WILLINGNESS-TO-PAY FOR INSULIN IN DIABETES TREATMENT: A SYSTEMATIC REVIEW AND META-ANALYSIS

Background: Insulin treatment is necessary for all patients with type 1 diabetes and a subset of patients with type 2 diabetes. However, lifetime insulin treatment is relatively costly that has put a heavy financial burden on insulin-dependent diabetics. Several studies thus have been conducted widely to estimate diabetes patients' willingness to pay (WTP) for insulin therapies worldwide. This study aimed to derive the diabetes patients' WTP for insulin therapy from the results of previous research studies. Methods: A systematic review and meta-analysis of diabetes patients’ WTP for insulin was conducted. All studies were searched and derived from PubMed combined with MeSH, Cochrane library combined with MeSH, ScienceDirect, and Springer Nature. The WTP values were estimated for three different types of insulin, including short-acting, rapid-acting insulin; long-acting, slow-acting insulin, and mixed insulin. Review Manager 5.1.4 software was used to conduct the meta-analysis. Results: Twelve studies were identified by the systematic review, in which eight studies were eligible for a meta-analysis. Most studies were conducted in high-income countries (83.3%), mainly in America (41.7%) and Europe (33.3%). The insulin formulation with the highest mean WTP value was Humalog Mix25 insulin, which was recorded at 410.42 USD per month in the UK and more than 120 USD per month in France, Italy, Spain, and Germany; while most of the other insulin formulations had mean WTP values less than 120 USD per month. Compared to diabetes patients, general populations were willing to pay less for insulin, which was observed in the case of Humalog Mix25 insulin (mean 95.77 USD per month vs 205.89 USD per month) and inhaled insulin (mean 50.43 USD per month compared to more than 120 USD per month). The meta-analysis showed the WTP value for insulin was 74.15 USD per month (95% CI; 55.82 - 92.48). Conclusion: This study showed a comparison of WTP values for different insulin formulations worldwide. The mean WTP value for insulin derived from all previous research may provide an initial understanding of the individuals' preference and WTP. This information could contribute to the effort of managing diabetes and reducing the financial burden of this chronic disease.