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Keith Sabin

Publications and source records attributed to Keith Sabin.

8 recordsLinked to original sources
PubMed2006

Effectiveness of respondent-driven sampling for recruiting drug users in New York City: findings from a pilot study.

A number of sampling methods are available to recruit drug users and collect HIV risk behavior data. Respondent-driven sampling (RDS) is a modified form of chain-referral sampling with a mathematical system for weighting the sample to compensate for its not having been drawn randomly. It is predicated on the recognition that peers are better able than outreach workers and researchers to locate and recruit other members of a "hidden" population. RDS provides a means of evaluating the reliability of the data obtained and also allows inferences about the characteristics of the population from which the sample is drawn. In this paper we present findings from a pilot study conducted to assess the effectiveness of RDS to recruit a large and diversified group of drug users in New York City. Beginning with eight seeds (i.e., initial recruits) we recruited 618 drug users (injecting and non-injecting) in 13 weeks. The data document both cross-gender and cross-race and -ethnic recruitment as well as recruitment across drug-use status. Sample characteristics are similar to the characteristics of the drug users recruited in other studies conducted in New York City. The findings indicate that RDS is an effective sampling method for recruiting diversified drug users to participate in HIV-related behavioral surveys.

Adult↗
PubMed2006

Assessment of respondent driven sampling for recruiting female sex workers in two Vietnamese cities: reaching the unseen sex worker.

Respondent driven sampling (RDS) is a relatively new method to sample hard-to-reach populations. Until this study, female sex workers (FSWs) in Vietnam were sampled using a variety of methods, including time location sampling (TLS), which may not access the more hidden types of FSWs. This paper presents an analysis from an HIV biological and behavioral surveillance survey to assess the feasibility and effectiveness of RDS to sample FSWs, to determine if RDS can reach otherwise inaccessible FSWs in Vietnam and to compare RDS findings of HIV risk factors with a theoretical TLS. Through face-to-face interviews with FSWs in Ho Chi Minh City (HCMC) and Hai Phong (HP), data were collected about the venues where they most often solicit their clients. These data were used to create three variables to assess whether FSWs solicit their clients in locations that are visible, semi-visible and non-visible. For this analysis, the visible group simulates a sample captured using TLS. Survey results in HIV prevalence and related risk factors and service utilization, adjusted for sampling methodology, were compared across each of the three FSW visibility groups to assess potential bias in TLS relative to RDS. The number of self-reported visible FSWs (HCMC: n=311; HP: n=162) was much larger than those of the semi-visible (HCMC: n=65; HP: n=43) and non-visible (HCMC: n=37; HP: n=10) FSWs in HCMC and HP. Non-visible FSWs in both cities were just as likely as visible and semi-visible FSWs to be HIV positive (HCMC: visible 14.5%, semi-visible 13.8%, non-visible 13.5%, p value = 0.982; HP: visible 35.2%, semi-visible 30.2%, non-visible 30.0%, p value = 0.801), to practice behaviors that put them at risk for contracting and transmitting HIV (injecting drug use-HCMC: visible 13.8%, semi-visible 12.3%, non-visible 5.4%, p value = 0.347; HP: visible 38.9%, semi-visible 23.3%, non-visible 30.0%, p value = 0.378, to have no condom use in the past month -HCMC only: visible 52.7%, semi-visible 63.1%, non-visible 48.6%, p value = 0.249) and to have symptoms of a sexually transmitted infection (STI) in the past year (HCMC: visible 16.1%, semi-visible 12.3%, non-visible 16.2%, p value = 0.742; HP: visible 13.6%, semi-visible 18.6%, non-visible 20.0%, p value = 0.640). There was a difference found among the visible, semi-visible and non-visible groups in HP for no past month condom use (visible 53.1%, semi-visible 79.1%, non-visible 60.0%, p value = 0.009). This study found that RDS was successful at recruiting hidden types of FSWs in Vietnam. Past reports of FSWs in Vietnam have assessed the more visible FSWs as being the most vulnerable and at risk for HIV. Although the number of visible FSWs is much higher than those of the semi and non-visible groups, this study found that the non-visible FSWs are very vulnerable to HIV infection. If prevention programs are targeting and responding to those who are most likely to be assessed (e.g., more visible types of FSWs) then this analysis indicates that a significant proportion of the FSW population at risk for HIV may not be receiving optimal HIV information and services.

Data Collection↗
PubMed2006

The mental health status of Mayan refugees after repatriation to Guatemala.

OBJECTIVE: Only one previous study had examined the epidemiology of mental health in Guatemalan refugees. The objective of this new study was to estimate the prevalence of mental illness and to assess factors associated with poor mental health among Guatemalan Mayan refugees who had been repatriated to Guatemala after spending 12-18 years in refugee camps in Mexico, and to compare the results for the repatriated Guatemalans with those for Guatemalan refugees who were continuing to live in Mexico. METHODS: In 2001 a cross-sectional survey of adults (> or = 16 years) was conducted with random household sampling proportional to the population size in each of the five repatriation villages surveyed. Posttraumatic stress disorder (PTSD), anxiety, and depression were measured by the Harvard Trauma Questionnaire and the Hopkins Symptom Checklist-25. RESULTS: Together, the five repatriation villages had 565 households. Of the 565 households, 203 of them were approached to solicit study participation. A total of 179 households (one adult per household) agreed to participate, representing an overall participation rate of 88%, and one-third of all the households in the five communities. The respondents had personally experienced a mean of 5.5 trauma events and had witnessed a mean of 7.3 other trauma events. Of the respondents, 8.9% met the symptom criteria for PTSD, 17.3% for anxiety, and 47.8% for depression. PTSD was associated with being seriously wounded and with having relatives or friends mutilated. Logistic regression analyses indicated that anxiety was associated with being sexually assaulted, being female, having friends or family mutilated, being seriously wounded, and having 6-12 children (vs. having 1-5 children). Depression was associated with having 6-12 children. Anxiety was significantly more prevalent among the refugees remaining in Mexico (54.4%) than it was among the repatriated refugees (17.3%). The difference in the prevalence rates was not significant for PTSD (11.8% for refugees remaining in Mexico vs. 8.9% for those repatriated) or for depression (38.8% for refugees remaining in Mexico vs. 47.8% for those repatriated). CONCLUSIONS: Psychiatric morbidity was common among the repatriated Mayans. The repatriation of refugees involves moving an already vulnerable, often traumatized population back to a place of distressing memories and still-unsettled conditions. There is a need to consider and plan for adequate mental health services for repatriating refugees.

Adolescent↗
PubMed2005

Review of sampling hard-to-reach and hidden populations for HIV surveillance.

Adequate surveillance of hard-to-reach and 'hidden' subpopulations is crucial to containing the HIV epidemic in low prevalence settings and in slowing the rate of transmission in high prevalence settings. For a variety of reasons, however, conventional facility and survey-based surveillance data collection strategies are ineffective for a number of key subpopulations, particularly those whose behaviors are illegal or illicit. This paper critically reviews alternative sampling strategies for undertaking behavioral or biological surveillance surveys of such groups. Non-probability sampling approaches such as facility-based sentinel surveillance and snowball sampling are the simplest to carry out, but are subject to a high risk of sampling/selection bias. Most of the probability sampling methods considered are limited in that they are adequate only under certain circumstances and for some groups. One relatively new method, respondent-driven sampling, an adaptation of chain-referral sampling, appears to be the most promising for general applications. However, as its applicability to HIV surveillance in resource-poor settings has yet to be established, further field trials are needed before a firm conclusion can be reached.

Epidemiologic Methods↗
PubMed2004

Prevalence and incidence of HIV, hepatitis B virus, and hepatitis C virus infections among males in Rhode Island prisons.

OBJECTIVES: We evaluated prevalence and intraprison incidence of HIV, hepatitis B virus, and hepatitis C virus infections among male prison inmates. METHODS: We observed intake prevalence for 4269 sentenced inmates at the Rhode Island Adult Correctional Institute between 1998 and 2000 and incidence among 446 continuously incarcerated inmates (incarcerated for 12 months or more). RESULTS: HIV, hepatitis B virus, and hepatitis C virus prevalences were 1.8%, 20.2%, and 23.1%, respectively. Infections were significantly associated with injection drug use (odds ratio = 10.1, 7.9, and 32.4). Incidence per 100 person-years was 0 for HIV, 2.7 for HBV, and 0.4 for HCV. CONCLUSIONS: High infection prevalence among inmates represents a significant community health issue. General disease prevention efforts must include prevention within correctional facilities. The high observed intraprison incidence of HBV underscores the need to vaccinate prison populations.

Adult↗
PubMed2003

Hepatitis A vaccination of infants: effect of maternal antibody status on antibody persistence and response to a booster dose.

BACKGROUND: Infants with passively transferred maternal antibody (PMA) to hepatitis A virus (HAV) have lower concentrations of antibody to HAV (anti-HAV) after vaccination. We examined the effect of PMA on persistence of anti-HAV and on immune memory. METHODS: We measured anti-HAV concentrations of 6-year-old children who had responded to a three dose hepatitis A vaccine series at ages 2, 4 and 6 months. Group 1 children were born to anti-HAV-negative women; Group 2 children had anti-HAV-positive mothers and PMA at 2 months of age. Children without detectable antibody at 6-year follow-up were offered a booster dose [360 enzyme-linked immunosorbent units (ELU)]. An anamnestic response was defined as a postbooster anti-HAV concentration of > or =400 mIU/ml. RESULTS: At follow-up, before the booster dose, Group 1 subjects had a higher geometric mean concentration (50 mIU/ml vs.18 mIU/ml, P = 0.007), and a larger proportion retained seroprotective concentrations of anti-HAV [21 of 31 (68%) vs.4 of 17 (24%)] compared with Group 2 subjects. The two stage antibody decline curves for the two groups from 8 months old to follow-up testing were parallel. An anamnestic response occurred in all (5 of 5) Group 1 and 67% (4 of 6) of Group 2 children. The geometric mean antibody concentrations after the booster were 1102 and 406 mIU/ml for Groups 1 and 2, respectively (P = 0.10). CONCLUSIONS: Infants with PMA who receive hepatitis A vaccine have significantly lower concentrations of anti-HAV 6 years later than infants with no PMA who receive hepatitis A vaccine. Immune memory may remain functional despite these lower anti-HAV concentrations.

Adult↗