According to the World Health Organization (WHO), 285 million people are currently suffering from diabetes. The latest projections predict that the number of cases will have risen to 439 million by 2030. Global costs for diabetes treatment in 2010 were estimated to 376billion dollars and according to the predictions they will have risen to 490 billion dollars by 2030. Despite the wide access to medication and physicians, good glycaemic control is not self-evident. Poor gylcemic control results in higher rates of diabetes complications occurrences and consequently influences diabetes costs. One of the vital factors is inappropriate medication adherence. WHO defined the term adherence as »extent to which a person’s behaviour – taking medication, following a diet, and/or executing lifestyle changes, corresponds with agreed recommendations from a healthcare provider«. As literature shows, medication adherence and type 2 diabetes (SB2) costs are widely researched. Studies indicate adherence results in cost savings for the healthcare payer. There are significantly less publications on the cost impact of diet and exercise adherence. Studies correlating the cost of illness with patient adherence rates are retrospective and crosssectional. However, they lack adherence enhancement and adherence maintaining costs. According to the published data, adherence impacts annual costs and effectiveness of medication. Medication adherence is not considered in incremental cost-effectiveness ratio (ICER) calculations. Sulphonilurea treatment results in weight gain and higher hypoglycaemia rates therefore patients using DPP-4 inhibitors are significantly more adherent than sulphonilurea users. No type 2 diabetes medication adherence assessment has been conducted in Slovenia to date. Diet and exercise adherence were assessed before; however, adherence determination was not the main study aim. The results are consequently not presented nor compared to the published literature from the adherence perspective. Type 2 diabetes burden from the healthcare payer perspective in Slovenia was published in 2006. Cardiovascular and cerebrovascular occurrences were taken into account. The burden assessment lacked information on nephropathy, retinopathy, neuropathy, foot ulcer and amputation impact. With regard to stated data, we prepared four studies
aiming to assess adherence in SB2 patients, determine adherence impact on cost-effectiveness and assess type 2 diabetes patient burden of illness. The aim of the first study was medication, diet and exercise adherence determination on a cohort of Slovenian SB2 patients. 93 SB2 patients who participated in the prospective pharmaceutical intervention impact on glycaemic control study were included. Hba1c, HDL, LDL, blood pressure, body mass and height were measured before and during the intervention study. Adherence was assessed through the Morisky 8-item (MMAS-8) questionnaire and the Summary of diabetes self-care activities (SDSCA) questionnaire. Adherence levels were determined with the help of measurements conducted before the beginning of the study. Medication adherence was assessed as good (90.75%) as was exercise adherence (90%) while diet adherence was assessed as low (60%). However, exercise adherence results are overestimated regarding SB2 risk factor improvements. SDSCA exercise chapter consists of two questions with the first aiming at general activities like »work around the house, walking ...« and the second aiming at specific exercise sessions. The results from the second question are generally 50% lower than the results from the first one. Interventions which are effective in SB2 risk factor improvements are considered as intensive therefore results from the second question indicate a generally lower exercise adherence score. Despite high medication adherence, the average HbA1c value in the study cohort was also elevated. The results obtained were similar to Canadian data and indicate that glycaemic control is suboptimal despite the fact that patients use medication regulary. The aim of the second study was type 2 diabetes healthcare payer burden assessment. The study used the bottom-up approach, was prevalence-based and estimated direct medical costs. Diabetes healthcare payer burden was assessed to 99,120,418 EUR (4.18% of planned public healthcare expenditures) which is similar to the data published earlier. The purpose of the third study was determination of medication adherence or lifestyle intervention impact on type 2 diabetes healthcare payer burden. Interventions enhance type 2 diabetes risk factors, consequntly complications occurrence rates and costs are lowered. However intervention costs can exceed savings, therefore the burden impact was assessed with cost-effectiveness determination of medication adherence and lifestyle interventions. Intervention types and efficacies were determined by a systematic literature review. United Kingdom Prospective Diabetes Study Outcomes model 2.0 and Slovenian type 2 diabetes patient cohort were used (n=93) for cost-effectiveness analysis-required disease progression simulation. The patient data encompassed gender, ethnicity, age, SB2 duration, body mass, height, HDL, LDL, systolic blood pressure and HbA1c. Average heart rate, white blood cells (WBC) count, haemoglobin concentration and estimated glomerular filtration rate were derived from literature data and further adapted to each patient with simulation model internal equations considering individual demographic and clinical data. Lifetime time horizon was used. The results indicate that intervention-induced adherence improvement impacts type 2 diabetes
healthcare payer burden. Disease costs increased for minimal 233 EUR (1 year intervention duration) to 5568 EUR (10 year intervention duration). Medication adherence intervention was the most cost-effective and had the highest efficacy and SB2 blood risk factors improvements. ICER in EUR/QALYg for medication adherence interventions (10 years duration) was assessed from 9,983 to 30,967 EUR/QALYg, for diet adherence interventions to 27,246 EUR/QALYg, for aerobic exercise interventions to 80,798 EUR/QALYg, for resistance exercise interventions to 111,847 EUR/QALYg and for combined exercise interventions to 46,411 EUR/QALYg. The goal of the fourth study was determination of type 2 diabetes medication adherence impact on medication cost-effectiveness. The impact was assessed with ICER determination of DPP-4 inhibitors compared to sulphonilureas as second line treatment. Medication costs and effectiveness were altered according to different adherence rates. United Kingdom Prospective Diabetes Study Outcomes model 2.0 and Slovenian type 2 diabetes patient cohort were used (n=93) for cost-effectiveness analysis-required disease progression simulation. The patient data encompassed gender, ethnicity, age, SB2 duration, body mass, height, HDL, LDL, systolic blood pressure and HbA1c. The results suggest that adherence impacts ICER. With no adherence consideration ICER amounted to 1,322,690 EUR/QALYg and with adherence consideration ICER amounted from 297,698 EUR/QALYg (2.5 weight increase in sulphonilurea users) to 553,170 EUR/QALYg (1.5 weight increase in sulphonilurea users). As a result of high DPP-4 inhibitors costs (425,6 EUR/year), sulphonilureas (70,4 EUR/year) represented a dominant treatment approach irrespective of adherence values.
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