Derivation of a tuberculosis screening rule for sub-Saharan African prisons.

SETTING: Lusaka Central Prison, Zambia. OBJECTIVE: To derive screening rules for tuberculosis (TB) using data collected during a prison-wide TB and human immunodeficiency virus (HIV) screening program. DESIGN: We derived rules with two methodologies: logistic regression and classification and regression trees (C&RT). We evaluated the performance of the derived rules as well as existing World Health Organization (WHO) screening recommendations in our cohort of inmates, as measured by sensitivity, specificity, and positive and negative predictive values. RESULTS: The C&RT-derived rule recommended diagnostic testing of all inmates who were underweight (defined as body mass index [BMI] < 18.5 kg/m(2)] or HIV-infected; the C&RT-derived rule had 60% sensitivity and 71% specificity. The logistic regression-derived rule recommended diagnostic testing of inmates who were underweight, HIV-infected or had chest pain; the logistic regression-derived rule had 74% sensitivity and 57% specificity. Two of the WHO recommendations had sensitivities that were similar to our logistic regression rule but had poorer specificities, resulting in a greater testing burden. CONCLUSION: Low BMI and HIV infection were the most robust predictors of TB in our inmates; chest pain was additionally retained in one model. BMI and HIV should be further evaluated as the basis for TB screening rules for inmates, with modification as needed to improve the performance of the rules.

Relationships between metrics of visit-to-visit variability of blood pressure.

This paper examines relationships between metrics of visit-to-visit variability (VVV) of blood pressure (BP) to determine which metrics should be calculated in studies of the association of VVV with health outcomes. We examined correlation and agreement between quintiles for standard deviation (s.d.), standard deviation independent of the mean (SDIM), coefficient of variation (CV), successive variation (SV), average real variability (ARV), range, maximum, peak size and trough size of systolic BP in the Trial of Preventing Hypertension placebo arm (n=288). The average age of participants was 48 years. Mean systolic BP was 133.5 mm Hg. VVV metrics were all significantly correlated (P<0.001). Correlations between s.d., SDIM, CV and range and between ARV and SV were ≥0.90. Kappa statistics between quintiles of SD, SDIM, CV and range and between ARV and SV were ≥0.80. In studies of the relationship of VVV with health outcomes, we recommend reporting results for one of the metrics of overall variability (s.d., SDIM, CV), one of the metrics of variability between consecutive visits (SV, ARV), and one or more of the metrics of extreme values at a single visit (maximum, peak size, trough size).

The effect of rest days on injury rates.

Despite the importance of recuperation, few have studied the impact of rest periods on injury prevention. We determined the effect of rest days (breaks) on injury rates and treatments using electronic injury records from an acrobatic circus company that employs former world-class athletes as acrobats. To account for accumulated fatigue, we considered breaks across SD3 (third consecutive week of 1-day rest) to SD6 as a single exposure level (SD3-6), and vacation and DD (2-day rest) as a single exposure level. Medical attention injury rates were increased post- vs pre-break {rate ratio 1.45 [95% confidence intervals (95% CI): 1.22-1.73]} with less of an effect for 1-day time loss [1.25 (95% CI: 0.58-2.67)] and 15-day time loss [1.10 (95% CI: 0.26-4.56)]. However, the increase in injury rate post break for SD3-6 was similar to that of DD-Vacation (P=0.48, 0.53, and 0.65) for medical attention, and both ≥1 day and ≥15 days time loss, respectively. The increase in the number of treatments post-break was less for SD3-6 vs DD-vacation. Our findings suggest that 2-day breaks every four to 6 weeks may be sufficient to avoid an increasing injury rate due to cumulative fatigue in professional acrobatic circus artists.

Fatty fish, marine omega-3 fatty acids and incidence of heart failure.

BACKGROUND/OBJECTIVES: Marine omega-3 fatty acids have beneficial effects on cardiovascular risk factors. Consumption of fatty fish and marine omega-3 has been associated with lower rates of cardiovascular diseases. We examined the association of fatty fish and marine omega-3 with heart failure (HF) in a population of middle-aged and older women. SUBJECTS/METHODS: Participants in the Swedish Mammography Cohort aged 48-83 years completed 96-item food-frequency questionnaires. Women without any history of HF, myocardial infarction or diabetes at baseline (n=36,234) were followed from 1 January 1998 until 31 December 2006 for HF hospitalization or mortality through Swedish inpatient and cause-of-death registers; 651 women experienced HF events. Cox proportional hazards models accounting for age and other confounders were used to calculate incidence rate ratios (RR) and 95% confidence intervals (CI). RESULTS: Compared with women who did not eat fatty fish, RR were 0.86 (95% CI: 0.67, 1.10) for <1 serving per week, 0.80 (95% CI: 0.63, 1.01) for 1 serving per week, 0.70 (95% CI: 0.53, 0.94) for 2 servings per week and 0.91 (95% CI: 0.59, 1.40) for >or=3 servings per week (P(trend)=0.049). RR across quintiles of marine omega-3 fatty acids were 1 (reference), 0.85 (95% CI: 0.67, 1.07), 0.79 (95% CI: 0.61, 1.02), 0.83 (95% CI 0.65, 1.06) and 0.75 (95% CI: 0.58, 0.96) (P(trend)=0.04). CONCLUSION: Moderate consumption of fatty fish (1-2 servings per week) and marine omega-3 fatty acids were associated with a lower rate of first HF hospitalization or death in this population.

Dietary glycemic index, dietary glycemic load and mortality among men with established cardiovascular disease.

BACKGROUND/OBJECTIVES: In men with established cardiovascular disease, the effect of diets with high glycemic index (GI) and glycemic load (GL) is unknown. We tested the hypothesis that diets with higher GI and GL are associated with increased mortality in men with established cardiovascular disease. SUBJECTS/METHODS: We measured dietary GI and GL using food-frequency questionnaires in 4617 men, 45-79 years old, with a history of cardiovascular disease. The men were followed for cardiovascular mortality (6-year follow-up, 608 cases) and all-cause mortality (8-year follow-up, 1303 cases) using the Swedish cause-of-death and death registers. We used Cox models with age as the timescale and adjusted for body mass index, physical activity, history of hypertension and diabetes, family history of myocardial infarction, aspirin use, cigarette smoking and dietary factors to estimate incidence rate ratios (RRs). RESULTS: Comparing top to bottom quartiles of dietary GI, the RR for cardiovascular mortality was 0.86 (95% confidence interval (CI) 0.67-1.10, P for linear trend=0.21), and the RR for all-cause mortality was 1.00 (95% CI 0.85-1.19, P for linear trend=0.87). Compared to quartile 1, the RR for men with dietary GL in quartile 4 was 1.02 (95% CI 0.70-1.49, P for linear trend=0.81) for cardiovascular and 1.15 (95% CI 0.89-1.49, P for linear trend=0.20) for all-cause mortality. CONCLUSIONS: In this population of men with prior cardiovascular disease, dietary GI and GL were not associated with cardiovascular or all-cause mortality.

Maternal smoking during pregnancy and child overweight: systematic review and meta-analysis.

OBJECTIVE: Perform a systematic review of studies reporting on the association between maternal prenatal cigarette smoking and child overweight. DESIGN: Meta-analysis of observational studies. DATA SOURCES: Medline search and review of reference lists among studies published through June 2006. REVIEW METHODS: Included studies reported an association between maternal smoking during pregnancy and risk of overweight among children at least 2 years of age. We did not include in the meta-analysis studies that provided only a continuous measure of adiposity, although those studies are discussed separately. RESULTS: Based on results of 84 563 children reported in 14 observational studies, children whose mothers smoked during pregnancy were at elevated risk for overweight (pooled adjusted odds ratio (OR) 1.50, 95% CI: 1.36, 1.65) at ages 3-33 years, compared with children whose mothers did not smoke during pregnancy. The pooled estimate from unadjusted odds ratios (OR 1.52, 95% CI: 1.36, 1.69) was similar to the adjusted estimate, suggesting that sociodemographic and behavioral differences between smokers and nonsmokers did not explain the observed association. Although we observed evidence for publication bias, simulating a symmetric set of studies yielded a similar estimate (OR 1.40, 95% CI: 1.26, 1.55). CONCLUSIONS: Prenatal smoking exposure appears to increase rates of overweight in childhood. In parts of the world undergoing the epidemiologic transition, the continuing increase in smoking among young women could contribute to spiraling increases in rates of obesity-related health outcomes in the 21st century.

HbA1c measured in stored erythrocytes and mortality rate among middle-aged and older women.

AIMS/HYPOTHESIS: Diabetes is known to increase mortality rate, but the degree to which mild hyperglycaemia may be associated with the risk of death is uncertain. We examined the association between HbA1c measured in stored erythrocytes and mortality rate in women with and without diabetes. METHODS: We conducted a cohort study of 27,210 women>or=45 years old with no history of cardiovascular disease or cancer who participated in the Women's Health Study, a randomised trial of vitamin E and aspirin. RESULTS: Over a median of 10 years of follow-up, 706 women died. Proportional hazards models adjusted for age, smoking, hypertension, blood lipids, exercise, postmenopausal hormone use, multivitamin use and C-reactive protein were used to estimate the relative risk of mortality. Among women without a diagnosis of diabetes and HbA1c<5.60%, those in the top quintile (HbA1c 5.19-5.59%) had a relative risk of mortality of 1.28 (95% CI 0.98-1.69, p value for linear trend=0.14) compared with those with HbA1c 2.27-4.79%. Women with HbA1c 5.60-5.99% and no diagnosis of diabetes had a 54% increased risk of mortality (95% CI 1-136%) compared with those with HbA1c 2.27-4.79%. HbA1c was significantly associated with mortality across the range 4.50-7.00% (p value for linear trend=0.02); a test of deviation from linearity was not statistically significant (p=0.67). Diabetic women had more than twice the mortality risk of non-diabetic women. CONCLUSIONS/INTERPRETATION: This study provides further evidence that chronic mild hyperglycaemia, even in the absence of diagnosed diabetes, is associated with increased risk of mortality. ClinicalTrials.gov ID no.: NCT00000479.

Effects of oral magnesium supplementation on glycaemic control in Type 2 diabetes: a meta-analysis of randomized double-blind controlled trials.

AIMS: The aim of this study was to assess the evidence on the effect of oral magnesium supplementation on glycaemic control in patients with Type 2 diabetes. METHODS: We searched the electronic databases of medline, embase and the Cochrane Controlled Trials Register up to January 2005. We identified nine randomized double-blind controlled trials with a total of 370 patients with Type 2 diabetes and of duration 4-16 weeks. The median dose of oral magnesium supplementation was 15 mmol/day (360 mg/day) in the treatment groups. The primary outcome was glycaemic control, as measured by glycated haemoglobin (HbA(1c)) or fasting blood glucose levels; the secondary outcomes included body mass index, blood pressure (BP) and lipids. Using a random-effects model, we calculated the weighted mean differences (WMD) and 95% confidence interval (CI). RESULTS: After a median duration of 12 weeks, the weighted mean post-intervention fasting glucose was significantly lower in the treatment groups compared with the placebo groups [-0.56 mmol/l (95% CI, -1.10 to -0.01); P for heterogeneity = 0.02]. The difference in post-intervention HbA(1c) between magnesium supplementation groups and control groups was not significant [-0.31% (95% CI, -0.81 to 0.19); P for heterogeneity = 0.10]. Neither systolic nor diastolic BP was significantly changed. Magnesium supplementation increased on high-density lipoprotein (HDL) cholesterol levels [0.08 mmol/l (95% CI, 0.03 to 0.14); P for heterogeneity = 0.36] but had no effect on total cholesterol, low-density lipoprotein (LDL) cholesterol and triglyceride. CONCLUSIONS: Oral magnesium supplementation for 4-16 weeks may be effective in reducing plasma fasting glucose levels and raising HDL cholesterol in patients with Type 2 diabetes, although the long-term benefits and safety of magnesium treatment on glycaemic control remain to be determined.