The health economics of obesity in adult populations in Ghana

Background: Obesity, a known risk factor for non-communicable diseases, reduces quality-adjusted life years (QALYs) and life expectancy (LE), predicts all-cause mortality and imposes a high economic burden. Overweight and obesity have become epidemic in most regions of the world, including Ghana. Compared with other sub- Saharan African countries, the rapid transition toward an ageing population in Ghana makes it particularly vulnerable to the increased burden caused by an associated rise in the prevalence of obesity. Although epidemiological studies aid understanding of the distribution and determinants of obesity and inform prevention and intervention programs aimed at reducing the impact of obesity, questions on which programs should be funded using scarce health care resources remain unanswered. The application of health economics allows the prevention and intervention programs that represent best value for money to be identified. In Ghana, there are no data on the health economics of obesity. Therefore, this thesis examined the health economics of obesity in the Ghanaian population, particularly among older adults. The specific objectives of this thesis were: 1. to determine the prevalence and factors associated with obesity in the adult population; 2. to determine the prevalence of obesity at two time-points in older adults from 2007 to 2015; 3. to derive age- and sex-specific health state utilities (HSUs) and HSUs stratified by body mass index (BMI) status in the adult population; 4. to examine the associations between health services utilization and direct healthcare costs as a function of BMI status in the older adult population; 5. to estimate annual transition probabilities between healthy weight, overweight and obese in the older adult population; and 6. to quantify the long-term impact of overweight and obesity on remaining LE, years of life lost (YLL), QALYs and total direct healthcare costs in the older adult population. Methods: Ghanaian data from the World health Organization (WHO) Study on global AGEing and adult health (SAGE) Wave 1 (2007/08, n=5573) and Wave 2 (2014/15, n=4735) were used. SAGE is a study on the health and well-being of the older adult populations aged ‚Äöv¢‚Ä¢50 years that includes a smaller sample of adults aged 18‚Äö-49 years. SAGE collected individual-level data using a stratified, multistage cluster design. Adult population was defined as those who were 18 years and above while older adult population was defined as those 50 years and above. Results: At Wave 2, the prevalence of overweight was 25%, obesity was 13% and underweight was 7% in the adult population. In the seven years between SAGE Wave 1 and Wave 2, the prevalence of overweight increased by 25% from 20% in Wave 1 to 25% in Wave 2 and obesity prevalence increased by 47% from 10% in Wave 1 to 15% in Wave 2 among the older adults. Being female, having high socioeconomic status, or low physical activity were associated with higher odds of overweight and obesity. HSUs were negatively associated with obesity. Overweight and obesity were associated with additional health service utilization and healthcare costs. Findings in study five showed that the annual transition probability was 4.0% (95% CI: 3.4%, 4.8%) from healthy weight to overweight, and 4.9% (95% CI: 3.8%, 6.2%) from overweight to obesity; and the chances of remaining obese were higher especially among female. Using estimates from aims one to four as input parameters for Markov modelling in aim six, overweight and obesity were found to reduce the average remaining LE and QALYs while increasing direct healthcare costs and YLL. Conclusion: These findings suggest that the prevalence of overweight and obesity has increased in the population; that overweight and obesity impose substantial health and economic burden in Ghana's older adults. Therefore, urgent sustainable and cost-effective interventions are needed to control and prevent overweight and obesity in Ghana.