Introduction
The steady increase of diabetes mellitus (DM) prevalence has triggered an important socioeconomic burden worldwide. In 2019, the age-adjusted prevalence of DM in Korea was estimated at 3.7 million patients.
1 Amongst diabetes types, the most common is Type 2 diabetes mellitus (T2DM) which accounts for approximately 90% of all diabetes cases, globally.
2,3 Diabetes patients are at high risk of developing diabetes-related vascular complications.
4 These complications often lead to productivity losses due to morbidity and mortality and increase the healthcare burden. In 2019, the economic implications of DM in Korea had been reported at 18293 million USD, with an average per capita cost of 4090 USD.
5 Total indirect costs accounted for 5141 million USD, out of which, the majority was attributed to caregivers (1860 million USD), followed by productivity losses due to patient morbidity and mortality (1461 USD and 1820 million USD respectively).
5 The same study showed that an increase in the number of complications or related comorbidities (1-3 or more) led to an increase of the per capita cost of diabetes treatment, by approximately 66%.
5 Thus, diabetes leads to considerable burden for the patients, the healthcare system and society while diabetes-related complications lead to higher healthcare costs.
Access to efficient diabetes care decreases the burden associated with morbidity and mortality. Early and patient-adjusted treatment is a core element of current treatment guidelines.
6 Korean guidelines suggest metformin monotherapy for newly diagnosed cases, unless contraindicated.
7 Depending on the patient’s clinical course, treatment intensification may be considered.
7 Early intensified treatment, an alternative strategy to curb the disease, is likely to lower the incidence of T2DM complications, compared to metformin monotherapy as initial therapy. Korean guidelines
6 suggest that early treatment intensification provides durable benefits and sustained glycemic control. Intensive glycemic control has been effective in preventing microvascular complications, as shown in both the Kumamoto study and the UK Prospective Diabetes Study (UKPDS).
8,9 During the Kumamoto study, a prospective 6-year study conducted on non-insulin dependent DM Japanese patients, the intensive glycemic control group achieved nerve conduction velocity improvement, as well as 69% and 70% decrease in retinopathy and nephropathy comorbidities, respectively.
8 In the VERIFY study (Vildagliptin Efficacy in combination with metformin for early treatment of type 2 diabetes, ClinicalTrials.gov number, NCT01528254) patients treated with early combination treatment had a lower incidence and extended time to treatment failure, compared to sequential intensification in newly diagnosed T2DM patients with mild hyperglycemia.
10 Hence, a greater proportion of patients starting early intensified treatment achieved the glycemic target.
Despite current evidence, due to healthcare systems’ budget constraints that may pose restrictions in adopting new treatment strategies, debate revolves around the widespread implementation of alternative treatment strategies.
11 Given that evidence has already highlighted the potential health benefits of early intensified treatment, this study primarily intends to showcase the societal value due to better health associated with early intensified treatment in patients with T2DM in Korea.
Discussion
T2DM complications lead to poor prognosis for diabetes patients. The socioeconomic burden that results from those complications is significant. Current treatment strategies aim to improve clinical outcomes by slowing the progression of T2DM. It is documented that early intensified treatment—compared to metformin monotherapy—delays the progression of TD2M by extending the time to treatment failure and by reducing the risk of microvascular complications.
1 In the present study, we examined the socioeconomic effects of early treatment intensification in Korea by quantifying the avoided productivity losses in paid work and unpaid activities due to diabetes complications. Early intensified treatment resulted in socioeconomic benefits of 23 million USD in 10 years.
In the current study, we used a comparable methodology with a previous publication
12 to measure and value productivity effects. In Mexico, the authors estimated approximately 13 000 avoided complication events leading to a societal impact of 53.5 million USD.
12 Given the methodological similarities, this variation is mainly driven by the difference in population size of T2DM patients in Korea and Mexico but also the difference in GDP per capita as per the World Bank classification.
24 Despite the divergence in the absolute number of findings, our results were consistent and confirmed the potential positive impact of early intensified treatment irrespective of the economic status of the country. There was a proportional decrease of complication events in relation to the overall prevalence considered in both studies. In Mexico, early intensified treatment led to approximately 20% fewer complication events. Our present study found that 14% of complications could be avoided. The small difference in the percentages could be attributed to better data availability in Korea for the percentage of patients receiving early intensified treatment with metformin plus vildagliptin, and proportion of patients receiving insulin and SUs. Furthermore, the monetized effects could be analogically comparable between the 2 countries considering the higher wages in Korea. However, the delivery and official recommendations of diabetes management substantially differ between the 2 countries. In Korea, early intensified treatment for high HbA1c levels in early stages is already included as an option in the treatment algorithm in the 2021 guidelines.
6 The guidelines use the findings from the VERIFY study to support the recommendation. In contrast to Korea and based on our current knowledge, the guidelines in Mexico do not incorporate a comparable recommendation.
25,26 Therefore, as of the present, early intensified treatment does not appear to be a standard practice in early diabetes stages.
26,27 Instead, the prevailing recommendation advocates for a combination treatment approach in cases of elevated HbA1c levels.
27 Despite this, existing literature discuss the necessity of treatment with metformin and vildagliptin in instances of glycemic dysfunction, particularly in cases where the patient has not undergone prior pharmacological interventions.
28 Concurrently, novel interventions have been introduced and evaluated in Mexico to attain metabolic objectives, resulting in preservation of treatment goals.
29,30Additionally, other differences between the populations (eg, obesity and lifestyle) may influence the onset of diabetes and diabetes outcomes. Global trends in obesity highlight that central Latin American nations, such as Mexico, exhibit elevated rates of obesity among adults compared to countries of the East Asia region, such as Korea.
31 In particular, Mexico exhibits one of the highest obesity rates globally, with almost 30% adults being classified as obese. In contrast, obesity rates in Korea rank among the lowest; however, there is an upward trend.
32,33 Approximately 4% of the adult population in Korea is categorized as obese, while around 30% are classified as overweight,
32-34 inclusive of those in the obese category. Consequently, the obesity in Mexico is estimated to be 10 times higher compared to Korea.
34 Concerning the lifestyle in Mexico, a substantial proportion, approximately 80% of adults, encounter barriers in the pursuit of a healthy lifestyle, specifically in maintaining a nutritious diet and engaging in physical activity.
35 Among the barriers to fostering dietary health are the financial constraints and cultural eating patterns. On the other hand, Koreans are more engaged to healthy eating habits.
36Overall, it is evident that diabetes exhibits a negative association with employment,
37 significantly influencing work habits and wages.
38 Particularly, individuals diagnosed with T2DM exhibit a higher frequency of absenteeism in comparison to their healthier counterparts, consequently exerting an adverse impact on their remuneration.
39 Furthermore, diabetes imposes a substantial burden on the healthcare system. In Mexico, the indirect costs reached 177 million USD, predominantly attributable to permanently disabled patients. Direct costs associated with diabetes are approximately 1164.8 million USD. Additionally, the costs related to diabetes complications are noteworthy, ranging from 82 million USD for nephropathy to 2.8 USD million for neuropathy.
40 While our evaluation does not specifically address the direct costs of complications, it is plausible that a substantial decrease in the incidence of macro- and microvascular complications would yield significant cost savings for the healthcare system.
To the best of our knowledge, this investigation represents the first attempt to evaluate the direct implications of early treatment intensification on productivity gains in the context of T2DM in Korea. Recent empirical evidence underscores the potential economic viability of this therapeutic approach. Notably, findings by Chin et al indicate that early treatment intensification demonstrates cost-effectiveness when compared with a delayed strategy within the framework of the Australian healthcare system.
11Although the present study was based on solid health and socioeconomic inputs and the methodology built on a previously published study, there are sources of uncertainty that should be acknowledged. We used evidence from the VERIFY study,
10 an international trial on time to treatment failure. The incidence of diabetes complication events while on metformin monotherapy and metformin plus vildagliptin was derived from the same clinical trial.
10 To estimate the probability of experiencing micro- and macrovascular events when our patient population receives insulin and SUs, we used a real-world study
16 with a small sample size since data on the Korean population was unavailable. Moreover, this was the only identified study in the literature assessing the treatment regimens of interest. The underlying assumption is that the findings of the VERIFY trial
10 and the real-world study
16 could be extrapolated to the Korean population. Differences in the population, such as education and nutrition, may affect the outcomes of our model. However, the VERIFY also included an Asian population, and 37 patients were from Korea.
Another source of uncertainty is the productivity parameters used to value the losses due to absenteeism, presenteeism, activity restriction and lost labor force. Due to the unavailability of Korean-specific inputs, most evidence came from other high-income countries. The primary aim of this analysis was to identify predominantly country-specific parameters, or evidence from similar countries, for example, Japan. This was possible for only 7 parameters. We utilized evidence from the USA or Europe for all the remaining parameters. We acknowledge that the proxy countries used may significantly differ regarding the social and healthcare system and the population characteristics. However, we assessed the clinical and productivity parameters in sensitivity analyses to understand the impact of base case variations.
The age and gender distribution of our model came from the VERIFY trial.
10 Generally, using evidence on the population distribution reported in trials is a common practice. However, in our case, this was preliminarily done to better align with the evidence on the probability of diabetes complication events, as certain age groups have a higher probability of experiencing complication events.