Differential profiles of crack users in respondent-driven and institutional samples: a three-site comparison

How well do hoarding research samples represent cases that rise to community attention?

This study used archival data from three different research groups and case file data from three independent community organizations to explore how well research samples reflect cases of hoarding that come to community attention. Using data from 824 individuals with hoarding, we found that research volunteers differ from community clients in several ways: community clients are older, more likely to be male and less likely to be partnered; they have lower socio-economic status and are less likely to demonstrate good or fair insight regarding hoarding severity and consequences. The homes of community clients had greater clutter volume and were more likely to have problematic conditions in the home, including squalor and fire hazards or fire safety concerns. Clutter volume was a strong predictor of these conditions in the home, but demographic variables were not. Even after accounting for the influence of clutter volume, the homes of community-based clients were more likely to have squalor. These findings suggest limitations on the generalizability of research samples to hoarding as it is encountered by community agencies.

Using Respondent Driven Sampling to Identify Malaria Risks and Occupational Networks among Migrant Workers in Ranong, Thailand

Background

Ranong Province in southern Thailand is one of the primary entry points for migrants entering Thailand from Myanmar, and borders Kawthaung Township in Myanmar where artemisinin resistance in malaria parasites has been detected. Areas of high population movement could increase the risk of spread of artemisinin resistance in this region and beyond.

Methods

A respondent-driven sampling (RDS) methodology was used to compare migrant populations coming from Myanmar in urban (Site 1) vs. rural (Site 2) settings in Ranong, Thailand. The RDS methodology collected information on knowledge, attitudes, and practices for malaria, travel and occupational histories, as well as social network size and structure. Individuals enrolled were screened for malaria by microscopy, Real Time-PCR, and serology.

Results

A total of 619 participants were recruited in Ranong City and 623 participants in Kraburi, a rural sub-district. By PCR, a total of 14 (1.1%) samples were positive (2 P. falciparum in Site 1; 10 P. vivax, 1 Pf, and 1 P. malariae in Site 2). PCR analysis demonstrated an overall weighted prevalence of 0.5% (95% CI, 0–1.3%) in the urban site and 1.0% (95% CI, 0.5–1.7%) in the rural site for all parasite species. PCR positivity did not correlate with serological positivity; however, as expected there was a strong association between antibody prevalence and both age and exposure. Access to long-lasting insecticidal treated nets remains low despite relatively high reported traditional net use among these populations.

Conclusions

The low malaria prevalence, relatively smaller networks among migrants in rural settings, and limited frequency of travel to and from other areas of malaria transmission in Myanmar, suggest that the risk for the spread of artemisinin resistance from this area may be limited in these networks currently but may have implications for regional malaria elimination efforts.

Using Respondent-Driven Sampling to Recruit Illegal Drug Purchasers to Evaluate a Drug Market Intervention

BACKGROUND

Violent drug markets are not as prominent as they once were in the United States, but they still exist and are associated with significant crime and lower quality of life. The drug market intervention (DMI) is an innovative strategy that uses focused deterrence, community engagement, and incapacitation to reduce crime and disorder associated with these markets. Although studies show that DMI can reduce crime and overt drug activity, one perspective is prominently missing from these evaluations: those who purchase drugs.

OBJECTIVES

This study explores the use of respondent-driven sampling (RDS)-a statistical sampling method-to approximate a representative sample of drug users who purchased drugs in a targeted DMI market to gain insight into the effect of a DMI on market dynamics.

METHODS

Using RDS, we recruited individuals who reported hard drug use (crack or powder cocaine, heroin, methamphetamine, or illicit use of prescriptions opioids) in the last month to participate in a survey. The main survey asked about drug use, drug purchasing, and drug market activity before and after DMI; a secondary survey asked about network characteristics and recruitment.

CONCLUSIONS

Our sample of 212 respondents met key RDS assumptions, suggesting that the characteristics of our weighted sample approximate the characteristics of the drug user network. The weighted estimates for market purchasers are generally valid for inferences about the aggregate population of customers, but a larger sample size is needed to make stronger inferences about the effects of a DMI on drug market activity.

Criminal involvement and crime specialization among crack users in the Netherlands

BACKGROUND/AIMS

Crack users in the Netherlands are an ageing and diverse population with longstanding criminal careers. Our aim was to assess factors associated with current criminal involvement and specialization in selling drugs, property crime and violence.

METHOD

A sample of 1,039 frequent crack users was recruited in three major Dutch cities, combining respondent-driven sampling with random institutional sampling. Bivariate and logistic regression analyses were performed to find factors associated with current criminality.

RESULTS

A total of 431 participants (41.5%) had engaged in crime in the past 30 days, mostly selling drugs (68.9%), followed by property crimes (34.4%) and a few cases of violent crime (9.7%). Younger age, homelessness, heavier patterns of use and a more prolific criminal justice history were associated with current criminality. Those receiving welfare benefits tended to be more likely to specialize only in selling drugs as opposed to (also) property crimes.

CONCLUSION

Reducing drug use among criminally involved crack users and addressing their housing conditions could have a significant impact on reducing drug-related crime. Welfare benefits might act as protective factor against committing property crimes but not against the selling of drugs.

Buying and Selling Crack

To assess key characteristics of the retail crack market and the role of users as buyers and sellers, data from a survey inside and outside institutional setting among 1,039 crack users in the three largest Dutch cities were analyzed to explore their role in the crack market as buyers and sellers. Of the total number of users, 42.3% bought crack in public places, 39.6% through home delivery, and 13.9% at dealer’s addresses. Near one-third reported participating in selling drugs, defining themselves as “go-betweens” (21.4%) or “dealers” (9.2%). User-sellers and nonselling users did not differ with regard to gender and ethnicity. Cluster analysis resulted in three distinct types of user-sellers (freelancers, assistants, and amateurs), each characterized by time spent selling drugs, type of drugs sold, and earnings. Amateurs seem quite similar to what scholars have labeled “social dealers” in recreational drugs markets. This study suggests the need for a more differentiated law enforcement policy toward drug-selling users.

Estimating the prevalence of crack dependence using capture-recapture with institutional and field data: a three-city study in The Netherlands

The aim of this study was to estimate the prevalence of crack dependence in the three largest Dutch cities (Amsterdam, Rotterdam, The Hague), stratified by gender and age. Three-sample capture-recapture, using data (collected between 2009 and 2011) from low threshold substitution treatment (n = 1,764), user rooms (n = 546), and a respondent-driven sample (n = 549), and applying log-linear modeling (covariates: gender, age, and city), provided a prevalence rate of 0.51% (95% CI: 0.46%-0.60%) for the population aged 15-64 years, with similar estimates for the three cities. Females (23.0% of total estimate) and younger crack users (12.8% aged <35 years) might be underrepresented in drug user treatment services.