Background: Despite criticism of self-reported alcohol intake, it is a valuable tool to screen for alcohol abuse as a risk factor for cardiovascular disease. We aimed to compare various self-reported estimates of alcohol use with γ-glutamyltransferase (GGT) and percentage carbohydrate deficient transferrin (%CDT) considering their relationship with blood pressure changes (%BP) over a 5-year period in black South Africans.
Method: We recruited 1994 participants and collected 5-year followed up data (N = 1246). Participants completed questionnaires on alcohol intake indicating their former and current alcohol use (‘yes’ response and ‘no’ if alcohol was never used). We assessed alcohol intake (in g) using a quantified food frequency questionnaire. We collected blood samples and measured GGT and %CDT. Brachial BP (bBP) was measured at baseline and follow-up and central BP (cBP) at follow-up only.
Results: Self-reported alcohol intake was significantly associated with the 5-year change in bBP before and after adjusting for confounders (%bSBP: R2 = 0.263, β = 0.06, P = 0.023; %bDBP: R2 = 0.326, β = 0.08 P = 0.005), as well as cSBP (R2 = 0.286, β = 0.09, P = 0.010) and central pulse pressure (R2 = 0.254, β = 0.06, P = 0.020). GGT and %CDT correlated well with self-reported alcohol intake (r = 0.44; P = 0.001; r = 0.34 P = 0.001), but did not associate significantly with %bBP or cBP at follow-up.
Conclusion: Self-reported alcohol use was strongly associated with a 5-year increase in BP in Africans with a low socio-economic status. This was not found for biochemical measures, GGT and %CDT. Self-reported alcohol intake could be an important measure to implement in primary healthcare settings in middle to low income countries, where honest reporting is expected.
aHypertension in Africa Research Team (HART)
bCentre of Excellence for Nutrition
cAfrica Unit for Transdisciplinary Health Research (AUTHeR), North-West University, Potchefstroom
dDepartment of Physiology, University of Limpopo (Medunsa), Pretoria, South Africa
Correspondence to Aletta E. Schutte, Hypertension in Africa Research Team (HART), North-West University, Private Bag X6001, Potchefstroom 2520, South Africa. Tel: +27 18 299 2444; fax: +27 18 299 1053; e-mail: Alta.Schutte@nwu.ac.za
Abbreviations: %CDT, percentage carbohydrate deficient transferrin; %DBP, percentage change in DBP; %SBP, percentage change in SBP; ALT, alanine aminotransferase; AST, aspartate aminotransferase; BP, blood pressure; cPP, central pulse pressure; CRP, C-reactive protein; cSBP, central SBP; CVD, cardiovascular disease; GGT, γ-glutamyltransferase; HbA1C, glycosylated haemoglobin; HDL-C, high-density lipoprotein cholesterol; PURE study, Prospective Urban and Rural Epidemiology study; TC, total cholesterol
Received 21 June, 2013
Accepted 27 November, 2013
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