Differential protein clearances and response to treatment in Nigerian nephrotic children

Childhood Nephrotic Syndrome in Africa: Epidemiology, Treatment Trends, and Outcomes

Nephrotic syndrome is a common childhood glomerular disease that is associated with massive proteinuria and edema. Children with nephrotic syndrome are at risk of chronic kidney disease, disease-related complications, and treatment-related complications. Patients with frequently relapsing disease or steroid toxicity may require newer immunosuppressive medications. However, access to these medications is limited in many African countries owing to prohibitive cost, the need for frequent therapeutic drug monitoring, and a lack of appropriate facilities. This narrative review examines the epidemiology of childhood nephrotic syndrome in Africa, including trends in treatment and patient outcomes. In most of North Africa, as well as among White and Indian populations in South Africa, the epidemiology and treatment of childhood nephrotic syndrome closely resembles that of European and North American populations. Historically, secondary causes of nephrotic syndrome (eg, quartan malaria nephropathy and hepatitis B-associated nephropathy) were predominant among Blacks in Africa. Over time, the proportion of secondary cases has decreased, along with rates of steroid resistance. However, focal segmental glomerulosclerosis increasingly has been reported among patients with steroid resistance. There is a need for consensus guidelines for the management of childhood nephrotic syndrome in Africa. Furthermore, establishing an African nephrotic syndrome registry could facilitate monitoring of disease and treatment trends, and provide opportunities for advocacy and research to improve patient outcomes.

Trends in the epidemiology of childhood nephrotic syndrome in Africa: A systematic review

Background

Childhood nephrotic syndrome, if left untreated, leads to progressive kidney disease or death. We quantified the prevalence of steroid-sensitive nephrotic syndrome, steroid-resistant nephrotic syndrome, and histological types as the epidemiology of nephrotic syndrome in Africa remains unknown, yet impacts outcomes.

Methods

We searched MEDLINE, Embase, African Journals Online, and WHO Global Health Library for articles in any language reporting on childhood nephrotic syndrome in Africa from January 1, 1946 to July 1, 2020. Primary outcomes included steroid response, biopsy defined minimal change disease, and focal segmental glomerulosclerosis (FSGS) by both pooled and individual proportions across regions and overall.

Findings

There were 81 papers from 17 countries included. Majority of 8131 children were steroid-sensitive (64% [95% CI: 63-66%]) and the remaining were steroid-resistant (34% [95% CI: 33-35%]). Of children biopsied, pathological findings were 38% [95% CI: 36-40%] minimal change, 24% [95% CI: 22-25%] FSGS, and 38% [95% CI: 36-40%] secondary causes of nephrotic syndrome.

Interpretation

Few African countries reported on the prevalence of childhood nephrotic syndrome. Steroid-sensitive disease is more common than steroid-resistant disease although prevalence of steroid-resistant nephrotic syndrome is higher than reported globally. Pathology findings suggest minimal change and secondary causes are common. Scarcity of data in Africa prevents appropriate healthcare resource allocation to diagnose and treat this treatable childhood kidney disease to prevent poor health outcomes.

Funding

Funding was provided by the Canadian Institute for Health Research (CIHR) and the National Institute of Health (NIH) for the H3 Africa Kidney Disease Research Network. This research was undertaken, in part, from the Canada Research Chairs program.

Childhood nephrotic syndrome in tropical Africa: then and now

This descriptive and comparative review examines the changing epidemiology, treatment, renal and patient outcome of childhood nephrotic syndrome (NS) in tropical Africa (TpAfr). In the 1960s to 1980s, corticosteroid-resistant non-minimal change disease (nMCD) including quartan malaria nephropathy (QMN) was the dominant renal histopathology type. The overall incidence of NS was 0.35-1.34% of hospital admissions. Median age at onset of NS ranged between 4.0 and 12.0 years while the mean (SD) age range was 5.8 (3.8) to 10.3 (4.8) years across studies. The male: female ratio was 1.6:1.0. The overall mean (SD) incidence of idiopathic minimal change disease (MCD) [21.6 (18.6%)] compared with idiopathic nMCD [59.1 (25.7%)] demonstrates significant dominance of the latter (p = 0.0001). Post-1989, the following mean (SD) incidences of histopathological types were: MCD 20.4 (17.7%), focal segmental glomerulosclerosis 39.0 (26.3%), membranoproliferative glomerulonephritis 25.4 (16.8%), proliferative glomerulonephritis 16.7 (27.0%) and membranous nephropathy 7.4 (4.5%). While the mean (SD) proportion of steroid resistance (SR) [73.5 (19.2%)] was significantly greater than the mean complete remission (CR) [26.5 (19.2%)] during 1960-1989 (p=0.005), mean (SD) SR [27.4 (25.3%)] was significantly lower than mean (SD) CR [66.1 (28.0%)] post-1989 (p < 0.001). Unlike QMN, hepatitis B virus, HIV infection, sickle cell disease and systemic lupus erythematosus are now increasingly being associated with NS in TpAfr. Mean (SD) renal survival post-1989 was 58.3 (37.0%) while all-cause mortality was 9.8%. Children with NS now survive better than before, reflecting improved access to healthcare and transition to a clinical pattern favouring idiopathic NS and increased sensitivity to corticosteroids.

Trends in the histopathology of childhood nephrotic syndrome in Ibadan Nigeria: preponderance of idiopathic focal segmental glomerulosclerosis

Background

Reports on the histopathology of childhood nephrotic syndrome (NS) had emanated from our Centre since the 1960s and by the late 1980s and early 1990s, a change was observed and reported. Taking into consideration the worldwide changing trend in the histopathology of the NS and our Unit policy change in the indications for renal biopsy, a change was envisaged. We therefore evaluated the current histologic pattern of childhood NS in Ibadan with the view to highlighting any variations from the past and comparing the findings with regional and global trends.

Methodology

We reviewed our database and analyzed the renal biopsy findings in patients who were biopsied before treatment was administered between 1997 and 2001 and those with mostly idiopathic steroid resistant NS (SRNS) and secondary NS, managed between 2006 and 2013. A comparative analysis of the findings from the present study was carried out with two previous reports from our Unit in the 1970s and early 1990s and also with reports from other Centres.

Results

A total of 78 patients had successful biopsies done during the study period in children aged between 2 ½ and 16 years. In both pre-treatment biopsy era (1997–2001) and post-treatment biopsy era (2006–2013), focal segmental glomerulosclerosis (FSGS) predominated. 75 % of the patients had idiopathic NS and among the patients that had idiopathic steroid resistant NS, FSGS was the most common followed by MPGN. For secondary NS, MCD was the most common but could be the early stages of either membranous nephropathy (MN) or FSGS. Chronic pyelonephritis and chronic interstitial nephritis occurred in 25 % of the study population but they were more prevalent in secondary nephrotic syndrome.

Conclusion

FSGS is the most common histopathology in children requiring renal biopsy in Ibadan presently. FSGS is also the most common histopathology in idiopathic SRNS, which is in keeping with reports from most parts of the world.

There has been a transition from the preponderance of Quartan Malarial Nephropathy (QMN) in the 1960s to MPGN in the 1980s to FSGS presently. This has great implications with regards to searching for new aetiologic factors, providing more efficacious treatment modalities and ensuring facilities for immunofluorescence, electron microscopic and genetic studies.

Increased steroid responsiveness of young children with nephrotic syndrome in Nigeria

A previous study on the nephrotic syndrome (NS) in our unit showed that the histological patterns associated with steroid resistance were more common in children over 5 years of age.

AIM

The aim of the study was to determine the incidence of steroid-responsiveness amongst nephrotic children <or=5 years.

SUBJECTS AND METHODS

All children with NS aged <or=5 years at the onset of disease presenting to University College Hospital, Ibadan were enrolled. Prednisolone was given daily, 60 mg/m2, for 4 weeks and then 40 mg/m2 on alternate days for at least 12 weeks.

RESULTS

Twenty children (9 boys and 11 girls) were enrolled between 1999 and 2002. The median age (range) at onset of disease was 4 (2-5) years. Remission was achieved in 12 (60%) children.

CONCLUSION

There is a satisfactory response to prednisolone in two-thirds of Nigerian children aged <or=5 years with NS.

The role of infectious agents in the aetiology and pathogenesis of childhood nephrotic syndrome in Africa

Childhood nephrotic syndrome is common in Africa where infectious agents are prevalent. This paper reviews the possible aetiological role of infectious agents in childhood nephrotic syndrome in Africa. There is a strong association, possibly causal, between childhood nephrotic syndrome on the one hand and Plasmodium malariae, Schistosoma mansoni and hepatitis B antigens on the other. Beta-haemolytic streptococci are less strongly associated with nephrotic syndrome, and a few other organisms are suspect. The many ubiquitous infectious agents and the prevalence of multiple infections make it difficult to define the role of any single infectious agent or to determine the interaction between the various agents. Control or eradication of infectious diseases should lower the incidence of childhood nephrotic syndrome in Africa.

Biochemical hypothyroidism in Nigerian children with nephrotic syndrome

The nephrotic syndrome in Nigerian children is known to be largely associated with the endemicity of quartan malaria. Routine thyroid function studies were carried out on 24 children with clinical and biochemical evidence of the nephrotic syndrome. The children, aged four to 14 years, were all in the active phase of their disease, presenting with facial and pedal oedema and ascites. There was severe hypoalbuninaemia [mean (S.E.); 19.2 (1.1) g/l], hypercholesterolaemia; 10.5 (1.0) mmol/l and severe albuminuria ranging from 1 to 10 g/l. There was no clinical evidence of thyroid disease. The results of thyroid function tests in these children were compared with those of 181 apparently healthy children of the same age range. The mean total serum thyroxine levels (S.E.) were 118.3 (2.6) and 50.0 (6.4) nmol/l in controls and patients, respectively; T3 resin uptake values were 29.8 (0.2)% and 33.1 (1.2)%; the free thyroxine index (FTI) was 34.7 (0.8) and 16.7 (1.9) while thyrotropin (TSH) levels were 4.8 (0.2) and 10.6 (1.0) mU/l (IRP. MRC 68/38), respectively. The findings of low levels of thyroxine and FTI in association with high levels of TSH suggest that a state of primary hypothyroidism exists in these nephrotic children.

Immunological aspects of nephrotic syndrome in northern Nigeria

Immunological aspects of 40 northern Nigerian children with nephrotic syndrome of recent onset are reported. Eight our of 30 had hepatitis-associated antigen in their sera. Hypocomplementaemia was rare. Measurement of serum C3, C4, and ASOT was not of diagnostic value. Proteinuria selectivity index was poor in half of the patients, and appeared t o depend on the severity of the kidney lesion. Abnormal immunofluorescence of kidney glomeruli to immunoglobulins, complement, Plasmodium malariae, and Plasmodium falciparum was found in 26 of the 29 children. The pattern of immunofluorescence was chiefly granular and was confined to the glomeruli. IgM was predominant. It was concluded that immunological reaction is involved in the pathogenesis of nephrotic syndrome in northern Nigerian children.

Quartan malarial nephrotic syndrome in children

Quartan malarial infection causes an immune complex nephritis in some individuals, which, once established, is sustained by mechanisms not yet fully explained, but which probably involve autoimmune processes. The presenting clinical and biochemical findings of the quartan malarial nephrotic syndrome are similar to those classically described for the nephrotic syndrome in childhood, but the renal pathology seen on light, electron, and immunofluorescent microscopy show striking differences and distinctive features. The disease tends to pursue a chronic course and in most patients is nonresponsive to treatment with antimalarial drugs, prednisolone, and immunosuppresive drugs. The overall prognosis is poor, with most patients developing hypertension and evidence of renal failure within 3 to 5 years of onset.

A controlled trial of cyclophosphamide and azathioprine in Nigerian children with the nephrotic syndrome and poorly selective proteinuria

In a controlled trial, symptomatic treatment alone, or 12 weeks of cyclophosphamide or azathioprine were compared in Nigerian children with nephrotic syndrome (mainly quartan malarial nephropathy) and poorly selective proteinuria. Full remission in 2 patients in each of the two groups treated with drugs, and diminution of proteinuria in most patients in the cyclophosphamide group showed possible evidence of benefit. Infections during treatment were significantly more common in the drug-treated groups but were controllable. Mortality from renal failure in the 2nd year after treatment was significantly greater in the azathioprine-treated group than in the other two, suggesting that the drug may have exacerbated the nephritis. The 5-year survival rate was similar in the cyclophosphamide and the control group.