Prognostic factors for atherosclerosis progression in saphenous vein grafts: the postcoronary artery bypass graft (Post-CABG) trial. Post-CABG Trial Investigators

OBJECTIVES: The study was done to assess patients in the Post-Coronary Artery Bypass Graft (Post-CABG) trial to determine prognostic factors for atherosclerosis progression. BACKGROUND: Saphenous vein grafts (SVGs) are effective in relieving angina and, in certain patient subsets, in prolonging life. However, the progression of atherosclerosis in many of these grafts limits their usefulness. METHODS: The Post-CABG trial studied moderate versus aggressive lipid-lowering and low-dose warfarin versus placebo in patients with a history of coronary artery bypass surgery and found that more aggressive lipid lowering was effective in preventing progression of atherosclerosis in SVGs, but warfarin had no effect. Using variables measured at baseline, we sought the independent prognostic factors for atherosclerosis progression in SVGs, employing the statistical method of generalized estimating equations with a logit-link function. RESULTS: Twelve independent prognostic factors for atherosclerosis progression were found. In the order of their importance they were: maximum stenosis of the graft at baseline angiography, years post-SVG placement; the moderate low-density lipoprotein-cholesterol (LDL-C) lowering strategy; prior myocardial infarction; high triglyceride level; small minimum graft diameter; low high-density lipoprotein-cholesterol (HDL-C); high LDL-C; high mean arterial pressure; low ejection fraction; male gender; and current smoking. CONCLUSIONS: This study identified Post-CABG patient and SVG characteristics associated with saphenous vein graft atherosclerosis progression. These data provide a basis for rational risk factor management to prevent progression of SVG atherosclerosis.     

Using lowess to remove systematic trends over time in predictor variables prior to logistic regression with quantile categories

In case-control studies one may employ logistic regression to model the relationship between binary responses and continuous predictor variables that have been categorized by the empirical quartiles of the controls. Sometimes, however, systematic trends over time (or drifts) contaminate the laboratory measurements of predictor variables. In this paper we consider the use of locally weighted robust regression (lowess) to estimate and remove these systematic trends when the trends for the cases and controls have a common shape. One can then use the lowess adjusted data in the desired logistic regression model. We illustrate these methods with a case-control study that was designed to assess the risk of oesophageal cancer as a function of the quartile categories of sphinganine levels in the blood serum. Upon examination of the data, it was discovered that the sphinganine laboratory measurements were contaminated by a systematic trend, the magnitude of which depended only on the day of analysis. This trend needed to be removed before performing further analyses of the data. In addition, we present simulations to examine the use of lowess methods to estimate and remove various shapes of trends from contaminated predictor data before constructing logistic regression models with quartile categories. We found that using the trend-contaminated data tends to give attenuated parameter estimates and hence lower significance and power levels than using the uncontaminated data. Conversely, using appropriate lowess methods to adjust the data tends to give nearly unbiased parameter estimates, near nominal significance levels, and improved power.     

A cross-sectional study of human serum sphingolipids, diet and physiologic parameters

Sphinganine and sphingosine, the two sphingoid base backbones of sphingolipids, are highly bioactive compounds that are of increasing interest to nutritionists because they occur in food and their metabolism can be altered by fungal toxins that contaminate some foods. Nonetheless, no studies of diet and sphinganine or sphingosine concentrations in serum have yet been reported. Here we describe a cross-sectional study of 265 residents of Linxian, People's Republic of China, which examines potential demographic, physiologic and dietary correlates of serum sphinganine and sphingosine in this population. Median concentrations of serum sphinganine and sphingosine were compared among strata for 29 different variables. For sphinganine, no significant differences were found. For sphingosine, significant differences were seen among strata of age, menstruation status, serum cholesterol, carotenoids, retinol, tocopherols, fresh and dried vegetable and fresh fruit consumption. Using multivariate linear regression with stepwise selection, we found that the significant predictors for serum sphingosine included total tocopherols, age, serum selenium and retinol, with a final R(2) = 0.22; for sphinganine, tooth loss was the sole correlate, with R(2) = 0.015. Analyses using ranked sphingolipid data or principal components analysis, to simplify the food variables, did not materially alter these results. This study represents the largest report of human serum sphingolipid concentrations to date and provides insight into potential explanatory variables that can be incorporated into future studies.     

Sexual Risk Behaviors among African-American and Hispanic Women in Five Counties in the Southeastern United States: 2008–2009

PurposeWe examined sexual risk behaviors and unrecognized HIV infection among heterosexually active African-American and Hispanic women.MethodsWomen not previously diagnosed with HIV infection were recruited in rural counties in North Carolina (African American) and Alabama (African American), and an urban county in southern Florida (Hispanic) using multiple methods. They completed a computer-administered questionnaire and were tested for HIV infection.ResultsBetween October 2008 and September 2009, 1,527 women (1,013 African American and 514 Hispanic) enrolled in the study. Median age was 35 years (range, 18–59), 33% were married or living as married, 50% had an annual household income of $12,000 or less, and 56% were employed full or part time. Two women (0.13%) tested positive for HIV. In the past 12 months, 19% had been diagnosed with a sexually transmitted infection (other than HIV), 87% engaged in unprotected vaginal intercourse (UVI), and 26% engaged in unprotected anal intercourse (UAI). In multivariate analysis, UAI was significantly (p < .05) more likely among those who reported ever being pregnant, binge drinking in the past 30 days, ever exchanging sex for things needed or wanted, engaging in UVI, or being of Hispanic ethnicity. UAI was also more likely to occur with partners with whom women had a current or past relationship as opposed to casual partners.ConclusionA high percentage of our sample of heterosexually active women of color had recently engaged in sexual risk behaviors, particularly UAI. More research is needed to elucidate the interpersonal dynamics that may promote this high-risk behavior. Educational messages that explicitly address the risks of heterosexual anal intercourse need to be developed for heterosexually active women and their male partners.     

Relationship between neonatal birth weight and maternal plasma amino acid profiles in lean and obese nondiabetic women and in type I diabetic pregnant women

Profiles of hemoglobin A1c (HbA1c) and concentrations of plasma glucose and 18 plasma amino acids were obtained in ten nonobese, insulin-dependent type I diabetic women, in 9 age- and weight-matched normal women and in ten obese nondiabetic women throughout pregnancy and postpartum. In late gestation, the period of maximum fetal growth, average HbA1c, plasma glucose, and total amino acid concentrations in diabetic mothers were significantly elevated above lean control values. No differences existed between the obese and lean control groups. Lean diabetic mothers also had significantly heavier babies (mean +/- SEM) relative to the 50th percentile for gestational age and sex (119 +/- 9%) than did the lean control group (94 +/- 3%, P less than .05). Relative birth weights among control lean and obese mothers did not differ significantly (94 +/- 3% v 104 +/- 5%). Late pregnancy profiles of HbA1c and average plasma glucose did not correlate with relative weight of neonates whereas average total plasma amino acids and six individual amino acids did correlate with this parameter. These data suggest that maternal plasma amino acid concentrations may influence fetal weight generally and may have an important role in the development of fetal macrosomia in diabetic pregnancies.     

Pilot Evaluation of the Ability of Men Who Have Sex with Men to Self-Administer Rapid HIV Tests,Prepare Dried Blood Spot Cards,and Interpret Test Results,Atlanta, Georgia, 2013

In the United States, an estimated 67% of new HIV diagnoses are among men who have sex with men (MSM), however 25% of HIV-positive MSM in the 2014 National HIV Behavioral Surveillance Survey were unaware of their infection. HIV self-testing (HIVST) with rapid diagnostic tests (RDTs) may facilitate access to HIV testing. We evaluated the ability of 22 MSM to conduct two HIV RDTs (OraQuick ^® In-Home HIV Test and a home-use prototype of Sure Check ^® HIV 1/2 Assay), interpret sample images of test results, and collect a dried blood spot (DBS) specimen. While some participants did not follow every direction, most participants were able to conduct HIVST and correctly interpret their results. Interpretation of panels of RDT images was especially difficult when the “control” line was missing, and 27% of DBS cards produced were rated as of bad quality. Modifications to the DBS instructions were necessary prior to evaluating the performance of these tests in real-world settings.     

The effect of a perinatal center on perinatal mortality.

The evolution of a perinatal center over the past 12 years was reviewed. Factors in obstetric practices, maternal morbidity, and perinatal mortality were evaluated. The reduction in conditions leading to uteroplacental insufficiency (toxemia, hypertension, high parity) has been the most significant result. This in turn has led to a decrease in deaths from abruption, asphyxia, and respiratory distress syndrome (RDS). The practice of referring high-risk mothers to a perinatal center for delivery can continue to reduce perinatal mortality significantly.     

Chronic-persistent hepatitis and pregnancy.

The course and possible risks of pregnancy in 7 women between the ages of 20 and 30 yr with chronic-persistent hepatitis (CPH) were evaluated. Ten pregnancies occurred in these women during the follow-up period which ranged from 3 to 8 yr. Four of the fetuses were aborted electively for nonmedical reasons. The other six pregnancies resulted in normal spontaneous vaginal deliveries at term. Each of the women experienced uneventful pre- and postnatal courses, and the neonates were all healthy and developmentally normal at birth. There was no biochemical or clinical evidence to suggest worsening liver disease during pregnancy. Normal menstrual patterns when not pregnant and normal biphasic basal body temperature patterns in 4 women suggested that ovulation and fertility were not impaired significantly. Pregnancy in women with CPH appears safe to both mother and fetus alike. This finding contrasts with the morbidity and mortality some authors have found to be associated with cirrhosis and with portal hypertension. We speculate that our findings may be relevant to women with other portal lesions resembling CPH such as resolving acute hepatitis and chronic active hepatitis in sustained remission.