Study design and population:
This prospective cohort study was conducted at Muhimbili University of Health and Allied Sciences Academic Medical Center (MAMC), medical wards in Dar es Salaam, Tanzania. MAMC is a tertiary teaching hospital that offers super specialized medical care to all specialties and receives referral patients from both public and private hospitals from all over the country.
We recruited consecutive participants who were admitted at MAMC with a clinical diagnosis of first ever stroke as classified by the World Health Organization (WHO) (15) between June 2018 to January 2019. Participants were eligible for enrollment if they were aged between 18 to 45 years. Written informed consent was obtained from either the participants or their next of kin if the participant was unable to consent prior to study enrollment.
Data collection:
An interviewer based structured questionnaire was administered to all study participants or their caregivers capturing the following: sociodemographic information, mobile numbers, premorbid stroke risk factors (e.g. hypertension, diabetes mellitus (DM), smoking, alcohol consumption and HIV infection). Medication history for hypertension, diabetes and HIV was also obtained.
Physical examination included measurement of blood pressure (BP) using a standard digital BP machine, AD Medical Inc. Three BP readings were collected spaced 5 minutes apart, while the participant was at rest and an average BP was computed. Hypertension was defined as a systolic blood pressure (SBP) ≥140 mmHg or diastolic blood pressure (DBP) ≥90 mmHg or those on current anti-hypertensive therapy according to the Joint National Committee 7 (JNC-7) definition (16). All participants had their waist and hip circumference measured using a tape measure and recorded in centimeters. The waist-hip ratio was interpreted according to the WHO guidelines; in males the ratio of ≥0.90 and females ≥0.85 was regarded as substantially increased (17).
Capillary fingertip blood samples were collected to check for random blood glucose (RBG) levels and HIV rapid testing using a glucometer GLUCOPLUSTM and SD Bioline respectively. A fasting blood glucose (FBG) sample was collected the following morning for participants with (RBG) levels of ≥11.1 mmol/l. DM diagnosis was defined as a RBG reading of ≥ 11.1 mmol/l or a FBG reading of ≥ 7 mmol/l. For participants who were HIV reactive to SD Bioline, were tested also using Unigold Biotech.
We aseptically collected 5mls of venous blood from each study participant and analyzed for random total cholesterol and low-density lipoprotein using BIO- SYSTEMS machine.
A non-contrast brain computed tomography scan (NCCT) using GE Healthcare Optima or magnetic resonance imaging (MRI) with GE SIGNA CREATOR were performed on study participants on admission and images interpreted by a senior radiologist.
TTE using GE Medical Systems was performed and interpreted by a qualified cardiologist. Evidence of LVH was defined according to the European Society of Cardiology/American Society of Echocardiography as a measure of severity of septal thickness in 4 chamber view at mid-septum in the end of diastole (18). A mid septal diameter of 11 – 13mm in males and 10 – 12 mm in females was defined as mild LVH, 14 – 16 mm in males and 13 – 15 mm in females as moderate LVH and ≥17 mm in males and ≥16 mm in females as severe LVH (19).
An ECG using Bionet model Cardio7 machine was performed on the study participants to look for evidence of LVH using the Sokolow-Lyon and Cornell criteria defined as S in V1 plus R in V5 or V6 required to surpass 3.5 mV (20), and the S in V3 plus R in aVL required to surpass 2.0 mV in females and 2.8 mV in males (21) respectively. Atrial fibrillation was defined as the presence of irregular RR intervals and no discernible distinct P waves (22).
Stroke severity was assessed using the National institute of health stroke scale (NIHSS) (15) and outcomes were assessed using the modified Rankin Scale (mRS) (15) at 24 hours, 72 hours, 7 days, 14 days and at 30 days from admission. Functional independence was defined as mRS score of 0-2.
Data analysis:
Data was analyzed using SPSS version 20.0. Continuous variables were summarized and presented as means and standard deviation (SD). Categorical variables were summarized as frequencies and proportions. Comparison between proportions were done using Pearson’s Chi square test or Fisher’s exact test. The outcome variable (LVH) was common, hence we used the modified Poisson regression to determine factors that were independently associated with LVH. All covariates with a p-value of <0.2 in bivariable analysis were included in the multivariable analysis model. Unadjusted and adjusted risk ratios (RR), 95% confidence intervals (CI) and corresponding p values were obtained from the models. A two-tailed significance level was set as a p value of < 0.05. Receiver operator characteristics (ROC) analysis was performed to estimate the performance of the electrical voltage criterions (Sokolow-Lyon and Cornell criterion) to the gold standard TTE in detecting LVH.