Urolithiasis Management in Resource-Limited Settings: A Multicentric Retrospective Study in the Democratic Republic of Congo

Objective This study aimed to analyze different therapeutic modalities used in the treatment of urolithiasis in the Democratic Republic of Congo. Results Among the 194 patients included in this study, 69% (n=133) were males, with a male to female ratio of 2.2: 1, and an age mean (SD) of 48.1 (17.3) years. Urolithiasis was symptomatic in 52.6% (n=141) of patients. Renal colic was the most common clinical expression. Overall, 86.1% (n=167) of stones were removed by surgery, 9.8% spontaneously resolved, 3.1% were extracted after ureteroscopy, and 1% of patients had undergone extracorporeal shock wave lithotripsy. Lumbotomy was the most frequent used route (39.2%) in conventional surgery. The mean (SD) size of the extracted stones was 23.4 (17.0) mm. Most patients in this study were treated by conventional surgery. These results suggest the need to increase the use of minimally invasive surgery.


Introduction
Urolithiasis is a common health problem and a source of morbidity and mortality around the world. Over time, the prevalence of lifetime risk for urolithiasis has been increasing [1][2][3]. In recent years, treatment options of this condition have evolved, mostly the surgical aspect. The surgical management is currently well standardized, both in emergency situations and in long-term treatment which requires a more complete assessment [4]. Various treatment modalities have evolved over the years. Recently, there have been important advancements in minimally invasive techniques. Treatment modalities include extracorporeal shock wave lithotripsy (ESWL), percutaneous nephrolithotomy (PCNL), ureteroscopy (URS) and laparoscopic ureterolithotomy. However, discrepancies exist regarding treatment options around the world. In industrialized countries, micro-invasive surgery became the standard of care while conventional surgery accounts only for one percent of treatments [4][5]. On the other hand, in a resource-limited setting such as the Democratic Republic of Congo (DRC), conventional surgery is still widespread and predominant. However, data on the various treatments options in this setting are lacking. Therefore, this study aimed to analyze the different therapeutic modalities used in the treatment of urolithiasis in the DRC.

Methods
Design, setting and period of the study This was a multicentric retrospective study including patients treated for urolithiasis in various public and private hospitals in the DRC from January 2010 through September 2019. Only patients treated during this study period and whose stones were analyzed at the Functional Explorations Department of TENON Hospital (APHP, Paris, France) were included. The setting included public and private hospitals in the 4 provinces of the DRC: the city of Kinshasa, Kongo Central Province, Sud Ubangi Province and the province of South Kivu.

Infrared analysis of stones and parameters of interest
The different layers of stones were analyzed by Fourier transform infrared spectrophotometry (Vector 22 FT-IR spectrophotometer, Bruker Optics, Champs-sur-Marne, France) in absorbance mode by accumulation of 32 spectra between 4000 and 400 cm-1, with a resolution of 4 cm-1.
Demographic and clinical data were extracted from the patients' records and included: age, sex, body mass index (BMI), site of the stones, their obstructive nature, the state of the ipsilateral kidney (for stones of the upper apparatus), the circumstances of discovery, the annual frequency, the profession of the patients, the large diameter of the stones, their mode of elimination, the approach used in conventional surgery, as well as the main components of the stones analyzed.
Also, we investigated the association between the mode of elimination, the site of the stones, their average diameter, and the main types of stones analyzed. BMI was categorized into four groups following the World Health Organization (WHO) guidelines; underweight (BMI <18.5), normal/healthy weight (BMI 18.5 to <25), overweight/pre-obesity (BMI 25 to <30), and obesity (BMI >=30). The profession was categorized as civil servant, liberal, student / pupil and unemployed. Stones were classi ed into two categories depending on whether or not their size was greater than 20mm.

Statistical analysis
Continuous variables were expressed as means and medians. Categorical variables were summarized into proportions. Differences in categorical variables between groups were assessed using Chi square test or the chi-square likelihood-ratio as appropriate. Differences in means were assessed by the student's t test. P values less or equal to 0.05 were interpreted as statistically signi cant. Statistical analysis was performed using SPSS Statistics software version 22 (IBM, Armonk, USA).

Results
Among the 194 patients included in this study, 69% (n=133) were males, with a male to female ratio of 2.2: 1. The ages ranged from 4 to 87 years with a median of 50 years and a mean (SD) of 48.1 (17.3) years. BMI was available for 99 patients, among which 40.4% had normal BMI, 39.4% were overweight, 16.2% were obese, and 4% were undernourished. Compared to males, females had a higher BMI (27.4 ± 4.7 vs. 24.9 ± 4.2, p = 0.002). The upper urinary tract was the commonest sites of lodgment accounting for 61.3% (n=119). Patients with upper urinary tract stones were young and female. (p 0.001). The ureters and the pelvi-ureteric junction were the anatomical sites most commonly involved. Ureteral, renal pelvic, and caliceal stones accounted for 26.3% (n=51), 12.9% (n=25), and 9.8% (n=19), respectively.
The lithiasis was symptomatic in 72.3% of patients and its discovery was incidental on medical imaging (ultrasound or standard radiography) in 22.7% of patients or discovered intraoperatively (during surgical treatment of lower obstructive uropathy) in 5% of cases. Renal colic was the most common clinical expression. It was responsible for the ank pain in 107 patients (55.1%) and it was accompanied by vomiting in 26.3% of cases. The other clinical signs included dysuria (11.9%), hematuria (5.7%) and urinary tract infection (1.0%) ( Table 1).
Regarding professional status, 28.9% of patients were unemployed, 16.5% were civil servants, 10.8% were self-employed, and 9.3% were students ( Table 2). Obstructive uropathies were 6.5 times more frequent in patients with lower tract stones compared to those with upper tract stones (p 0.001) (Table S 2).
The mean (SD) size of the extracted stones was 23.4 (17.0) mm. Forty-ve (60%) stones from the lower tract had a diameter of 20 mm or larger (Figure S 2). The mean size of lower tract stones was twice as large as that of upper tract stones (34.1 ± 21.0 mm vs. 16.6 ± 8.6mm, p 0.001). Stones that resolved spontaneously had a mean size 2.9 times smaller than that of stones removed by conventional surgery (8.4 ± 3.9 mm vs. 24.8 ± 17.1mm, p = 0.005) ( Table 3).

Discussion
Our ndings revealed that most lithiasic patients were males and ank pain was the most frequent presenting feature. Urolithiasis was symptomatic in 52.6% of patients and its discovery was incidental (on medical imaging or during surgery) in 20.1% of cases. Renal colic was the most common presenting feature. This is consistent with ndings from earlier studies conducted elsewhere [6,7]. Indeed, clinical features revealing urolithiasis are often unrelated to the chemical type of stones and lend themselves to a common description. Typical renal colic is the most frequent revealing feature [2,4]. Pain in renal colic results from the sudden and signi cant increase in intrapyelic pressure above the urethral obstacle [2,4,[8][9][10]. The increase in intrapyelic pressure can be explained by two factors. The rst is anatomical due to the presence of a circular edematous ridge in the wall of the ureter around and above the enclosed stone and the second is functional due to an uncontrolled homeostatic reaction with the secretion of prostaglandins E2; hence justifying the use of non-steroidal anti-in ammatory drugs in the symptomatic treatment of renal colic [2,4]. Therefore, males patients presenting with ank pain should be carefully evaluated for urolithiasis. Additionally, less characteristic pain or other signs such as hematuria and urinary tract infection should have higher index of suspicion. It should also be noted that typical ank pain is rare in young children. In case of diagnostic doubt, after performing the unprepared abdomen xray and ultrasound, the CT scan without injection is now recognized as the preferred imaging examination [5,11].
Regarding management, our study revealed that most stones (85.6%) were extracted by conventional surgery. This is in line with studies conducted in other sub-Saharan African countries. A study conducted in Cameroon reported that conventional surgery accounted for 96% [12]. In Burkina-Faso, authors reported a 100% use of conventional surgery [13,14]. However, our ndings are in contrast with those from studies conducted in other settings. Indeed, Laziri et al. [15] in Morocco performed modern techniques (ESWL, PCNL and URS) in 72.7% of cases. A study in France reported that URS accounted for 76% of treatment, followed by ESWL (21.3%), PCNL (2.6%), and conventional surgery (0.1%) [16]. Another study in France reported a 100% use of URS [17,18]. The difference might be explained, at least partially, by the lack of equipment and a limited expertise in most African countries. Current treatment modalities are minimally invasive and include ESWL, URS, and PCNL [19]. However, the use of these techniques poses a huge challenge in our regions. The high cost associated with the acquisition of adequate materials and their maintenance, the lack of quali ed personnel to maintain the equipment and the lack of local expertise are obstacles to their implementation. Clinically, the large diameter of stones described in this study poses a challenge with minimally invasive surgery. We performed conventional surgery for stones with destruction of the kidney, stones with associated anatomical anomaly, coralliform stones or obstructive ureteral or pyelic stones with a large diameter. Caliceal stones, sometimes di cult to access with conventional surgery and often responsible for partial renal obstruction, were managed medically until the conditions were met for endourological treatment. Finally, large-diameter bladder stones were systematically treated with conventional surgery.
Besides the constraints related to our setting, it is important to remember that recommendations for surgical management of urinary stones have shifted towards endourological procedures such as URS, PCNL and ESWL [4,19,20]. However, ESWL has lost its place as a rst-line modality for many indications despite its proven e cacy [19]. Open and laparoscopic surgical techniques have limited indications.
Finally, it is well known that conventional surgery is associated with various complications compared to minimally invasive techniques. However, it offers the possibility of obtaining a urinary tree without calculus ("stone free"). Minimal invasive techniques, beyond their complications such as lesions of the renal parenchyma (sub capsular, intra and peri-renal hematomas) and arterial hypertension linked to ESWL, do not always offer the possibility of obtaining a urinary tree "Stone free": ESWL 30 to 76% of cases, URS 95% of cases for pelvic ureteral stones and 80% for kidney stones less than 10 mm and 72% for those of 10 and 20 mm and PCNL 80 in 85% of cases [4,11]. ESWL remains the gold standard for kidney stones and ureteral stones in children, and open surgery is still one of the treatment options for urinary stones in children [11].
The main components of stones were calcium and oxalate, ndings which are in keeping with prior studies conducted across various parts of the world [3,12,18]

Conclusion
The use of minimally invasive surgery techniques in resource-constrained regions is limited due to the various reasons such as lack of equipment, limited number of expertise, and socio-economic. Thus, preventive measures including balanced and varied diet, adequate uid intake (>2.5 L daily), and early diagnosis would help mitigate severe cases and complications.

STRENGTHS AND LIMITATIONS
To the best of our knowledge, this is the rst study describing urolithiasis management in the DRC. This study was multi-centric including data from various regions across the country. Furthermore, analysis of the chemical composition of the renal stones was conducted. Information on the composition of renal stones is key in understanding the pathophysiology of urolithiasis. However, some limitations should be considered. The relatively low sample size and missing data from some variables such as the BMI. Thus, cautious is warranted while interpreting ndings from this study.