Cost-effectiveness study

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NEUTRAL: See Quality Criteria Checklist below.

To evaluate whether two dietary weight loss interventions [the Dietary Approaches to Stop Hypertension (DASH) program and a low-fat diet program] would be cost-effective in the Australian context.

Not described: Methodology for this review was described elsewhere.

Not described: Methodology for this review was described elsewhere.

Recruitment

Recruitment was assumed to be through mass-media campaigns and postal mailings.

Design

• The authors constructed a multi-state life table Markov model to calculate health outcomes resulting from a reduction in body weight
• The target population was the overweight and obese adult population in Australia in 2003
• The model simulated and compared a reference population that has the BMI distribution and disease pattern of the target population, with an identical population that received the intervention
• The model was populated with data from Medline and Cochrane searches, Australian Bureau of Statistics published catalogs, Australian Institute of Health and Welfare and Department of Health and Ageing.

Intervention

The study considered two dietary weight loss interventions:

1. DASH: This intervention emphasizes consumption of fruit, vegetables, low-fat dairy products, whole grains, poultry, fish and nuts, and the reduced consumption of fats, red meat, sweets and sugar-containing beverages. The trials that evaluated the DASH diet also recommended 180 minutes per week of moderate intensity physical activity. The trials provided 10 group-based and two individual meetings with dietitians. Additionally, there were two group meetings and two individual meetings with exercise physiologists over a six-month period.
2. Low-fat diet: This intervention emphasizes reducing fat intake while maintaining adequate levels of micro- and macronutrients. During this one-year-long program, subjects participated in a series of monthly small group meetings with dietitians.

Statistical Analysis

Not described.

Timing of Measurements

N/A.

Dependent Variables

• Disability adjusted life years (DALYs) averted
• Incremental cost-effectiveness ratios (ICERs)
• Proportions of disease burden avoided.

Independent Variables

DASH intervention or low-fat intervention.

• Initial N: Not reported
• Attrition (final N): Not reported
• Age: Not reported
• Ethnicity: Australian
• Other relevant demographics: Not reported
• Anthropometrics: Not reported
• Location: Australia.

 

Key Findings

• On average, each participant in the DASH intervention could expect to gain the equivalent of 5.9 (95% UI, 3.0 to 14.1) days in perfect health [0.016 (0.008 to 0.039) DALYs]. Participants in the low-fat intervention gained 2.9 (0.3 to 14.4) healthy days [0.008 (0.001 to 0.040) DALYs].
• The DASH and low-fat interventions have ICERs of AUS $12,000 per DALY and AUS $13,000 per DALY, respectively, when the participants’ time and travel costs are not factored in (ICERs under AUS $50,000 per DALY are considered cost-effective). When these costs are included, the ICERs are AUS $75,000 per DALY and AUS $49,000 per DALY, respectively.
• The DASH intervention and low-fat intervention reduced the body weight-related disease burden by 0.10% and 0.05%, respectively.

• The dietary interventions can be considered cost-effective when only health care costs are considered. This becomes doubtful when participants’ time investments are also considered.
• The overall effect of these interventions on the obesity-related burden of disease is negligible.

Government:

Australian National Health and Medical Research Council Health Services

• Rationale and methodology for this review have been described elsewhere
• The benefits of exercise and diet are only modeled through reductions in BMI, whereas improved diet and increased physical activity can be expected to have health benefits independent of BMI
• This study concentrated on expected disease outcomes and did not attribute any value to weight loss itself, general welfare or happiness. Adding such effects could considerably improve the cost-effectiveness estimates.
• The results cannot be generalized to all interventions with diet and exercise components, as this study only modeled two specific interventions
• Both interventions had a relatively high participation rate and a low drop-out rate, which improves the estimated cost-effectiveness
• The modeling accounts for expected future trends in overweight and obesity but no future trends in disease incidence and mortality were modeled
• The modeling may underestimate the health effects of BMI reductions and bias cost-effectiveness results in a direction unfavorable to the interventions modeled
• The study does not take into account any increases in productivity that may result from reduced BMI. Including these benefits would improve the cost-effectiveness of the interventions.