Naomi S. Levitt

Development and validation of a short questionnaire to assess sodium intake

OBJECTIVES To develop and validate a short food-frequency questionnaire to assess habitual dietary salt intake in South Africans and to allow classification of individuals according to intakes above or below the maximum recommended intake of 6 g salt day-1. DESIGN Cross-sectional validation study in 324 conveniently sampled men and women. METHODS Repeated 24-hour urinary Na values and 24-hour dietary recalls were obtained on three occasions. Food items consumed by >5% of the sample and which contributed > or =50 mg Na serving-1 were included in the questionnaire in 42 categories. A scoring system was devised, based on Na content of one index food per category and frequency of consumption. RESULTS Positive correlations were found between Na content of 35 of the 42 food categories in the questionnaire and total Na intake, calculated from 24-hour recall data. Total Na content of the questionnaire was associated with Na estimations from 24-hour recall data (r = 0.750; P < 0.0001; n = 328) and urinary Na (r = 0.152; P = 0.0105; n = 284). Urinary Na was higher for subjects in tertile 3 than tertile 1 of questionnaire Na content (P < 0.05). Questionnaire Na content of <2400 and > or =2400 mg day-1 equated to a reference cut-off score of 48 and corresponded to mean (standard deviation) urinary Na values of 145 (68) and 176 (99) mmol day-1, respectively (P < 0.05). Sensitivity and specificity against urinary Na > or =100 and <100 mmol day-1 was 12.4% and 93.9%, respectively. CONCLUSION A 42-item food-frequency questionnaire has been shown to have content-, construct- and criterion-related validity, as well as internal consistency, with regard to categorising individuals according to their habitual salt intake; however, the devised scoring system needs to show improved sensitivity.

A food-based dietary strategy lowers blood pressure in a low socio-economic setting: a randomised study in South Africa

OBJECTIVE To assess the impact of a food-based intervention on blood pressure (BP) in free-living South African men and women aged 50-75 years, with drug-treated mild-to-moderate hypertension. METHODS A double-blind controlled trial was undertaken in eighty drug-treated mild-to-moderate hypertensive subjects randomised to an intervention (n 40) or control (n 40) arm. The intervention was 8-week provision of six food items with a modified cation content (salt replacement (SOLO ), bread, margarine, stock cubes, soup mix and a flavour enhancer) and 500 ml of maas (fermented milk)/d. The control diet provided the same quantities of the targeted foods but of standard commercial composition and 500 ml/d of artificially sweetened cooldrink. FINDINGS The intervention effect estimated as the contrast of the within-diet group changes in BP from baseline to post-intervention was a significant reduction of 6.2 mmHg (95 % CI 0.9, 11.4) for systolic BP. The largest intervention effect in 24 h BP was for wake systolic BP with a reduction of 5.1 mmHg (95 % CI 0.4, 9.9). For wake diastolic BP the reduction was 2.7 mmHg (95 % CI -0.2, 5.6). CONCLUSIONS Modification of the cation content of a limited number of commonly consumed foods lowers BP by a clinically significant magnitude in treated South African hypertensive patients of low socio-economic status. The magnitude of BP reduction provides motivation for a public health strategy that could be adopted through lobbying of the food industry by consumer and health agencies.

Review of three tests of motor proficiency in children

The present purpose is to provide clinicians, occupational and physical therapists, and educators with a comparative analysis of three tests of motor proficiency. The Bruininks-Oseretsky Test of Motor Proficiency, Movement Assessment Battery for Children, and Tufts Assessment of Motor Performance were developed to assess the motor skills of children with developmental delays. The selection criteria, interrater reliability, reproducibility, and recommended use of each test are reported here. Recommendations for use of each test include standardization of the sample population to ensure its appropriateness.

G-protein-coupled receptor kinase 4 polymorphisms predict blood pressure response to dietary modification in Black patients with mild-to-moderate hypertension

Dopamine via G-protein-coupled receptor kinase 4 (GRK-4) regulates sodium (Na) balance in the proximal tubule of the kidney. Single-nucleotide polymorphisms of GRK-4 have been linked to impaired natriuresis and salt-sensitive hypertension. The purpose of this report was to determine the effect of GRK-4 gene polymorphisms on the blood pressure (BP) responses to dietary intervention. Black subjects aged 50–75 years with mild-to-moderate hypertension were randomised to an 8-week dietary intervention (n=40) or standard diet (n=40). BP was measured at baseline and at 8 weeks using 24-h ambulatory BP. All subjects underwent DNA analysis for the R65L and A142V polymorphisms. Data were analysed using generalised linear models. For the whole group, between-diet differences in mean 24-h ambulatory systolic BP was −4.53 mm Hg (95% confidence interval −9.05 to −0.01, P=0.05). In the intervention arm, the combined CC and CT group of the A142V showed a significant reduction in both systolic and diastolic ambulatory BP (−10 mm Hg, P=0.023 and −6.5 mm Hg, P=0.01, respectively), whereas the TT group demonstrated no reduction. Similarly, the combined GG and GT groups of the R65L showed a significant reduction in ambulatory BP (−10.6 mm Hg for systolic, P=0.004 and 5.8 mm Hg for diastolic, P=0.006). There was no response in the TT group. GRK-4 polymorphisms predict BP response to dietary modification in Black subjects with mild-to-moderate hypertension. These data may provide at least one among a range of clinical tools to target selected hypertensives to dietary intervention.

Blood pressure and social support observations from Mamre, South Africa, during social and political transition.

Objective: Social support, by moderating cardiovascular reactivity, has been demonstrated to attenuate the effects of stress on blood pressure in American communities. This is the first report to examine the relationship between social support and blood pressure in a South African context, during a period of infrastructure modernisation and political change.Methods: A total of 1240 residents (542 men, 698 women) of mixed ethnic origin, older than 14 years and stratified by age and sex, participated in a survey to determine risk factors for hypertension and cardiovascular diseases. Social support was assessed by a questionnaire developed in consultation with the community. It was defined by interactions that may threaten family harmony (score 1) and by networking between relatives, friends, colleagues and neighbours (score 2). Results: Mean blood pressure of the sample was 130/79 mm Hg (s.d. 25/14 mm Hg). Hypertension prevalence was 26.9%. Only 36% of women compared to 57.3% of men (P < 0.0001) were employed. more women (29%) than men (22%) reported threats to family harmony, but social support networks were similarly perceived by both sexes. systolic and diastolic blood pressure correlated weakly with score 1 (r = 0.096, P < 0.0007) but no association was observed with score 2. score 1 was not associated with blood pressure by multiple regression analysis, that included confounding by age, sex, bmi, alcohol consumption and smoking status. Conclusions: Neither threats to family harmony nor networking between relatives, friends or neighbours, significantly influences blood pressure in this community. Measures of social support thought to moderate blood pressure may have limited cross-cultural application. Attitudinal changes during socio-political transition may impact on the generalisability of instruments for measurement.

Smoking intervention programme in the Mamre community, South Africa

The Mamre community comprises 5000 working-class descendants of the inhabitants of a Moravian mission station 55 km north of Cape Town. A community-based tobacco control programme was initiated in response to a baseline survey in 1989 which found that 78% of the men and 48% of the women smoked tobacco. We have evaluated the impact on the prevalence of tobacco smoking and the community’s response to a demonstration prooject in 1996.