Diabetes-Related Complication in Canada; Prevalence of Complication, Their Association with Determinants and Future Potential Cost-Effectiveness of Pharmacy-Based Intervention

Abstract

In the 21st century, diabetes mellitus (DM) emerged as one of the most prevalent non-communicable diseases, and poses a major problem for every health system in the world. Its global prevalence has more than doubled in the last three decades. As diabetes has become more prevalent, the health programming designed to target diabetes patients has remained inadequate and only heightened the burden. This heightened burden has manifested itself in the increased risk of complications common among patients with diabetes. These complications vary widely, and are typically categorized as either micro-vascular or macro-vascular depending upon the size of blood vessels that are compromised. Due to the havoc that can ensue by either type of complication, the increased risk of diabetes-related complications has been recognized as a serious threat to population health. To gain insight into the threat posed and how it will likely present in the Canadian population, patient’s data from the diabetes component of Survey on Living with Chronic Diseases in Canada (SLCDC-DM-2011) was analyzed. This analysis revealed that among Canadian diabetes patients, 80.26 percent reported having at least one type of diabetes-related complication. The most frequently reported complications were high blood pressure (54.65%), cataracts (29.52%), poor circulation (21.68%), and heart disease (19.4%). This analysis also revealed the predictive role of socio-economic factors associated with diabetes-related complications in Canada. Being married, having a higher income, and having a higher level of education were protective against most complications. In contrast, low levels of physical activity and high levels of HbA1C were important risk factors for many diabetes–related complications. Identifying common diabetes-related complications, protective factors and risk factors is useful for combating the threat posed by diabetes-related complications. To combat this threat in practice, healthcare professionals will play a significant role in the control and management of diabetes and its complications. Diabetes is a chronic disease that needs long-term treatment, and thus multi-disciplinary teams will be required. Increasingly, pharmacists are being determined as having a prominent position on these teams due to their accessibility to the Canadian population, and their expanding scope of practice. This profession has contributed positively to the long-term prognosis of patients with diabetes, in part, by aiding in the control and management of the disease. This aid oftentimes comes in the form of pharmacy-based interventions. Pharmacy-based interventions include a variety of services aimed at enabling patients with diabetes to have better control of their condition. I conducted a systematic review and meta-analysis to evaluate the effects of pharmacy-based interventions on clinical and non-clinical outcomes associated with diabetes-related complications. Four main databases were searched. Based upon my meta-analysis, the standardized absolute mean difference in reduction of HbA1C (%) from baseline to the time of the last follow-up significantly favoured patients in the pharmacy-based intervention group compared to those receiving care as usual (0.96%; 95% CI 0.71: 1.22, P<0.001). In addition, the standardized absolute mean difference in reduction of BMI unit (kg/m2) was 0.61 (95% CI 0.20: 1.03, P<0.001) in favour of the pharmacy-based intervention group. Both of these results demonstrate the positive effect pharmacy-based interventions can have on clinical outcomes. However, there is a dearth of evidence about the effects of pharmacy-based interventions on non-clinical outcomes, including health care utilization and quality of life. Therefore, it was not possible to evaluate non-clinical outcomes associated with diabetes-related complications in the same way. Each year healthcare expenses incurred from diabetes and its complications total more than US$827 billion. This health care cost is significant, and is only expected to grow alongside diabetes’ increasing prevalence. In light of this, a debate over the comparative effectiveness of the different strategies used to manage diabetes and its complications has been sparked. The development of analytic models that can be used as tools in determining budget prioritization and cost-effectiveness of interventions is beginning to be prioritized. To conduct an economic evaluation of these interventions, simulation models are necessary. These models estimate health outcomes, such as life years saved or Quality Adjusted Life Years (QALYs) gained, and account for the costs and health consequences associated with diabetes, its complications and risk factors. I developed a hybrid (agent-based/system dynamic) individual-level micro simulation model using 2,931 patient records from the SLCDC-2011. This model extrapolated the effects of pharmacy-based interventions on health outcomes, costs and health-related quality of life (HRQOL) over time through time-varying risk factors of diabetes-related complications. The treatment effects of pharmacy-based interventions were modeled as reductions in HbA1c levels, BMI, systolic blood pressure and LDL, all of which can affect the risk of progressing long-term complications. The annual costs of diabetes-related complications, as well as, costs associated with pharmacy-based intervention from a societal prospective, were also considered. Using this data, the micro-simulation model was able to estimate the expected number of major health events (heart failure, stroke, amputation, and blindness), QALYs over a patient’s lifetime, the patient’s economic burden on the health care system, and the extent to which pharmacy-based intervention can modify these outcomes. Deterministic and probabilistic sensitivity analyses were conducted to evaluate the uncertainty around the results. Based on the results from my micro-simulation model, a pharmacy–based intervention could avert a total of 155 deaths associated with complications, 19 heart failures, 159 strokes, 24 amputations and 29 blindness events in a population of 2,931 patients over the next 50 years. In addition, the intervention could add 1,246 additional life-years (0.42 per patients) and 953 additional quality-adjusted life-years (0.32 per patients). The intervention would also be cost-effective in comparison to usual care, as indicated by the incremental discounted cost per QALY gained ($3928). Overall, these results suggest that an integrated pharmacy-based intervention could be a cost-effective strategy to control and manage diabetes-related complications in Canada. This is promising and has important public health implications that should not be ignored.