Association of Increasing the Minimum Wage in the US With Experiences of Maternal Stressful Life Events

Importance

Exposure to stressful life events (SLEs) before and during pregnancy is associated with adverse health for pregnant people and their children. Minimum wage policies have the potential to reduce exposure to SLEs among socioeconomically disadvantaged pregnant people.

Objective

To examine the association of increasing the minimum wage with experience of maternal SLEs.

Design, Setting, and Participants

This repeated cross-sectional study included 199 308 individuals who gave birth between January 1, 2004, and December 31, 2015, in 39 states that participated in at least 2 years of the Pregnancy Risk Assessment Monitoring Survey between 2004 and 2015. Statistical analysis was performed from September 1, 2022, to January 6, 2023.

Exposure

The mean minimum wage in the 2 years prior to the month and year of delivery in an individual's state of residence.

Main Outcomes and Measures

The main outcomes were number of financial, partner-related, traumatic, and total SLEs in the 12 months before delivery. Individual-level covariates included age, race and ethnicity, marital status, parity, educational level, and birth month. State-level covariates included unemployment, gross state product, uninsurance, poverty, state income supports, political affiliation of governor, and Medicaid eligibility levels. A 2-way fixed-effects analysis was conducted, adjusting for individual and state-level covariates and state-specific time trends.

Results

Of the 199 308 women (mean [SD] age at delivery, 25.7 [6.1] years) in the study, 1.4% were American Indian or Alaska Native, 2.5% were Asian or Pacific Islander, 27.2% were Hispanic, 17.6% were non-Hispanic Black, and 48.8% were non-Hispanic White. A $1 increase in the minimum wage was associated with a reduction in total SLEs (-0.060; 95% CI, -0.095 to -0.024), financial SLEs (-0.032; 95% CI, -0.056 to -0.007), and partner-related SLEs (-0.019; 95% CI, -0.036 to -0.003). When stratifying by race and ethnicity, minimum wage increases were associated with larger reductions in total SLEs for Hispanic women (-0.125; 95% CI, -0.242 to -0.009).

Conclusions and Relevance

In this repeated cross-sectional study of women with a high school education or less across 39 states, an increase in the state-level minimum wage was associated with reductions in experiences of maternal SLEs. Findings support the potential of increasing the minimum wage as a policy for improving maternal well-being among socioeconomically disadvantaged pregnant people. These findings have relevance for current policy debates regarding the minimum wage as a tool for improving population health.

Childhood Stunting and Wasting Following Independence in South Sudan

BACKGROUND

South Sudan has experienced ongoing civil and environmental problems since gaining independence in 2011 that may influence childhood nutritional status.

OBJECTIVE

To estimate the prevalence of undernutrition among children in South Sudan in 2018 and 2019 compared to the prevalence in 2010.

METHODS

Data on height and weight were collected using a 2-stage stratified sample framework in which households were randomly selected at the county level and nutritional status was calculated for all children under 5 years of age to determine height-for-age, weight-for-height, and weight-for-age Z-scores (HAZ, WHZ, and WAZ) and the prevalence of stunting, wasting, and underweight. Linear and logistic regression analyses were used to determine factors associated with nutritional status and the odds ratio for nutritional outcomes.

RESULTS

In 2010, the mean HAZ, WHZ, and WAZ was -0.78, -0.82, and -1.15, respectively, and the prevalence of stunting, wasting, and underweight was 30%, 23%, and 32%, respectively. In 2018 and 2019, the mean HAZ, WHZ, and WAZ was -0.50, -0.70, -0.77 and -0.53, -0.77, -0.76, respectively. The prevalence of stunting, wasting, and underweight in 2018 and 2019 was 17%, 14%, 15% and 16%, 16%, 17%, respectively. Age was negatively associated with all nutritional indices and girls had higher HAZ, WHZ, and WAZ and a lower mid upper arm circumference (P < .01) compared to boys. The risk of poor nutritional outcomes was associated with vaccine status and varied by state of residence.

CONCLUSIONS

Following independence in 2010, the prevalence of undernutrition in South Sudan decreased, but the risk for undernutrition varied by state and efforts to address food security and health need to ensure equitable access for all children in South Sudan.

Maternal depression and economic well-being: A quasi-experimental approach

Maternal depression is associated with adverse impacts on the health of women and their children. However, further evidence is needed on the extent to which maternal depression influences women's economic well-being and how unmeasured confounders affect estimates of this relationship. In this study, we aimed to measure the association between maternal depression and economic outcomes (income, employment, and material hardship) over a 15-year time horizon. We conducted longitudinal analyses using the Fragile Families and Child Wellbeing Study, an urban birth cohort study in the United States. We assessed the potential contribution of time-invariant unmeasured confounders using a quasi-experimental approach and also investigated the role of persistent versus transient depressive symptoms on economic outcomes up to 15 years after childbirth. In models that adjusted for time-invariant unmeasured confounders, maternal depression was associated with not being employed (an adjusted risk difference of 3 percentage points (95% CI 0.01 to 0.05)) and experiencing any material hardship (an adjusted risk difference of 14 percentage points (95% CI 0.12 to 0.16)), as well as with reductions in the ratio of household income to poverty by 0.10 units (95% CI -0.16 to -0.04) and annual household income by $2114 (95% CI -$3379 to -$850). Impacts at year 15 were strongest for those who experienced persistent depression. Results of our study strengthen the case for viewing mental health support services as interventions that may also foster economic well-being, and highlight the importance of including economic impacts in assessments of the cost-effectiveness of mental health interventions.

Characterization of HCV-infected people who inject drugs (PWID) in the setting of clinical care in Canada (CAPICA): A retrospective study

BACKGROUND: People who use drugs (PWUD) are among the highest risk category for becoming infected with the hepatitis C virus (HCV) in Canada. There is a need for more information on the demographics of HCV-infected PWUD/PWID who have recently injected drugs or who are actively injecting drugs. METHODS: CAPICA was a multicentre, retrospective database/chart review conducted from October 2015 to February 2016 that was designed to characterize HCV-infected people who inject drugs (PWID) and are enrolled in clinical care in Canada. The aim was to identify factors of health care engagement essential in the design systems of HCV care and treatment in this population. The study enrolled 420 patients with a history of injection drug use within the last 12 months who had been diagnosed with chronic viremic HCV infection and had been participants in an outpatient clinical care setting in the past 12 months. Patients who were co-infected with HIV/HCV were excluded. RESULTS: Harm reduction programs were in place at 92% (11/12) of the sites, and 75% (9) of these sites offered opioid agonist therapy (OAT), with 48% of the patients currently taking OAT. HCV genotype 1a was most prevalent (56%), followed by G3 (34%), and the most common fibrosis score was F1 (34%). The average reinfection rate was about 5%. Seventeen percent of the patients were undergoing HCV treatment or had recently failed therapy, while 83% were not being treated. CONCLUSIONS: In a multivariate analysis, the following factors were significantly associated with treatment: increasing age (OR 1.10), a fibrosis score of F4 (OR 4.91), moderate alcohol consumption (OR 3.70), and not using a needle exchange program (OR 6.95).

Testosterone concentrations and risk of cardiovascular events in androgen-deficient men with atherosclerotic cardiovascular disease

BACKGROUND

Whether androgen deficiency among men increases the risk of cardiovascular (CV) events or is merely a disease marker remains a subject of intense scientific interest.

OBJECTIVES

Among male subjects in the AIM-HIGH Trial with metabolic syndrome and low baseline levels of high-density lipoprotein (HDL)-cholesterol who were randomized to niacin or placebo plus simvastatin, we examined the relationship between low baseline testosterone (T) concentrations and subsequent CV outcomes during a mean 3-year follow-up.

METHODS

In this post hoc analysis of men with available baseline plasma T concentrations, we examined the relationship between clinical/demographic characteristics and T concentrations both as a continuous and dichotomous variable (<300 ng/dL ["low T"] vs. ≥300 ng/dL ["normal T"]) on rates of pre-specified CV outcomes, using Cox proportional hazards models.

RESULTS

Among 2118 male participants in whom T concentrations were measured, 643 (30%) had low T and 1475 had normal T concentrations at baseline. The low T group had higher rates of diabetes mellitus, hypertension, elevated body mass index, metabolic syndrome, higher blood glucose, hemoglobin A1c, and triglyceride levels, but lower levels of both low-density lipoprotein and HDL-cholesterol, and a lower rate of prior myocardial infarction (MI). Men with low T had a higher risk of the primary composite outcome of coronary heart disease (CHD) death, MI, stroke, hospitalization for acute coronary syndrome, or coronary or cerebral revascularization (20.1%) compared with the normal T group (15.2%); final adjusted HR 1.23, P = .07, and a higher risk of the CHD death, MI, and stroke composite endpoint (11.8% vs. 8.2%; final adjusted HR 1.37, P = .04), respectively.

CONCLUSIONS

In this post hoc analysis, there was an association between low baseline testosterone concentrations and increased risk of subsequent CV events in androgen-deficient men with established CV disease and metabolic syndrome, particularly for the composite secondary endpoint of CHD death, MI, and stroke.

CONDENSED ABSTRACT

In this AIM-HIGH Trial post hoc analysis of 2118 men with metabolic syndrome and low HDL-cholesterol with available baseline plasma testosterone (T) samples, 643 males (30%) had low T (mean: 229 ng/dL) and 1475 (70%) had normal T (mean: 444 ng/dL) concentrations. The "low T" group had a 24% higher risk of the primary 5-component endpoint (20.1%) compared with the normal T group (15.2%); final adjusted HR 1.23, P = .07). There was also a 31% higher risk of the secondary composite endpoint: coronary heart disease death, myocardial infarction, and stroke (11.8% vs. 8.2%, final adjusted HR 1.37, P = .04) in the low vs. normal T group, respectively.

Effects of Extended-Release Niacin on Quartile Lp-PLA2 Levels and Clinical Outcomes in Statin-treated Patients with Established Cardiovascular Disease and Low Baseline Levels of HDL-Cholesterol: Post Hoc Analysis of the AIM HIGH Trial

Background:

Lipoprotein-associated phospholipase A2 (LpPLA2) is an inflammatory marker that has been associated with the presence of vulnerable plaque and increased risk of cardiovascular (CV) events.

Objective:

To assess the effect of extended-release niacin (ERN) on Lp-PLA2 activity and clinical outcomes.

Methods:

We performed a post hoc analysis in 3196 AIM-HIGH patients with established CV disease and low baseline levels of high-density lipoprotein cholesterol (HDL-C) who were randomized to ERN versus placebo on a background of simvastatin therapy (with or without ezetimibe) to assess the association between baseline Lp-PLA2 activity and the rate of the composite primary end point (CV death, myocardial infarction, stroke, hospitalization for unstable angina, and symptom-driven revascularization).

Results:

Participants randomized to ERN, but not those randomized to placebo, experienced a significant 8.9% decrease in LpPLA2. In univariate analysis, the highest quartile of LpPLA2 activity (>208 nmol/min/mL, Q4) was associated with higher event rates compared to the lower quartiles in the placebo group (log rank P = .032), but not in the ERN treated participants (log rank P = .718). However, in multivariate analysis, adjusting for sex, diabetes, baseline LDL-C, HDL-C, and triglycerides, there was no significant difference in outcomes between the highest Lp-PLA2 activity quartile versus the lower quartiles in both the placebo and the ERN groups.

Conclusion:

Among participants with stable CV disease on optimal medical therapy, elevated Lp-PLA2 was associated with higher CV events; however, addition of ERN mitigates this effect. This association in the placebo group was attenuated after multivariable adjustment, which suggests that Lp-PLA2 does not improve risk assessment beyond traditional risk factors.

How much does birth weight matter for child health in developing countries? Estimates from siblings and twins

About 200 million children globally are not meeting their growth potential, and as a result will suffer the consequences in terms of future outcomes. I examine the effects of birth weight on child health and growth using information from 66 countries. I account for missing data and measurement error using instrumental variables and adopt an identification strategy based on siblings and twins. I find a consistent effect of birth weight on mortality risk, stunting, wasting, and coughing, with some evidence for fever, diarrhoea, and anaemia. Bounds analysis indicates that coefficients may be substantially underestimated due to mortality selection. Improving the pre-natal environment is likely to be important for helping children reach their full potential.

Accounting for non-response bias using participation incentives and survey design: An application using gift vouchers

Standard corrections for missing data rely on the strong and generally untestable assumption of missing at random. Heckman-type selection models relax this assumption, but have been criticized because they typically require a selection variable which predicts non-response but not the outcome of interest, and can impose bivariate normality. In this paper we illustrate an application using a copula methodology which does not rely on bivariate normality. We implement this approach in data on HIV testing at a demographic surveillance site in rural South Africa which are affected by non-response. Randomized incentives are the ideal selection variable, particularly when implemented ex ante to deal with potential missing data. However, elements of survey design may also provide a credible method of correcting for non-response bias ex post. For example, although not explicitly randomized, allocation of food gift vouchers during our survey was plausibly exogenous and substantially raised participation, as did effective survey interviewers. Based on models with receipt of a voucher and interviewer identity as selection variables, our results imply that 37% of women in the population under study are HIV positive, compared to imputation-based estimates of 28%. For men, confidence intervals are too wide to reject the absence of non-response bias. Consistent results obtained when comparing different selection variables and error structures strengthen these conclusions. Our application illustrates the feasibility of the selection model approach when combined with survey metadata.

The economic burden of noncommunicable diseases and mental health conditions: results for Costa Rica, Jamaica, and Peru

Objective

We extend the EPIC model of the World Health Organization (WHO) and apply it to analyze the macroeconomic impact of noncommunicable diseases (NCDs) and mental health conditions in Costa Rica, Jamaica, and Peru.

Methods

The EPIC model quantifies the impact of NCDs and mental health conditions on aggregate output solely through the effect of chronic conditions on labor supply due to mortality. In contrast, the expanded EPIC-H Plus framework also incorporates reductions in effective labor supply due to morbidity and negative effects of health expenditure on output via the diversion of productive savings and reduced capital accumulation. We apply this methodology to Costa Rica, Jamaica, and Peru and estimate gross domestic product (GDP) output lost due to four leading NCDs (cardiovascular disease, cancer, chronic respiratory disease, and diabetes) and mental health conditions in these countries from 2015 to 2030. We also estimate losses from all NCDs and mental health conditions combined.

Results

Overall, our results show total losses associated with all NCDs and mental health conditions over the period 2015–2030 of US$ 81.96 billion (2015 US$) for Costa Rica, US$ 18.45 billion for Jamaica, and US$ 477.33 billion for Peru. Moderate variation exists in the magnitude of the burdens of diseases for the three countries. In Costa Rica and Peru, respiratory disease and mental health conditions are two leading contributors to lost output, while in Jamaica, cardiovascular disease alone accounts for 20.8% of the total loss, followed by cancer.

Conclusions

These results indicate that the economic impact of NCDs and mental health conditions is substantial and that interventions to reduce the prevalence of chronic conditions in countries of Latin America and the Caribbean are likely to be highly cost-beneficial.

Do gifts increase consent to home-based HIV testing? A difference-in-differences study in rural KwaZulu-Natal, South Africa

Background

Despite the importance of HIV testing for controlling the HIV epidemic, testing rates remain low. Efforts to scale up testing coverage and frequency in hard-to-reach and at-risk populations commonly focus on home-based HIV testing. This study evaluates the effect of a gift (a US$5 food voucher for families) on consent rates for home-based HIV testing.

Methods

We use data on 18 478 individuals (6 418 men and 12 060 women) who were successfully contacted to participate in the 2009 and 2010 population-based HIV surveillance carried out by the Wellcome Trust's Africa Health Research Institute in rural KwaZulu-Natal, South Africa. Of 18 478 potential participants contacted in both years, 35% (6 518) consented to test in 2009, and 41% (7 533) consented to test in 2010. Our quasi-experimental difference-in-differences approach controls for unobserved confounding in estimating the causal effect of the intervention on HIV-testing consent rates.

Results

Allocation of the gift to a family in 2010 increased the probability of family members consenting to test in the same year by 25 percentage points [95% confidence interval (CI) 21-30 percentage points; P  < 0.001]. The intervention effect persisted, slightly attenuated, in the year following the intervention (2011).

Conclusions

In HIV hyperendemic settings, a gift can be highly effective at increasing consent rates for home-based HIV testing. Given the importance of HIV testing for treatment uptake and individual health, as well as for HIV treatment-as-prevention strategies and for monitoring the population impact of the HIV response, gifts should be considered as a supportive intervention for HIV-testing initiatives where consent rates have been low.

A review of the evidence linking child stunting to economic outcomes

Background

To understand the full impact of stunting in childhood it is important to consider the long-run effects of undernutrition on the outcomes of adults who were affected in early life. Focusing on the costs of stunting provides a means of evaluating the economic case for investing in childhood nutrition.

Methods

We review the literature on the association between stunting and undernutrition in childhood and economic outcomes in adulthood. At the national level, we also evaluate the evidence linking stunting to economic growth. Throughout, we consider randomized controlled trials (RCTs), quasi-experimental approaches and observational studies.

Results

Long-run evaluations of two randomized nutrition interventions indicate substantial returns to the programmes (a 25% and 46% increase in wages for those affected as children, respectively). Cost-benefit analyses of nutrition interventions using calibrated return estimates report a median return of 17.9:1 per child. Assessing the wage premium associated with adult height, we find that a 1-cm increase in stature is associated with a 4% increase in wages for men and a 6% increase in wages for women in our preferred set of studies which attempt to address unobserved confounding and measurement error. In contrast, the evidence on the association between economic growth and stunting is mixed.

Conclusions

Countries with high rates of stunting, such as those in South Asia and sub-Saharan Africa, should scale up policies and programmes aiming to reduce child undernutrition as cost-beneficial investments that expand the economic opportunities of their children, better allowing them and their countries to reach their full potential. However, economic growth as a policy will only be effective at reducing the prevalence of stunting when increases in national income are directed at improving the diets of children, addressing gender inequalities and strengthening the status of women, improving sanitation and reducing poverty and inequities.

Education, gender, and state-level disparities in the health of older Indians: Evidence from biomarker data

Using new biomarker data from the 2010 pilot round of the Longitudinal Aging Study in India (LASI), we investigate education, gender, and state-level disparities in health. We find that hemoglobin level, a marker for anemia, is lower for respondents with no schooling (0.7g/dL less in the adjusted model) compared to those with some formal education and is also lower for females than for males (2.0g/dL less in the adjusted model). In addition, we find that about one third of respondents in our sample aged 45 or older have high C-reaction protein (CRP) levels (>3mg/L), an indicator of inflammation and a risk factor for cardiovascular disease. We find no evidence of educational or gender differences in CRP, but there are significant state-level disparities, with Kerala residents exhibiting the lowest CRP levels (a mean of 1.96mg/L compared to 3.28mg/L in Rajasthan, the state with the highest CRP). We use the Blinder-Oaxaca decomposition approach to explain group-level differences, and find that state-level disparities in CRP are mainly due to heterogeneity in the association of the observed characteristics of respondents with CRP, rather than differences in the distribution of endowments across the sampled state populations.

Adjusting HIV prevalence estimates for non-participation: an application to demographic surveillance

INTRODUCTION

HIV testing is a cornerstone of efforts to combat the HIV epidemic, and testing conducted as part of surveillance provides invaluable data on the spread of infection and the effectiveness of campaigns to reduce the transmission of HIV. However, participation in HIV testing can be low, and if respondents systematically select not to be tested because they know or suspect they are HIV positive (and fear disclosure), standard approaches to deal with missing data will fail to remove selection bias. We implemented Heckman-type selection models, which can be used to adjust for missing data that are not missing at random, and established the extent of selection bias in a population-based HIV survey in an HIV hyperendemic community in rural South Africa.

METHODS

We used data from a population-based HIV survey carried out in 2009 in rural KwaZulu-Natal, South Africa. In this survey, 5565 women (35%) and 2567 men (27%) provided blood for an HIV test. We accounted for missing data using interviewer identity as a selection variable which predicted consent to HIV testing but was unlikely to be independently associated with HIV status. Our approach involved using this selection variable to examine the HIV status of residents who would ordinarily refuse to test, except that they were allocated a persuasive interviewer. Our copula model allows for flexibility when modelling the dependence structure between HIV survey participation and HIV status.

RESULTS

For women, our selection model generated an HIV prevalence estimate of 33% (95% CI 27-40) for all people eligible to consent to HIV testing in the survey. This estimate is higher than the estimate of 24% generated when only information from respondents who participated in testing is used in the analysis, and the estimate of 27% when imputation analysis is used to predict missing data on HIV status. For men, we found an HIV prevalence of 25% (95% CI 15-35) using the selection model, compared to 16% among those who participated in testing, and 18% estimated with imputation. We provide new confidence intervals that correct for the fact that the relationship between testing and HIV status is unknown and requires estimation.

CONCLUSIONS

We confirm the feasibility and value of adopting selection models to account for missing data in population-based HIV surveys and surveillance systems. Elements of survey design, such as interviewer identity, present the opportunity to adopt this approach in routine applications. Where non-participation is high, true confidence intervals are much wider than those generated by standard approaches to dealing with missing data suggest.

Vaccination and all-cause child mortality from 1985 to 2011: global evidence from the Demographic and Health Surveys

Based on models with calibrated parameters for infection, case fatality rates, and vaccine efficacy, basic childhood vaccinations have been estimated to be highly cost effective. We estimated the association of vaccination with mortality directly from survey data. Using 149 cross-sectional Demographic and Health Surveys, we determined the relationship between vaccination coverage and the probability of dying between birth and 5 years of age at the survey cluster level. Our data included approximately 1 million children in 68,490 clusters from 62 countries. We considered the childhood measles, bacillus Calmette-Guérin, diphtheria-pertussis-tetanus, polio, and maternal tetanus vaccinations. Using modified Poisson regression to estimate the relative risk of child mortality in each cluster, we also adjusted for selection bias that resulted from the vaccination status of dead children not being reported. Childhood vaccination, and in particular measles and tetanus vaccination, is associated with substantial reductions in childhood mortality. We estimated that children in clusters with complete vaccination coverage have a relative risk of mortality that is 0.73 (95% confidence interval: 0.68, 0.77) times that of children in a cluster with no vaccinations. Although widely used, basic vaccines still have coverage rates well below 100% in many countries, and our results emphasize the effectiveness of increasing coverage rates in order to reduce child mortality.

Taking aim at HDL-C

Although statin therapy has revolutionized management of coronary heart disease (CHD), the lowering of low-density lipoprotein cholesterol (LDL-C) levels is not the whole story. Increased plasma concentrations of high-density lipoprotein cholesterol (HDL-C) have a cardioprotective effect that is just as important for reducing risk of heart attack and stroke. In this article, Dr McGovern examines the evidence that provides the rationale for HDL-C as a therapeutic target for cardiovascular risk reduction.

On the assumption of bivariate normality in selection models: a Copula approach applied to estimating HIV prevalence

BACKGROUND

Heckman-type selection models have been used to control HIV prevalence estimates for selection bias when participation in HIV testing and HIV status are associated after controlling for observed variables. These models typically rely on the strong assumption that the error terms in the participation and the outcome equations that comprise the model are distributed as bivariate normal.

METHODS

We introduce a novel approach for relaxing the bivariate normality assumption in selection models using copula functions. We apply this method to estimating HIV prevalence and new confidence intervals (CI) in the 2007 Zambia Demographic and Health Survey (DHS) by using interviewer identity as the selection variable that predicts participation (consent to test) but not the outcome (HIV status).

RESULTS

We show in a simulation study that selection models can generate biased results when the bivariate normality assumption is violated. In the 2007 Zambia DHS, HIV prevalence estimates are similar irrespective of the structure of the association assumed between participation and outcome. For men, we estimate a population HIV prevalence of 21% (95% CI = 16%-25%) compared with 12% (11%-13%) among those who consented to be tested; for women, the corresponding figures are 19% (13%-24%) and 16% (15%-17%).

CONCLUSIONS

Copula approaches to Heckman-type selection models are a useful addition to the methodological toolkit of HIV epidemiology and of epidemiology in general. We develop the use of this approach to systematically evaluate the robustness of HIV prevalence estimates based on selection models, both empirically and in a simulation study.

Using interviewer random effects to remove selection bias from HIV prevalence estimates

BACKGROUND

Selection bias in HIV prevalence estimates occurs if non-participation in testing is correlated with HIV status. Longitudinal data suggests that individuals who know or suspect they are HIV positive are less likely to participate in testing in HIV surveys, in which case methods to correct for missing data which are based on imputation and observed characteristics will produce biased results.

METHODS

The identity of the HIV survey interviewer is typically associated with HIV testing participation, but is unlikely to be correlated with HIV status. Interviewer identity can thus be used as a selection variable allowing estimation of Heckman-type selection models. These models produce asymptotically unbiased HIV prevalence estimates, even when non-participation is correlated with unobserved characteristics, such as knowledge of HIV status. We introduce a new random effects method to these selection models which overcomes non-convergence caused by collinearity, small sample bias, and incorrect inference in existing approaches. Our method is easy to implement in standard statistical software, and allows the construction of bootstrapped standard errors which adjust for the fact that the relationship between testing and HIV status is uncertain and needs to be estimated.

RESULTS

Using nationally representative data from the Demographic and Health Surveys, we illustrate our approach with new point estimates and confidence intervals (CI) for HIV prevalence among men in Ghana (2003) and Zambia (2007). In Ghana, we find little evidence of selection bias as our selection model gives an HIV prevalence estimate of 1.4% (95% CI 1.2% - 1.6%), compared to 1.6% among those with a valid HIV test. In Zambia, our selection model gives an HIV prevalence estimate of 16.3% (95% CI 11.0% - 18.4%), compared to 12.1% among those with a valid HIV test. Therefore, those who decline to test in Zambia are found to be more likely to be HIV positive.

CONCLUSIONS

Our approach corrects for selection bias in HIV prevalence estimates, is possible to implement even when HIV prevalence or non-participation is very high or very low, and provides a practical solution to account for both sampling and parameter uncertainty in the estimation of confidence intervals. The wide confidence intervals estimated in an example with high HIV prevalence indicate that it is difficult to correct statistically for the bias that may occur when a large proportion of people refuse to test.

Physical stature decline and the health status of the elderly population in England

Few research papers in economics have examined the extent, causes or consequences of physical stature decline in aging populations. Using repeated observations on objectively measured data from the English Longitudinal Study of Aging (ELSA), we document that reduction in height is an important phenomenon among respondents aged 50 and over. On average, physical stature decline occurs at an annual rate of between 0.08% and 0.10% for males, and 0.12% and 0.14% for females-which approximately translates into a 2-4 cm reduction in height over the life course. Since height is commonly used as a measure of long-run health, our results demonstrate that failing to take age-related height loss into account substantially overstates the health advantage of older birth cohorts relative to their younger counterparts. We also show that there is an absence of consistent predictors of physical stature decline at the individual level. However, we demonstrate how deteriorating health and reductions in height occur simultaneously. We document that declines in muscle mass and bone density are likely to be the mechanism through which these effects are operating. If this physical stature decline is determined by deteriorating health in adulthood, the coefficient on measured height when used as an input in a typical empirical health production function will be affected by reverse causality. While our analysis details the inherent difficulties associated with measuring height in older populations, we do not find that significant bias arises in typical empirical health production functions from the use of height which has not been adjusted for physical stature decline. Therefore, our results validate the use of height among the population aged over 50.

Comparing the Relationship Between Stature and Later Life Health in Six Low and Middle Income Countries

This paper examines the relationship between stature and later life health in 6 emerging economies, each of which are expected to experience significant increases in the mean age of their populations over the coming decades. Using data from the WHO Study on Global Ageing and Adult Health (SAGE) and pilot data from the Longitudinal Ageing Study in India (LASI), I show that various measures of health are associated with height, a commonly used proxy for childhood environment. In the pooled sample, an additional 10cm increase in height is associated with between a 2 and 3 percentage point increase in the probability of being in very good or good self-reported health, a 3 percentage point increase in the probability of reporting no difficulties with activities of daily living or instrumental activities of daily living, and between a fifth and a quarter of a standard deviation increase in grip strength and lung function. Adopting a methodology previously used in the research on inequality, I also summarise the height-grip strength gradient for each country using the concentration index, and provide a decomposition analysis.

Do Fertility Transitions Influence Infant Mortality Declines? Evidence from Early Modern Germany

The timing and sequencing of fertility transitions and early-life mortality declines in historical Western societies indicates that reductions in sibship (number of siblings) may have contributed to improvements in infant health. Surprisingly however, this demographic relationship has received little attention in empirical research. We outline the difficulties associated with establishing the causal effect of sibship on infant mortality, and discuss the inherent bias associated with conventional empirical approaches. We offer a solution that permits an empirical test of this relationship whilst accounting for reverse causality. Our approach is illustrated by evaluating the causal impact of family size on infant mortality using genealogical data from 13 German parishes spanning the 16th, 17th, 18th and 19th centuries. Overall, our findings do not support the hypothesis that declining fertility led to increased infant survival probabilities in historical populations.

Niacin and fibrates in atherogenic dyslipidemia: pharmacotherapy to reduce cardiovascular risk

Although statin therapy represents a cornerstone of cardiovascular disease (CVD) prevention, a major residual CVD risk (60-70% of total relative risk) remains, attributable to both modifiable and non-modifiable risk factors. Among the former, low levels of HDL-C together with elevated triglyceride (TG)-rich lipoproteins and their remnants represent major therapeutic targets. The current pandemic of obesity, metabolic syndrome, and type 2 diabetes is intimately associated with an atherogenic dyslipidemic phenotype featuring low HDL-C combined with elevated TG-rich lipoproteins and small dense LDL. In this context, there is renewed interest in pharmacotherapeutic strategies involving niacin and fibrates in monotherapy and in association with statins. This comprehensive, critical review of available data in dyslipidemic subjects indicates that niacin is more efficacious in raising HDL-C than fibrates, whereas niacin and fibrates reduce TG-rich lipoproteins and LDL comparably. Niacin is distinguished by its unique capacity to effectively lower Lp(a) levels. Several studies have demonstrated anti-atherosclerotic action for both niacin and fibrates. In contrast with statin therapy, the clinical benefit of fibrates appears limited to reduction of nonfatal myocardial infarction, whereas niacin (frequently associated with statins and/or other agents) exerts benefit across a wider range of cardiovascular endpoints in studies involving limited patient numbers. Clearly the future treatment of atherogenic dyslipidemias involving the lipid triad, as exemplified by the occurrence of the mixed dyslipidemic phenotype in metabolic syndrome, type 2 diabetes, renal, and auto-immune diseases, requires integrated pharmacotherapy targeted not only to proatherogenic particles, notably VLDL, IDL, LDL, and Lp(a), but also to atheroprotective HDL.

Aspirin reduces cutaneous flushing after administration of an optimized extended-release niacin formulation

OBJECTIVE

Niacin is an effective treatment for dyslipidemia due to its favorable effects on multiple lipid parameters. Clinical utility of niacin is sometimes limited, however, because of cutaneous flushing. A once-daily, extended-release (ER) niacin formulation has been shown to significantly reduce flushing compared to immediate-release niacin. An optimized (reformulated) version of niacin ER has recently been developed and was shown in a previous study to significantly reduce flushing intensity (severity) compared to the non-optimized (commercial) formulation. The current study was designed to evaluate the effect of aspirin on various indices of flushing when administered with the optimized niacin ER formulation.

METHOD

This was a randomized, double-blind, double-dummy, placebo-controlled flush provocation crossover study in healthy males. To increase the probability of flushing, subjects received a single dose of reformulated niacin ER 2,000 mg, which is the upper limit of the approved dosage range. Subjects received 650 mg aspirin orally either 30 minutes before or concomitantly with niacin ER, or placebo with niacin ER, in 3-way crossover fashion. The primary endpoint was the number of subjects who reported at least one flushing event. Secondary endpoints included the perceived intensity and duration of flushing symptoms.

RESULTS

In the 148 men who completed all treatments, aspirin significantly reduced flushing incidence (the primary endpoint) following administration of niacin ER compared with placebo. Among subjects receiving placebo, 77% of subjects reported flushing with niacin ER. Among subjects receiving aspirin, 53-61% of subjects reported flushing (pretreatment and concomitant treatment, respectively, both p < 0.001 compared with placebo) with niacin ER. Aspirin also significantly reduced intensity and duration of flushing (by 30-40%) compared with no aspirin. The two aspirin-containing treatments (i.e. pre- or concomitant treatment) were similar in their effects on flushing incidence, intensity and duration. Median intensity on a 100 mm visual analogue scale (VAS) was reduced from 33 mm with placebo to 19-23 mm with aspirin. Median duration was reduced from approximately 1 hour with placebo to 37-48 minutes with aspirin.

CONCLUSION

Aspirin significantly reduced the incidence, intensity and duration of flushing associated with reformulated niacin ER. These results support the administration of aspirin prophylactically to decrease niacin-induced cutaneous flushing and to improve patient adherence and acceptability of chronic niacin treatment at therapeutic doses.

Time as a Variable With Niacin Extended‐Release/Lovastatin vs. Atorvastatin and Simvastatin

Time may be an important variable when evaluating the efficacy of lipid-altering drugs. In this analysis of the Advicor Versus Other Cholesterol-Modulating Agents Trial Evaluation, niacin extended-release/lovastatin 1000/40 mg was as effective as atorvastatin 10 mg and more effective than simvastatin (both 10 mg and 20 mg) in achieving low-density lipoprotein cholesterol and non-high-density lipoprotein cholesterol treatment goals. The titration schedule for this study included the initiation of niacin-extended release/lovastatin 500/20 mg once a day for 4 weeks, titrated to the starting dose of 1000/40 mg after 4 weeks, and then titrated to the final dose of 2000/40 mg. The titration schedule for both atorvastatin and simvastatin was 10 mg per day for 8 weeks and then titrated to 40 mg per day. Using this schedule, 50% of niacin extended-release/lovastatin and atorvastatin patients reached low-density lipoprotein cholesterol and non-high-density lipoprotein cholesterol treatment goals within approximately 7 weeks, compared with simvastatin, in which 50% reached both treatment goals in 13-14 weeks. These time differences may have potential clinical relevance in reducing coronary heart disease risk.

A dose-ranging study of a new, once-daily, dual-component drug product containing niacin extended-release and lovastatin

BACKGROUND

Combination therapy for dyslipidemia holds promise as effective treatment for patients with multiple lipid disorders, especially those at high risk.

HYPOTHESIS

This study evaluated dose-response relationships and safety of a new dual-component drug product containing niacin extended-release (niacin ER) and lovastatin.

METHODS

The 28-week double-blind multicenter trial randomized 237 patients with type IIA or IIB hyperlipidemia to one of four escalating-dose treatment groups: niacin ER/lovastatin 1,000/20 mg, niacin ER/lovastatin 2,000/40 mg, niacin ER 2,000 mg, or lovastatin 40 mg.

RESULTS

Niacin ER/lovastatin was more effective than each of its components for improving levels of low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides (TG), and exhibited a clear dose-response effect and additivity across the dosage range. The 2,000/40 dose achieved greater mean reductions in LDL-C (-42%) than 1,000/20 (-28%, p < 0.001), lovastatin 40 mg (-32%, p < 0.05), or niacin ER 2,000 mg (-14%, p < 0.05). The 2,000/40 dose was significantly more effective in increasing HDL-C levels (+30%) than the 1,000/20 dose (+21%, p = 0.016). The decrease in TG was greater with 2,000/40 (-43%) than with 1,000/20 (-26%, p = 0.009). All three niacin-containing treatments were more effective than lovastatin monotherapy in reducing lipoprotein (a) [Lp(a)] levels. Flushing caused 12 (11%) patients receiving niacin ER/lovastatin and I patient receiving lovastatin alone to withdraw. No drug-related myopathy was noted. One patient each in the 2,000/40 group and the lovastatin 40-mg group had reversible elevations in liver transaminases.

CONCLUSIONS

Niacin ER/lovastatin is well tolerated and effective for patients with multiple lipid disorders.

Safety and Efficacy of Extended-Release Niacin for the Treatment of Dyslipidaemia in Patients with HIV Infection: Aids Clinical Trials Group Study A5148

Background

Dyslipidaemia is very common in patients with HIV infection, but current therapies are often suboptimal. Since niacin may cause insulin resistance and hepatotoxicity, it has generally been avoided in this setting.

Methods

Non-diabetic male subjects ( n=33) who had well-controlled HIV infection on antiretroviral therapy, fasting triglycerides ≥2.26 mmol/l and non-high density lipoprotein cholesterol (non-HDL-C) ≥4.66 mmol/l received escalating doses of extended-release niacin (ERN) up to 2,000 mg nightly for up to 44 weeks.

Results

Fourteen subjects (42%) had pre-diabetes at entry. Twenty-three subjects (70%) received the maximum dose, eight (24%) received 1,500 mg. Niacin was well-tolerated. Only four subjects (12%) discontinued study treatment. There were small increases in fasting glycaemia and insulin resistance estimated by the homeostasis model assessment, but insulin resistance measures from the 2-h oral glucose tolerance test only transiently worsened. No subject developed persistent fasting hyperglycaemia; one had persistently elevated 2-h glucose >11.1 mmol/l. There were no significant changes in serum transaminases or uric acid. At week 48, the median change in fasting lipid levels in mmol/l (interquartile range) were: total cholesterol -0.21 (-1.35, -0.05), HDL-C +0.013 (-0.03,+0.28), non-HDL-C -0.49 (-1.37, +0.08) and triglycerides -1.73 (-3.68, -0.72). Favourable changes in large HDL and large very low density lipoprotein particle concentration were observed by nuclear magnetic resonance spectroscopy.

Conclusions

ERN in doses up to 2,000 mg daily was safe, well-tolerated and efficacious in HIV-infected subjects with atherogenic dyslipidaemia. Increases in glycaemia and insulin resistance tended to be transient.

Benefits of niacin in patients with versus without the metabolic syndrome and healed myocardial infarction (from the Coronary Drug Project)

This post hoc analysis from the Coronary Drug Project (CDP) evaluated the effects of niacin monotherapy on clinical outcomes in patients with and without the metabolic syndrome (MS). The CDP was a randomized, placebo-controlled clinical trial of lipid-modifying agents in men with previous myocardial infarction (MI). Of the 5 drug regimens, only niacin significantly decreased definite recurrent nonfatal MI at 6 years and total mortality at a 15-year follow-up. Patients treated with niacin (n = 1,119) and placebo (n = 2,787) were grouped according to the presence or absence of the MS at baseline. The MS was defined on the basis of meeting > or =3 of 5 criteria from the current National Cholesterol Education Program guidelines in a small subgroup of patients with high-density lipoprotein cholesterol determinations at baseline and on the basis of > or =3 of 4 criteria in the total population, excluding the high-density lipoprotein cholesterol criterion. Niacin decreased the occurrence of 6-year MI and 15-year total mortality similarly among patients with or without the MS. For example, in the total population, 15-year total mortality rates were 60% and 64% (hazard ratio 0.86) in patients with the MS treated with niacin and placebo, respectively, and 50% and 57% (hazard ratio 0.86) in those without the MS (Z for interaction = 0.06, indicating homogeneity of the treatment effect across groups). In conclusion, these results support the use of niacin in postinfarction patients with and without the MS.

Safety and efficacy of extended-release niacin for the treatment of dyslipidaemia in patients with HIV infection: AIDS Clinical Trials Group Study A5148

BACKGROUND

Dyslipidaemia is very common in patients with HIV infection, but current therapies are often suboptimal. Since niacin may cause insulin resistance and hepatotoxicity, it has generally been avoided in this setting.

METHODS

Non-diabetic male subjects (n=33) who had well-controlled HIV infection on antiretroviral therapy, fasting triglycerides > or =2.26 mmol/l and non-high density lipoprotein cholesterol (non-HDL-C) > or =4.66 mmol/l received escalating doses of extended-release niacin (ERN) up to 2,000 mg nightly for up to 44 weeks.

RESULTS

Fourteen subjects (42%) had pre-diabetes at entry. Twenty-three subjects (70%) received the maximum dose, eight (24%) received 1,500 mg. Niacin was well-tolerated. Only four subjects (12%) discontinued study treatment. There were small increases in fasting glycaemia and insulin resistance estimated by the homeostasis model assessment, but insulin resistance measures from the 2-h oral glucose tolerance test only transiently worsened. No subject developed persistent fasting hyperglycaemia; one had persistently elevated 2-h glucose >11.1 mmol/l. There were no significant changes in serum transaminases or uric acid. At week 48, the median change in fasting lipid levels in mmol/l (interquartile range) were: total cholesterol -0.21 (-1.35, -0.05), HDL-C +0.013 (-0.03,+0.28), non-HDL-C -0.49 (-1.37,+0.08) and triglycerides -1.73 (-3.68, -0.72). Favourable changes in large HDL and large very low density lipoprotein particle concentration were observed by nuclear magnetic resonance spectroscopy.

CONCLUSIONS

ERN in doses up to 2,000 mg daily was safe, well-tolerated and efficacious in HIV-infected subjects with atherogenic dyslipidaemia. Increases in glycaemia and insulin resistance tended to be transient.

Benefits of niacin by glycemic status in patients with healed myocardial infarction (from the Coronary Drug Project)

The Coronary Drug Project, conducted during 1966 to 1974, was a randomized, double-blind, placebo-controlled trial of 5 lipid-modifying agents in 8,341 men with previous myocardial infarction. Among the 5 drug treatment regimens, only niacin significantly reduced the risk of (1) cardiovascular events during a mean follow-up of 6.2 years and (2) total mortality during 6.2 years with study treatment plus an additional 9 years of post-trial follow-up (Figure 1). Cardiovascular and total mortality outcomes in the niacin and placebo groups are presented by baseline glycemic status and by change in glycemic status from baseline to year 1.

Differential effect of two nicotinic acid preparations on low-density lipoprotein subclass distribution in patients classified as low-density lipoprotein pattern A, B, or I

We tested the hypothesis that treatment with nicotinic acid results in a differential blood lipid response in subjects classified as having a low-density lipoprotein (LDL) pattern A or B. One hundred eighty hypercholesterolemic subjects were randomized to placebo (n = 61), immediate-release niacin (3,000 mg/day, n = 59), or extended-release niacin (1,500 mg/day, n = 60) for 14 weeks. Lipids and lipoprotein cholesterol were determined with enzymatic methods. LDL subclass distribution was determined with 2% to 16% polyacrylamide gradient gel electrophoresis. Extended- and immediate-release niacin had significant effects on the decrease of triglycerides, total cholesterol, LDL cholesterol, apoprotein B, lipoprotein(a), and apoprotein A-I and significantly increased high-density lipoprotein cholesterol. The 2 nicotinic acid compounds and doses significantly increased mean LDL peak particle diameter and percent distribution in large LDL I and IIa, with a significant decrease in small LDL IIIa, IIIb, and IVb. In patients with LDL pattern B compared with those with pattern A, extended-release niacin (1,500 mg/day) increased LDL peak particle diameter significantly more and decreased the percent distributions of small LDL IIIa, LDL IIIb, and LDL IVa significantly more. With 3,000 mg/day, immediate-release nicotinic acid in patients with LDL pattern B exhibited a significantly greater increase in LDL peak particle diameter and large LDL IIa and IIb and significantly greater decreases in small LDL IIIa, IIIb, and IVa compared with patients with pattern A. These differences in response between patients with LDL pattern A and those with pattern B were not reflected by changes in the standard lipid profile, including apoproteins A-I and B. Nicotinic acid has a significantly different effect on lipids and lipoprotein subclass distribution in subjects classified as having LDL subclass pattern A or B. Nicotinic acid has a significantly greater effect on the decrease of small LDL subclass distribution and increase in LDL peak particle diameter in pattern B versus pattern A.

Efficacy of Extended-Release Niacin With Lovastatin for Hypercholesterolemia

BACKGROUND

Combination therapy to improve the total lipid profile may achieve greater coronary risk reductions than lowering low-density lipoprotein cholesterol (LDL-C) alone. A new extended-release niacin (niacin ER)/lovastatin tablet substantially lowers LDL-C, triglyceride, and lipoprotein(a) levels and raises high-density lipoprotein cholesterol (HDL-C) level. We evaluated these serum lipid responses to niacin ER/lovastatin at all clinically reasonable doses.

METHODS

Men (n = 85) and women (n = 79) with type IIa or IIb primary hyperlipidemia after diet were randomized among 5 parallel treatment arms. Each arm had 5 sequential 4-week treatment periods: niacin ER (starting at 500 mg/d, increasing in 500-mg increments to 2500 mg/d); lovastatin (starting at 10 mg, increasing to 20 mg, then 40 mg/d); and 3 combinations arms, each with a constant lovastatin dose and escalating niacin ER doses.

RESULTS

For primary comparisons, mean LDL-C level reductions from baseline were greater with niacin ER/lovastatin (1500/20 mg) than with lovastatin (20 mg) (35% vs 22%, P<.001) and with niacin ER/lovastatin (2000/40 mg) than with lovastatin (40 mg) (46% vs 24%, P<.001). Each 500-mg increase in niacin ER, on average, decreased LDL-C levels an additional 4% and increased HDL-C levels 8%. The maximum recommended dose (2000/40 mg/d) increased HDL-C levels 29% and decreased LDL-C levels 46%, triglyceride levels 38%, and lipoprotein(a) levels 14%. All lipid responses were dose dependent and generally additive. Graphs of the dose-response relationships as 3-dimensional surfaces documented the strength and consistency of these responses.

CONCLUSIONS

Niacin ER/lovastatin combination therapy substantially improves 4 major lipoprotein levels associated with atherosclerotic disease. Dose-response surfaces provide a practical guide for dose selection.

Once-Daily Niacin Extended Release/Lovastatin Combination Tablet Has More Favorable Effects on Lipoprotein Particle Size and Subclass Distribution Than Atorvastatin and Simvastatin

Standard lipoprotein measurements may not adequately reflect the increased atherogenic risk found in patients with abnormalities in lipoprotein particle size and subfraction distribution such as disproportionate amounts of small, dense low-density lipoprotein particles, small high-density lipoprotein particles, or large very-low-density lipoprotein particles. Measurement or anticipation of patients most susceptible to lipoprotein subfraction abnormalities may influence therapeutic choices for the optimal management of dyslipidemia. Previously, the ADvicor Vs. Other Cholesterol-modulating Agents Trial Evaluation demonstrated that niacin extended release/lovastatin provided greater global improvement in lipid parameters such as low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, lipoprotein (a), apolipoprotein B, and apolipoprotein A-I blood levels compared with atorvastatin and simvastatin monotherapies. In this report, niacin extended release/lovastatin was also more effective than atorvastatin and simvastatin monotherapies in reducing small, dense low-density lipoprotein particles and improving low-density lipoprotein phenotype pattern at relative starting doses, and was more effective in increasing the proportion of high-density lipoprotein in the potentially cardioprotective 2b subclass at all doses.

Comparison of once-daily, niacin extended-release/lovastatin with standard doses of atorvastatin and simvastatin (the ADvicor Versus Other Cholesterol-Modulating Agents Trial Evaluation [ADVOCATE])

This study compared the relative efficacy of a once-daily niacin extended-release (ER)/lovastatin fixed-dose combination with standard doses of atorvastatin or simvastatin, with a special emphasis on relative starting doses. Subjects (n = 315) with elevated low-density lipoprotein (LDL) cholesterol and decreased high-density lipoprotein (HDL) cholesterol blood levels (defined as LDL cholesterol blood levels > or =160 mg/dl without coronary artery disease, or > or =130 mg/dl if coronary artery disease was present, and HDL cholesterol <45 mg/dl in men and <50 mg/dl in women) were randomized to atorvastatin, simvastatin, or niacin ER/lovastatin for 16 weeks. The primary efficacy variables were the mean percent change in LDL cholesterol and HDL cholesterol levels from baseline. After 8 weeks, the starting dose niacin ER/lovastatin 1,000/40 mg and the 10-mg starting dose atorvastatin both lowered mean LDL cholesterol by 38%. After 12 weeks, niacin ER/lovastatin 1,000/40 mg lowered LDL cholesterol by 42% versus 34% with the 20-mg starting dose of simvastatin (p <0.001). Niacin ER/lovastatin increased HDL cholesterol significantly more than atorvastatin or simvastatin at all compared doses (p <0.001). Niacin ER/lovastatin also provided significant improvements in triglycerides, lipoprotein(a), apolipoprotein A-1, apolipoprotein B, and HDL subfractions. A total of 6% of study subjects receiving niacin ER/lovastatin withdrew because of flushing. No significant differences were seen among study groups in discontinuance due to elevated liver enzymes. No drug-induced myopathy was observed. Niacin ER/lovastatin was comparable to atorvastatin 10 mg and more effective than simvastatin 20 mg in reducing LDL cholesterol, was more effective in increasing HDL cholesterol than either atorvastatin or simvastatin, and provided greater global improvements in non-HDL cholesterol, triglycerides, and lipoprotein(a).

Efficacy, safety, and tolerability of once-daily niacin for the treatment of dyslipidemia associated with type 2 diabetes: results of the assessment of diabetes control and evaluation of the efficacy of niaspan trial

BACKGROUND

Diabetic dyslipidemia is characterized by high triglyceride levels; low high-density lipoprotein cholesterol levels; small, dense low-density lipoprotein particles; and high free fatty acid levels. Niacin reduces concentrations of triglyceride-rich and small low-density lipoprotein particles while increasing high-density lipoprotein cholesterol levels. It also lowers levels of free fatty acids and lipoprotein(a). However, the use of niacin in patients with diabetes has been discouraged because high doses can worsen glycemic control. We evaluated the efficacy and safety of once-daily extended-release (ER) niacin in patients with diabetic dyslipidemia.

METHODS

During a 16-week, double-blind, placebo-controlled trial, 148 patients were randomized to placebo (n = 49) or 1000 (n = 45) or 1500 mg/d (n = 52) of ER niacin. Sixty-nine patients (47%) were also receiving concomitant therapy with statins.

RESULTS

Dose-dependent increases in high-density lipoprotein cholesterol levels (+19% to +24% [P<.05] vs placebo for both niacin dosages) and reductions in triglyceride levels (-13% to -28% [P<.05] vs placebo for the 1500-mg ER niacin) were observed. Baseline and week 16 values for glycosylated hemoglobin levels were 7.13% and 7.11%, respectively, in the placebo group; 7.28% and 7.35%, respectively, in the 1000-mg ER niacin group (P=.16 vs placebo); and 7.2% and 7.5%, respectively, in the 1500-mg ER niacin group (P=.048 vs placebo). Four patients discontinued participation because of inadequate glucose control. Rates of adverse event rates other than flushing were similar for the niacin and placebo groups. Four patients discontinued participation owing to flushing (including 1 receiving placebo). No hepatotoxic effects or myopathy were observed.

CONCLUSION

Low doses of ER niacin (1000 or 1500 mg/d) are a treatment option for dyslipidemia in patients with type 2 diabetes.

Long-term safety and efficacy of a once-daily niacin/lovastatin formulation for patients with dyslipidemia

Combination therapy is increasingly recommended for patients with multiple lipid disorders, especially those at high risk for coronary events. We investigated the long-term safety and effectiveness of a new drug formulation containing once-daily extended-release niacin and lovastatin. A total of 814 men and women (mean age 59 years) with dyslipidemia were enrolled in a 52-week multicenter, open-label study. We used 4 escalating doses (niacin/lovastatin in milligrams): 500/10 for the first month, 1,000/20 for the second, 1,500/30 for the third, and 2,000/40 for the fourth month through week 52. Dose-dependent effects were observed for all major lipid parameters. At week 16, mean low-density lipoprotein (LDL) cholesterol and triglycerides were reduced by 47% and 41%, respectively; mean high-density lipoprotein (HDL) cholesterol was increased by 30% (all p <0.001). LDL/HDL cholesterol and total/HDL cholesterol ratios were also decreased by 58% and 48%, respectively. These effects persisted through week 52, except for the mean increase in HDL cholesterol, which had increased to 41% at 1 year. Lipoprotein (a) and C-reactive protein also decreased in a dose-related manner (by 25% and 24%, respectively, on 2,000/40 mg; p <0.01 vs baseline). Treatment was generally well tolerated. The most common adverse event was flushing, which caused 10% of patients to withdraw. Other adverse events included gastrointestinal upset, pruritus, rash, and headache. Drug-induced myopathy did not occur in any patient. The incidence of elevated liver enzymes to >3 times the upper limit of normal was 0.5%. Once-daily niacin/lovastatin exhibits substantial effects on multiple lipid risk factors and represents a significant new treatment option in the management of dyslipidemia.

High surface density immobilization of oligonucleotide on silicon

Oligonucleotide (11-mer) molecules are immobilized on silicon in high surface population using either a permanent thioether bond or a chemo-selectively reversible disulfide bond to the surface thiol functionality. Substrate hydroxy groups are first silanized with an 11 carbon trichlorosilane containing a terminal, protected thiol moiety. Oligonucleotide modified with a tether possessing a terminal thiol group is further derivatized with a water-soluble, halobenzylic bifunctional reagent, which allows the complete conjugate to be attached to the surface through a permanent thioether bond. Alternatively, the oligonucleotide-tether complex can be combined with a pyridyldisulfide compound, which, in turn, facilitates the formation of a reversible disulfide bond with surface thiol. The amount of immobilized oligonucleotide was determined by radiochemical labeling with 32P. Additional verification of surface amounts was obtained from X-ray photoelectron spectroscopic analysis of substrates. The results of the immobilization protocols are compared with the oligonucleotide surface population achieved through the conventional silanizing agent, mercaptopropyltrimethoxysilane. Finally, a preliminary confirmation of duplex formation of a TTU-attached 25-mer with its complementary strand is outlined.

Surface immobilized biochemical macromolecules studied by scanning Kelvin microprobe

The measurement of work function is a particularly effective method for the characterization of surfaces because of the sensitivity of the parameter to interfacial structure, modification and overall chemistry. Accordingly, techniques for the analysis of work function offer a powerful tool for monitoring surface chemical changes, especially for situations involving the immobilization of new moieties at the interface. In the present paper, we describe the performance of a new, modified scanning Kelvin microprobe which is capable of the tandem measurement of contact potential and surface topography with resolutions of 1 mV and 10 nm, respectively. The lateral resolution is 1 micron. The instrument has been applied to the study of substrates modified by the attachment of biochemical macromolecules such as oligonucleotides and DNA. This preliminary work confirms the great potential of the technique in the study of biocompatibility, macromolecular structure and microarray devices.

Pentafluorinated probes for the X-ray photoelectron spectroscopic study of immobilized bifunctional silanes

Bifunctional silanes constitute valuable linking agents for attachment of biomolecules at high levels of surface population density through the formation of thioether or disulfide bonds. Three such compounds, 1-((trifluoroacetyl)-thio)-11-(trichlorosilyl)undecane, 1-bromo-11-(trichlorosilyl)undecane, and 1-((bromoacetyl)oxy)-11-(trichlorosilyl)undecane, are discussed in terms of their surface chemistry on silicon wafers. To examine the electrophilic and nucleophilic generation of sulfur-containing linkages, three new probes, N'-(pentafluorophenyl)iodoacetohydrazide, N'-(pentafluorophenyl)-3-(2-pyridylthio)propriono-hydrazide, and N'-(pentafluorophenyl)mercaptoacetohydrazide, are introduced with respect to their reactions with silanized surfaces (studied by X-ray photoelectron spectroscopy). Thiol-functionalized surfaces obtained by silanization act as nucleophiles toward the probes. In air, low yields of conjugation are exhibited which are attributed to the unavailability of thiol groups because of intramolecular disulfide group formation instigated by oxygen or by disulfide exchange with the proprionyl probe. The behavior of electrophilic silanized surfaces toward the mercaptoacetyl-containing probe is governed by the nature of the leaving group and by steric factors.

Article

The immobilization of biomolecules on substrate surfaces for biosensor development requires linking molecules that must meet a specific set of criteria. Two such agents based on bifunctional alkyltrichlorosilane structures, 1-bromo-11-(trichlorosilyl)-undecane and 1-(thiotrifluoroacetato)-11-(trichlorosilyl)-undecane, are employed to generate thiol-functionalized surfaces either by nucleophilic substitution followed by reduction (bromine-containing derivative) or deprotection (fluorine-containing compound). Both molecules have been attached to the surfaces of silicon wafers in conjunction with the diluent silane, octyltrichlorosilane. X-ray photoelectron spectroscopic analysis in the conventional and angle-resolved modes confirms that both silanization reactions were successful. The alkyl-bromine surfaces were subjected to treatment with a set of nucleophilic reactants followed by reduction and derivatization with trifluoroacetic anhydride. The latter in conjunction with surface analysis was used to estimate the level of thiol functionalization achieved. The fluorine-containing undecane surface has been studied by surface analysis both before and after deprotection of the thiol group by hydroxylamine solution. The results indicate that a high coverage of the surface was found for the protected moiety, with approximately 10% of the trifluoro acetate groups remaining after the deprotection procedure.Key words: bifunctional silanes, thiol surface functionalization, biomolecule immobilization, X-ray photoelectron spectroscopy.

Acoustic waves and the real-time study of biochemical macromolecules at the liquid/solid interface

The adsorption of the proteins, bovine serum albumin, fibrinogen, avidin and neutravidin (non-glycosylated form of avidin) to a variety of surfaces imposed on thickness shear mode sensors in examined in a flow-injection analysis format. In all cases, adsorption of these moieties was essentially irreversible, although the magnitude of adsorption was dependent on surface free energy and functional group chemistry. Also described is the direct, real-time detection of the binding of peptides to HIV-1 TAR RNA bound on a thickness-shear mode (TSM) sensor surface. The results clearly indicate that responses are discriminatory for two different peptides. In order to provide a theoretical backcloth for the experimental measurements, a new model for the operation of the TSM in liquids is presented.

Pravastatin limitation of atherosclerosis in the coronary arteries (PLAC I): reduction in atherosclerosis progression and clinical events. PLAC I investigation

OBJECTIVES

This study was designed to evaluate the effect of pravastatin on progression of coronary atherosclerosis and ischemic events in patients with coronary artery disease and mild to moderate hyperlipidemia.

BACKGROUND

Few clinical trial data support the use of lipid-lowering therapy in patients with coronary artery disease and mild to moderate elevations in cholesterol levels.

METHODS

Four hundred eight patients (mean age 57 years) with coronary artery disease and low density lipoprotein (LDL) cholesterol > or = 130 mg/dl (3.36 mmol/liter) but < 190 mg/dl ([4.91 mmol/liter]) despite diet were randomized in a 3-year study to receive pravastatin or placebo. Atherosclerosis progression was evaluated by quantitative coronary arteriography.

RESULTS

Baseline mean LDL cholesterol was 164 mg/dl (4.24 mmol/liter). Pravastatin decreased total and LDL cholesterol and triglyceride levels by 19%, 28% and 8%, respectively, and increased high density lipoprotein cholesterol by 7% (p < or = 0.001 vs. placebo for all lipid variables). Progression of atherosclerosis was reduced by 40% for minimal vessel diameter (p = 0.04), particularly in lesions < 50% stenosis at baseline. There was a consistent although not statistically significant effect on mean diameter and percent diameter stenosis. There were also fewer new lesions in those assigned pravastatin (p < or = 0.03). Myocardial infarction was reduced during active treatment (8 in the pravastatin group, 17 in the placebo group; log-rank test, p < or = 0.05; 60% risk reduction), with the benefit beginning to emerge after 1 year.

CONCLUSIONS

In patients with coronary artery disease and mild to moderate cholesterol elevations, pravastatin reduces progression of coronary atherosclerosis and myocardial infarction. The time course of event reduction increases the potential for a relatively rapid decrease in the clinical manifestations of coronary artery disease with lipid lowering.

Efficacy and safety of pravastatin in the treatment of patients with type I or type II diabetes mellitus and hypercholesterolemia

PURPOSE

Patients with type I and type II diabetes mellitus have an increased risk of coronary heart disease. In many diabetics, hypercholesterolemia is present and further exacerbates this risk. We investigated the efficacy and safety of pravastatin in the treatment of patients with type I or type II diabetes mellitus and hypercholesterolemia.

PATIENTS AND METHODS

In this 24-week, multi-center, double-blind, placebo-controlled study, 94 patients (45 men, 49 women), 18 to 70 years of age, with type I or type II diabetes mellitus and hypercholesterolemia (fasting plasma low-density lipoprotein cholesterol [LDL-C] levels > 150 mg/dL and above the 75th percentile for the US population by age and gender) were randomized to receive pravastatin 20 mg hs or matching placebo. Two patients were randomized to treatment with drug for every 1 randomized to placebo. The dose could be doubled after 10 weeks, and cholestyramine or colestipol could be added after 18 weeks, as needed, to attempt to lower the LDL-C levels to below the 50th percentile for the US population.

RESULTS

Significant reductions in LDL-C (-27.6%), total cholesterol (-22.1%), very-low-density lipoprotein cholesterol (-22.6%), and triglycerides (-12.8%) (P < or = 0.001 versus placebo for all reductions), and significant increases in high-density lipoprotein cholesterol (4.4%) (P < or = 0.05 versus placebo) were noted in the pravastatin treatment group (average dose 29.5 mg) at 16 weeks. The beneficial lipid-lowering effects of pravastatin were maintained throughout the 24 weeks of the study. Pravastatin was well tolerated, and the frequency of side effects was similar in the pravastatin and placebo groups. No clinically significant changes in the control of diabetes, as assessed by fasting blood glucose levels and glycosylated hemoglobin measurements, were seen during this study.

CONCLUSION

The results of this study demonstrate that pravastatin is well tolerated and effective in lowering total cholesterol and LDL-C in patients with type I or type II diabetes mellitus and hypercholesterolemia.