Some recent studies show changes in the distribution of urolithiasis disease over the few last years [5, 10]. This study explored the incidence of urolithiasis in 204 countries during the last decades. We have investigated the urolithiasis rates among various regions across the world. Also, we clustered countries into subgroups, in which countries within each group had similar trends of urolithiasis rates over the study period 1990–2019.
According to our data, Eastern Europe countries and also countries in central Europe had a considerably decreasing trend of urolithiasis rate during past decades. However, differences in health care systems cause regional differences, but the overall trend is decreasing. This result is in line with Jacob Lang et al., which showed that Eastern Europe had a higher average annual percentage change of urolithiasis than other regions [10]. However, further study claims that the kidney stone has increased markedly in European nations and other industrialized countries during the last decades which contradicts our results [13,14,15]. We could not find a preventive program whose implementation caused this reduction. But changing social conditions such as changes in lifestyle, eating habits, and physical activity may be important in this context. There seems to be little research on primary urolithiasis prevention [16]. No single preventive program has been found that covers all aspects of urolithiasis prevention. Different types of interventions are needed to address the various causes and complications of urolithiasis. Some of the main interventions that can be suggested to be proposed in current preventive programs are metabolic evaluation and recurrence prevention, infection control and management, genetic counselling and screening, education and awareness, as well as dietary, lifestyle, and environmental factors [17, 18]. Metabolic evaluation and recurrence prevention involves finding out the metabolic imbalances and risk factors that make a person prone to developing stones, and also prescribing suitable drugs or diets to fix them. For example, drinking more water, eating less salt, making the urine less acidic, or taking certain medications can help prevent calcium oxalate or uric acid stones, which are very common [19]. Detecting and treating any urinary tract infections that can lead to or worsen urolithiasis, especially in cases of struvite or infection stones [17]. Genetic counselling and screening through using molecular techniques, biochemical assays, or family history analysis, can help identifying and testing for genetic disorders relating to urolithiasis, especially in cases of cystine or rare stones [19, 20]. Increasing the education and awareness through providing information and guidance to patients and the general public about the causes, symptoms, diagnosis, treatment, and prevention of urolithiasis [17, 21]. Using leaflets, posters, websites, social media, or mass media campaigns are some of the common strategies for raising awareness and promoting prevention of urolithiasis. A comprehensive preventive program, which include all mentioned points could have a more significant impact on the overall burden of urolithiasis, and improve the quality of life and health outcomes of stone formers and reduce the economic costs associated with urolithiasis.
Our results show that the urolithiasis rate in African regions increased over time. There were few studies on the epidemiology of urolithiasis in African countries [22]. We found one study that investigated the trend of kidney study in this area, and our results were consistent with their finding [10].
Based on our results, the global trend of urolithiasis rate was increasing with an increasing rate of 6.5 every five years. The study on urolithiasis average annual percentage change rate, demonstrated a decreasing average annual percentage change rate [10]. The increasing prevalence of nephrolithiasis might be due to the availability of new and more accurate diagnostic tools contributing to an increased diagnosis [23].
Our results showed that countries were classified into 7 clusters based on the trend of urolithiasis incidence. Since urolithiasis is a multifactorial disease, countries in different parts of the world have shown a similar trend of urolithiasis. For example, Afghanistan, Andorra, and Comoros countries (Dedicated to the first cluster in Table 2) have a rapid decline in urolithiasis, even though they are on different continents and even in different climatic conditions. These countries have a high incidence rate of urolithiasis, with a sharp downward trend. These are developing countries which may have similar lifestyles in terms of nutrition and physical activity. However, Afghanistan may be in this cluster due to an incomplete data registry system. Also, based on the results, countries with a moderate and low decline in urolithiasis (countries clustered in class 2 and in the next rank class, 3, presented in Table 2) are located on different continents. However, the common point between them is that some are close to the sea, the weather is mild, and the climate temperate is year-round. Given that ambient temperature is an effective factor for nephrolithiasis, a similar trend of stone kidneys in these countries seems to be correct [24].
Most countries had an increasing trend of Urolithiasis rates (Clusters number 4 to 7). Congo, Eswatini, Gabon, and Grenada have the sharpest increasing rates of urolithiasis. In the next rank, Bahrain, Bosnia and Herzegovina, Bulgaria, Chad, Cook Islands, Costa Rica, Croatia, Guatemala, Honduras, Kazakhstan, Lebanon, Liberia, Morocco, and Yemen had the most increasing rate of urolithiasis. Other countries not mentioned so far have also seen an increase in the Urolithiasis incidence rate. These findings are in line with other studies [7]. These countries are from different continents with various environments and climates. They do not have considerable similarities in social conditions, showing how the multifactor is associated with urolithiasis. Global warming seems to be a common factor among countries. Studies in Arab countries show that their remarkably hot environment and climate are associated with developing nephrolithiasis for most of the year. The studies have showed the role of climate on urolithiasis [25, 26]. It is established that with increasing temperature in an exact area, the prevalence of urolithiasis also increases, and the peak incidence of calculus formation was seen in the hot season [27]. As a result, an epidemic of stone formation can be on the way [28, 29]. Besides many contributing factors, the improvement of socioeconomic conditions unarguably affects this subject. Observations show a very high prevalence of urolithiasis in the wealthier countries of the middle east, like the United Arab Emirates and Saudi Arabia, in contrast to their less affluent neighbors living under the same environmental and cultural conditions [30].
It is notable that gender, race, and median age of the population are important factors that can influence the prevalence of urolithiasis in different countries.
According to a recent review, the prevalence of kidney stones is increasing and historically more common in males [31]. However, recent evidence questions if this gender gap is closing. Changes in diet, obesity rates, metabolic syndrome, and urinary tract infections among women could be factors. Further research and clinical management are needed to understand gender differences in kidney stones.
There is evidence that urolithiasis varies among different racial and ethnic groups [32]. Traditional urinary physicochemical risk factors may not fully explain these differences. Factors such as genetics, environment, diet, and lifestyle may contribute to the racial and ethnic variation of urolithiasis. For instance, a study found that white and Hispanic populations have a higher prevalence of urolithiasis compared to black and Asian populations in the US. The prevalence of urolithiasis has also increased more prominently among women and African Americans in recent years [33].
Urolithiasis is known to increase with age [31, 33]. However, some studies show a rise in urolithiasis among younger age groups, possibly due to obesity, diabetes, and metabolic syndrome in children and adolescents [31]. Therefore, age distribution may influence urolithiasis trends in different countries.
Finally, it is notable that due to the availability of new and more accurate diagnostic tools contributing to an increased diagnosis, asymptomatic stones are more detected due to the more frequent use of high-resolution imaging techniques [23, 34]. On the other hand, some studies have claimed that these data are usually based on hospitalized patients, not those not requiring hospital treatment, making less than 10% of all stone episodes [26].
Potential biases and limitations
However, the GBD is a comprehensive and systematic effort to estimate the burden of diseases and injuries for 204 countries and territories from 1990 to 2019, it also faces several challenges and uncertainties in the data collection which can introduce potential biases and limitations in the results. One of the main challenges is the variation in healthcare infrastructure, diagnosis practices, and data reporting among different countries. These factors can affect the accuracy and comparability of urolithiasis incidence rates across countries. For example, some countries may have more advanced diagnostic tools or more frequent screening programs than others, which can lead to higher detection rates of urolithiasis. Similarly, some countries may have more reliable and comprehensive data sources or more consistent definitions and classifications of urolithiasis than others, which can influence the quality and comparability of the data. These factors can introduce bias in the data, so caution is advised in interpreting and comparing the results across countries and over time.
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