For this longitudinal study, observational study, prospective participants were recruited through the kidney transplant programme for HIV-infected patients at Groote Schuur Hospital, Cape Town. Participants were recruited based on whether they were transplant recipients or transplant candidates awaiting a transplant and hence managed on dialysis. From the outset they were therefore categorised as: (i) HIV-infected kidney transplant recipients who have received a kidney from a HIV-infected donor and (ii) HIV-infected transplant candidates on the waiting list to receive a kidney from a HIV-infected donor. Prospective participants were contacted telephonically or at their respective outpatient clinics and invited to participate in the study which ran from May 2015 to June 2016. Participants were included if they were clinically stable at the time of recruitment. Participants were excluded if they declined participation, were severely ill, were not contactable, uncooperative or had missed several interview appointments (typically two or more without reason). In total, seventy six patients agreed to participate, from whom written informed consent was obtained. The study was approved by The University of KwaZulu-Natal’s Biomedical Research Ethics Committee (Approval number BE 327/13).
6.2.2 Socio-demographic and clinical information
Socio-demographic information was collected using an interviewer-administered structured questionnaire, developed for the purpose of the study. Clinical information was obtained from medical records or during participant interviews. The socio-demographic questionnaire was reviewed by researchers experienced in questionnaire design, and then pilot tested for comprehension.
125 6.2.3 Anthropometry
Dietitians were recruited to take anthropometric measurements due to their training and experience in this area. In addition, all dietitians received a brief refresher training session which was followed by a post-training test. To ensure uniformity and appropriate standards of training, both the training and the test were accredited for continuing professional development (CPD) purposes with the Health Professions Council of South Africa (HPCSA). All body measurements namely weight (WT), height (Ht) and waist circumference (WC) were taken using protocols described in the National Health and Nutrition Examination Survey (NHANES) anthropometry procedure manual (24). Height in centimetres (cm) and weight in kilograms (kg) were obtained using equipment present at various outpatient and dialysis centres. Weights measurements of dialysis patients were taken post-dialysis (dry weight). WC (cm) was measured using standardised measuring tapes (SECA 201, Germany). A mean of three readings were recorded. BMI and WC were used as measures of overall and central adiposity respectively. BMI was calculated as WT divided by Ht squared (kg/m2) and classified according to the World Health Organization categories: Underweight (<18.5), normal (18.5 – 24.9), overweight (≥ 25.0-29.9), obese class I (30.0-34.9), obese class II (35.0-39.9) and obese class III (≥ 40) (1). WC cut-offs used, were WC ≥ 88cm for women and ≥ 102cm for men that indicated a substantially increased risk for metabolic complications (25).
6.2.4 Biochemical metabolic parameters
Participants had their blood samples tested through the National Health Laboratory Services (NHLS) or through any one of three private laboratories across the six provinces. The choice of laboratory was based on their proximity to the laboratory to their place of work or place of residence, whether they were state or private patients or whether the laboratory was their usual laboratory service provider. Serum glucose and lipids were measured in the morning after an overnight fast. Serum total cholesterol (TC) and glucose were determined enzymatically using cholesterol oxidase and glucose hexokinase respectively. Triglycerides (TG), high-density lipoprotein cholesterol (HDL), and low-density lipoprotein cholesterol (LDL) were determined using the enzymatic colour test on Beckman Coulter analysers. Serum albumin was measured using the bromocresol green colour reaction method, with a cut-off of < 38g/l set as a criterion for hypoalbuminaemia (26)
126 6.2.5 The metabolic syndrome
The presence of MetS was based on a recent consensus definition of MetS that encompasses the MetS definitions of the International Diabetes Federation (IDF), American Heart Association (AHA) and the National Heart, Lung and Blood Institute (NHLBI) (13). Using this definition, MetS is diagnosed as the presence of any three of five given criteria listed in Table 6.1. It should be noted that the WC used in this MetS definition differs from the general WC cut-offs (paragraph 6.2.3).
Table 6.1: Consensus definition of the metabolic syndrome
Metabolic Syndrome Criteria Raised WC using ethnic specific cut-offs a, b
Triglycerides ≥ 1.7 mmol/l
HDL-Cholesterol < 1.03 mmol/l for males and < 1.29 mmol/l for females Blood pressure ≥ 130/85mm/Hg
Fasting plasma glucose ≥ 5.6 mmol/l
a WC ≥ 94cm for males or ≥ 80cm for females, based on European data in the absence of suitable WC cut-offs for African ethnic groups.
b In the absence of a WC measurement, BMI > 30kg/m2 assumed the presence of central obesity (27) Participants also met the criteria if they were receiving medication to manage hypertension, diabetes or were on treatment for lipid abnormalities (27)
6.2.6 Dietary intake
Macronutrient intake was obtained from a single quantified 24-hour recall. These were administered by registered dietitians with experience in recording of dietary intake data.
Additional training was provided to ensure the use of standardized protocols during the dietary interview technique such as the use of similar probing questions to minimise interviewer bias.
(28). Portion size estimation was improved through the use of household measuring utensils and a food-portion booklet that referenced food portions against common household objects, applicable to the South African context (29). All dietary data was analysed using Foodfinder 3 for WindowsR (The South African Medical Research Council), and macronutrient content of the diet was compared to the recommendations of the renal nutrition guidelines for South Africans (30).
127 6.2.7 Statistics
Data was analysed using the Statistical package for Social Sciences (SPSS®) version 25.0.
Means and standard deviation were calculated for all continuous variables, while frequencies and percentages were calculated for categorical variables. A p value of <0.05 was taken as statistically significant.
Chi-square test of independence or Fisher’s exact test was used to test for differences in categorical variables between the two treatment groups. The means of groups were compared at baseline and 6 months using the independent samples t-test. The change in weight and WC from baseline to six months was calculated for all participants with both sets of weights, and expressed as a percentage. Paired samples t-test was used to determine whether the changes in weight between the two assessment points differed significantly. Pearson’s correlation coefficients were used to calculate the strength of the associations between macronutrients, weight and WC.