Use of alternating logistic regression in studies of drug-use clustering

Seroprevalence of Antibodies to SARS-CoV-2 in Rural Households in Eastern Uganda, 2020-2022

Importance

Estimating the true burden of SARS-CoV-2 infection has been difficult in sub-Saharan Africa owing to asymptomatic infections and inadequate testing capacity. Antibody responses from serologic surveys can provide an estimate of SARS-CoV-2 exposure at the population level.

Objective

To estimate SARS-CoV-2 seroprevalence, attack rates, and reinfection in eastern Uganda using serologic surveillance from 2020 to early 2022.

Design, Setting, and Participants

This cohort study was conducted in the Tororo and Busia districts of eastern Uganda. Plasma samples from participants in the Program for Resistance, Immunology, Surveillance, and Modeling of Malaria in Uganda Border Cohort were obtained at 4 sampling intervals: October to November 2020, March to April 2021, August to September 2021, and February to March 2022. Each participant contributed up to 4 time points for SARS-CoV-2 serology, with almost half of all participants contributing at all 4 time points, and almost 90% contributing at 3 or 4 time points. Information on SARS-CoV-2 vaccination status was collected from participants, with the earliest reported vaccinations in the cohort occurring in May 2021.

Main Outcomes and Measures

The main outcomes of this study were antibody responses to the SARS-CoV-2 spike protein as measured with a bead-based serologic assay. Individual-level outcomes were aggregated to population-level SARS-CoV-2 seroprevalence, attack rates, and boosting rates. Estimates were weighted by the local age distribution according to census data.

Results

A total of 1483 samples from 441 participants living in 76 households were tested. Of the 441 participants, 245 (55.6%) were female, and their mean (SD) age was 16.04 (16.04) years. By the end of the Delta wave and before widespread vaccination, adjusted SARS-CoV-2 seroprevalence was 67.7% (95% credible interval [CrI], 62.5%-72.6%) in the study population. During the subsequent Omicron wave, 84.8% (95% CrI, 67.9%-93.7%) of unvaccinated, previously seronegative individuals were infected for the first time, and 50.8% (95% CrI, 40.6%-59.7%) of unvaccinated, already seropositive individuals were likely reinfected, leading to an overall seropositivity of 96.0% (95% CrI, 93.4%-97.9%) in this population. These results suggest a lower probability of reinfection in individuals with higher preexisting antibody levels. There was evidence of household clustering of SARS-CoV-2 seroconversion. No significant associations were found between SARS-CoV-2 seroconversion and gender, household size, or recent Plasmodium falciparum malaria exposure.

Conclusions and Relevance

In this cohort study in a rural population in eastern Uganda, there was evidence of very high SARS-CoV-2 infection rates throughout the pandemic inconsistent with national level case data and high reinfection rates during the Omicron wave.

Reconstructing the SARS-CoV-2 epidemic in eastern Uganda through longitudinal serosurveillance in a malaria cohort

Importance

Estimating the true burden of SARS-CoV-2 infection has been difficult in sub-Saharan Africa due to asymptomatic infections and inadequate testing capacity. Antibody responses from serologic surveys can provide an estimate of SARS-CoV-2 exposure at the population level.

Objective

To estimate SARS-CoV-2 seroprevalence, attack rates, and re-infection in eastern Uganda using serologic surveillance from 2020 to early 2022.

Design

Plasma samples from participants in the Program for Resistance, Immunology, Surveillance, and Modeling of Malaria in Uganda (PRISM) Border Cohort were obtained at four sampling intervals: October-November 2020; March-April 2021; August-September 2021; and February-March 2022.

Setting

Tororo and Busia districts, Uganda.

Participants

1,483 samples from 441 participants living in 76 households were tested. Each participant contributed up to 4 time points for SARS-CoV-2 serology, with almost half of all participants contributing at all 4 time points, and almost 90% contributing at 3 or 4 time points. Information on SARS-CoV-2 vaccination status was collected from participants, with the earliest reported vaccinations in the cohort occurring in May 2021.

Main Outcomes and Measures

The main outcomes of this study were antibody responses to the SARS-CoV-2 spike protein as measured with a bead-based serologic assay. Individual-level outcomes were aggregated to population-level SARS-CoV-2 seroprevalence, attack rates, and boosting rates. Estimates were weighted by the local age distribution based on census data.

Results

By the end of the Delta wave and before widespread vaccination, nearly 70% of the study population had experienced SARS-CoV-2 infection. During the subsequent Omicron wave, 85% of unvaccinated, previously seronegative individuals were infected for the first time, and ~50% or more of unvaccinated, already seropositive individuals were likely re-infected, leading to an overall 96% seropositivity in this population. Our results suggest a lower probability of re-infection in individuals with higher pre-existing antibody levels. We found evidence of household clustering of SARS-CoV-2 seroconversion. We found no significant associations between SARS-CoV-2 seroconversion and gender, household size, or recent Plasmodium falciparum malaria exposure.

Conclusions and Relevance

Findings from this study are consistent with very high infection rates and re-infection rates for SARS-CoV-2 in a rural population from eastern Uganda throughout the pandemic.

A Review of Drug Side Effect Identification Methods

Drug side effects have become an important indicator for evaluating the safety of drugs. There are two main factors in the frequent occurrence of drug safety problems; on the one hand, the clinical understanding of drug side effects is insufficient, leading to frequent adverse drug reactions, while on the other hand, due to the long-term period and complexity of clinical trials, side effects of approved drugs on the market cannot be reported in a timely manner. Therefore, many researchers have focused on developing methods to identify drug side effects. In this review, we summarize the methods of identifying drug side effects and common databases in this field. We classified methods of identifying side effects into four categories: biological experimental, machine learning, text mining and network methods. We point out the key points of each kind of method. In addition, we also explain the advantages and disadvantages of each method. Finally, we propose future research directions.

A prospective study of newly incident cannabis use and cannabis risk perceptions: Results from the United States Monitoring the Future study, 1976-2013

BACKGROUND

A prevailing epidemiological theory about drug use occurrence among secondary school students is that trends in perceived risk of drug-related harms can drive use. If so, cannabis risk perceptions during one school year should predict newly incident cannabis use in the same school the following year. We aimed to study trends in incidence and epidemiological clustering of cannabis use among United States (US) 12th-graders, and a novel prediction that incidence in school-year 't' is influenced by school-specific cannabis risk perceptions (CRP) of 12th-graders a year prior at 't-1'.

METHODS

US schools sampled each year from 1976 to 2013 (∼130 schools per year) yielded an annual nationally representative sample of ∼15-16,000 12th-graders with questionnaire assessments. Analyses involved Alternating Logistic Regressions (ALR) to study trends in school-level clustering and slopes that estimate the degree to which CRP levels at 't-1' might predict newly incident cannabis use at 't'.

RESULTS

School-level CRP levels at 't-1' predict newly incident cannabis use in the next year's 12th-grade class. For each unit CRP increment, the next year's class shows tangibly reduced incidence of starting to use cannabis (overall odds ratio, OR = 0.10; 95% CI: 0.03, 0.33). Within-school clustering of newly incident cannabis smoking also can be seen (e.g., pairwise odds ratio, PWOR = 1.11; 95% CI: 1.07, 1.15).

CONCLUSIONS

Programmatic manipulation of perceived risk in one year's senior class via public health/school alliances might dampen the subsequent risk of newly incident cannabis use in the next year's class.

Social rank and inhalant drug use: the case of lança perfume use in São Paulo, Brazil

BACKGROUND

Lanca perfume (chloroform/ether) is an inhalant used mainly by higher social class students in Brazil. In light of the social and epidemiological features of lanca use, supply, and distribution, this investigation tests hypotheses about the degree to which use of inhalant lanca might be occurring in clusters, consistent with social sharing and diffusion, and might show a direct association with social rank even within the relatively privileged social context of private schools in a large mega-city of Latin America.

METHODS

Epidemiologic self-report survey data were from a large representative sample of urban post-primary private school students in São Paulo city, Brazil, in 2008. Newly incident lanca use was studied, first with estimates of clustering from the alternating logistic regressions (ALR) and then with conditional logistic regressions to probe into the hypothesized direct social rank association.

RESULTS

ALR disclosed a clustering of newly incident lanca users within private school classrooms (pairwise odds ratio (PWOR)=2.1; 95% CI=1.3, 3.3; p=0.002) as well as clusters of recently active lanca use (PWOR=1.9; 95% CI=1.1, 3.3; p=0.02). Occurrence of lanca use within private school classrooms was directly associated with social rank (odds ratio (OR)=0.2; 95% CI=0.1, 0.8; p=0.03 in the contrast of lowest socio-economic status (SES) versus highest SES strata within classrooms). Thereafter, study of other drugs disclosed similar patterns.

CONCLUSIONS

The clustering estimates are consistent with concepts of person-to-person sharing of lanca within private school classrooms as well as other dynamic processes that might promote lanca clusters in this context. An observed direct association with social rank is not specific to lanca use. Direct SES estimates across a broad profile of drug compounds suggests causal processes over and above the more specific initially hypothesized social rank gradients in the lanca diffusion process. A novel facet of the evidence is greater occurrence of drug use among the higher social rank private school students, which should be of interest in the social science community.

Drug use opportunities as opportunities for drug use prevention: Bogotá, Colombia a case in point

BACKGROUND

As drugs become more ubiquitous and fewer resources are available for drug prevention and treatment, understanding the early stages of drug use involvement becomes increasingly important for prevention efforts. This study aims to explore the concept of drug use opportunity, and to disentangle, from a socio-ecological perspective, the factors associated with experiencing a drug use opportunity.

METHODS

Data from 2279 standardized questionnaires administered in 23 schools in Bogotá was analyzed. Schools were selected in a multistage probability cluster sample. Multilevel logistic regression modeling estimated the effects of multiple level factors on the likelihood of having experienced an opportunity to use illicit drugs or inhalants.

RESULTS

One-third of respondents (32.1%) reported having had an opportunity to use drugs. Even among those who perceived drugs to be readily available and/or expressed intentions to use drugs in the near future, most reported never having experienced an opportunity to use drugs. For most of the drugs assessed, peer drug use, cigarette smoking, alcohol drinking, problematic behavior, and degree of school safety were the strongest correlates of having had a drug use opportunity.

CONCLUSIONS

Despite living in an environment of high drug availability, most adolescents do not experience opportunities to use drugs. The likelihood of experiencing an opportunity is influenced by multiple interacting individual and macro-social factors, just as drug use is. Drug use opportunities were mainly promoted by friends, suggesting the need to consider their role within close social networks, alongside that of drug suppliers, in the design of intervention activities and drug policy development.

Place effects for areas defined by administrative boundaries: a life course analysis of mortality and cause specific morbidity in Scania, Sweden

To understand the origin of disease risk in adulthood, factors in all stages of life and on different contextual levels should be considered. Therefore, the aim of this study was to investigate the relevance of a person's area of residence over their life course with regard to four outcomes: all-cause mortality; ischemic heart disease mortality and morbidity; cancer mortality and morbidity; and respiratory diseases and related mortality. We applied a cross-classified multilevel model for three age groups on a longitudinal data set spanning a 35 year period in Scania, Sweden. According to our analyses, the proportion of the total variance at the district level for all the outcomes studied was below 2% for the 65 to 84 age group, below 4.5% for those ages 50-64 years, and below 6.5% for those 30-49 years old. Our results suggest that the parish of residence, at four different time points during the individual life course, had little influence on individual all-cause mortality, or on mortality or morbidity from IHD, cancer, and respiratory diseases; i.e., knowing when and where an individual resided during their life course gives little indication of future mortality and morbidity. Such knowledge is essential in assisting decision makers determine the relevant geographical level of intervention (in our case whether to direct interventions toward the entire region of Scania or to specific parishes) needed. Valuable information for planning public health interventions might be obtained by considering measures of variance and clustering from specific contexts before implementing strategic programs.

Intercenter differences in bronchopulmonary dysplasia or death among very low birth weight infants

OBJECTIVES

To determine (1) the magnitude of clustering of bronchopulmonary dysplasia (36 weeks) or death (the outcome) across centers of the Eunice Kennedy Shriver National Institute of Child and Human Development National Research Network, (2) the infant-level variables associated with the outcome and estimate their clustering, and (3) the center-specific practices associated with the differences and build predictive models.

METHODS

Data on neonates with a birth weight of <1250 g from the cluster-randomized benchmarking trial were used to determine the magnitude of clustering of the outcome according to alternating logistic regression by using pairwise odds ratio and predictive modeling. Clinical variables associated with the outcome were identified by using multivariate analysis. The magnitude of clustering was then evaluated after correction for infant-level variables. Predictive models were developed by using center-specific and infant-level variables for data from 2001 2004 and projected to 2006.

RESULTS

In 2001-2004, clustering of bronchopulmonary dysplasia/death was significant (pairwise odds ratio: 1.3; P < .001) and increased in 2006 (pairwise odds ratio: 1.6; overall incidence: 52%; range across centers: 32%-74%); center rates were relatively stable over time. Variables that varied according to center and were associated with increased risk of outcome included lower body temperature at NICU admission, use of prophylactic indomethacin, specific drug therapy on day 1, and lack of endotracheal intubation. Center differences remained significant even after correction for clustered variables.

CONCLUSION

Bronchopulmonary dysplasia/death rates demonstrated moderate clustering according to center. Clinical variables associated with the outcome were also clustered. Center differences after correction of clustered variables indicate presence of as-yet unmeasured center variables.

Use and accidental exposure to hallucinogenic agents reported to the Czech Toxicological Information Centre from 1995 to 2008

Intoxication by hallucinogenic agents is relatively common in the Czech Republic, with most cases of the use of these agents being by adolescents and young people. The objective of the study was to evaluate the number, trends, gender and age of the subjects, and the severity of exposure in intoxication by hallucinogenic plant and mushroom substances, in comparison with synthetic drugs, brought to the attention of the Toxicological Information Centre (TIC) through inquiries over the past 14 years (1995-2008) (from total 3,702 calls concerning the use of both natural and synthetic drugs, 917 calls were due to the use of hallucinogenic plants and mushrooms).

The epidemiological profile of alcohol and other drug use in metropolitan China

PURPOSE

There is evidence that alcohol, tobacco, and other drug use may be rising in China, but epidemiological studies that examine several drugs simultaneously and the transition from initial try to current use are limited. The present study provides an epidemiological profile of drug use in contemporary metropolitan China.

METHODS

A multistage probability sampling method was used to select household-dwelling adults in Beijing and Shanghai. Standard face-to-face interviews with 5,201 participants were completed during 2002-2003.

RESULTS

An estimated 70-76% had used any type of drug: alcohol and tobacco were the most commonly used drugs (alcohol, 67%; tobacco, 39%). Regarding extra-medical use of internationally regulated drugs, sedatives and analgesics were most common and illegal drug use was rare. The majority of tobacco users used it recently (82.5%), especially young adults. Male-female differences were observed in lifetime tobacco use, but not for recent use. Concurrent use of alcohol and tobacco was very common.

CONCLUSION

Psychoactive drug use is common in metropolitan China. Public health policies and prevention initiatives may be needed to address associated problems that may increase following the country's rapid socioeconomic change.

Geographic clustering of underage drinking and the influence of community characteristics

The aim of this paper was to examine the extent to which underage drinking clusters geographically in a sample of communities, and to investigate the manner in which community-level contexts are related to this process. We used data from a randomized community trial of underage drinking to provide the first quantitative estimates of the magnitude of the geographic clustering of underage drinking based upon pairwise odds ratios (PWORs). The Enforcing Underage Drinking Laws Randomized Community Trial provided data from repeated cross-sectional samples of youth aged 14-20 from 68 communities surveyed in 2004, 2006, and 2007 (n=18,730). Past 30-day drinking, binge drinking, getting drunk, experiencing non-violent consequences as a result of drinking and making a purchase attempt all significantly clustered within-communities with PWORs ranging from 1.05 to 1.21. After adjustment for individual-level characteristics, results remained relatively unchanged. However, there was evidence that the magnitude of the clustering varied as a function of neighborhood disadvantage, neighborhood disorder, and family structure. Clustering of drunkenness and experiencing non-violent consequences as a result of drinking was greatest in the least economically disadvantaged and least disordered communities with the greatest percentage of married-couple families. The clustering of making a purchase attempt, however, was greatest in more disordered communities, specifically the largest communities with the highest degree of residential mobility and housing density. These findings that clustering of underage drinking behaviors varies by community context has the potential for identifying the types of communities to target for underage drinking behavior-specific preventive interventions.

Geographical clustering of cannabis use: results from the New Zealand Mental Health Survey 2003-2004

BACKGROUND

In epidemiology, it always has been important to study local area patterns of disease occurrence. New methods to quantify local area and household clustering of disease emerged late in the 19th century and were refined during the 20th century. Nonetheless, multi-level models to estimate local area clustering of illegal drug use did not appear until the 1990s, and to date, there is just one study with estimates of local neighbourhood clustering of cannabis use, based on a United States sample. Here, seeking the first replication of that single prior study, we estimate the degree to which cannabis use might cluster within neighbourhoods of New Zealand (NZ), and we also study higher level clustering and suspected individual-level determinants of recent cannabis use.

METHODS

A national probability community sample (n=12,992) of adults aged 16 years or more with standardized assessment of cannabis use. Alternating logistic regression produced estimates for cannabis clustering.

RESULTS

In NZ, use of cannabis was common: 41.6% had ever used it and 13.1% had used it in the past year. There was clustering within the smallest local areas (pairwise odds ratio=1.3-1.5) but not within larger government districts (PWOR=1.02). Age, male sex, ethnicity, education, and marital status were all associated with cannabis use, but did not account for observed clustering.

CONCLUSIONS

Neighborhood clustering of recent cannabis use has emerged in New Zealand, as in the US. Standard individual-level characteristics explain only some of this clustering. Other explanations must be sought, perhaps including personal networks and local supply.

Therapeutic traditions, patient socioeconomic characteristics and physicians' early new drug prescribing--a multilevel analysis of rosuvastatin prescription in south Sweden

PURPOSE

To investigate the role that both patient and outpatient factors related to health care practice (HCP) play in physicians' early adoption of rosuvastatin.

MATERIALS AND METHODS

Generalized estimation equations (GEEs) and alternating logistic regression (ALR) with pair-wise odds ratios (PWORs) were used to measure similarities in rosuvastatin prescription within HCPs for all individuals with statin prescriptions in Skåne region, Sweden.

RESULTS

After 12 months, 53% of the HCPs had adopted the new statin. Rosuvastatin prescriptions co-occurred within certain HCPs 3.56 times more often than one would have expected based on a random distribution. Private HCPs had four times higher probability of prescribing rosuvastatin than public HCPs.

CONCLUSION

Contextual characteristics of the HCP seem to be relevant for understanding physicians' motivation to adopt rosuvastatin. Moreover, our study reveals inequity in health care as the socioeconomic status of the patients appears to influence the prescribing behavior of the physicians irrespective of medical reasons.

Geographical clustering of eating disordered behaviors in U.S. high school students

OBJECTIVE

The aim of this study was to determine if eating disorder behaviors geographically clustered among U.S high school students.

METHOD

Our sample consisted of 15,349 high school students who responded to the 1999 Youth Risk Behavior Study (YRBS). Weight control and eating disordered behaviors under investigation included dieting, exercising, fasting, using diet pills, and purging to control weight in the last 30 days. We calculated pairwise odds ratios (PWORs) to determine the degree of within-county clustering.

RESULTS

Among all participants, adjusted analyses revealed that having any weight control or eating disorder symptom, severe restricting, dieting, exercising, and diet pill use each showed significant clustering (p < .05). Purging did not significantly cluster by county. The magnitude of clustering was stronger for female students than male students.

CONCLUSION

The significant clustering of weight control and eating disorder behavior in U.S. high school students confirms evidence of a social contagion effect of eating disorders.

Case ascertainment of alcohol dependence in general population surveys: 'gated' versus 'ungated' approaches

Social role impairment and other forms of maladaptation are referenced explicitly in the case definitions for the drug use disorders within DSM-IV-TR, but there is continuing debate about whether and how to include these manifestations of 'clinical significance' in diagnostic criteria and assessment protocols. When a 'gated' approach (based on impairment or other maladaptation) has been taken during recent large scale psychiatric surveys with coverage of drug dependence (e.g. to reduce participant fatigue or burden), the net effect may include (a) a reduced number of identified cases, and (b) biases in the estimates of association linked to the occurrence of drug dependence. In this report focused on alcohol dependence, we probe these issues, making use of data from the cross-sectional US National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), a household survey with 44,093 adult participants. NESARC alcohol dependence assessments were 'ungated', but allowed simulation of a 'gated' approach; the end result was a robust decrement in the estimated prevalence of this condition. Nonetheless, patterns of association linking suspected background characteristics to prevalence of alcohol dependence were not appreciably different when the gated and ungated estimates were contrasted. In summary, there are reasons to take the ungated approach in detailed research on alcohol use and dependence. Nevertheless, in panoramic mental health surveys, the inefficiency of an ungated approach must be balanced against the anticipated yield of cases who have experienced alcohol dependence without alcohol related social role impairments or other maladaptation, particularly when the dependence syndromes without these consequences are sometimes thought to lack clinical significance.

Assessing cannabis dependence in community surveys: methodological issues

Drug-related social role impairments and social maladaptation are referenced explicitly in the case definitions for drug dependence within DSM-IV-TR. Nonetheless, cases of drug dependence without this type of secondary consequence have been observed in recent epidemiological studies. When an 'impairment/maladaptation gating' approach has been taken during recent large-scale psychiatric surveys (for example, to reduce participant fatigue or burden), the net effect may include (a) a reduced number of identified drug dependence cases and (b) biases in the estimates of association linked to the occurrence of drug dependence. In this report, we probe these issues with respect to cannabis dependence, making use of data from the cross-sectional United States National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), a household survey of 43,093 adults aged 18 years and over. In this process, we shed light on actual impact of the gating approach mentioned above. Specifically, when we simulated a social impairment/maladaptation 'gated' assessment of cannabis dependence, the end result was a very modest reduction in the estimated prevalence of cannabis dependence. It suggested that for every 10 000 general population survey respondents there would be no more than 12 cases of cannabis dependence without the above-referenced impairments/maladaptations. Patterns of association linking suspected background characteristics to the prevalence of cannabis dependence were not appreciably different when the 'gated' and 'ungated' approaches were applied. In summary, there are reasons to take the ungated approach in detailed research on cannabis use and dependence. Nevertheless, in panoramic mental health surveys, the inefficiency of an 'ungated' approach must be balanced against the anticipated yield of cannabis dependence cases who lack social role impairments or socially maladaptive behaviours.

Decomposing the total variation in a nested random effects model of neighborhood, household, and individual components when the dependent variable is dichotomous: implications for adolescent marijuana use

Multilevel modeling techniques have become a useful tool that enables substance abuse researchers to more accurately identify the contribution of multiple levels of influence on drug-related attitudes and behaviors. However, it is difficult to determine the relative importance of the different hierarchical levels because, in the case of dichotomous outcomes, the variance components estimation involves calculations using a log-odds metric at the lowest level of estimation. We present methods introduced by Goldstein and Rasbash [Goldstein, H., Rasbash, J., 1996. Improved approximations for multilevel models with binary responses. J. Roy. Stat. Soc. A 159, 505-513.] to convert the variance components from the log-odds to the probability metric. This method provides a more logical and interpretable way to examine variation for nonlinear outcomes, which tend to be heavily utilized in substance use research. Using data from the National Household Survey on Drug Abuse [Substance Abuse and Mental Health Services Administration (SAMHSA), 2001. 1999 National Household Survey on Drug Abuse. Data Collection Final Report. Office of Applied Studies (OAS), Rockville, MD. Available at . Accessed on July 1, 2003.], we partition variation among individual, household, and neighborhood levels for the binary outcome of past year marijuana use to illustrate this approach. We also conduct a stability analysis to examine the robustness across different estimation procedures commonly available in commercial multilevel software packages. Finally, we partition the variance components using a conventional continuously distributed outcome and compare the relative magnitudes across binary and continuous outcomes.

The development of suicide ideation and attempts: an epidemiologic study of first graders followed into young adulthood

Studying community residing youths originally recruited for an intervention trial upon entry into first grade, this project sought to estimate risk of suicide ideation and attempts to young adulthood, with focus on those who used drugs before age 16, as compared to youths who used later in development or not at all. Standardized interview assessments in 1989-1994 were completed with 2311 youths age 8-15. Roughly 15 years after recruitment, our study team reassessed 1695, nearly 75% of the survivors (mean age = 21), finding 155 to have made suicide attempts (SA) and 218 with onset of depression-related suicide ideation (SI). We estimate relative risk (RR), from survival analysis and logistic regression models, to study early use of tobacco, alcohol, cannabis, and inhalants, with covariate adjustments for age, sex, race-ethnicity, and other pertinent covariates. Early-onset of cannabis use and inhalant use for females, but not for males, signaled modestly excess risk of suicide attempt (cannabis-associated RR = 1.9; p = 0.04; inhalant-associated RR = 2.2; p = 0.05). Early-onset of cannabis use by females (but not for males) signaled excess risk for suicide ideation (RR = 2.9; p = 0.006). Early-onset alcohol and tobacco use were not associated with later risk of SA or SI. In light of the relatively modest strength of association, the evidence may well reflect an underlying common diathesis or unmeasured prior confounding influences that link early-onset illegal drug use with later risk of these suicide-related events, rather than an influence of early-onset drug use per se.

Neighborhood environment and opportunity to try methamphetamine ("ice") and marijuana: evidence from Guam in the Western Pacific region of Micronesia

Although the American popular press and films might generally lead one to think otherwise, illegal drug use and drug trafficking occur outside the boundaries of disadvantaged American inner-city neighborhoods. Nonetheless, the occurrence of youthful drug involvement may be determined by similar community conditions in many parts of the world. In Spring 1998, a probability sample of 776 high school students living in Guam, Micronesia, completed a self-report anonymous survey, one that assessed their village and metropolitan neighborhood environments as well as drug involvement. On Guam, higher levels of neighborhood disadvantage were associated with youths being more likely to have been offered a chance to try drugs. This study adds new evidence on the potential importance of environmental and psychosocial contexts of neighborhood environment that might help account for the nonrandom distribution of youthful drug involvement.

Aggressive behavior and opportunities to purchase drugs

Robins, Kellam, and others found robust evidence linking youthful aggression and deviance to later illicit drug use. Some investigators favor the interpretation that drug use is just one manifestation or complication of a more general problem behavior syndrome or conduct disorder. In this work, we test the complementary hypothesis that aggressive youth are more likely to be approached with offers to buy drugs, and found the most aggressive youths were about five times more likely to be offered drugs for purchase. However, this association was much attenuated when levels of delinquency were taken into account. In this respect, delinquent rather than aggressive behavior might be more salient. This study's evidence does not contradict previous problem behavior theories, but rather prompts new ideas about how aggression, delinquency, and drug use might be linked. One testable hypothesis is that youths with both aggression and delinquency are more likely to enter microenvironments where drug dealing is more prevalent. Or, their observable behaviors or physical appearance might function as signs of apparent willingness to try drugs. These results add to our understanding of links between aggression, delinquency, and drug use, and introduce a new line of epidemiological inquiry focused upon drug purchase opportunities.

Clusters of drug involvement in Panama: results from Panama's 1996 National Youth Survey

This report is based on the first epidemiological investigation of clustering of tobacco, alcohol, inhalant, and other drug involvement within individual schools using data from Panama's 1996 National Youth Survey on Alcohol and Drug Use. Clustering was estimated with the Alternating Logistic Regression method. Adjusted estimates of pair-wise cross-product ratios (PWCPR), a measure of clustering, show modest clustering (i.e. PWCPR>1.0) at the school level for tobacco smoking (PWCPR=1.41; 95% confidence interval, CI=1.22-1.64), alcohol consumption (PWCPR=1.33; 95% CI=1.22-1.45), use of inhalants, (PWCPR=1.35; 95% CI=1.07-1.69), and other drug use (PWCPR=1.38; 95% CI=1.14-1.68). These findings provide preliminary evidence that the odds of drug use among school-attending youths increase when another youth in the same school uses drugs, and suggest a new line of research on within-school diffusion that should include the identification of school-level factors that contribute to student drug use.