Pattern and presentation of cardiac diseases among patients with chronic kidney disease attending a national referral hospital in Uganda: a cross sectional study

We conducted a cross sectional study between June 2012 and February 2013 at Mulago
National Referral Hospital in Kampala, Uganda. The hospital is located in central
Uganda, East Africa and doubles as the teaching hospital for Makerere University’s
college of health sciences. It serves the 33million people of Uganda as well as Referrals
from the neighboring Eastern Democratic Republic of Congo and the Republic of South
Sudan.

We consecutively recruited adults with CKD aged 18 years and above. An online sample
size calculator by survey systems (http://www.surveysystem.com/sscalc.htm) was used to determine sample size. Considering a nephrology outpatient clinic population
of 500 patients, we calculated a total sample size of 217 subjects to enable estimates
to a precision of 5 %.

All patients attending the nephrology outpatient clinic were invited to participate
in the study as potential respondents. Only patients with evidence of kidney disease
(serum creatinine 1.4 mg/dL for males and 1.2 mg/dL for females) for ?3 months as
well as those with impaired renal function in the setting of atrophic kidneys (8 cm
in length), were recruited. Patients who had any form of renal replacement therapy
(Hemodialysis, peritoneal dialysis or renal transplant) were excluded from the study.

Ethical approval was obtained from the School of Medicine Research and Ethics Committee
of the College of Health Sciences, Makerere University. A written informed consent
was obtained from all study participants before recruitment into the study.

A standardized pretested questionnaire was used to collect data on socio-demographic
characteristics, medical history, and physical signs with emphasis on cardiovascular
risk factors, laboratory test parameters, electrocardiography (ECG) and echocardiography
variables. ECG was done primarily to evaluate cardiac rhythm with particular interest
in atrial fibrillation (absent P waves). ECG changes suggestive of ischemic heart
disease (Q waves, S-T and T wave changes) were also evaluated. Echocardiography was
performed to evaluate cardiac structure and function. Left ventricular hypertrophy
(Interventricular septum and/or left ventricular posterior wall diameter 11 mm),
ischemic heart disease (regional wall motion abnormalities), valvular heart disease,
pericarditis (pericardial thickening and/or effusion), left ventricular systolic failure
(Left ventricular ejection fraction 50 %), left ventricular diastolic failure (E/A
ratio 1), and pulmonary artery hypertension (PAH) (Tricuspid regurgitation pressure
gradient/TRPG 35 mmHg) were the key parameters studied at echocardiography.

Rest ECGs were done using the Schillar ECG Recorder, (Basal Switzerland). Echocardiograms
were done using Vivid 7 Dimension, GE Medical Systems (Horten, Norway).

Statistical analyses

Data was double entered into epidata version 3.1 and exported to STATA version 10
(after validation) for analysis. Results were expressed as percentages (frequencies
of the different cardiac diseases, stratification of respondents by stage of CKD)
and means (age) with standard deviations and presented in tables and graphs. Chi ²
tests were used to determine associations (LVH and anemia, LVH and hypertension, cardiac
failure and LVH, determination of trends i.e., variation of frequencies of each variable across the different CKD stages). Results
were statistically significant when the P value was 0.05.