Introduction

The lifetime risk of developing kidney stone disease (urolithiasis) continues to increase worldwide. Knowing the epidemiology of kidney stones is important for urologists, nephrologists, and medical practitioners (Alelign and Petros 2018). Urolithiasis can be one of the leading causes of complications manifested by pain and urinary tract infection (UTI), which can lead to chronic kidney disease and even kidney loss (Rule et al. 2009). Urolithiasis is the third most common disorder of urinary tract complication after benign prostatic hyperplasia (BPH) and urinary tract infection (UTI) (Zhu et al. 2021).

Urolithiasis is a highly prevalent disease worldwide, with rates of 7–13% in North America, 5–9% in Europe, and 1–5% in Asia (Sorokin et al. 2017). Approximately 10–12% of men and 5–6% of women develop symptomatic urolithiasis at least once in their lifetime (Edvardsson et al. 2013). Iran is located on the urolithiasis belt, with a high prevalence (5.7%) of its incidence (Farshid et al. 2020). The average age of urolithiasis was reported to be 41.5 years old (BASIRI et al. 2011), with a recurrence rate of 16% after one year, 33% after five years, and 53% after ten years (Safarinejad 2007). There is also an increase in the prevalence with the increasing age group, and men were more likely to report a history of urolithiasis than women (10.6% vs. 7.1%) (Scales et al. 2012). Data from the Health Professionals Follow-up Study and the Nurses’ Health Study I and II reported associations between incident stone disease and body mass index (BMI) (Taylor et al. 2005a, b). It is known that urolithiasis is strongly associated with loss of kidney function. It has now been identified as a systemic disorder associated with an increased risk of several common diseases such as coronary artery disease, bone loss, hypertension, metabolic syndrome, and type 2 diabetes mellitus (T2DM) (Zisman et al. 2015; Abu-Ghanem et al. 2016).

Although this disease can cause kidney damage and loss in advanced stages, which is very costly for both the patient and the community (for nephrectomy and dialysis), early diagnosis will eliminate it with medical treatment, and no surgery is required. Due to the high prevalence of hematuria in the Guilan cohort population (34.1%) and to better patient care and even prevention of recurrence, we aimed to investigate the prevalence of urolithiasis and the associated factors among the Prospective Epidemiological Research Studies of Iranian Adults (PERSIAN) Guilan cohort study (PGCS) population.

Methods

Participants

This cross-sectional study was conducted based on the PERSIAN (Poustchi et al. 2018) in Sowmeh' E Sara (GPS coordinator Latitude: 37.308003 and Longitude: 49.315022), Guilan, Northern Iran, with both genders aged 35–70 years from 2014 to 2017 (Mansour-Ghanaei et al. 2019). Informed consent was obtained from all individual participants. Demographic data and clinical characteristics, including age, gender, marital status, educational level, employment status, habitat, history of smoking and hookah (waterpipe), alcohol consumption, opium consumption, the metabolic equivalent of task (MET) divided into four quartiles (sedentary (Q1), mild (Q2), moderate (Q3), and high (Q4) level of activity in a day by assessing the number of hours of walking, working, exercise, etc.), wealth score index (WSI) divided into four quartiles (low income, low-middle income, middle-high income, and high-income status), body mass index (BMI) classified as underweight (under 18.5 kg/m2), average weight (18.5–24.99 kg/m2), overweight (25–29.9 kg/m2), and obese (30 kg/m2 or more), and self-report history of urolithiasis (kidney, ureter, and bladders stones), hypertension, and T2DM from October 2014 to January 2016 were collected from a total of 10,520 individuals.

Statistical analysis

Continuous variables are reported by mean ± standard deviation (SD), and categorical variables as numbers (percentage). Simple and multiple logistic regression analyses examined the relationship between demographic/clinical data and urolithiasis. The crude and adjusted odds ratio (OR) and 95% confidence interval (CI) were calculated. All statistical analyses were performed using IBM SPSS Statistics for Windows, version 21.0 (IBM Corp., Armonk, NY, USA), and the significance level was set at 0.05.

Results

The demographic data and clinical characteristics of the participants have been illustrated in Table 1. According to our results, urolithiasis was 15.6% more prevalent in men than women (18.5% vs 13.1%). The prevalence of urolithiasis increased with age (Table 2). Logistic regression analysis showed that men had 1.5-fold increased odds of urolithiasis compared to women (P < 0.001). Married, widow, and divorced participants represented a higher prevalence of urolithiasis than unmarried participants (P < 0.001). Education, employment status, and MET represented no statistically significant association with urolithiasis (P > 0.05). Individuals with higher BMI (overweight and obese) illustrated a higher prevalence of urolithiasis (P = 0.010 and P = 0.012, respectively). Regarding the WSL, participants with middle-high WSI were at significantly increased odds for urolithiasis compared to others (P = 0.011). According to our results, cigarette smoking and hookah smoking showed a significant association with urolithiasis (P < 0.05), while opium consumption did not (P = 0.821). Alcohol consumption represented a protective effect against urolithiasis (P = 0.03). Also, the presence of hypertension and DM were associated with urolithiasis (OR = 1.48, 95% CI 1.33–1.65; OR = 1.45, 95% CI 1.29–1.63, respectively, P < 0.001) (Table 3).

Table 1 Demographic and clinical characteristics of the participants in the PERSIAN Guilan Cohort Study (n = 10520)
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Table 2 Prevalence of kidney stone disease in the PERSIAN Guilan Cohort Study
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Table 3 Logistic regression analyses for a relationship between demographic/clinical factors and urolithiasis among adults (>35 years old) in the PERSIAN Guilan Cohort Study (n = 10,520)
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Discussion

Adult urolithiasis is still the most common urological problem worldwide. It has been reported that the prevalence and incidence of urolithiasis have increased significantly for both genders, and the costs related to providing medical care to these patients have increased, especially in Iran, with a significant prevalence of kidney stones (Pourmand and Pourmand 2012). Our results illustrated that urolithiasis was higher in men of upper age, overweight, smokers, and in middle-high income status.

A meta-analysis by Wang et al. showed that the prevalence of urolithiasis was 10.34% in men and 6.62% in women, demonstrating that men are more likely to suffer from this disease than women (Wang et al. 2022). Also, in line with our results, a study by Khalili et al. on the risk factors for urolithiasis reported that 46.54% of the participants were male and 53.46% were female, with a mean age of 49/94±9.56 years, and about 24.08% of the population presented urolithiasis (Khalili et al. 2021).

In the Korean population, the annual incidence of nephrolithiasis was estimated to be approximately 457 per 100,000, with a higher incidence in men (1.8:1) (Bae et al. 2014). A population-based analysis using the Longitudinal Health Insurance Database in Taiwan demonstrated that the prevalence of urolithiasis was 9.0%, 5.8%, and 7.4% in men, women, and overall, respectively, with the overall prevalence peak at 19.4% in 60–69-year-old adults (Huang et al. 2013). Nouri et al. showed that the prevalence of urolithiasis was about 1.8%. The ratio of men to women was 1.35:1, with a mean age of 55.9±15.3 years old. Approximately 14.4% of these patients were smokers, and about 30% of participants had a previous history of urolithiasis (Nouri and Hassali 2018).

Rafiei et al. illustrated in their study that there was a significant difference in stone formation between male and female patients (P < 0.05). Approximately 73.5% of patients were between 65 and 74 years, which showed the risk of developing urolithiasis in older people (over 65 years). Also, urolithiasis was reported to be more prevalent in women, which differs from our result (Rafiei et al. 2014). The healthcare system should also consider changing gender prevalence in urolithiasis and identifying the relationship between gender and risk factors for stone disease (Cicerello et al. 2021). According to Fouladi et al.’s study results, 60.6% of patients were male, and 39.4% were female, with a mean age of 41.90±14.41 years (Fouladi et al. 2012).

Similar to our results, in several studies, the association between overweight and obese individuals and a history of hypertension and T2DM with a higher frequency of urolithiasis was reported (Basiri et al. 2010; Fouladi et al. 2012; Nouri and Hassali 2018; Khalili et al. 2021). Another study by Shirazi et al. showed that socioeconomic factors, including education level, economic status, employment status, type of job, work environment, and family history, were positively associated with increased risk of urinary tract complications (SHIRAZI et al. 2010; Fouladi et al. 2012). The prevalence of urolithiasis among workers exposed to high occupational heat was higher than others (Luo et al. 2014; Venugopal et al. 2020). According to economic status and diet patterns, diets containing high animal-derived proteins, salt, and sugar put individuals at higher risk of urolithiasis (Boarin et al. 2018; Thakore and Liang 2021). The results of a study on the prevalence of urolithiasis regarding lifestyle habits in Saudi Arabia reported that cigarette smokers had an increased risk of urolithiasis (70%). In comparison, hookah smokers had a 45% increased risk of urolithiasis incidence (Baatiah et al. 2020); although, in the current study, only hookah smokers represented higher prevalence of urolithiasis (P = 0.016).

Limitation

One limitation of the current study was that the participants reported their lifetime history of urolithiasis, which may lead to recall bias, and its onset may have occurred at a younger age. Furthermore, water intake was not recorded, and patients tend to recall only symptomatic stone events, as asymptomatic stones are relatively common.

Conclusion

According to our study, the prevalence of urolithiasis was higher in men, upper age, overweight, rural residents, cigarette and hookah smokers, middle-high income families, and widow/widower/divorced participants. Further research is needed to evaluate the prevalence of urolithiasis according to lifestyle, access to health care, working status, compliance with medical care, and other related factors.