches provide important insights into potential cost savings through optimizing dietary quality, we have only been able to locate a limited number of studies interna- tionally that have prospectively examined the
relationship between diet quality and health care costs. Two studies have examined the national government Medicare charges in relation to aspects of dietary intake. Daviglus et al. [ 19 ] looked at US Medicare charges over a 15-year period in relation to fruit and fruit plus vegetable intakes in mid-aged men from the Chicago Western Electric Study, while we examined Australian Medicare costs incurred over a 6-year period by mid-aged women ( n > 10,000) from the ALSWH in relation to diet quality as measured by the ARFS [ 20 ].
Daviglus et al. demonstrated that in 1,063 men from the Chicago Western Electric Study, those in the highest tertile of fruit and fruit plus vegeta- ble intakes during middle age had lower mean annual and cumulative Medicare charges over a 15-year period [ 19 ]. They found that, after adjust- ing for baseline age, education, total energy intake and baseline risk factors, high fruit and vegetable intakes were associated with lower mean annual and cumulative Medicare charges, including total charges and cardiovascular dis- ease and cancer- related charges, although the P value for trend ranged from 0.019 to 0.862.
While many of the results were not statistically signifi cant, the trends do suggest that having higher fruit and vegetable intakes earlier in adult- hood has the potential to lower health care costs in older age, as well as improve health status.
While we hypothesized lower costs would be associated with higher diet quality, our Australian data demonstrated a positive association between having a higher ARFS (i.e. better diet quality) and higher cumulative Medicare (Australia) costs. Although those in the highest quintile of ARFS incurred higher Medicare costs, the num- ber of Medicare claims for this quintile was lower than for the lowest quintile of ARFS for the period 2002–2007, P = 0.002.
Firstly, it is important to note that there are some differences between the national Medicare programmes in the USA and Australia. In the USA, Medicare is a social insurance programme administered by the government, which provides health insurance cover to people who are aged 65 and over, or who meet specifi c criteria. Medicare
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(USA) covers hospital-related inpatient and outpa- tient services, skilled nursing facility services and charges related to outpatient services, including emergency room visits, clinic and ambulatory sur- gery, laboratory tests, radiography, rehabilitation therapy, radiation therapy and renal dialysis. This contrasts with Medicare Australia, who administer a universal health care programme called Medicare for the Australian government. Medicare (Aus) is funded by income tax and an income-related Medicare levy. Medicare (Aus) is the largest source of primary health care spending and covers scheduled fees for out-of-hospital services for doctors (including specialists), tests and examina- tions by doctors, X-rays and pathology tests, eye tests performed by optometrists, most surgical and other therapeutic procedures performed by doctors, some surgical procedures performed by approved dentists, specifi ed items under the Cleft Lip and Palate Scheme, and specifi ed items for allied health services as part of the Enhanced Primary Care (EPC) programme. In-hospital services are only covered by Medicare (Aus) for treatment as a public patient by doctors and specialists nomi- nated by the hospital. Medicare (Aus) also admin- isters a separate Pharmaceutical Benefi ts Scheme (PBS), which makes a range of prescription medi- cines available at affordable prices to Australian residents, through government subsidy.
While the above two studies are the only ones we have found that actually calculate costs, van Baal et al. [ 21 ], in three cohorts from the Netherlands, estimated the annual and lifetime medical costs attributed to obesity for people aged 20 years at baseline. They compared obese people to those who were smokers and those with a healthy lifestyle (including following a high quality diet). The obese group were modelled as having the highest annual health expenditure, followed by smokers, but life- time health expenditure was highest among healthy- living individuals, due to their longer life expectancy.
The authors concluded that while obesity prevention is an important and cost-effective way of improving public health, it is not the only strategy for reducing health expenditures.
Other than these studies, we were not able to locate any other studies that have examined
associations between diet quality and subsequent cost of health service use. This relationship needs further study with both costs and claims moni- tored over time to examine patterns of health care usage and costs in the longer term for those with the dietary patterns that adhere more closely to national recommendations.
Evaluating the Association Between Diet Quality and 10-Year
Cumulative Medicare Costs
On this basis, we have recently extended the 1946–1951 (mid-aged) ALSWH cohort follow- up period to 10 years, to examine whether higher diet quality, as measured by the ARFS was still associated with higher health care costs but lower number of claims.
The data for this analysis comes from ALSWH, which was established to investigate multiple factors affecting the health and wellbeing of women over a 20-year period. Women in three age groups (“younger” 18–23, “mid-aged” 45–50 and
“older” 70–75 years) were randomly selected from the national health insurance database, Medicare (Aus) that includes all permanent residents of Australia, with over-representation of women living in rural and remote areas. The methods have been previously published [ 22 – 24 ].
Diet Quality and Health Care Costs in Mid-Aged Women in Australia Data used in this analysis have been derived from the mid-aged cohort of the ALSWH. Survey 1 ( n = 13,716) was conducted in 1996 and the respon- dents have been shown to be broadly representative of the national population of women in the target age groups [ 22 ]. Survey 2 ( n = 12,338) was con- ducted in 1998 and Survey 3 ( n = 11,228) was con- ducted in 2001. The response rate for Survey 3 of the mid-aged cohort was 83 % of women who had completed Survey 1 and had not died or become too ill to complete further surveys. The non-respon- dents included those who did not complete Survey
4 Diet Quality and Its Potential Cost Savings
3 (7.4 %), withdrew from the study completely (2.8 %) or could not be contacted (6.8 %) [ 24 ]. Of the women who completed Survey 3 (then aged 50–55 years), 11,194 completed a usable Food Frequency Questionnaire (FFQ).
Assessment of Dietary Intake
Dietary intake was assessed using the Dietary Questionnaire for Epidemiological Studies (DQES) FFQ. The DQES asks respondents to report their usual consumption of 74 foods and six alcoholic beverages over the preceding 12 months using a 10-point frequency option from “never” up to “three or four times per day”. Portion size pho- tographs are used to adjust the serve size for vege- tables, meat and casseroles. Additional questions are asked about total number of daily serves of fruits, vegetables, bread, dairy products, eggs, fat spreads and sugar, as well asking the type of bread, dairy products and fat spreads used. Nutrient intakes are computed from NUTTAB 1995, a food composition database of Australian foods [ 25 ], using software developed by the Cancer Council of Victoria. Both the development of the DQES [ 26 ] and its validation in mid-aged Australian women have been previously reported [ 27 ]. FFQs with greater than four missing values were discarded.
Australian Recommended Food Score
The ARFS was modelled on the RFS by Kant and Thompson [ 28 ] and has been previously described [ 13 ]. Briefl y, it is calculated based on DQES items consistent with national recommendations in the Dietary Guidelines for Australian Adults [ 29 ]. In brief, items consumed less than once a week are scored zero and those consumed once a week or more score one. Additional points are awarded for type and variety of core foods consistent with national dietary intake recommendations. A maxi- mum of two points was added for alcohol con- sumption: one point for moderate frequency and the second point for moderate quantity, when they drank alcohol. The maximum ARFS is 74.
Medicare Data
The health services utilization and cost data was provided by Medicare Australia. In the third survey of the mid-aged cohort, 7,225 out of the 11,226 women (64 %) gave consent for linkage of their Medicare data to their survey. There were signifi - cant but small differences between consenters and non-consenters by area of residence, and those consenting to Medicare linkage tended to be better educated, more likely to be able to manage on their available income and more likely to say their health was excellent, very good or good [ 23 , 24 ]. Only ALSWH respondents who consented to link their Medicare data were used in this analysis. There were 6,781 women who had given both Medicare consent and had an ARFS.
All Medicare data were collected for the 10 years from 2001 to 2010. Annual data was totalled for each woman to determine the amount the women spent on Medicare health care and the
“Number of claims”. Women with no claims for a particular year had values of zero imputed into their claims and cost fi elds for that year, as Medicare Australia only provides data for women for which there are charges recorded. The “Charge”
item is the total cost of the treatment. There are two other Medicare variables, the “Benefi t” and the
“Gap”. The Benefi t is what was paid back to the patient, while the Gap is the difference between the Charge and the Benefi t (i.e. what the patient paid out of their own pocket). The Charge is almost always higher than the Benefi t.
Those with the highest ( n = 67) and lowest 1 % ( n = 68) of charges were excluded from data analysis to avoid extreme values (<$634 and
>$49,395). Therefore, the sample included data for n = 6,646 women. Level of education was recorded at Survey 1 and was missing for n = 39, hence a total sample of n = 6,607 are included in the multi- variate regressions with adjustment for baseline area of residence and education. The Medicare data used in this study were from the Medicare Benefi ts Schedule and did not include data from the PBS.
The analysis followed the same approach as that described previously [ 20 ]. Data manipulation and statistical analyses were performed using