Epidemiology of Parkinson’s disease in the Southern Ukraine

Background. Parkinson’s disease (PD) is a slowly progressing neurodegenerative disease with accumulation of alpha-synuclein and the formation of Lewy bodies inside nerve cells. The prevalence of PD ranges from 100 to 200 cases per 100,000 population. However, in the Ukrainian reality, many cases of the disease remain undiagnosed, which affects the statistical indicators of incidence and prevalence. The purpose of the study is to compare PD epidemiological indices in the Southern Ukraine with all-Ukrainian rates. Material and methods. Statistical data of the Ministry of Health of Ukraine, public health departments of Odesa, Mykolaiv and Kherson regions for 2015–2017 were analyzed. There were used the methods of descriptive statistics and analysis of variance. Results. Average prevalence of PD in Ukraine is 67.5 per 100,000 population — it is close to the Eastern European rate. The highest prevalence was registered in Lviv (142.5 per 100,000), Vinnytsia (135.9 per 100,000), Cherkasy (108.6 per 100,000) and Kyiv (107.1 per 100,000) regions. The lowest rates were in Luhansk (37.9 per 100,000), Kyrovohrad (42.5 per 100,000), Chernivtsi (49.0 per 100,000) and Ternopil (49.6 per 100,000) regions. In the Southern Ukraine, the highest prevalence of PD was found in Mykolaiv region. The prevalence was higher in urban area and in the districts located closely to the regional capital city. Based on the total population and demographic characteristics of Odesa, Mykolaiv and Kherson regions, it can be concluded that at least 40–50 % of patients with PD are left outside the sphere of medical care, and in some areas, this index is 80–90 %. Conclusions. To optimize the diagnostic process and standardize epidemiological data, it is necessary to intensify the work of centers of extrapyramidal diseases in all regions of Ukraine, including intracenter and intercenter information databases to obtain adequate and pertinent statistical data.


Introduction
The number of reported cases of any nosology depends on many parameters: its detectability, professional competence and qualification of specialists, their motivation, organizational and methodological activities in the regions, the establishment of specialized centers for the diagnosis and treatment of extrapyramidal diseases, the economic development, life expectancy, etc. [1].
Significant dispersion of prevalence, morbidity, medical records of patients with Parkinson's disease (PD) is associ-ated with the features of the organization of medical care at the local level, the lack of the uniform method of registration for all neuropathologists, and, therefore, with insufficient detection of these patients [2,3].
PD is the second most frequent neurodegenerative pathology after Alzheimer's disease [2,4,5]. According to E. Dorsey, B. Bloem (2018), there are more than 6 million patients diagnosed with PD in the world, most of them live in Europe and North America. According to the authors, the prevalence of PD in the world has increased 2.5 times in the last 20 years [4]. The cause of this phenomenon is not only the population ageing, but also improved diagnosis.
According to various studies, the incidence rate for PD ranges from 5 to 25 per 100,000 population per year. With age, prevalence and morbidity rates are steadily increasing: among persons over 60 years, the prevalence of PD reaches 1-2 %, and among persons over 80 years -4 % [6].
The prevalence of PD varies from 15 cases per 100,000 population in China to 657 per 100,000 population in Argentina. In Europe and North America, this figure ranges from 100 to 250 cases per 100,000 population. In the USA, the highest values are recorded in the state of Nebraska -329.3 cases per 100,000 population [5]. Among European countries, the high prevalence is characteristic of Albania (800/100,000) and Italy, where in the province of Brescia the rate was 407 cases of PD per 100,000 population [4,5,7]. The lowest prevalence of PD is characteristic of developing countries: in Ethiopia, this index is only 7 cases per 100,000 population, and in Central Africa -20 cases per 100,000 population [7].
The incidence of PD varies greatly in different regions of the world and within individual countries. Thus, in China, the incidence of new cases of PD varies from 1.5 to 8.7 cases per 100,000 population. France has the highest incidence rates -49.4 cases per 100,000 population, Argentina -31.2, Taiwan -28 and Italy -23.1 cases per 100,000 population. The lowest incidence rates are typical for the Russian Federation -9.0 per 100,000 population, India -5.7, Libya -4.5 cases per 100,000 population [7].
Given the current tendency to an increase in the prevalence associated with population ageing and improved survival of patients with PD, it is estimated that in various countries the number of patients may reach 9 million by 2030 [4,6].
Epidemiological data on the prevalence of PD are interesting because they can potentially improve our understanding of the environmental impact on the development and course of the disease and identifying possible risk factors. Also, these data may be useful and relevant for the formation of the correct structure of on-site health care delivery [1,8].
In Ukraine in recent years, there has been an increase in the prevalence of PD, with the largest one observed in Kyiv and Kyiv region, as well as in Lviv, Chernihiv, and Ivano-Frankivsk regions. The number of registered cases of PD decreased by 43.14-77.87 % in the territories of Joint Forces Operation. The highest prevalence rates of PD were noted in Vinnytsia (126.1 per 100,000), Kyiv (111.6 per 100,000), Lviv (109.5 per 100,000) and Cherkasy (90.0 per 100,000) regions [9,10].
Currently, there are no scientifically substantiated and statistically reliable epidemiological data on the prevalence and incidence of PD and parkinsonian syndrome in the Southern Ukraine.
The purpose of the study: to compare PD epidemiological indices in the Southern Ukraine with all-Ukrainian rates.

Material and methods
Statistical data of the Ministry of Health of Ukraine, public health departments of Odesa, Mykolaiv and Kherson regions for 2015-2017 were analyzed. There were used the methods of descriptive statistics and analysis of variance.

Results and discussion
Number of registered patients with PD in Ukraine in 2017 was 214,226 (Table 1), which corresponds to the prevalence of 67.5 per 100,000 population. It should be noted that this indicator is heterogeneous in the various regions of Ukraine. The largest number of patients was registered in Lviv (142.5 per 100,000), Vinnytsia (135.9 per 100,000), Cherkasy (108.6 per 100,000) and Kyiv (107.1 per 100,000) regions. The lowest prevalence rates are in Luhansk (37.9 per 100,000), Kyrovohrad (42.5 per 100,000), Chernivtsi (49.0 per 100,000) and Ternopil (49.6 per 100,000) regions.
The prevalence rates of PD in the south of Ukraine also differ. Thus, in Mykolaiv region, 65 cases per 100,000 population were registered, in Kherson region -56, in Odesa region -49.8 per 100,000.
The differences may be due to the various causes and, above all, variations in the methodology of patient examination, non-compliance with the diagnostic criteria, bad training of specialists, their poor motivation, lack of specialized offices and centers for the study and treatment of this pathology at the local level, low rates of seeking medical care by patients in a weak economy and ineffective reform of the health care system. This can be confirmed by epidemiological indicators in selected regions of Odesa, Mykolaiv and Kherson regions, supporting the thesis that underdiagnosis is not due to environmental or geographical factors, but depends on the availability of trained specialists, their professional interests and a sufficient level of organizational and methodological work.
Unfortunately, there are no reliable statistical data on the age-weighted prevalence of PD in Ukraine. Nevertheless, it seems that the epidemiological patterns in the Southern Ukraine are close to the European ones.

Conclusions
Based on the total population and demographic characteristics in Odesa, Mykolaiv and Kherson regions, it can be concluded that at least 40-50 % of patients with PD are left outside the sphere of medical care, and in some areas, this index is 80-90 %.
The revealed variability in the prevalence and incidence of Parkinson's disease in the Southern region of Ukraine indicates not so much about the territorial  differences of these indicators, but rather the fact of non-compliance with standards of epidemiological surveillance, untimely submission of information to statistical centers, bad training of specialists, as well as wrong summarization of the results of the studies by the total population. Epidemiological studies in Odesa, Mykolaiv and Kherson regions have shown a large dispersion of data but comparatively low prevalence of PD compared to other regions of Ukraine. It could be a consequence of insufficient detection of PD by the specialists.
In order to optimize the diagnostic process and standardize epidemiological data, it is necessary to intensify the work of centers of extrapyramidal diseases in all regions of Ukraine, including intracenter and intercenter information databases to obtain adequate and pertinent statistical data.

Conflicts of interests.
Author declares the absence of any conflicts of interests and their own financial interest that might be construed to influence the results or interpretation of their manuscript.