Confidence interval estimation in R-DAS

Similarities and Differences in Alcohol & Other Drug Dependence Among Hispanic/Latino Subgroups: A Disaggregation Approach

Background

Hispanic/Latino (H/L) heritage civilians out-number all other non-White ethnic groups in the United States. When studied as one group, H/L diversity is ignored, including rates of drug misuse. This study's aim was to examine H/L diversity regarding drug dependence by disaggregating how the burdens of active alcohol or other drug dependence (AODD) might change if we were to address syndromes drug by drug.

Method

Studying non-institutionalized H/L residents from the National Surveys on Drug Use and Health (NSDUH) 2002-2013 probability samples, we utilized online Restricted-use Data Analysis System variables to identify ethnic heritage subgroups and active AODD via computerized self-interviews. We estimated case counts of AODD with analysis-weighted cross-tabulations and variances from Taylor series. Radar plots disclose AODD variations when we simulate the reductions of drug-specific AODD one by one.

Results

For all H/L heritage subgroups, the most substantial AODD decline might be achieved by reducing active alcohol dependence syndromes, followed by declines of cannabis dependence. The burdens due to active syndromes attributed to cocaine and pain relievers vary somewhat across subgroups. For the Puerto Rican subgroup, our estimates reveal potentially important burden reduction if active heroin dependence can be decreased.

Conclusion

A sizeable reduction in the H/L population health burden attributable to AODD syndromes might be achieved via the effective decline of alcohol and cannabis dependence among all subgroups. Future research includes a systematic replication with recent NSDUH survey data, as well as various stratifications. If replicated, the need for targeted drug-specific interventions among H/L will become unequivocal.

Cocaine dependence: "Side effects" and syndrome formation within 1-12 months after first cocaine use

BACKGROUND

This project offers new epidemiological estimates for DSM-IV cocaine dependence among sub-groups of newly incident cocaine users in the United States (US), including estimated attack rates for 21 dependence-related cocaine side effect problems and experiences occurring <12 months after onset.

METHOD

In 2002-2016, US National Surveys on Drug Use and Health (NSDUH) sampled, recruited, and assessed cocaine experiences of non-institutionalized civilians. Unweighted estimates for year-pairs (2002-3,…,2015-16) are from 3488 cocaine powder-only initiates and 275 powder-then-crack initiates (all evaluated <12 months after onset). Analysis-weighted attack rate estimates are incidence proportions with 95% confidence intervals (CI), summarized via meta-analysis.

RESULTS

Evaluated <12 months after onset, meta-analysis summaries show 5% of powder-only initiates developed cocaine dependence (95% CI = 4%, 6%) versus 22% of powder-then-crack initiates (95% CI = 17%, 29%). For several cocaine side effect problems and experiences (e.g., 'loss of control' indicators) there is a statistically robust crack-associated excess risk.

CONCLUSIONS

Three interpretations of observed crack-associated excess risk are especially cogent and deserving of continued inquiry: (1) Powder-then-crack initiates start with heightened dependence risk susceptibilities (i.e., pre-dating onset); (2) Powder-using initiates become cocaine dependent and then start using crack; (3) The cocaine delivery variant of 'crack-smoking' is more toxic than powder insufflation. For powder-then-crack initiates, the cocaine dependence risk (22%) is modestly lower but statistically undifferentiable from a recently estimated risk of heroin dependence <12 months after heroin onset (30%). Clinicians can use these side effect estimates in an evidence-based diagnostic workup when patients disclose new onsets of cocaine use.

Estimated effect of US state syringe sale policy on source of last-used injection equipment

BACKGROUND

Many people who inject drugs (PWID) lack access to a new sterile syringe each time they inject, with increased risk of injection-related harms, including spread of communicable diseases. In the United States (US), restricted access is largely due to state laws and policies regulating syringe access. Our aim in this US-focused study is to estimate variations in syringe acquisition behavior in relation to state-level syringe sale policies, drawing upon self-identified PWID in a nationally representative sample survey.

METHODS

Estimates were obtained on the source of the last used syringe from participants of the National Survey on Drug Use and Health (NSDUH) years 2002-2011. States were classified as having restricted syringe policies if they had any restriction on the sale of syringes during the study period (e.g., required a prescription or limited the number being sold).

RESULTS

In states with unrestricted syringe sale policies, PWID were more likely to have obtained their most recently used syringe from a safe source (Difference (%) = 9.8, 95% CI: 1.9, 17.7). This difference was largely driven by a larger percent of injectors obtaining syringes from a pharmacy in unrestricted states (Difference = 20.4, 95% CI: 12.2, 28.6) but was partially offset by fewer injectors obtaining syringes from syringe exchange programs (Difference = -10.7, 95% CI: -16.1, -5.3).

CONCLUSION

These new findings, taken with other evidence, should help promote removal of policy barriers that now thwart syringe acquisition from a safe source. We hope this additional evidence will provoke policy discussions and may influence regulations that promote public health and reduce the spread of communicable diseases.

Cannabis use among women of reproductive age in the United States: 2002-2017

BACKGROUND

In this study of cannabis use in large nationally representative samples of United States (US) women aged 12-44 years, we evaluate variation by pregnancy month and by trimester. We also evaluate cannabis dependence, which might explain why some women continue using cannabis during pregnancy.

METHODS

Large nationally representative samples drawn for the US National Surveys on Drug Use and Health included 12-44-year-old women asked about pregnancy month, cannabis use, and cannabis dependence (n = 381,199). For this research, we produced month-specific estimates across four-time intervals (2002-2005, 2006-2009, 2010-2013, 2014-2017).

RESULTS

Overall from 2002 to 2017, estimates for non-pregnant women and for pregnant women in Trimester 1 indicate 7%-8% had used cannabis at least once in the 30 days prior to assessment. For pregnancy Month 1, the corresponding estimate is 11%, double Month 3 estimate of 5%. This degree of month-to-month variation is not seen for pregnant women in Trimesters 2 and 3, for whom estimates are 3% and 2%, respectively. Among women using cannabis during pregnancy, an estimated 19% have cannabis dependence, versus an expected value of 13% among non-pregnant women (p < .05).

CONCLUSION

Evidence of a possibly ameliorative pregnancy-associated reduction of cannabis use prevalence was seen by Month 3 during pregnancy. Cannabis dependence may help account for cannabis use early during pregnancy. Identification and outreach to reproductive age women with cannabis dependence might decrease prenatal cannabis exposure.

Young, American Indian or Alaskan Native, and born in the USA: at excess risk of starting extra-medical prescription pain reliever use?

BACKGROUND

Prescription pain reliever (PPR) overdoses differentially affect 'American Indian/Alaskan Natives' in the United States (US). Here, studying onset of extra-medical PPR use in 12-24-year-olds, we examine subgroup variations in rates of starting to use prescription pain relievers extra-medically (i.e., to get 'high' or for other reasons outside boundaries of prescriber's intent). Risk differences (RD) are estimated for US-born versus non-US-born young people, stratified by American Indian/Alaskan Natives versus other ethnic self-identities.

METHODS

Between 2002-2009, nationally representative cross-sectional samples of 12-24-year-old non-institutionalized civilians completed interviews for the US National Surveys of Drug Use and Health. Analysis-weighted annual incidence estimates, RD, and confidence intervals (CI) are from the Restricted-use Data Analysis System, an online software tool for US National Surveys of Drug Use and Health.

RESULTS

Each year, an estimated 2.5% of 12-24-year-olds in the US start using PPR extra-medically (95% CI [2.1%-3.0%]). Estimates for the US-born (3.8%; 95% CI [3.7%-3.9%]) are larger (non-US-born: 1.8%; 95% CI [1.5%-2.0%]; RD = 2.0; p < 0.05). US-born American Indian/Alaskan Natives youths have the largest incidence rate (4.8%). Robust RD for US-born can be seen for 'non-Hispanic White' subgroups, and for others (e.g., 'Cuban', 'Dominican').

DISCUSSION

Each year, one in 20 of US-born American Indian/Alaskan Natives starts using PPR extra-medically. Overdose prevention is important, but is no substitute for primary prevention initiatives for all young people. The observed epidemiological patterns can guide targeted prevention initiatives for the identified higher risk subgroups in complement with more universal prevention efforts intended to reduce incidence of first extra-medical PPR use, a crucial rate-limiting step on the path toward more serious drug involvement (i.e., progressing past initial use).

Newly incident cannabis use in the United States, 2002-2011: a regional and state level benchmark

Background

Cannabis use and cannabis regulatory policies recently re-surfaced as noteworthy global research and social media topics, including claims that Mexicans have been sending cannabis and other drug supplies through a porous border into the United States. These circumstances prompted us to conduct an epidemiological test of whether the states bordering Mexico had exceptionally large cannabis incidence rates for 2002–2011. The resulting range of cannabis incidence rates disclosed here can serve as 2002–2011 benchmark values against which estimates from later years can be compared.

Methods

The population under study is 12-to-24-year-old non-institutionalized civilian community residents of the US, sampled and assessed with confidential audio computer-assisted self-interviews (ACASI) during National Surveys on Drug Use and Health, 2002–2011 (aggregate n ∼ 420,000) for which public use datasets were available. We estimated state-specific cannabis incidence rates based on independent replication sample surveys across these years, and derived meta-analysis estimates for 10 pre-specified regions, including the Mexico border region.

Results

From meta-analysis, the estimated annual incidence rate for cannabis use in the Mexico Border Region is 5% (95% CI [4%–7%]), which is not an exceptional value relative to the overall US estimate of 6% (95% CI [5%–6%]). Geographically quite distant from Mexico and from states of the western US with liberalized cannabis policies, the North Atlantic Region population has the numerically largest incidence estimate at 7% (95% CI [6%–8%]), while the Gulf of Mexico Border Region population has the lowest incidence rate at 5% (95% CI [4%–6%]). Within the set of state-specific estimates, Vermont’s and Utah’s populations have the largest and smallest incidence rates, respectively (VT: 9%; 95% CI [8%–10%]; UT: 3%; 95% CI [3%–4%]).

Discussion

Based on this study’s estimates, among 12-to-24-year-old US community residents, an estimated 6% start to use cannabis each year (roughly one in 16). Relatively minor variation in region-wise and state-level estimates is seen, although Vermont and Utah might be exceptional. As of 2011, proximity to Mexico, to Canada, and to the western states with liberalized policies apparently has induced little variation in cannabis incidence rates. Our primary intent was to create a set of benchmark estimates for state-specific and region-specific population incidence rates for cannabis use, using meta-analysis based on independent US survey replications. Public health officials and policy analysts now can use these benchmark estimates from 2002–2011 for planning, and in comparisons with newer estimates.

Estimated probability of becoming a case of drug dependence in relation to duration of drug-taking experience: a functional analysis approach

Measured as elapsed time from first use to dependence syndrome onset, the estimated "induction interval" for cocaine is thought to be short relative to the cannabis interval, but little is known about risk of becoming dependent during first months after onset of use. Virtually all published estimates for this facet of drug dependence epidemiology are from life histories elicited years after first use. To improve estimation, we turn to new month-wise data from nationally representative samples of newly incident drug users identified via probability sampling and confidential computer-assisted self-interviews for the United States National Surveys on Drug Use and Health, 2004-2013. Standardized modules assessed first and most recent use, and dependence syndromes, for each drug subtype. A four-parameter Hill function depicts the drug dependence transition for subgroups defined by units of elapsed time from first to most recent use, with an expectation of greater cocaine dependence transitions for cocaine versus cannabis. This study's novel estimates for cocaine users one month after first use show 2-4% with cocaine dependence; 12-17% are dependent when use has persisted. Corresponding cannabis estimates are 0-1% after one month, but 10-23% when use persists. Duration or persistence of cannabis smoking beyond an initial interval of a few months of use seems to be a signal of noteworthy risk for, or co-occurrence of, rapid-onset cannabis dependence, not too distant from cocaine estimates, when we sort newly incident users into subgroups defined by elapsed time from first to most recent use. Copyright © 2016 John Wiley & Sons, Ltd.

Epidemiological research on parent-child conflict in the United States: subgroup variations by place of birth and ethnicity, 2002-2013

Background

Chronically escalated parent–child conflict has been observed to elicit maladaptive behavior and reduced psychological well-being in children and youth. In this epidemiological study, we sought to estimate the occurrence of escalated parent–child conflict for United States (US) adolescent subgroups defined by (a) ethnic self-identification, and (b) nativity (US-born versus foreign-born).

Methods

US study populations of 12-to-17-year-olds were sampled, recruited, and assessed for the National Surveys on Drug Use and Health (NSDUH), 2002–2013 (n = 111, 129). Analysis-weighted contingency table analyses contrasted US-born versus foreign-born who self-identified as: (a) Hispanic, (b) non-Hispanic African-American, (c) non-Hispanic Asian, and (c) non-Hispanic White.

Results

Frequently escalated parent–child conflict was most prevalent among US-born non-Hispanic White adolescents, from 18% at age 12 (95% CI [17.6%, 18.9%]) to 29% at age 17 (95% CI [28.3%, 29.7%]), followed by US-born Hispanic and non-Hispanic Asian children. Estimated prevalence proportions were markedly lower for African-American children, from 8% at age 12 (95% CI [6.8, 8.5]) to 16% at age 17 (95% CI [14.3, 16.7]). Broad and sometimes overlapping CI indicate that larger sample sizes are needed for complete evaluation of an apparent excess occurrence of frequent parent-child conflict among US-born versus foreign-born. Nonetheless, in the larger subgroups, the US-born show a clear excess occurrence of frequent parent-child conflict. For example, US-born Mexican children have 1.7 times higher odds of experiencing frequent parent-child conflict than foreign-born Mexican children (OR = 1.7, 95% CI [1.5, 2.0], p-value < 0.001).

Discussion

The main discovery from this multi-ethnic sample investigation is a rank-ordering of parent-child conflict prevalence estimates from high (non-Hispanic White) to low (non-Hispanic African-American). The pattern also suggests a possibly generalizable excess associated with US-born sub-groups. The epidemiological estimates presented here merit attention in future cross-cultural research focused on parent-child conflict.

Taking the First Full Drink: Epidemiological Evidence on Male-Female Differences in the United States

BACKGROUND

This research extends prior epidemiological estimates for the United States and re-examines a previously described male excess in alcohol drinking. Its aim was to estimate fine-grained age-specific incidence of becoming a drinker among 12- to 24-year-old U.S. males and females, and to compare incidence estimates with prevalence proportions.

METHODS

The study population is 12- to 24-year-old noninstitutionalized U.S. civilian residents. Estimates are from 12 successive U.S. National Surveys on Drug Use and Health (NSDUH), with nationally representative samples drawn each year from 2002 to 2013 and assessed via computer-assisted self-interviews (n ~ 390,000). Analysis-weighted incidence and prevalence estimates are generated using the NSDUH Restricted Data Analysis System for 6 year-pairs. Meta-analysis-derived summary estimates are provided, treating each year-pair as a replication.

RESULTS

In this 21st century evidence, there no longer is male excess of incidence with respect to underage drinking. Indeed, in mid-adolescence, there is a clear female excess for the risk of becoming an underage drinker. Meta-analytic summaries disclosed no other male-female differences in incidence. Nevertheless, a male excess in the prevalence of recently active drinking can be seen after the age of 19 years.

CONCLUSIONS

This new evidence from the United States shows that the so-called "gender gap" in risk of becoming a drinker has narrowed to the point of there being no gap at all. Indeed, in mid-adolescence, risk of starting to drink is greater for females than for males.

Monthly Estimates of Alcohol Drinking During Pregnancy: United States, 2002-2011

OBJECTIVE

Taking a step beyond prior alcohol research on pregnancy trimesters, we produced pregnancy month-specific drinking estimates for women in the United States in order to shed light on time variations of alcohol drinking during pregnancy, as might be determined by alcohol dependence. We posited that (a) pregnancy might prompt cessation of drinking soon after pregnancy status is discovered, a finding obscured in trimester-specific estimates, and (b) a possible alcohol-dependence effect on drinking persistence among pregnant women might be observed via the monthly approach.

METHOD

Data are from the 2002-2011 National Surveys on Drug Use and Health (Restricted-Data Analysis System [R-DAS]), with large nationally representative samples of U.S. civilians, including 12- to 44-year-old females stratified by pregnancy status and month of pregnancy, and with assessment of recent alcohol dependence as well as heavy episodic drinking (HED).

RESULTS

Pregnancy's possibly protective constraints on drinking can be seen as early as Month 2. We observed considerable variability of drinking prevalence (%) before Trimester 1 ended, with no appreciable variation across Months 4-9. A possible alcohol-dependence effect on drinking persistence is seen when the contrast is made in relation to expected values for pregnant women without alcohol dependence.

CONCLUSIONS

We detected a possibly ameliorative pregnancy effect on alcohol use and HED, with variation in drinking prevalence across the months of the first trimester. Alcohol dependence might be affecting drinking persistence among pregnant women, but this effect cannot account for the drinking persistence observed here.

Inter-relationships Linking Probability of Becoming a Case of Nicotine Dependence With Frequency of Tobacco Cigarette Smoking

INTRODUCTION

Once smoking starts, some tobacco cigarette smokers (TCS) can make very rapid transitions into tobacco dependence syndromes (TCD). With adjustment for smoking frequency, we posit female excess risk for this rapid-onset TCD. In a novel application of functional analysis for tobacco research, we estimate four Hill function parameters and plot TCD risk against a gradient of smoking frequency, as observed quite soon after smoking onset.

METHODS

In aggregate, the National Surveys of Drug Use and Health, 2004-2013, identified 1546 newly incident TCS in cross-sectional research, each with standardized TCD assessment.

RESULTS

Hill function estimates contradict our apparently over-simplistic hypothesis. Among newly incident TCS males with only 1-3 recent smoking days, an estimated 1%-3% had become rapid-onset TCD cases; non-overlapping confidence intervals show lower TCD risk for females. In contrast, among daily smokers, closer to 50% of female TCS showed rapid-onset TCD, versus under 20% of male TCS, but a larger sample will be needed to confirm the apparent female excess risk at the daily smoking frequency level.

CONCLUSIONS

Smoking frequency and TCD onset become inter-dependent quite soon after TCS onset. Feedback loops are expected, and might explain a potential reversal of male-female differences across smoking frequency gradients. These novel epidemiological estimates prompt new thinking and questions about interventions.

IMPLICATIONS

In this large sample epidemiological study, with a nationally representative sample of newly incident TCS assessed cross-sectionally, we see a quite rapid onset of tobacco dependence, with an early male excess that fades out at higher levels of smoking frequency. Next steps include development of outreach and intervention for this very rapid-onset tobacco dependence.

Transitioning from First Drug Use to Dependence Onset: Illustration of a Multiparametric Approach for Comparative Epidemiology

Studying transitions from first drug use (DU) to drug dependence (DD) onset, we estimate a parsimonious set of parameters based on epidemiological data, with plans for future longitudinal research on newly incident drug users and with tracking of self-administration frequencies and DD clinical features. Our expectation is a distinctive sigmoid pattern with one asymptote for lower DD probability (when DU is insubstantial), upturning slopes of DD risk beyond a middle value (PD50), and eventual higher DD risk asymptotes at higher DU frequencies. We illustrate this novel approach using cross-sectional data from the United States National Surveys on Drug Use and Health, 2002-2011. Empirical DD probabilities observed soon after newly incident use are estimated across DU frequency values, using parametric Hill functions and four governing parameters for differential comparison across drugs and DU subgroups. Among drug subtypes considered, cocaine shows larger estimates, especially among females (estimated P(min)=7% for females vs 3% for males; p<0.001), for whom PD50 is shorter by 8 days of use (p=0.027), conditional on the same rate of use in the past 30 days. Clear alcohol male-female differences also are observed (eg, female PD50 < male PD50; p=0.002). Although based on cross-sectional snapshots soon after DU onset, this novel multiparametric statistical approach for comparative epidemiological DD research creates new opportunities in planned studies with prospectively gathered longitudinal data. The cross-sectional estimates provide starting values needed to plan future longitudinal research programs on transitions from initial DU until formation of a DD syndrome.

Epidemiological evidence on extra-medical use of prescription pain relievers: transitions from newly incident use to dependence among 12-21 year olds in the United States using meta-analysis, 2002-13

Background. When 12-to-21-year-olds start using prescription pain relievers extra-medically, some of them transition into opioid dependence within 12 months after such use. Our main aim for this epidemiological research on 12-to-21-year-olds in the United States (US) is to estimate the risk of becoming a newly incident case of opioid dependence within 12 months after onset of using prescription pain relievers extra-medically (EMPPR). Methods. Meta-analyses from multiple independent replication samples now are possible, based upon nationally representative survey samples of US adolescents age 12-21 years. All 12-to-21-year-olds were sampled and recruited for the US National Surveys on Drug Use and Health, with standardized assessments of EMPPR use and opioid dependence (NSDUH, 2002-2013). Results. Peak risk for a transition from start of EMPPR use to opioid dependence within 12 months is seen at mid-adolescence among 14-to-15-year-olds (6.3%, 8.7% per year), somewhat earlier than peak risk for starting EMPPR use (seen for 16-to-19-year-olds at 4.1%, 5.9% per year). Applied to 12-to-21-year-olds in the US between 2002-2013, an estimated 8 million started using PPR extra-medically. Each year, roughly 42,000 to 58,000 transitioned into opioid dependence within 12 months after onset of such use. Discussion. These epidemiological estimates for the US in recent years teach us to expect one transition into adolescent-onset opioid dependence within 12 months for every 11-16 newly incident EMPPR users, yielding perhaps 120 newly incident opioid dependent cases in need of practitioner attention or treatment services, each day of each year. This evidence can be used to motivate more effective public health prevention, outreach, and early intervention programs as might prevent or delay occurrence of EMPPR use and opioid dependence.