Cardiovascular Journal of Africa: Vol 26 No 3 (May/June 2015)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 26, No 3, May/June 2015

AFRICA

125

Sickle cell trait is not associated with chronic kidney

disease in adult Congolese patients: a clinic-based,

cross-sectional study

K Mukendi, FB Lepira, JR Makulo, KE Sumaili, PK Kayembe, MN Nseka

Abstract

Objective:

The aim of this study was to evaluate the determi-

nants of chronic kidney disease (CKD) with special emphasis

on sickle cell trait (SCT).

Methods:

Three hundred and fifty-nine patients (171 men

and 188 women), aged 18 years or older, with reduced kidney

function (eGFR

90 ml/min/1.73 m

) and seen at second-

ary and tertiary healthcare in Kinshasa were consecutively

recruited in this cross-sectional study. Serum creatinine and

haemoglobin electrophoresis were performed in each patient.

CKD was defined as

60 ml/min/1.73 m

. Logistic regres-

sion analysis was used to assess determinants of CKD with

a special emphasis on SCT. A

value

0.05 defined the level

of statistical significance.

Results:

SCT was present in 19% of the study population;

its frequency was 21 and 18% (

0.05) in patients with and

without CKD, respectively. In multivariate analysis, sickle cell

trait was not significantly (OR: 0.38; 95% CI: 0.559–1.839;

0.235) associated with CKD; the main determinants were

dipstick proteinuria (OR: 1.86; 95% CI: 1.094–3.168;

0.02), the metabolic syndrome (OR: 1.69; 95% CI: 1.033–

2.965;

0.03), haemoblobin

≥

12 g/dl (OR: 0.36; 95% CI:

0.210–0.625;

0.001), and personal history of hypertension

(OR: 2.16; 95% CI: 1.202–3.892;

0.01) and of diabetes

mellitus (OR: 2.35; 95% CI: 1.150–4.454;

0.001).

Conclusion:

SCT was not an independent determinant of

CKD in the present case series. Traditional risk factors

emerged as the main determinants of CKD.

Keywords:

chronic kidney disease, determinants, sickle cell trait,

black Africans

Submitted 9/8/14, accepted 1/12/14

Cardiovasc J Afr

2015;

: 125–129

www.cvja.co.za

DOI: 10.5830/CVJA-2014-076

Chronic kidney disease (CKD) and end-stage renal disease

(ESRD) are associated with significant cardiovascular (CV) and

renal morbidity and mortality rates, with substantial economic

burden.

1,2

Therefore, early identification of CKD patients at high

risk of progression is urgently needed for early and targeted

treatment to improve patient care.

1-3

Diabetes and hypertension

are the primary risk factors for CKD and ESRD but do not fully

account for CKD and ESRD risk.

1-3

Marked variability in the

incidence of CKD suggests that factors other than diabetes and

hypertension contribute to its aetiology.

Family studies have suggested a genetic component to the

aetiology of CKD and ESRD.

In African Americans, high-risk

common variants in the Apol1/MYH9 locus may explain up to

70% of the differences in ESRD rates between European and

African Americans.

While this finding has great implications

for ESRD, the identification of additional risk factors for CKD,

including genetic loci in association with estimated glomerular

filtration rate (eGFR), may help to advance our understanding

of the underpinnings of CKD in African Americans.

In this era

of identifying genetic risk factors for kidney disease, it may be

appropriate to revisit one of the most common genetic disorders:

sickle cell haemoglobinopathies.

In this regard, sickle cell trait (SCT), present in approximately

7–9% of African Americans, has been reported to be a potential

candidate gene.

However, conflicting reports exist as to whether

SCT is a risk factor for the progression of nephropathy.

6,7

Haemoglobin S (HbS) was selected for in Africa because of the

protection it affords from malarial infection, a scenario similar

to the protection from trypanosomal infection provided by

heterozygosity for APOL1 nephropathy risk variants.

Whereas APOL1 contributes to risk for nephropathy in an

autosomal recessive inheritance pattern, HbS reportedly had

a dominant effect on risk, with SCT being associated with

ESRD.

In line with this finding, a few small studies on African

Americans reported HbS as an independent risk factor for

CKD and ESRD.

However, other studies using a large sample

of African Americans stated that SCT was not independently

associated with susceptibility to ESRD in African Americans,

highlighting the need for further studies in other populations

such as those of sub-Saharan Africa where SCT is prevalent.

Although SCT is very prevalent in black Africans,

few

studies have been conducted to assess the association between

SCT and CKD.

In Democratic Republic of Congo (DRC), the

prevalence of CKD and SCT has been reported to be 12% and

17–24%, respectively.

11-13

No study has evaluated the frequency of

SCT among CKD patients to assess its association with reduced

kidney function. Therefore, the aim of this clinic-based, cross-

sectional study was to assess the potential association between

SCT and CKD among adult Congolese patients.

Division of Nephrology and Hypertension, Department

of Internal Medicine, University of Kinshasa Hospital,

Kinshasa, Democratic Republic of Congo

K Mukendi, MD

FB Lepira, MD, PhD,

lepslepira@yahoo.fr

KE Sumaili, MD

MN Nseka, MD

School of Public Health/University of Kinshasa, Kinshasa,

Democratic Republic of Congo

PK Kayembe, MD