Improved quality of diabetes control reduces complication costs in Bulgaria

Abstract

The study investigates the quality of diabetes control and its economic implications in Bulgaria for the years 2012–2016. It is a retrospective study of the national diabetes register. Patients were categorized according to type of diabetes, gender, newly diagnosed cases per year, body-mass index (BMI) and achieved disease control. The relative risks for reducing the diabetes-related complications achieved through a 1% reduction of HbA1c were taken from literature data, and macrocosting was used to calculate the saved cost for diabetes complications. The new cases of type 1 diabetes decreased (10% lower in 2016 than in 2012) but the number of new cases with type 2 diabetes increased (12%). In 2012, the average percentage of glycosylated hemoglobin in the second recording at the end of the year was 7.59% (SD 1.85), whereas the second recording of values for 2016 revealed an average value of 7.3% (SD 1.32). The mean yearly reduction in 2012 was 0.05% (SD 1.1) with a slow increase to 0.07% (SD 0.46) in 2016. The absolute risk reduction for all diabetes-related complications was 20.6. The total prevented costs for all complications in the entire population were 20 million BGN. The results for the period 2012–2016 showed improved control of diabetes. The proportion of patients who achieved control increased over the period, reaching over 40% of the afflicted population. The achieved adequate control led to a reduced risk of developing diabetes-related complications, thereby saving costs of 20 million BGN associated with them, and decreasing the burden on the healthcare system.

Keywords:

• Diabetes control
• diabetes complications
• diabetes registry
• glycosylated hemoglobin
• saved costs
• macroeconomic analysis

Introduction

Diabetes mellitus (DM) is a serious debilitating disease which poses an increasing socio-medical challenge to all countries worldwide. Diabetes-related deaths in 2017 reached 4.0 (3.2–5.0) million people [1]. During the last two decades, the number of new diabetes cases has increased twofold, which has led to higher healthcare costs and a serious economic burden on healthcare systems [2, 3]. DM affects more than 32 million citizens of the European Union [4]. In Bulgaria, the number of diabetics has grown and is estimated to affect 9.6% of the population, with a mortality rate of 23.3 per 100,000 individuals [5]. Around 75% of diagnosed diabetics in Bulgaria also have poor metabolic control, which is a factor in developing diabetes-related complications: myocardial infarction, stroke, retinopathy and blindness, limb amputations and chronic kidney failure. The number of deaths due to DM is far greater if deaths due to complications and bad disease control are included in the mortality estimates [6]. Estimates of the long-term quality of life of patients are largely influenced by the development of comorbidities, as well as their severity—such as diabetic retinopathy, diabetic nephropathy, macroangiopathy, brain and cardiovascular diseases and ischemic heart disease. The association between DM, hypertension, increased serum cholesterol levels and smoking greatly increases the risk of health [7]. Major studies have found that DM type 1 decreases the life expectancy with 15 years, whereas type 2 DM, with 5–10 years [8]. Ultimately DM complications lead to lower health-related quality of life, with studies estimating 50–80% increased risk of disability compared to the healthy population [9, 10]. At the same time, a substantial body of literature shows that good disease control is associated with higher life expectancy and reduced risk of developing diabetes-related complications [11, 12].

This study aims to investigate the quality of diabetes control and its economic implications in Bulgaria for the years 2012–2016.

Materials and methods

This is a retrospective study of the national diabetes register. It was conducted for the Bulgarian population of patients with DM.

Analysing diabetes control

We extracted data from the national diabetes register concerning the total number of patients with DM for the years 2012–2016. Patients were categorized according to type of diabetes, gender, newly diagnosed cases per year, body-mass index (BMI) and achieved disease control. Patients with glycosylated hemoglobin (HgA1c) values of less than 7% were considered to have good disease control.

The subgroup analysis was performed for all patients for whom there were at least two HgA1c values recorded per year. These values were determined at the beginning and end of each year and were documented. Based on this, we calculated the change in the recorded levels (higher, no change, lower).

The reduction in the relative risks (RRs) of development of diabetes-related complications achieved through a 1% reduction in HbA1c (Table 1) were taken from published literature [11, 12]. The RR of reducing these diabetes-related incidents in the population observed by us was calculated by multiplying the average reduction of HbA1c by the expected RR according to Table 1. This was done only for the group of patients for whom data were available and who showed reduction in the HbA1c levels for all 5 years. Thus, we evaluated the reduction in RR of diabetes-related complications occurring through the reduction of glycosylated hemoglobin.

Table 1. Reduction of relative risk of diabetes-related complications upon achieving 1% reduction in HbA1c, according to UKPDS35 [11, 12].

Diabetes-related complications	Relative risk (RR) reduction for 1% reduction in HbA1c level	95% CI for RR
Any diabetes-related endpoint	21	17	24
Diabetes-related mortality	21	15	27
All-cause mortality	14
Fatal or non-fatal myocardial infarction	14	8	21
Fatal or non-fatal stroke	12
Microvascular endpoints	37	33	41
Cataracts extraction	19
Amputation or death due to peripheral vascular disease	43
Heart failure	16

The mean duration of follow-up varies in the literature from ca. 10.4 years for all-cause mortality to 10 years for all diabetes-related endpoints; therefore we assumed the median duration of follow-up of RR to be 10 years.

Analysis of costs of diabetes-related complications

The calculated reduction in the RR of diabetes-related incidents was expressed as prevented complications and the corresponding prevented costs were calculated. A macro-costing approach was used. The costs were calculated by multiplying the number of prevented incidents by the respective costs as illustrated in Table 2. Total costs were calculated as a sum of ambulatory costs and the cost of in-hospital treatment. Data on the costs of ambulatory treatment were taken from Ostrowska et al. [13], an international study that includes data for Bulgaria. The costs of hospitalization were taken from the published tariffs of the National Health Insurance Fund of Bulgaria [14].

Table 2. Costs of healthcare services offered by hospitals and reimbursed through clinical pathways.

Diabetes-related complications	Hospital treatment cost (BGN)	Yearly costs of ambulatory treatment^a (BGN)
Any diabetes-related endpoint	600	427.92
Diabetes related death	600	0
All-cause mortality	2134	0
Fatal and non-fatal myocardial infarction^b	200	51.22
Fatal and non-fatal stroke^b	650.56	43.13
Microvascular endpoints^c	744	36,38
Cataract extraction	360	10.08
Amputation or death from peripheral vascular disease	2050	20.68
Heart failure	420	112.72

a Ostrowska et al. [13].

b Average weighed costs obtained by multiplying expected number of patients by the corresponding clinical pathways.

c Arithmetic mean costs for a singular patient according to the designated clinical pathways.

Several assumptions were made. First, we assumed that before occurrence of death by any cause, patients had been hospitalized as being “comatose and admitted for intensive care”. The other two assumptions made were in the calculation of the average weighed costs of stroke hospitalizations and microvascular complications. A further assumption was that the deaths by any cause fell under the intensive care clinical tariff, while the deaths due to diabetes hospitalizations were under the tariff of diabetes complications. The costs of ambulatory therapy of complications were calculated for the period of 10 years, which was the mean duration of follow-up in literature, after which mean yearly costs were multiplied by 5 to obtain the total costs for a 5-year period of follow-up [12].

The number of prevented diabetes-related complications was multiplied by the costs of hospitalizations plus the costs of ambulatory treatment, so as to give a final estimate of the total prevented costs. We also assumed that every patient indicated for hospitalization had only one type of diabetes-related complication.

The costs are presented in national currency at the exchange rate of 1 BGN = 0.51 Euro.

Results and discussion

Patients’ demographics

For the duration of the observed period, there was a reduction of new cases of type 1 diabetes (10% lower in 2016 than in 2012) and an increase in the number of new cases of type 2 diabetes (12% more cases in 2016 than in 2012)—Table 3. Over a period of 5 years, the number of patients with type-2 diabetes increased by 52,639 people. The yearly mean incidence rate for type 1 diabetes was 1500 people, whereas it was ∼73,000 for type 2 diabetes (Table 3).

Table 3. Prevalence and incidence of diabetes recorded in the national diabetes register.

Description	2012	2013	2014	2015	2016
Total number of DM cases	431,197	446,881	461,645	473,192	483,836
Patients with type-1 DM	28,108	27,886	27,193	26,259	25,426
Patients with type-2 DM	397,154	413,331	428,972	441,199	452,490
New cases of type-1 DM	1474	1982	1722	1613	1538
New Cases of type-2 DM	72,973	75,120	75,447	71,948	713,31

Obesity, as a major risk factor for the development of type 2 diabetes, was prevalent in the observed population and probably a leading cause of developing the disease. The data showed that 30–35% of the registered patients had a BMI over 30 (Table 4).

Table 4. Percentage of patients with body mass index above 30.

BMI (as per available data)	2013	2014	2015	2016	2017
>30	23.79	24.01	24.06	23.76	24.05
>35	11.22	11.32	11.58	11.85	12.39

Regarding the percentage of patients with levels of glycosylated hemoglobin under 7%, we observed a lower proportion among the patients with type 1 diabetes (average 30% had ‘good’ control), with the highest proportion of patients achieving good control gradually increasing through the years to 32% (in 2016). In contrast, on average 42% of patients with type 2 diabetes achieved good control, this trend increasing over the years (Table 5).

Table 5. Percentage of patients with HgA1c below 7%.

Indicator	2012	2013	2014	2015	2016
Patients with HgA1c below 7% with type 1 DM (%)	24.6	23.89	27.69	33.88	32.44
Patients with HgA1c below 7% with type 2 DM (%)	41.68	40.05	42.52	44.13	43.91

Diabetes control in a subgroup analysis

Approximately a third of the patients had at least two changes in the HbA1c levels recorded per year. The number of closely monitored and recorded patients increased during the period (Table 6). The mean age of the patients with recorded values was 63, with data predominantly available for type 2 diabetics. The average recorded value of glycosylated hemoglobin at the beginning of the period was 7.6% (SD 1.88) in 2012, which decreased to 7.4% (SD 1.35) at the end of the period in 2016. The data showed a reduction in HbA1c level and a trend towards improvement in the control: in 2012 the average percent of glycosylated hemoglobin in the second recording at the end of the year was 7.59% (SD 1.85), whereas the second recording of values for 2016 revealed an average value of 7.3% (SD 1.32). The mean yearly reduction in 2012 was 0.05% (SD 1.1) with a slow trend towards reaching 0.07% (SD 0.46) in 2016. The number of patients who achieved a reduction in the levels of glycosylated hemoglobin increased from 18,000 to 26,000 in 2016, which indicates a positive trend towards improvement of glycosylated hemoglobin checks and records. However, the number of patients who showed no change was also significant: it increased from 59,000 do 93,000 people in 2016.

Table 6. Characteristics of the cohort of patients with two measures of HgA1c.

Demographics	Year
	2012	2013	2014	2015	2016
Total number of diabetics with at least two measurements of HbA1c	92,748	103,592	107,477	127,916	155,288
Men	41,882	46,913	48,490	58,219	10,430
Women	50,866	56,679	58,987	69,697	144,858
Average age (SD)	63 (13.06)	63 (13.08)	63.02 (13.02)	63 (9.6)	64 (9.5)
Type of diabetes
Type 1 diabetes (ICD code е10)	10,784	11,133	10,390	10,056	10,430
Type 2 diabetes (ICD code е11)	81,669	92,110	96,703	117,417	144,048
Malnutrition diabetes (ICD code е12)	3	3	2	3	3
Other identified diabetes (ICD code е13)	6	15	9	8	18
Other unidentified diabetes (ICD code е14)	286	331	373	432	790
HbA1c-1 (SD)	7.63 (1.88)	7.6 (1.82)	7.501(1.81)	7.5 (1.34)	7.4 (1.35)
HbA1c-2 (SD)	7.59 (1.85)	7.5 (1.77)	7.45(1.75)	7.4 (1.32)	7.3 (1.32)
HBA1c-average diff. (SD)	0.05 (1.11)	0.08 (1.23)	0.048 (1.2)	0.06 (0.59)	0.07 (0.46)
Number of patients with increases in HbA1c	15,509	26,863	25,135	33,154	32,135
Number of patients with decreases in HbA1c	17,869	22,364	26,812	29,071	26,360
Number of patients with no change	59,370	54,365	55,530	65,691	96,793
Average increase (SD)	1.24 (0.35)	1.3 (1.33)	1.26 (0.81)	1.2 (0.87)	1,19 (0.89)
Average decrease (SD)	1.33 (0.88)	0.08 (1.23)	1.14 (0.93)	1.1 (0.8)	1.04 (0.77)

Prevented complications

Reduction in the values of glycosylated hemoglobin has been proved to reduce the risk of developing many diabetes-related complications, whereby the absolute risk reduction for all events was 20.6. The most significant reduction in risk was for amputations, followed by microvascular complications (Table 7).

Table 7. Reduction in relative risk (RR) of various diabetes-related complications.

Diabetes-related complications	2012	2013	2014	2015	2016	Total mean reduction in RR (%) for the whole period
Any diabetes-related endpoint	28	2	24	23	22	19.8
Diabetes related death	28	2	24	23	22	19.8
All-cause mortality	19	1	16	15	15	13.2
Fatal and non-fatal myocardial infarction	19	1	16	15	15	13.2
Fatal and non-fatal stroke	16	1	14	13	13	11.4
Microvascular endpoints	49	3	42	40	39	34.6
Cataract extraction	25	2	22	21	20	18
Amputation or death from peripheral vascular disease	57	3	49	47	45	40.2
Heart failure	21	1	18	18	17	15
Total mean reduction	29.1	1.8	25.0	23.9	23.1	20.6

For the whole observed population with at least two cases of recorded HbA1c (approx. 25%), the reduction in the RR of developing a diabetes-related complication would lead to the prevention of 5065 incidents (Table 8). Since the sample is representative of the total diabetic population, we can calculate that the total number of prevented incidents would be ca. 20,000.

Table 8. Mean number of prevented complications for the observed period.

Diabetes-related complications	2012	2013	2014	2015	2016	Total mean number of prevented diabetes incidents for all years
Any diabetes-related endpoint	224	281	337	365	331	1538
Diabetes related death	83	104	125	136	123	572
All-cause mortality	77	96	115	125	113	526
Fatal and non-fatal myocardial infarction	75	93	112	121	110	512
Fatal and non-fatal stroke	17	21	25	27	25	114
Microvascular endpoints	179	224	268	291	264	1225
Cataract extraction	24	30	36	39	35	164
Amputation or death from peripheral vascular disease	44	56	67	72	65	304
Heart failure	16	20	24	26	23	109
Total mean number of prevented incidents for the whole period	739	925	1109	1202	1090	5065

Costs of prevented complications

The total costs that would have been incurred for treatment of the 5056 incidents, which were prevented due to reduction of glycosylated hemoglobin, are ca. 5 million BGN (Table 9). The total saved costs for all predicted diabetes-related complications in the entire population are 20 million BGN for the whole period.

Table 9. Cost of prevented complications.

Diabetes-related complications	Costs for hospital treatment (BGN)	Costs for ambulatory treatment (BGN)	Total mean number of prevented incidents for the period	Total costs (BGN)
Any diabetes-related endpoint	600	427.92	1538	158,0941
Diabetes-related death	600	0	572	343,200
All-cause mortality	2134	0	526	1,122,484
Fatal and non-fatal myocardial infarction	200	51.22	512	128,624.6
Fatal and non-fatal stroke	650.56	43.13	114	79,080.66
Microvascular endpoints	744	36.38	1225	955,965.5
Cataract extraction	360	10.08	164	60,693.12
Amputation or death from peripheral vascular disease	2050	20.68	304	629,486.7
Heart failure	420	112.72	109	58,066.48
Total mean number of prevented incidents for the whole period			5065	4,958,542

These results from this study are representative of the population of diabetic patients in Bulgaria. For the period, the observed reduction in the incidence of type 1 diabetes by 10% and increase in the cases of type 2 by 12% could be interpreted as good detection of new cases of diabetes, but also as a high incidence rate. The newly diagnosed cases of type 1 diabetes yearly are around 1500, which demonstrates a stable type 1 diabetic population, since this trend did not change over the years. The fact that the prevalence of type 1 diabetes has remained relatively constant in Bulgaria, but the prevalence of type 2 diabetes is continuously increasing at a growing rate, is indicative of the country’s aging population and people living a sedentary life. This observation is in agreement with other reports [15, 16].

The average age of patients with type 2 diabetes did not change in our study and remained at ∼65 years, which could be considered a positive trend. Despite this, the standard deviation in the age of the patients (8 and 11 years) indicates that many of the diabetics in Bulgaria are diagnosed at an early age.

The percentage of patients with values of glycosylated hemoglobin under 7% was approx. 30% in type 1 diabetes and 32% in type 2. Among the type 2 diabetics, the level of control was overall better, with 42% experiencing a slight increase over the studied period. However, it is still important that these values are far lower than the desired targets and it could be argued that there is room for improvement [17]. Data indicate that the control of the disease is gradually improving, with the number of undiagnosed or late-diagnosed cases decreasing, as well as an observed improvement in the healthcare services provided to the affected population. Therefore we might expect an improvement in the diabetes related complications [18–20].

The analysis showed a definite observable improvement in the control of glycosylated hemoglobin. The average difference was 0.05% for the observed period. The number of patients who showed a reduction in the levels of glycosylated hemoglobin increased from 18,000 to 26,000 from 2012 to 2016, which is also a positive trend. The most significant proportion of the population was the one with no change in glycosylated hemoglobin percentages, increasing from 59,000 people in 2012 to 97,000 people in 2016. The average reduction in the HbA1c values was 1%, while the average increase in the HbA1c level was 1.1%. No significant differences were observed between genders [21].

The control of DM is much less satisfactory in Bulgaria than in other countries. The PANORAMA study, for instance, documented that 37.4% of patients do not achieve adequate glycemic control, which they consider a serious issue, since the main factors influencing the poor control were: patient characteristics, inadequately targeted levels of glycosylated hemoglobin by physicians, duration of disease and treatment [22]. Another study of 1853 diabetic patients from Bulgaria and other countries, with an average age of 63.5 ± 10.7 years, and average disease duration of 8.9 ± 7.1 years, showed that 40% of the patients had HbA1c measurements every 6 months and 34% had at least one measurement every 12 months [23], which is in accordance with our data. The average levels of HbA1c were 7.3 ± 1.5, and 35% of patients had levels of <6.5% HbA1 [23], which also agrees with our dataset.

The recorded reduction in glycosylated hemoglobin is expected to lead to a 20-fold reduction in the risk of developing diabetes-related complications, which in turn would lead to saving costs amounting to 20 million BGN for the entire diabetic population for the period. These costs do not take into account hypertension; thus, we could speculate that the real-life benefits would be higher.

This study, however, has some limitations. We took the risk reduction from UKPDS study, which concerns type-2 diabetes. To account for this, we compared the UKPDS risk reduction results with similar studies on the control of type 1 diabetes [24–28] by using chi-square analysis to compare the difference in risk reduction between all studies. We did not find a statistically significant difference among the related risks between type 2 and type 1 studies and therefore we used the UKPDS results due to similar reporting of the risks in the Bulgarian practice. Another limitation is that the control was not correlated with the type of diabetes therapy. This will be the next step in our study, i.e. to combine the control and type of medications.

Conclusions

For the period 2012–2016, the control of diabetes has improved in Bulgaria. The levels of glycosylated hemoglobin measured at different instances within a year, as well as throughout the years, point towards overall better treatment. The proportion of patients that achieved good control also increased throughout the years, reaching over 40% of the afflicted population. Among this population, the achieved adequate control leads to a reduced risk of developing diabetes-related complications, thereby saving costs associated with them, and decreasing the burden on the healthcare system.

Authors’ contribution

Study design, data processing, analysis and writing (KT, GP and VV), statistical analysis, data extraction and processing (KM, GA, MDoneva and DT), data collection, systematization, calculations, referencing (ZM, MK, MDimitrova, VP, AS and MM).

Acknowledgement

This study is part of the national science program “Electronic health in Bulgaria“(е-health).

Disclosure statement

V.V. works at NovoNordisk Bulgaria.