Chronic Nephropathies in the Internal Medicine Department of the Sylvanus Olympio University Hospital

Introduction: The chronic nephropathies constitute a real global public health concern due to the constant increase in the prevalence estimated between 10% and 15%. In Sub-Saharan Africa, this prevalence has been estimated at 13.9%. This study will allow knowing the epidemiological, clinical, paraclinical and etiological aspects of chronic kidney disease in the internal medicine department of CHU-SO Lomé. Method: This was a cross-sectional, retrospective and descriptive study. It concerned all the patients suffering from a chronic kidney disease, hospitalized between the 1st of January 2014 and the 31st of December 2018, for a duration of 5 years. Results: During our study, 330 cases of chronic nephropathy were identified. The prevalence of chronic kidney disease was 8.3% of admissions. The mean age of the patients was 46.3 years with extremes of 19 and 86 years and a sex ratio of 1.32. A low socioeconomic level of patients was observed in 63.9% with an urban origin in 69.7%. The main risk factors for renal impairment were hypertension (55.2%), diabetes mellitus (29.1%), obesity (20.6%),


Introduction
Chronic nephropathies (CNP) are defined by the presence of markers of renal damage (structural or functional) and/or a decrease in estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73m 2 [1] for more than three months. They constitute a real global public health concern due to the constant increase in the prevalence estimated between 10% and 15% [2] [3]. In Sub-Saharan Africa, this prevalence has been estimated at 13.9% [4]. Projections for 2030 predict that more than 70% of the world's population with end-stage renal disease (ESRD) will end up in developing countries, including most of the countries of Sub-Saharan Africa [4]. The cost of medical care for patients with CNP is very high according to the International Society of Nephrology (ISN) [5]. In Togo, the average global cost of care for a non-dialyzed CKD patient, hospitalized at the Sylvanus Olympio University Hospital (CHU-SO) in Lomé amounted to 199.289.4 FCFA i.e. 5.7 times the Guaranteed Minimum Interprofessional Wage (SMIG) [6]. When the patient is on dialysis, the average annual cost including hemodialysis and medical expenses was 11,422,490.7 FCFA [7] and could be higher in private clinics.
Faced with this important medico-economic issue, the prevention of CNP becomes a necessity and implies a better knowledge of the profile of patients suffering from CNP. This work was carried out to describe the global profile of chronic nephropathies. The specific objectives were to: -Describe the epidemiological aspects of chronic nephropathies.
-Describe the clinical and paraclinical aspects of chronic nephropathies.
-Describe the pathologies associated with chronic nephropathies.

Framework and Method
The internal medicine department of the Sylvanus Olympio University Hospital (CHU-SO) served as the study setting. This was a descriptive and cross-sectional study with retrospective data collection. It focused on the records of patients suffering from chronic nephropathy, hospitalized in the internal medicine department of the CHU-SO from January 1, 2016 to December 31, 2021, i.e. a period of 5 years. We extracted deidentified data from the unit registry.
Were included in this study, all patients aged 16 years and over, hospitalized during the study period in the internal medicine department, having presented a chronic nephropathy defined by the presence for more than 3 months, of markers of renal damage that were: morphological abnormalities of the renal parenchyma on ultrasound (small kidney < 10 cm, large kidney > 120 cm, loss of differentiation) and/or biological abnormalities (proteinuria, albuminuria, hematuria, leukocyturia, and/or decrease in glomerular filtration rate (GFR) below 60 mL/min/1.73m 2 ) Glomerular filtration rate is estimated by calculating serum creatinine clearance according to the simplified MDRD (Modified Diet in Renal Diseases) [1].
All patients with chronic nephropathy receiving hemodialysis or having already undergone transplantation before admission to the department were excluded.
In the absence of a renal puncture biopsy, the following semiological classification was adopted to identify the type of initial nephropathy: • Chronic glomerular nephropathies (CGN): they were defined by proteinuria > 1 g/24 hours, microscopic or macroscopic hematuria, more or less important hydrosodic retention (edemas) preceding arterial hypertension (HTA) and small regular symmetrical kidneys.

Study Techniques
The medical records carried out by the doctors were used to collect the data collected on a survey form.
• Associated factors: current or past smoking or alcohol use; lack of physical activity; family history of diabetes mellitus, hypertension and kidney disease; personal history of hypertension, diabetes mellitus, heart disease, dyslipidemia, kidney disease, gout, sickle cell disease, HIV infection, systemic disease; notion of taking non-steroidal anti-inflammatory drugs (NSAIDs) or other nephrotoxic products, traditional products; notion of repeated urinary tract infection.
• Socioeconomic level (SEL) was subdivided into three groups according to the patients' supposed income: high SEL when the income is estimated above 150,000 FCFA per month, average SEL when the income is between 35,000 and 150,000 FCFA per month, low SEL when the income is less than or equal to 35,000 FCFA per month i.e. the minimum wage. BMI ≥ 30 (obesity); BMI between 25 -29.9 (overweight); BMI between 18.5 -24.9 (normal); BMI < 18.5 (thinness); Chronic kidney disease was classified according to KDIGO 2012 (Table 1) [1].
• Data and Statistical analysis All data were entered into a data entry mask developed in Epi data version 3.1 software and then analyzed using IBM SPSS Statistics 20 statistical software.
Categorical data were expressed as percentages. The chi-square test was used to compare proportions. A p-value < 5% was considered statistically significant.
• Creatinine was measured using the Jaffé colorimetric method.
• Urinary sediment is sought in fresh morning urine and proteinuria by collecting 24-hour urine. • The following ultrasound classification has been adopted for the renal echostructure: stage 0 or normal kidney for a hypoechoic renal cortex relative to that of the liver; stage I for an isoechoic renal cortex relative to the liver; stage II for a renal cortex that is hyperechoic relative to the liver but hypoechoic relative to the renal sinus with preservation of cortico-medullary differentiation; and stage III for a hyperechoic renal cortex relative to the liver and isoechoic relative to the renal sinus with disappearance of cortico-medullary differentiation.

Socio-Demographic Data
During our study, 3988 patients were hospitalized in the internal medicine department among whom we identified 330 cases of chronic nephropathy according to the predefined criteria. Only 8% of the patients are senior executives. The majority of patients, i.e. 81%, did not have health insurance coverage. Among the patients who had health insurance, 13% were insured with INAM, the public insurance company.
The majority of our patients, i.e. 69.7%, lived in urban areas.

Associated Clinical Etiological Factors
Known hypertension in 55.2% of patients was the main risk factor, followed for diabetes in 29.1% of cases. The distribution of patients according to the associated factors is shown in Table 2.
The study of the different fractions had shown a predominance of: hypercholesterolemia > 2 g/l in 36.8%, hypertriglyceridemia > 1.50 g/l in 48.1%.

Stages of Chronic Kidney Disease
The majority of patients had end-stage CKD, i.e. 69.7%. Figure 1 shows the distribution of patients according to CKD stages

Causal Pathologies of CNPs
Unbalanced hypertension (33.3%), unbalanced diabetes (25.5%) and HIV (17%) were the main probable causes of CNPs. The toxic origin was related to the use of medicinal plants and the other origins included 8 HBV and 4 HCV. The cases of obstructive uropathy were due to 6 prostate adenocarcinomas and 2 cervical neoplasia.

Main Complications of CNP
Anemia is the main complication of CNP in 98.2%. Table 4 shows the distribution of major complications of CNPs.

Length of Hospitalization
The mean hospital stay was 15 ± 10.8 days, with extreme values of 2 and 67 days.
This value of 67 days corresponds to the length of hospitalization of a patient with end-stage HIV-related CNP associated with nephrotic syndrome and a profound deterioration in general condition.

Overall Mortality
Of the CNP patients with CKD requiring hemodialysis, only 56 (24.3%) had sufficient financial resources to access it.
One hundred and eighty-nine patients died during hospitalization, i.e. a mortality rate of 57.3%. The average age among the deceased was 46.8 ± 14.2 years.
Anemia was the main cause of death in our series followed by APO 43 cases (22.7%) and severe sepsis 39 cases (20.6%).

Limitation of Study
This study suffered from the lack of renal biopsy which is important to improve the classification of the chronic nephropathies.

Sociodemographic Aspect
The mean age was 46.3 ± 14.4 years with a peak in the age range 35 -44 years i.e.

31.5%. This is similar to the results obtained in a meta-analysis published in The
Lancet in 2014, where the most represented age range of patients from 13 sub-Saharan African countries, carriers of CNP, was 35 to 46 years [5]. This can be A. K. Djagadou et al. explained by the fact that this is the socially active population category that is easily exposed to certain environmental factors such as the use of alcohol, tobacco as well as medicinal plants that are sometimes nephrotoxic. Hypertension, one of the main causes of the disease, is also a factor affecting this category of the population due to social stress. This average age is lower than those obtained in developed countries where most patients are over 60 years old [2] [3]. This discrepancy between African and Western countries could be explained on the one hand by the young age of the African population and on the other hand by the greater accessibility to healthcare in industrialized countries and the aging of the Western population.  [7]. Obesity has been identified as a risk factor for hypertension, diabetes and the occurrence of kidney disease [8].

Aspect of Associated Factors
Alcohol and tobacco consumption were significantly more common in men (p < 0.001). A study conducted in patients with chronic nephropathy showed that GFR declined twice as fast in smokers as in non-smokers [9]. Another preventable risk factor for CNP is the use of herbal remedies, which was found in 19.4% of cases.
At this stage of observation, histopathological and toxicological studies are recommended to establish the causal relationship and the specific components of the incriminating products. HIV infection was reported in 17% in our study.
As in a previous study, Sabi et al. [10] [9]. Due to technical limitations, renal puncture biopsy was not performed. This remains a major challenge.

Etiological Aspect of Chronic Nephropathies
The etiological research of CNP constitutes a difficult stage of the management in our regions, renal biopsy being rarely performed as well as immunological assessments. This difficulty could largely explain the non-negligible rate of undetermined causes of CNP reported in 10.9% in our study. In our series, probable causes were dominated by nephro-angiosclerosis (33.3%), followed by diabetic nephropathy (25.5%) and HIV-associated nephropathy (17%).
The same observation is made in most African studies where the known causes are by far dominated by nephro-angiosclerosis (NAS) with rates varying between 25% and 62.1% [10] [11] [12] [13].
On the contrary, Benja in Madagascar [14] and Bah in Guinea [15] had noted a predominance of chronic glomerulonephritis in 36.6% and 37.8% respectively, followed by NAS in 32.44% and 31.2% of cases. In developed countries, about 50% of severe kidney disease is the result of diabetes followed by hypertension [6].

Stages of Chronic Nephropathy
The majority (69.7%) of our patients had chronic end stage nephropathy. Our result is similar to that of Benja [14] in Madagascar who found 75.31% of patients who were in the end-stage. The same observation was made by Naiker [7] who found more than 70% of end-stage CNP cases in most Sub-Saharan African countries. These data contrast with those of developed countries [2] [3] [16] where the majority of patients are seen before stage 3. This late presentation of CNP in our series would be due to the poor screening policy and insufficient education on CNP; all this based on the low socioeconomic level and the lack of universal health insurance. This results in an inadequacy of the therapeutic management. Indeed, due to lack of financial means, 75.7% of the patients could not benefit from a replacement therapy (hemodialysis or kidney transplant). The high hospital mortality during our study (57.3%) is therefore due to the absence of adequate treatment, as in Côte d'Ivoire (54%) [17] and in Guinea Conakry 20.6% [15].

Conclusion
Chronic nephropathy is a real global public health concern, and its prevention requires a better knowledge of the profile of patients suffering from it. At the Sylvanus Olympio University Hospital, they represent 8.3% of admissions to the internal medicine department. They concerned young adults of low socioeconomic level seen in the majority of cases at the end stage of the disease requiring supplementary treatment. The main etiological factors are hypertension, diabetes mellitus and HIV. The high mortality was related to the lack of access to adequate care in the majority of cases. It is essential to focus on preventive measures, early detection and adequate treatment of risk factors for CNP.