Differences in time to onset of smoking and nicotine dependence by race/ethnicity in a Midwestern sample of adolescents and young adults from a high risk family study

Associations between racial and socioeconomic discrimination and risk behaviors among African-American adolescents and young adults: a latent class analysis

PURPOSE

Discrimination is a common stressor among African Americans and may increase vulnerability to risk behaviors, such as early initiation of substance use, substance use problems, and physical aggression; however, few studies have examined different types of discrimination and their associations with patterns of risk behaviors. This study examines the relationship between experiences of racial and socioeconomic discrimination and risk behaviors in African-American adolescents and young adults.

METHODS

We investigated associations of two discrimination types with risk behavior patterns identified with latent class analysis in a high-risk sample of African Americans (N = 797, M_age = 17.9 years, 50.2% female).

RESULTS

Four distinct classes of risk behaviors were characterized by High Use and Aggression (10%), Moderate Use and Aggression (10%), High Alcohol (17%), and Low Use and Aggression (63%). Classes that exhibit general risk behaviors, including substance use and aggression, were significantly associated with racial and socioeconomic discrimination, even in the fully adjusted model. Relative to other classes, the High Use and Aggression class demonstrated an elevated likelihood of experiencing both racial and socioeconomic discrimination.

CONCLUSIONS

Findings support a link between racial and socioeconomic discrimination and risk behavior in African-American youth, which may be stronger for socioeconomic discrimination. Understanding the relationship between discrimination and risk behavior can inform future interventions to prevent substance misuse and conduct problems in youth. Further study is needed to elucidate the relationship between discrimination and other risk behaviors.

Integrative Data Analysis of Gender and Ethnic Measurement Invariance in Nicotine Dependence Symptoms

Little research has evaluated whether conflicting evidence for gender and racial/ethnic differences in nicotine dependence (ND) may be attributed to differences in psychometric properties of ND symptoms, particularly for young Hispanic smokers. Inadequate racial/ethnic diversity and limited smoking exposure variability has hampered research in young smokers. We used integrative data analysis (IDA) to pool DSM-IV ND symptom data for current smokers aged 12-25 (N = 20,328) from three nationally representative surveys (1999, 2000 National Surveys on Drug Use and Health (NSDUH) and Wave 1 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC). Moderated nonlinear factor analysis (MNLFA) tested symptom measurement invariance in the pooled sample containing greater ethnic and smoking exposure variability. There was study noninvariance for most symptoms. NESARC participants were more likely to report tolerance, using larger amounts or for longer periods, inability to cut down/quit, and more time spent smoking at higher levels of ND severity, but reported emotional/physical health problems at lower ND severity. Four symptoms showed gender or race/ethnicity noninvariance, but observed differences were small. An ND severity factor score adjusting for symptom noninvariance related to study membership, gender, and race/ethnicity did not differ substantively from traditional DSM-IV diagnosis and number of endorsed symptoms in estimated gender and race/ethnicity differences in ND. Results were consistent with studies finding minimal gender and racial/ethnic differences in ND, and suggest that symptom noninvariance is not a major contributor to observed differences. Results support IDA as a potentially promising approach for testing novel ND hypotheses not possible in independent studies.

Developmental considerations in survival models as applied to substance use research

Survival analysis is a class of models that are ideal for evaluating questions of timing of events, which makes them well-suited for modeling the development of a process such as initiation of substance use, development of addiction, or post-treatment recovery. The focus of this review paper is to demonstrate how survival models operate in a broader developmental framework and to offer guidance on selecting the appropriate model on the basis of the research question at hand. We provide a basic overview of survival models and then identify several key issues, explain how they pertain to research in the addiction field, and describe studies that utilize survival models to address questions about timing. We discuss the importance of carefully selecting the metric and origin of the time scale that corresponds to developmental process under investigation and we describe types of censoring/truncation. We describe the value of modeling covariates as time-invariant versus time-varying, and make the distinction between time-varying covariates and time-varying effects of covariates. We also explain how to test for substantive differences due to the timing of the assessment of the predictor. We finish the paper with a presentation of relatively novel extensions of survival models, including models that integrate standard statistical mediational analysis with discrete-time survival analysis, models that simultaneously consider order and timing of multiple events, and models that involve joint modeling of longitudinal and survival data. We also present our own substantive examples of various models in an Appendix containing annotated syntax and output.

Use of the Fagerström test to assess differences in the degree of nicotine dependence in smokers from five ethnic groups: The HELIUS study

BACKGROUND

The prevalence of smoking varies across ethnic groups in developed countries, but little is known about ethnic variations in specific aspects of nicotine dependence (ND). We conducted item-response analyses in current smokers to compare ND factors across five ethnic groups.

METHODS

Data were obtained from a population-based, multi-ethnic cohort study conducted in the Netherlands. The Fagerström Test for Nicotine Dependence (FTND) was assessed in 1147 Dutch, 991 South-Asian Surinamese, 1408 African Surinamese, 1396 Turkish, and 584 Moroccan smokers (N = 5526). We tested whether the factorial structure of the FTND was invariant across ethnic groups using a multi-group confirmatory factor analysis. FTND item and total scores and factor means were compared across groups.

RESULTS

The two-factor model representing "morning smoking" and "smoking patterns" provided an adequate fit. The items "Cigarettes smoked daily" and "Time until first cigarette" showed differential item functioning (DIF) as a function of ethnicity. Three out of four ethnic minority groups scored significantly higher on both factors compared to the Dutch origin group (all p < 0.001) before and after taking DIF into account, while the African Surinamese scored higher only on "morning smoking" when DIF was accounted for.

DISCUSSION

The factor structure of the FTND is not measurement invariant across ethnic groups in this population-based sample. Accounting for DIF affecting the nicotine dependence factor scores, although South-Asian Surinamese, Turkish, and Moroccan groups showed higher levels of dependence than the Dutch origin group, genetic as well as environmental factors may account for the observed differences.

Age of tobacco use initiation and association with current use and nicotine dependence among US middle and high school students, 2014-2016

INTRODUCTION

Tobacco use mostly begins in adolescence and young adulthood. Earlier age of initiation of cigarette smoking is associated with greater nicotine dependence and sustained tobacco use. However, data are limited on the age of initiation of non-cigarette tobacco products, and the association between using these products and nicotine dependence and progression to established use.

METHODS

Combined 2014-2016 National Youth Tobacco Survey data, a nationally representative cross-sectional survey of US students in grades 6-12 yielded 19 580 respondents who reported ever using any of five tobacco products: electronic cigarettes, cigarettes, cigars, smokeless tobacco and hookah. Analyses assessed age of reported first use of each product among ever-users, overall and by sex and race/ethnicity. Current daily use, past 30-day use, feelings of craving tobacco and time to first tobacco use after waking were assessed by age of first use.

RESULTS

Among ever-users, weighted median age for first use was 12.6 years for cigarettes, 13.8 years for cigars, 13.4 years for smokeless tobacco, 14.1 years for hookah and 14.1 years for e-cigarettes. First trying these tobacco products at age ≤13 years was associated with greater current use of the respective product and nicotine dependence compared with initiating use at age >13 years.

CONCLUSIONS

First tobacco use at age ≤13 years is associated with current daily and past 30-day use of non-cigarette tobacco products, and with the development of nicotine dependence among youth ever-users. Proven tobacco prevention interventions that reach early adolescents are important to reduce overall youth tobacco use.

Examination of the Involvement of Cholinergic-Associated Genes in Nicotine Behaviors in European and African Americans

Introduction

Cigarette smoking is a physiologically harmful habit. Nicotinic acetylcholine receptors (nAChRs) are bound by nicotine and upregulated in response to chronic exposure to nicotine. It is known that upregulation of these receptors is not due to a change in mRNA of these genes, however, more precise details on the process are still uncertain, with several plausible hypotheses describing how nAChRs are upregulated. We have manually curated a set of genes believed to play a role in nicotine-induced nAChR upregulation. Here, we test the hypothesis that these genes are associated with and contribute risk for nicotine dependence (ND) and the number of cigarettes smoked per day (CPD).

Methods

Studies with genotypic data on European and African Americans (EAs and AAs, respectively) were collected and a gene-based test was run to test for an association between each gene and ND and CPD.

Results

Although several novel genes were associated with CPD and ND at P < 0.05 in EAs and AAs, these associations did not survive correction for multiple testing. Previous associations between CHRNA3, CHRNA5, CHRNB4 and CPD in EAs were replicated.

Conclusions

Our hypothesis-driven approach avoided many of the limitations inherent in pathway analyses and provided nominal evidence for association between cholinergic-related genes and nicotine behaviors.

Implications

We evaluated the evidence for association between a manually curated set of genes and nicotine behaviors in European and African Americans. Although no genes were associated after multiple testing correction, this study has several strengths: by manually curating a set of genes we circumvented the limitations inherent in many pathway analyses and tested several genes that had not yet been examined in a human genetic study; gene-based tests are a useful way to test for association with a set of genes; and these genes were collected based on literature review and conversations with experts, highlighting the importance of scientific collaboration.

The Association Between Racial Discrimination and Suicidality among African-American Adolescents and Young Adults

This study assessed the association between racial discrimination and suicidality (ideation, plan, or attempt) in African-American adolescents and young adults (n = 806, mean age = 17.9 years). Structured psychiatric phone interviews were conducted in offspring and their mothers in a high-risk alcoholism family study. Logistic regression analyses using offspring's own racial discrimination as a predictor revealed elevated odds of suicidality, even after adjusting for correlated psychiatric conditions (OR = 1.76) but was reduced to non-significance after adjusting for maternal experiences of racial discrimination (OR = 3.19 in males), depression, and problem drinking. Findings support a link between racial discrimination and suicidality in African-American youth that, for males, is partially explained by maternal racial discrimination.

The Influence of Paternal Separation, Paternal History of Alcohol Use Disorder Risk, and Early Substance Use on Offspring Educational Attainment by Young Adulthood

OBJECTIVE

This study aimed to determine the associations among paternal alcohol problems, separation, and educational attainment in European American and African American offspring and whether offspring early alcohol/tobacco/marijuana use influenced these associations.

METHOD

Families with offspring ages 13-19 years at intake were selected from state birth records and screened by telephone to determine high-risk or low-risk status (with/without paternal heavy drinking). Families of men with two or more driving-under-the-influence offenses were added as a very-high-risk group. Data from 340 African American and 288 European American offspring who were not enrolled in school at their last interview were analyzed. Educational attainment was modeled as less than high school, high school only (reference category), and some college or higher. Separation was defined as offspring report of not having lived continuously in the same household with their biological father from birth to age 14. Analyses were stratified by race.

RESULTS

In European Americans, neither family risk status nor early alcohol/tobacco/marijuana use was associated with educational outcomes. However, paternal separation significantly elevated the likelihood of not completing high school in all models (relative risk ratios [RRRs] = 6.0-8.1, p <.001). For African American offspring, likelihoods of high school noncompletion were elevated marginally for paternal separation in only one model, but significantly for early marijuana use (RRRs = 2.8-3.2, p < .05). Very-high-risk status significantly reduced the likelihood of post-high school education in an adjusted model (RRR = 0.4, p < .05).

CONCLUSIONS

High school noncompletion was significantly associated with paternal separation in European Americans and with early marijuana use in African American offspring. In addition, very-high-risk status reduced the likelihood of post-high school education in African American offspring only, suggesting that research with ethnically diverse samples yields important differences when examining outcomes of both separation and substance use on offspring education.

Gender difference in early initiation of methamphetamine use among current methamphetamine users in Muse, Northern Shan State, Myanmar

Background

Globally, methamphetamine (MA) use is a significant public health concern due to unprecedented health effects of its use. However, gender similarities and differences in early age of MA initiation and its risk factors among current MA users have been understudied in a developing country setting.

Methods

A community-based, cross-sectional study was conducted using a computer assisted self-interviewing program from January to March 2013 in Muse, Northern Shan State, Myanmar. A total of 1362 (775 male and 587 female) self-reported current MA users aged between 18 and 35 years were recruited using respondent-driven sampling. Two gender-stratified multiple logistic regression models (models I and II) were done for analysis.

Results

For similarities, 73.0% of males and 60.5% of females initiated MA before their 18th birthday. The early age of MA initiation was positively associated with the reasons and places of the first time MA use among both genders. For differences, males [hazard ratio 1.35; 95% confidence interval, 1.18–1.54] had a significantly higher risk than females to initiate MA at earlier age. Among male users, participants who had bisexual/homosexual preferences were more likely to initiate MA use earlier. In contrast, female users who exchanged sex for money and/or drugs were more likely to initiate MA in earlier age.

Conclusions

More than 60.0% of male and female participants initiated MA use early; however, males initiated use earlier than females. Although similarities were found among both genders, differences found in key risk factors for early age MA initiation suggest that gender-specific, MA prevention programs are urgently needed in Myanmar.

Racial differences in heritability of cigarette smoking in adolescents and young adults

INTRODUCTION

Although epidemiologic studies suggest low levels of cigarette use among African American adolescents relative to White U.S. adolescents, it is not known whether this may be due to racial differences in the relative contribution of genes and environment to cigarette use initiation and progression to regular use.

METHODS

Using data from White (n=2665) and African American (n=809) twins and full siblings sampled in the National Longitudinal Study of Adolescents, we fitted age-, sex- and race-specific variance decomposition models to estimate the magnitude of genetic and environmental effects on cigarette use initiation and cigarette use quantity in Whites and African Americans across adolescence and adulthood. We employ a causal-contingent-common pathway model to estimate the amount of variance explained in quantity of cigarettes smoked contingent on cigarette use initiation.

RESULTS

African Americans had lower cigarette use prevalence from adolescence through adulthood, and used cigarettes less heavily than Whites. Race-specific causal-contingent-common pathway models indicate that racial differences in genetic and environmental contributions to cigarette use initiation and cigarette use quantities are not present in adolescence but appear in young adulthood. Additive genetic factors were an important risk factor for cigarette use initiation for White but not African American young adults and adults.

CONCLUSIONS

Genetic and environmental contributions for cigarette use are similar by race in adolescence. In adulthood, genes have a stronger influence for cigarette use among White adolescents while the influence of the environment is minimal. For African Americans, both genetic and environmental influences are important in young adulthood and adulthood.

Childhood sexual abuse and two stages of cigarette smoking in African-American and European-American young women

OBJECTIVE

The aim of the current study was to determine whether the higher rates of childhood sexual abuse (CSA) but lower rates of cigarette smoking in African-American vs. European-American women can be explained in part by a lower magnitude of association between CSA and smoking in African-American women.

METHODS

Data were drawn from a same-sex female twin study of substance use (n=3521; 14.3% African-American). Cox proportional hazards regression analyses using CSA to predict smoking initiation and progression to regular smoking were conducted separately by race/ethnicity. Co-twin status on the smoking outcome was used to adjust for familial influences on smoking (which may overlap with family-level influences on CSA exposure).

RESULTS

After adjusting for co-twin status, CSA was associated with smoking initiation in European Americans (hazard ratio (HR)=1.43, 95% confidence intervals (CI): 1.26-1.62) and with smoking initiation ≤16 in African Americans (HR=1.70, CI: 1.26-2.29). CSA was associated with regular smoking onset ≤15 in European Americans (HR=1.63, CI: 1.21-2.18), with no change in HR after adjusting for co-twin status. In the African-American subsample, the HR for CSA was reduced to non-significance after adjusting for co-twin status (from HR=3.30, CI: 1.23-8.89 to HR=1.16, CI: 0.71-1.92 for regular smoking ≤15).

CONCLUSIONS

CSA is associated with moderate elevation in risk for initiating smoking among African-American and European-American women. By contrast, CSA is associated with elevated risk for (adolescent onset) regular smoking only in European-American women. Furthermore, there is significant overlap between risk conferred by CSA and familial influences on regular smoking in African-American but not European-American women.

The Association of Low Parental Monitoring With Early Substance Use in European American and African American Adolescent Girls

OBJECTIVE

Research indicates that low parental monitoring increases the risk for early substance use. Because low parental monitoring tends to co-occur with other familial and neighborhood factors, the specificity of the association is challenging to establish. Using logistic regression and propensity score analyses, we examined associations between low parental monitoring and early substance use in European American (EA) and African American (AA) girls, controlling for risk factors associated with low parental monitoring.

METHOD

Participants were 3,133 EA and 523 AA girls from the Missouri Adolescent Female Twin Study with data on parental monitoring assessed via self-report questionnaire, and with ages at first use of alcohol, tobacco, and cannabis queried in at least one of three diagnostic interviews (median ages = 15, 22, and 24 years).

RESULTS

The rate of early alcohol use was greater in EA than AA girls, whereas the proportion of AA girls reporting low parental monitoring was higher than in EA girls. EA girls who experienced low parental monitoring were at elevated risk for early alcohol, tobacco, and cannabis use, findings supported in both logistic regression and propensity score analyses. Evidence regarding associations between low parental monitoring and risk for early substance use was less definitive for AA girls.

CONCLUSIONS

Findings highlight the role of parental monitoring in modifying risk for early substance use in EA girls. However, we know little regarding the unique effects, if any, of low parental monitoring on the timing of first substance use in AA girls.

Genetic and environmental contributions to initiation of cigarette smoking in young African-American and European-American women

BACKGROUND

Distinctions in the relative contributions of genetic and environmental factors to initiation of cigarette smoking may explain, in part, the differences between African Americans and European Americans in the prevalence of smoking. The current investigation is the first to compare heritable and environmental influences on smoking initiation between African-American and European-American women.

METHODS

Data were drawn from Missouri Adolescent Female Twin Study participants and female Missouri Family Study participants (n=4498; 21% African-American, the remainder European-American). Mean ages at first and last assessments were 17.0 (SD=3.5) and 24.0 (SD=3.2), respectively. Twin-sibling modeling was conducted to estimate the proportion of variance in smoking initiation (i.e., ever trying a cigarette) attributable to additive genetic, shared environmental, special twin environmental, and unique environmental factors.

RESULTS

Additive genetic influences accounted for approximately half of the variance in smoking initiation in both African-American and European-American women. In the African-American subsample, the remaining variance was attributable primarily to unique environmental factors (46%; 95% CI: 28-71%). In the European-American subsample, only 12% (95% CI: 8-16%) of the variance was attributable to unique environmental factors, with the remainder accounted for by shared environmental (13%; 95% CI: 0-41%) and special twin environmental (24%; 95% CI: 0-52%) factors.

CONCLUSIONS

The estimated heritability of smoking initiation is substantial and nearly identical for African-American and European-American women, but the type of environmental factors that contribute to risk differ by race/ethnicity. Whereas the primary environmental influences on European-American women's smoking initiation are at the family level, those that impact African-American women's smoking initiation are primarily individual-specific.

Intergenerational Patterns of Smoking and Nicotine Dependence Among US Adolescents

OBJECTIVES

We examined associations between parental and adolescent smoking and nicotine dependence in the United States.

METHODS

We used data from the 2004 to 2012 National Survey on Drug Use and Health, which ascertained smoking behaviors of 1 parent and 1 adolescent aged 12 to 17 years in 35 000 dyads. We estimated associations between parental and adolescent smoking behaviors, adjusted for covariates.

RESULTS

Parental current dependence was strongly associated with adolescents' lifetime smoking (adjusted odds ratio [AOR] = 2.96; 95% confidence interval [CI] = 2.47, 3.55), whereas parental current nondependent smoking (AOR = 2.26; 95% CI = 1.92, 2.67) and former smoking (AOR = 1.51; 95% CI = 1.31, 1.75) were less strongly associated. Only parental nicotine dependence was associated with adolescent nicotine dependence (AOR = 1.66; 95% CI = 1.00, 2.74). Associations between parental and adolescent smoking did not differ by race/ethnicity. Parents' education, marital status, and parenting and adolescents' mental health, beliefs about smoking, perception of schoolmates' smoking, and other substance use predicted adolescent smoking and dependence.

CONCLUSIONS

Reducing parental smoking would reduce adolescent smoking. Prevention efforts should encourage parental smoking cessation, improve parenting, address adolescent mental health, and reinforce adolescents' negative beliefs about smoking.

Developmental Changes in Genetic and Shared Environmental Contributions to Smoking Initiation and Subsequent Smoking Quantity in Adolescence and Young Adulthood

BACKGROUND

Few studies examining the genetic architecture of cigarette smoking have focused on adolescents or examined developmental changes in additive genetic, shared environment, and unique environmental influences on liability to initiate cigarette smoking and quantity of cigarettes smoked. The aim of this study was to add to the literature on liability to initiate and use cigarettes during adolescence using a nationally representative sample.

METHOD

Data for this study came from adolescent and young adult twin pairs (aged 14-33 years) from the National Longitudinal Study of Adolescent to Adult Health. We ran a series of developmental causal-contingent-common pathway models to examine whether additive genetic, shared, and unique environmental influences on liability to the initiation of cigarette use are shared with those on smoking quantity, and whether their contributions change across development.

RESULTS

We found evidence for a developmental shift in genetic and shared environmental contributions to cigarette use. Early in adolescence, genetic and environmental influences work independently on liability to cigarette smoking initiation and quantity of cigarettes smoked, but liability to these behaviors becomes correlated as individuals age into young adulthood.

CONCLUSIONS

These findings provide insight into the causal processes underlying the liability to smoke cigarettes. With age, there is greater overlap in the genetic and environmental factors that influence the initiation of cigarette smoking and quantity of cigarettes smoked.

Predictors, indicators, and validated measures of dependence in menthol smokers

This article presents a comprehensive review of the menthol cigarette dependence-related literature and results from an original analysis of the Total Exposure Study (TES), which included 1,100 menthol and 2,400 nonmenthol adult smokers. The substantial scientific evidence available related to age of first cigarette, age of regular use, single-item dependence indicators (smoking frequency, cigarettes per day, time to first cigarette, night waking to smoke), smoking duration, numerous validated and widely accepted measures of nicotine/cigarette dependence, and our analysis of the TES do not support that menthol smokers are more dependent than nonmenthol smokers or that menthol increases dependence.

Smoking and the developing brain: altered white matter microstructure in attention-deficit/hyperactivity disorder and healthy controls

Brain white matter (WM) tracts, playing a vital role in the communication between brain regions, undergo important maturational changes during adolescence and young adulthood, a critical period for the development of nicotine dependence. Attention-deficit/hyperactivity disorder (ADHD) is associated with increased smoking and widespread WM abnormalities, suggesting that the developing ADHD brain might be especially vulnerable to effects of smoking. This study aims to investigate the effect of smoking on (WM) microstructure in adolescents and young adults with and without ADHD. Diffusion tensor imaging was performed in an extensively phenotyped sample of nonsmokers (n = 95, 50.5% ADHD), irregular smokers (n = 41, 58.5% ADHD), and regular smokers (n = 50, 82.5% ADHD), aged 14-24 years. A whole-brain voxelwise approach investigated associations of smoking, ADHD and their interaction, with WM microstructure as measured by fractional anisotropy (FA) and mean diffusivity (MD). Widespread alterations in FA and MD were found for regular smokers compared to irregular and nonsmokers, mainly located in the corpus callosum and WM tracts surrounding the basal ganglia. Several regions overlapped with regions of altered FA for ADHD versus controls, albeit in different directions. Irregular and nonsmokers did not differ, and ADHD and smoking did not interact. Results implicate that smoking and ADHD have independent effects on WM microstructure, and possibly do not share underlying mechanisms. Two mechanisms may play a role in the current results. First, smoking may cause alterations in WM microstructure in the maturing brain. Second, pre-existing WM microstructure differences possibly reflect a risk factor for development of a smoking addiction.

A history of ashes: an 80 year comparative portrait of smoking initiation in American Indians and Non-Hispanic whites--the Strong Heart Study

The consequences of starting smoking by age 18 are significant. Early smoking initiation is associated with higher tobacco dependence, increased difficulty in smoking cessation and more negative health outcomes. The purpose of this study is to examine how closely smoking initiation in a well-defined population of American Indians (AI) resembles a group of Non-Hispanic white (NHW) populations born over an 80 year period. We obtained data on age of smoking initiation among 7,073 AIs who were members of 13 tribes in Arizona, Oklahoma and North and South Dakota from the 1988 Strong Heart Study (SHS) and the 2001 Strong Heart Family Study (SHFS) and 19,747 NHW participants in the 2003 National Health Interview Survey. The participants were born as early as 1904 and as late as 1985. We classified participants according to birth cohort by decade, sex, and for AIs, according to location. We estimated the cumulative incidence of smoking initiation by age 18 in each sex and birth cohort group in both AIs and NHWs and used Cox regression to estimate hazard ratios for the association of birth cohort, sex and region with the age at smoking initiation. We found that the cumulative incidence of smoking initiation by age 18 was higher in males than females in all SHS regions and in NHWs (p < 0.001). Our results show regional variation of age of initiation significant in the SHS (p < 0.001). Our data showed that not all AIs (in this sample) showed similar trends toward increased earlier smoking. For instance, Oklahoma SHS male participants born in the 1980s initiated smoking before age 18 less often than those born before 1920 by a ratio of 0.7. The results showed significant variation in age of initiation across sex, birth cohort, and location. Our preliminary analyses suggest that AI smoking trends are not uniform across region or gender but are likely shaped by local context. If tobacco prevention and control programs depend in part on addressing the origin of AI smoking it may be helpful to increase the awareness in regional differences.

Determinants of incident chronic kidney disease and progression in a cohort of HIV-infected persons with unrestricted access to health care

OBJECTIVES

As socioeconomic factors may impact the risk of chronic kidney disease (CKD), we evaluated the incidence and risk factors of incident CKD among an HIV-infected cohort with universal access to health care and minimal injecting drug use (IDU).

METHODS

Incident CKD was defined as an estimated glomerular filteration rate (eGFR) <60 ml/min/1.73 m(2) for ≥ 90 days. eGFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Rates were calculated per 1000 person-years (PY). Associations with outcomes were assessed using two separate Cox proportional hazard models, adjusting for baseline and time-updated covariates.

RESULTS

Among 3360 participants [median age 29 years; 92% male; 44% African American (AA)] contributing 23,091 PY of follow-up, 116 developed incident CKD [5.0/1000 PY; 95% confidence interval (CI) 4.2-6.0/1000 PY]. The median first eGFR value was 97.0 mL/min/1.73 m(2) [interquartile range (IQR) 85.3-110.1 mL/min/1.73 m(2)]. Baseline factors associated with CKD included older age, lower CD4 count at HIV diagnosis [compared with CD4 count ≥ 500 cells/μL, hazard ratio (HR) 2.1 (95% CI 1.2-3.8) for CD4 count 350-499 cells/μL; HR 3.6 (95% CI 2.0-6.3) for CD4 count 201-349 cells/μL; HR 4.3 (95% CI 2.0-9.4) for CD4 count ≤ 200 cells/μL], and HIV diagnosis in the pre-highly active antiretroviral therapy (HAART) era. In the time-updated model, low nadir CD4 counts, diabetes, hepatitis B, hypertension and less HAART use were also associated with CKD. AA ethnicity was not associated with incident CKD in either model.

CONCLUSIONS

The low incidence of CKD and the lack of association with ethnicity observed in this study may in part be attributable to unique features of our cohort such as younger age, early HIV diagnosis, minimal IDU, and unrestricted access to care. Lower baseline CD4 counts were significantly associated with incident CKD, suggesting early HIV diagnosis and timely introduction of HAART may reduce the burden of CKD.