This was a descriptive cross-sectional study conducted over a six-year period from January 1, 2017 to December 31, 2022, in the nephrology department of the Departmental University Hospital Center of Borgou and l’Alibori (CHUD-B/A) in Parakou, northeastern Benin.

The study population consisted of patients diagnosed with chronic renal failure according to the classification criteria for chronic kidney disease [5] (KDIGO 2012). All patients received during the study period and meeting the diagnosis of CKD according to KDIGO 2012 regardless of stage were included in the study.

・ Study variables were:

- Socio-demographic characteristics (age, gender, socio-professional group, professional status, marital status, place of residence, income, distance travelled).

- Lifestyle habits (herbal abuse, self-medication, alcohol abuse, tobacco abuse).

- Clinical data:

o Personal medical history and associated pathologies: hypertension, diabetes mellitus, stroke, urinary tract infections, heart failure, liver pathologies, bronchial asthma, human immunodeficiency virus (HIV) infection, prostate pathologies, polycystic kidney disease, cancers, gastric and duodenal ulcers, eclampsia).

o Clinical features (previous treatment, reason for consultation, mode of admission, general condition, vital signs, stage of chronic kidney disease, heart rate and blood pressure).

- Paraclinical characteristics (uremia, creatinemia, glomerular filtration rate (GFR), uric acid, natremia, kalemia, calcemia, total cholesterol, hemoglobin level and blood glucose).

- Therapeutic data (consultation time, number of molecules, hemodialysis treatment, duration of current treatment, time to first follow-up check-up).

・ Operational definitions of variables

- CKD was diagnosed according to the classification criteria for chronic kidney disease (KDIGO 2012). Stages 3, 4 and 5 were retained for a glomerular filtration rate (GFR) at entry of between: 30 and 59 mL/min/1.73m²; 15 and 29 mL/min/1.73m² and less than 15 mL/min/1.73m² respectively. The Chronic Kidney Disease―Epidemiology Collaboration (CKD-EPI) equation was used to calculate GFR [5] ;

- The distance travelled is the distance from the patient’s place of residence to the CHUD/D-A;

- Alcohol consumption was considered abusive (according to the WHO) if the subject consumed more than 21 glasses per week. Moreover, 1 glass of alcohol = 10 g of pure alcohol (according to the WHO) [6] ;

- Phytotherapy was abused by the subject, who regularly took a mixture of more than two elements per dose;

- Tobacco exposure was considered abusive in subjects who smoked more than once a day [6] ;

- Self-medication is defined as the habit of using one or more medicines without the intervention of a doctor or pharmacist, in order to treat oneself independently [7] ;

- The consultation delay is the time elapsed between the appearance of the first symptoms and the first contact with the health services;

- Initial check-up time is the time elapsed between diagnosis and the first check-up appointment;

- Treatment duration is the time spent in the department under treatment;

- Blood pressure was measured in seated patients after 15 minutes’ rest, using an automatic digital sphygmomanometer fitted with a cuff (belonging to the list of sphygmomanometers validated by the French Hypertension Society). It was taken on the bare right arm, placed on a table with the palm facing upwards. Three measurements were taken at 5-minute intervals; the average of the last two measurements was the blood pressure retained for each patient. Blood pressure was considered high if the post-measurement value was greater than or equal to 140/90 mmHg [8] ;

- Heart rate (HR) was considered normal for a number of heartbeats between 60 and 100 beats per minute. It was taken 15 minutes after the patient’s arrival, on the bare right arm, placed on a table, palm upwards, with the same automatic digital blood pressure meter fitted with a cuff used for blood pressure measurement;

- The following normal values were defined for paraclinical variables as follows: The following normal values were defined for paraclinical variables as follows:

o Hemoglobin in grams per deciliter (g/dL) between [11 - 16];

o Uremia in grams per liter (g/L) between [0.15 - 0.45];

o Plasma creatinine in mg/dL between [0.6 - 1.4];

o GFR greater than or equal to 90 mL/min/1.73m²;

o Uricemia in milligrams per liter (mg/L) between [40 - 60];

o Natremia in milliequivalents per liter (mEq/L) between [135 - 158];

o Kalemia (mEq/L) between [3.5 - 5.3];

o Calcemia (mEq/L) between [85 - 105];

o White blood cells per microliter (µL) [3000 - 8000];

o Total cholesterol below 2 g/L;

o Fasting blood glucose (g/dL) between [0.70 - 1.26].

Data were collected using a medical record form, covering patients’ socio-demographic, clinical and therapeutic variables. Data were analyzed using R 4.3.1 software. The mean and standard deviation were determined for quantitative variables. Qualitative variables were expressed as a proportion.

The mean age (SD) of patients was 50 years (±14.9) [13 to 90 years]. Patients between 40 and 60 years of age were the most numerous. Nearly 67.1% of patients were male, giving a sex ratio (M/F) of 2.03. Most patients (36.4%) did not attend school. Civil servants, housewives and shopkeepers were the three predominant occupational groups, accounting for 14.3%, 23.6% and 15.2% of cases respectively. Two out of three patients (67.6%) were still working (Table 1).

Arterial hypertension (AH) and diabetes mellitus were the associated pathologies most frequently found in patients, accounting for 59.1% and 18.1% of cases respectively (Figure 3). The lifestyle habit most frequently incriminated was self-medication (41.2%) (Figure 3 and Figure 4).

Most patients (47.2%) had consulted their doctor within three months, most often in a context of deteriorating general condition. The vast majority (85.4%) had received treatment prior to admission. The main reasons for consultation were asthenia, headaches and dyspnea, as well as edema. In 44% of cases, renal function was already impaired on admission. According to the mode of admission to the department, 66% of patients had been referred by healthcare professionals, the majority of whom (70%) were general practitioners. Tachycardia was observed in 32.7% of patients, and high blood pressure in 72% (Table 2).

Mean GFR (SD) was 11.9 mL/min/1.73m² (±13.3). Main disturbances revealed by paraclinical examinations were: anemia (90.7%), hyperuricemia (86.3%), hyperuricemia (77.6%), hypocalcemia (40.2%), hyponatremia (31.2%), hypercholesterolemia (29.7%) hyperleukocytosis (29.7%), hyperkalemia (19.5%) and hyperglycemia (13.4%) (Table 3).

All patients consulted during the study period had received advice on dietary and nutritional measures, as well as drug prescriptions. The majority of patients were seen in the terminal stage of the disease (stage 5). Most of them (82.2%) had spent less than a year on treatment in the department. The main drug groups used were antihypertensives (22.2%), alkalinizes and calcium (18.7%) and antianemics (17.8%) (Table 4).

Chronic renal failure is a frequent condition in the CHUD/B-A nephrology department. Its hospital prevalence was 55.2%. This prevalence is close to that of Eyeni Sinomono et al. [9] who reported that CKD accounted for 50.7% of admissions to the nephrology department of Brazzaville University Hospital. This is lower than that reported by Vigan et al. [4] in whom CKD accounted for 91% of admissions in the nephrology department of the CNHU-HKM in Cotonou, Benin.

However, our prevalence is higher than that of Gbaguidi et al. [10] , who reported a prevalence of 16.1%. This difference is due to the fact that this study was carried out in a general population, in a rural setting, unlike ours, which was carried out in a hospital setting, in a specialized department.

Age and gender: In our study, the mean age of patients was 50 ± 14.9 years. The majority were 60 years old. Our average age is close to those of 47 and 52 years reported in Benin [4] [10] ; 51.4 years in DRC [11] ; 51.2 years in Congo [9] . On the other hand, it is lower than the average of 72 years reported in France [12] .

Male patients were the most affected, accounting for 67.1% of cases. The same male predominance was reported by Tia, et al. Ahoui et al. and Vigan et al. [4] [13] [14] .