Capturing crack cocaine use: estimating the prevalence of crack cocaine use in London using capture-recapture with covariates

AIM: To estimate the prevalence of crack cocaine use in 12 London Boroughs (and London as a whole). SETTING: Twelve London Boroughs, 2000-01. METHODS: (1) Covariate capture-recapture techniques applied to three data sources of subjects reporting crack cocaine use: specialist drug treatment (2905), arrest referral (1188) and accident and emergency and community survey (531); and (2) ratio-estimation multiplier, using an estimate of number of injecting drug users and proportion that use crack cocaine. FINDINGS: After matching, 4117 individuals aged 15-44 were identified. The best-fitting model estimated 16 855 unobserved crack cocaine users, giving an overall estimate of approximately 21 000 [95% confidence interval (CI) 13 000-43,000] and a prevalence of 1.5% (95% CI 1.0-3.2%). Prevalence of crack cocaine use was 2.4% (95% CI 1.5-5.0%) among men and 0.7% (95% CI 0.5-1.0%) among women, and similar by age groups 15-29 and 30-44 years. Overall, approximately 11 900 (57%) of the estimated number of crack cocaine users were also opiate users. In London as a whole there may be 46,000 (1.3%) crack cocaine users aged 15-44 years, with 28 000 (1.9%) in inner London-four times higher than estimates from population surveys. Some corroboration was provided by the ratio-estimation method, which estimated 23 000 users in the 12 Boroughs. CONCLUSIONS: Capture-recapture can be applied to crack cocaine and obtain better estimates than population surveys. The size of the crack cocaine-using population in London is large, although currently the majority are also opiate users. Given that half of current users are under 30 the problems associated with crack cocaine use are likely to increase in the future.     

Is Crack Cocaine Use Associated with Greater Violence than Powdered Cocaine Use? Results from a National Sample

Background: The question of whether crack cocaine use is associated with increased violence compared to powdered cocaine use has not been adequately explored in large nationally representative general population samples. Methods: This study used data from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) to 1) determine the comparative prevalences of violent behaviors among crack cocaine users and powdered cocaine users, 2) examine these differences while controlling for sociodemographic variables, lifetime psychiatric, alcohol and drug use disorders (a majority of cocaine users use other substances), and levels of crack cocaine and powdered cocaine use. Results: The likelihood of violence associated with crack cocaine users was greater compared to powdered cocaine users at the bivariate level. However, these differences were almost uniformly statistically nonsignificant when demographic, mood and non-cocaine substance use disorders were controlled for. Conclusions: The substantial attenuation of the association of crack cocaine use with violence after adjustment suggests that the sociodemographic characteristics, psychiatric variables, and non-cocaine substance use disorders that make some individuals more likely to use crack cocaine than powder cocaine are responsible for the increased prevalence of violence observed among crack users, rather than crack itself.     

Status of the HIV/AIDS epidemic and methods to monitor it in the Latin America and Caribbean region

The paper presented is a review of the available epidemiological data on the situation in the Latin America and Caribbean (LAC) region, and looks at HIV prevalence in specific population groups. At the end of 2001, HIV remains an important health issue in the LAC region. Twelve countries in the region have an estimated prevalence of 1% or higher among pregnant women. Most of the LAC countries with generalized epidemics are located in the Caribbean basin. In the past decade there has been a slow but continuous increase in HIV prevalence rates among the general population and vulnerable groups, although information in some countries is limited. In many countries, the highest HIV prevalence among vulnerable groups is found among men who have sex with men. HIV infections related to injecting drug use are concentrated in the countries of the Southern Cone and Brazil. HIV is well anchored in the region, concentrated in vulnerable groups in most countries, but with an increasing presence in some countries in the general population. There is a need to improve data collection and introduce new tools to monitor behavior trends and the impact of interventions.     

Drug use and phylogenetic clustering of hepatitis C virus infection among people who use drugs in Vancouver,Canada: A latent class analysis approach

This study estimated latent classes (ie, unobserved subgroups in a population) of people who use drugs in Vancouver, Canada, and examined how these classes relate to phylogenetic clustering of hepatitis C virus (HCV) infection. HCV antibody‐positive people who use drugs from two cohorts in Vancouver, Canada (1996‐2012), with a Core‐E2 sequence were included. Time‐stamped phylogenetic trees were inferred, and phylogenetic clustering was determined by time to most common recent ancestor. Latent classes were estimated, and the association with the phylogenetic clustering outcome was assessed using an inclusive classify/analyse approach. Among 699 HCV RNA‐positive participants (26% female, 24% HIV+), recent drug use included injecting cocaine (80%), injecting heroin (70%), injecting cocaine/heroin (ie, speedball, 38%) and crack cocaine smoking (28%). Latent class analysis identified four distinct subgroups of drug use typologies: (i) cocaine injecting, (ii) opioid and cocaine injecting, (iii) crack cocaine smoking and (iv) heroin injecting and currently receiving opioid substitution therapy. After adjusting for age and HIV infection, compared to the group defined by heroin injecting and currently receiving opioid substitution therapy, the odds of phylogenetic cluster membership was greater in the cocaine injecting group (adjusted OR [aOR]: 3.06; 95% CI: 1.73, 5.42) and lower in the crack cocaine smoking group (aOR: 0.06; 95% CI: 0.01, 0.48). Combining latent class and phylogenetic clustering analyses provides novel insights into the complex dynamics of HCV transmission. Incorporating differing risk profiles associated with drug use may provide opportunities to further optimize and target HCV treatment and prevention strategies.     

Cardiac and mood-related changes during short-term abstinence from crack cocaine: the identification of possible withdrawal phenomena.

Studies assessing withdrawal phenomenon during short-term abstinence from chronic cocaine use have been limited. Although cocaine abusers are reported to be at increased risk for cardiac disorders, little research has assessed cardiac parameters in cocaine abusers and subsequent changes in these parameters that may be associated with the discontinuation of cocaine use. In this study, we categorize 441 chronic cocaine abusers into three groups based on self-reported length of abstinence from cocaine use at entry into a trial approved by the National Institute on Drug Abuse (NIDA) assessing the use of pergolide mesylate in treating relapse and craving in crack cocaine abuse. Electrocardiogram (ECG) PR intervals were found to be correlated positively with length of abstinence, returning to normal population levels within 30 days. In addition, levels of generalized anxiety, nervousness, and heart racing were found to be correlated negatively with length of abstinence from crack cocaine. This work provides preliminary evidence of cardiac and mood-related parameters that are associated with cocaine abstinence and that may indicate specific withdrawal phenomena in chronic users. In addition, these results suggest that the risk of cardiomyopathies associated with abnormal atrial-ventricular polarization may dissipate relatively quickly in abusing individuals.     

An Australian profile on the use of cocaine

Data collected on cocaine in Australia in the mid to late 1980s, when law enforcement and treatment centres were concerned with possible increases in cocaine use, indicated a low prevalence of use. This article reports findings from the Australian component of the 1993-94 World Health Organization study entitled "Initiative on Cocaine", which provides an updated analysis of cocaine use patterns and consequences. The two components of this study were a "country profile" which summarized existing health, law enforcement and survey data on cocaine use from national, regional and city level records, and a key informant study which consisted of interviews with people from Sydney and Melbourne who were familiar with cocaine use through personal, professional or observational experience. Findings show that the prevalence of cocaine use has remained low among the general population in Australia (around 2%), and few people present to treatment services with primary cocaine problems or are arrested. However, the use of cocaine seems to have increased among inner Sydney injecting drug users. There have also been indications of larger police seizures of cocaine, reflecting a possible increase in availability. Recommendations are made to provide relevant interventions and continually monitor patterns of cocaine use, particularly among at-risk groups.     

Substance Use and Sexual Risk Behavior in HIV-Positive Men Who Have Sex With Men: An Episode-Level Analysis

Men who have sex with men (MSM) make up nearly half of all people living with HIV in the United States. The prevalence of the epidemic in this population makes it vitally important to understand the transmission of the infection and to develop methods to prevent its spread. The current study uses longitudinal diary methods to examine relationships between substance use and unprotected anal intercourse in a sample of 158 HIV-positive, mostly ethnic minority MSM. Results indicate that both general substance use and use of specific drugs (i.e., inhalants, cocaine, crack, and club drugs) have a substantial impact on the sexual risk behavior of this population.     

Cocaine use and the utilisation of drug help services by consumers of the open drug scene in Hamburg.

In order to describe the patterns of use in the open drug scene in Hamburg, a study was carried out among 616 drug users in the drug scene and in or in the vicinity of low-threshold institutions close to the drug scene in summer 2000. The special focus was on the prevalence of cocaine and crack use as well as on the utilisation of help services for drug users. 80% of the interviewed persons were male, the average age was 32.6 years. They had been using drugs such as heroin or cocaine for an average of 11 years. 84% had used heroin and 74% cocaine within the last 24 h. Use was intravenous for 66%. 57% used cocaine intravenously, the percentage of crack smokers was 22%. Compared to previous studies, an increase in cocaine use can be noted among the scene users in Hamburg, mainly related to intravenous cocaine use. Crack smoking has only increased slightly over the past few years. Based on cluster analysis, four consumption pattern groups can be established. The largest group (38%) mainly uses cocaine and heroin. The second group (26%) consists of polyvalent drug consumers using methadone in addition to heroin and cocaine, as well as, partially, benzodiazepines, cannabis or alcohol. Group 3 (19%) mainly uses heroin only, some of them also using methadone and/or cannabis. The fourth group (17%) is mainly related to alcohol, the greater part of them additionally using heroin. On the whole, it appears that those users who currently do not use cocaine (or crack) are in a better health and social situation. The group using only heroin (cluster 3) also compares favourably with the other three consumption pattern groups with regard to the intensity of use, consumption in public and risk behaviour. Almost all the interviewed persons are in contact with general practitioners. However, the increasing cocaine use has not been met by sufficient intervention and treatment programmes so far.     

Cocaine use in Europe - a multi-centre study: patterns of use in different groups

AIM: The study investigates patterns of cocaine powder and crack cocaine use of different groups in nine European cities. DESIGN, SETTING, PARTICIPANTS: Multi-centre cross-sectional study conducted in Barcelona, Budapest, Dublin, Hamburg, London, Paris, Rome, Vienna, and Zurich. Data were collected by structured face-to-face interviews. The sample comprises 1,855 cocaine users out of three subgroups: 632 cocaine users in addiction treatment, mainly maintenance treatment; 615 socially marginalized cocaine users not in treatment, and 608 socially integrated cocaine users not in treatment. MEASUREMENTS: Use of cocaine powder, crack cocaine and other substances in the last 30 days, routes of administration, and lifetime use of cocaine powder and crack cocaine. Findings: The marginalized group showed the highest intensity of cocaine use, the highest intensity of heroin use and of multiple substance use. 95% of the integrated group snorted cocaine powder, while in the two other groups, injecting was quite prevalent, but with huge differences between the cities. 96% of all participants had used at least one other substance in addition to cocaine in the last 30 days. CONCLUSIONS: The use of cocaine powder and crack cocaine varies widely between different groups and between cities. Nonetheless, multiple substance use is the predominating pattern of cocaine use, and the different routes of administration have to be taken into account.     

Prevalence and sociodemographic determinants of uninvestigated dyspepsia in the Czech Republic

OBJECTIVE: There are no data on the epidemiology of dyspepsia in Central Europe. The aim of this study was to evaluate the prevalence of uninvestigated dyspepsia in a representative sample of the Czech population. METHODS: A total of 2509 persons, aged 5-100 years, randomly selected from 30 012 individuals in the general population, entered this multicentre, prospective, questionnaire-based epidemiological study. RESULTS: We found a 17% prevalence of long-lasting (>12 months) dyspeptic symptoms in the general population. Two subgroups were distinguished: (i) persons with dyspepsia as the only one long-lasting symptom and themselves feeling otherwise healthy (9%), mostly among younger patients (subgroup A); and (ii) patients with dyspepsia as part of the complex of previously recognized diseases (8%), mostly in older patients (subgroup B). The prevalence of dyspepsia was significantly higher among women. The excess cases of dyspepsia among the highly educated seemed to be cases of dyspepsia of subgroup A, and the higher prevalence of dyspepsia among the lower social classes was largely dyspepsia of subgroup B. Being a widow/widower had a significant effect on the risk of self-reported dyspepsia among 25-64-year-olds. No association between Helicobacter pylori infection and dyspepsia was found. CONCLUSION: The prevalence of uninvestigated dyspepsia in the Czech Republic is comparable with data from other European countries. Clearly distinct subgroups of dyspeptic patients exist that should be further studied.     

Sequences of powder cocaine and crack use among arrestees in Los Angeles County

The epidemic of cocaine abuse has led to numerous studies on the substance. While extent of use, characteristics of users, patterns of use, and consequences of dependence are well documented for both powder cocaine and crack, few studies have dealt with the sequence or progression of use between the two forms of cocaine. This paper draws on arrestee data collected from county jails in Los Angeles, California. It identifies four sequences of powder cocaine and crack use and examines each sequence in terms of user characteristics, history of use, dependence, contact with the criminal justice system, and concomitant use of other drugs. Findings not only confirm some already established observations, but also offer new knowledge on powder cocaine and crack abuse. For instance, (a) whereas powder cocaine-initiated users are more likely to progress to crack than to restrict their use to powder cocaine only, crack-initiated users tend more often to use crack only than to progress to powder cocaine; and (b) powder cocaine and crack, when used interchangeably, can interact and reinforce each other, resulting in a higher level of use and dependence on both forms of the substance. This paper contributes to the understanding of powder cocaine and crack use among criminal offenders, in particular, and across the adult population, in general. It also sheds light on prevention, treatment, and social control policies of both cocaine abuse and overall illicit drug use.     

Age-specific prevalence of infection with herpes simplex virus types 2 and 1: a global review

Information on age- and sex-specific prevalence of herpes simplex virus (HSV) types 2 and 1 infections is essential to optimize genital herpes control strategies, which increase in importance because accumulating data indicate that HSV-2 infection may increase acquisition and transmission of human immunodeficiency virus. This review summarizes data from peer-reviewed publications of type-specific HSV seroepidemiologic surveys. HSV-2 prevalence is, in general, highest in Africa and the Americas, lower in western and southern Europe than in northern Europe and North America, and lowest in Asia. HSV-2 and -1 prevalence, overall and by age, varies markedly by country, region within country, and population subgroup. Age-specific HSV-2 prevalence is usually higher in women than men and in populations with higher risk sexual behavior. HSV-2 prevalence has increased in the United States but national data from other countries are unavailable. HSV-1 infection is acquired during childhood and adolescence and is markedly more widespread than HSV-2 infection. Further studies are needed in many geographic areas.     

Ethnic inequalities in acute myocardial infarction hospitalization rates among young and middle-aged adults in Northern Italy: high risk for South Asians

The knowledge of ethnic-specific health needs is now essential to design effective health services and population-based prevention strategies. However, data on migrant populations living in Southern Europe are limited. The study is designed to investigate ethnic inequalities in hospitalization for acute myocardial infarction (AMI) in the Veneto region (Italy). Hospital admissions for AMI in Veneto for the whole resident population aged 20–59 years during 2008–2013 were studied. Age and gender-specific AMI hospitalization rates for immigrant groups (classified by country of origin according to the United Nations geoscheme) and Italians were calculated. The indirect standardization method was used to estimate standardized hospitalization ratios (SHR) for each immigrant group, with rates of Italian residents as a reference. Overall, 8200 AMI events were retrieved, 648 among immigrants. The highest risk of AMI is seen in South Asians males (SHR 4.2, 95% CI 3.6–4.9) and females (SHR 2.5, 95% CI 1.4–4.5). AMI rates in South Asian males sharply increase in the 30–39 years age class. Other immigrant subgroups (Eastern Europe, North Africa, Sub-Saharan Africa, other Asian countries, Central-South America, high-income countries) displayed age- and gender-adjusted hospitalization rates similar to the native population. Present findings stress the urgent need for implementation of ethnic-specific health policies in Italy. The awareness about the high cardiovascular risk in subjects from South Asia must be increased among general practitioners and immigrant communities.     

Type of substance use and access to HIV-related health care

HIV-infected substance users have poorer health outcomes than other HIV risk groups. Few studies have examined the impact of specific types of substance use on health care. This study investigated the associations between specific types of substances of abuse and access to health care. HIV-infected individuals living in eight different single room occupancy hotels in the Bronx, New York, were interviewed between August 1999 and February 2001 regarding demographics, health care access and utilization, and drug and alcohol use. Of the 238 participants, the majority were male (59%), black or Hispanic (93%), and active drug users (61%). Individuals reporting any drug or crack/cocaine use were less likely to have a regular provider than those reporting no drug or no crack/cocaine use (adjusted odds ratio [AOR] = 0.50, p = 0.05; AOR =0.35, p = 0.004, respectively), while those with binge alcohol use were more likely to have a regular doctor than those without binge alcohol use (AOR = 2.61, p = 0.05). Individuals reporting any drug or crack/cocaine use were also less likely to perceive quality of health care positively (AOR = 0.50, p = 0.02; AOR = 0.37, p = 0.002, respectively). Heroin use, and injection drug use were not associated with these outcomes. When the sample was limited to recent drug users, similar patterns were found. Although drug use in general is associated with negative health outcomes, in this study, poorer measures of access to health care among substance users was associated predominantly with crack/cocaine use. It is important that clinicians and researchers working with substance-using populations understand how specific types of substance use differentially impact on health care.     

Crack use and injection on the increase among injecting drug users in London

Fears of a crack ‘epidemic’ in the United Kingdom of the kind experienced in the United States remain unfounded. However, findings from an ongoing serial point HIV prevalence study indicate that the use and injection of crack cocaine among injecting drug users (IDUs) in London is on the increase. Data on patterns of drug use and drug injection were collected over 4 years (1990–93), from IDUs recruited from both drug treatment and community-based settings. All respondents were asked about their drug use in the 6-month period prior to interview. The use of crack cocaine increased significantly from 16% in 1990 to 59% in 1993 and the injection of crack cocaine from 1% to 27%, respectively. The findings suggest that crack cocaine is being injected more regularly, with increases over the 4-year period in those who reported injecting the drug at least once per week. In response this paper considers both the health implications of, and the treatment response to, the increasing use and injection of crack cocaine among IDUs in London.     

Cocaine use and syphilis trends: findings from the arrestee drug abuse monitoring (ADAM) program and syphilis epidemiology in Houston

There has been speculation that trends in syphilis have been fueled by crack cocaine use. This study examined the data on syphilis notifications and arrestee drug abuse monitoring (ADAM) to ascertain the relationships between syphilis and cocaine use trends in three racial/ethnic groups. Syphilis notifications and data from the ADAM project were compared in Houston/Harris County, Texas, from 1991-1998 using a linear regression equation. Data indicated significant relationships between the data for cocaine use and syphilis in African Americans but not Hispanics or non-Hispanic whites. For African Americans, 58% of the variance between cocaine use and syphilis was explained. When data limited to jail syphilis notifications and ADAM cocaine in African Americans were examined, the association was stronger for males than for females. For African Americans, cocaine (probably crack cocaine) use trends were significantly associated with syphilis trends in this population. These data suggest that control of crack cocaine may have an impact on syphilis rates and that there may be close relationships between some STDs and drug abuse.     

Changing cocaine smoking rituals in the Dutch heroin addict population

Recently the use patterns, circumstances and consequences of cocaine have become of interest to both researchers and policy makers in Europe. Currently only a few studies have been conducted of the social epidemiology of cocaine. In this article, focus is placed upon the use of cocaine in one subpopulation, heroin addicts. Based mainly upon ethnographic research conducted in the city of Rotterdam it can be estimated that the prevalence of cocaine use in this population has reached a very high level. The mode of ingesting cocaine parallels that of heroin; Injecting Drug Users inject cocaine-hydrochloride, heroin smokers smoke cocaine base. This cocaine base is mainly processed by users themselves. An exception to this rule of self-processing can be found in the most marginalized addicts who do not have access to the house addresses where both heroin and cocaine-hydrochloride are sold. In this group the selling of ‘cooked cocaine’, a crack-like product, has occurred. The circumstances and potential consequences of the emergence of ‘cooked cocaine’ are discussed.     

Trends in illicit drug use in the United States: conflicting results from national surveys.

Data from several national studies lead to divergent conclusions regarding trends in illicit drug use in the United States. Two major population studies point to a downturn in drug use dating to the late 1970s. However, a study of drug-related deaths and hospital emergency room visits shows increases in these events in recent years. Studies also show drug use, especially cocaine, continuing to increase among criminals. Additionally, drugs were identified as the most important problem facing the nation in a Gallup poll conducted during the summer of 1989. This paper offers some possible explanations for the divergent trends. Most notably, we suggest that methodological differences in the studies being compared, and lags between trends in the general population and certain subgroups, account for most of the variation in the trend estimates. The paper concludes that illicit drug use is decreasing in the United States.     

Epidemiology of hepatitis C in Croatia in the European context

We analyzed prevalence, risk factors and hepatitis C virus (HCV) genotype distribution in different population groups in Croatia in the context of HCV epidemiology in Europe, with the aim to gather all existing information on HCV infection in Croatia which will be used to advise upon preventive measures. It is estimated that 35000-45000 of the Croatian population is chronically infected with HCV. Like in other European countries, there have been changes in the HCV epidemiology in Croatia over the past few decades. In some risk groups (polytransfused and hemodialysis patients), a significant decrease in the HCV prevalence was observed after the introduction of routine HCV screening of blood/blood products in 1992. Injecting drug users (IDUs) still represent a group with the highest risk for HCV infection with prevalence ranging from 29% to 65%. Compared to the prevalence in the Croatian general population (0.9%), higher prevalence rates were found in prison populations (8.3%-44%), human immunodeficiency virus-infected patients (15%), persons with high-risk sexual behavior (4.6%) and alcohol abusers (2.4%). Low/very low prevalence was reported in children and adolescents (0.3%) as well as in blood donors (0%-0.009%). In addition, distribution of HCV genotypes has changed due to different routes of transmission. In the general population, genotypes 1 and 3 are most widely distributed (60.4%-79.8% and 12.9%-47.9%, respectively). The similar genotype distribution is found in groups with high-risk sexual behavior. Genotype 3 is predominant in Croatian IDUs (60.5%-83.9%) while in the prison population genotypes 3 and 1 are equally distributed (52.4% and 47.6%). Data on HCV prevalence and risk factors for transmission are useful for implementation of preventive measures and HCV screening.     

Can cocaine use be evaluated through analysis of wastewater? A nation‐wide approach conducted in Belgium

Aims Cocaine is the second most‐used illicit drug world‐wide and its consumption is increasing significantly, especially in western Europe. Until now, the annual prevalence has been estimated indirectly by means of interviews. A recently introduced and direct nation‐wide approach based on measurements of the major urinary excreted metabolite of cocaine, benzoylecgonine, in wastewater is proposed. Design Wastewater samples from 41 wastewater treatment plants (WWTPs) in Belgium, covering approximately 3 700 000 residents, were collected. Each WWTP was sampled on Wednesdays and Sundays during two sampling campaigns in 2007–08. Samples were analysed for cocaine (COC) and its metabolites, benzoylecgonine (BE) and ecgonine methylester (EME) by a validated procedure based on liquid chromatography coupled with tandem mass spectrometry. Concentrations of BE were used to calculate cocaine consumption (g/day per 1000 inhabitants) for each WWTP region and for both sampling campaigns (g/year per 1000 inhabitants). Findings Weekend days showed significantly higher cocaine consumption compared with weekdays. The highest cocaine consumption was observed for WWTPs receiving wastewater from large cities, such as Antwerp, Brussels and Charleroi. Results were extrapolated for the total Belgian population and an estimation of a yearly prevalence of cocaine use was made based on various assumptions. An amount of 1.88 tonnes (t) per year [standard error (SE) 0.05 t] cocaine is consumed in Belgium, corresponding to a yearly prevalence of 0.80% (SE 0.02%) for the Belgian population aged 15–64 years. This result is in agreement with an earlier reported estimate of the Belgian prevalence of cocaine use conducted through socio‐epidemiological studies (0.9% for people aged 15–64 years). Conclusions Wastewater analysis is a promising tool to evaluate cocaine consumption at both local and national scale. This rapid and direct estimation of the prevalence of cocaine use in Belgium corresponds with socio‐epidemiological data. However, the strategy needs to be refined further to allow a more exact calculation of cocaine consumption from concentrations of BE in wastewater.