Hardeo Sahai

Between-city variation in frequency of injection among Puerto Rican injection drug users: East Harlem, New York, and Bayamon, Puerto Rico

Summary: Frequency of injection has been consistently found to be higher among Puerto Rican Injection drug users (IDUs) than among other groups of IDUs. Several explanations have been suggested, but an empirical explanation has yet to be presented. This study compares the frequency of injection of Puerto Rican IDUs in East Harlem, New York, with that of IDUs in Bayamon, Puerto Rico. Study subjects comprised 521 Puerto Rican IDUs from East Harlem and 303 IDUs from Bayamon. The mean frequency of injection among IDUs in East Harlem was 2.8, the corresponding mean in Bayamon was 5.4. Younger IDUs reported a higher number of daily injection episodes than older IDUs, and the IDU group in Bayamon was 5 years younger than the group in East Harlem. The drug use variables accounted for a greater portion of the between‐city difference than the demographic and psychosocial variables. Use of noninjected drugs, as well as the use of prescribed methadone, were found to be associated with a lower number of daily injections. Conversely, injection of cocaine, injection of cocaine mixed with heroin (“speedball”), and injection of larger amounts of drug solution were found to be associated with a higher number of daily injections.

The validity of drug use self-reports among hard core drug users in a household survey in Puerto Rico: comparison of survey responses of cocaine and heroin use with hair tests

The extent to which underreporting of drug use in household surveys affects the validity of epidemiological studies of drug use disorders is largely unknown. We developed a list of known hard core drug users as part of a larger household study in Puerto Rico. The known drug users were recruited and interviewed with the same procedures used for the respondents selected through area-probability sampling. Upon completion of the interview, subjects were asked to provide a sample of scalp hair. A total of 78 hair specimens were collected from the known drug users. Hair specimens were screened for cocaine and heroin using radio immunoassay, and confirmed using gas chromatography/mass spectrometry. Using the cutoff of 0.2 ng/mg of hair, 93.2% of the hair specimens were classified positive for cocaine and 75.7% for heroin. With the hair test results as the gold-standard, we calculated specificity and sensitivity statistics as measures of the validity of self-reports. Self-reports of drug use in the past 3 months had a specificity of 78% or higher for both drugs. The sensitivity of self-reports was 69.6% for reports of recent cocaine use and 78.6% for reports of recent heroin use. Sensitivity increased with reports of use in more remote time periods, among subjects reporting DSM-IV drug disorder symptoms, and among those reporting use of both drugs. The results suggest that while drug reports of hard core drug users interviewed in household surveys might be more valid than those of the general population, there still remains considerable under-reporting.

Analysis of Variance for Random Models

Analysis of variance for random models , Analysis of variance for random models , کتابخانه دیجیتال جندی شاپور اهواز

Determinants of health care use among Puerto Rican drug users in Puerto Rico and New York City.

This study was conducted to identify factors accounting for differences in health care and drug treatment utilization between Puerto Rican drug users residing in 2 separate locations. Survey findings from 334 drug users in Puerto Rico and 617 in New York City showed that those in Puerto Rico were 6 times less likely than their counterparts in New York to have used inpatient medical services and 13 to 14 times less likely to have used outpatient medical services or methadone. They also were less likely to have health insurance or past drug treatment. After site was controlled for, health insurance and previous use of physical or mental health services remained significant predictors of health care and drug treatment utilization during the study period. Although Puerto Rican drug users in Puerto Rico are not an ethnic minority, they reported significant disparities in health services use compared with Puerto Rican drug users in New York.

Risk behaviors, HIV seropositivity, and tuberculosis infection in injecting drug users who operate shooting galleries in Puerto Rico.

This study was designed to assess HIV risk behaviors, HIV seroprevalence, and tuberculosis (TB) infection in shooting gallery managers in Puerto Rico. The subjects were 464 injection drug users (IDUs), of whom 12.5% reported managing shooting galleries. The median frequency of drug injection was higher in shooting gallery managers than in nonmanagers. A trend was observed for purified protein derivative (PPD) reactivity to increase according to the length of time spent as a gallery manager, but this trend was not statistically significant. However, anergy rates increased significantly with increase in the number of months spent as shooting gallery manager (p = .021). Multivariate analyses showed that IDUs reporting shooting gallery management experience of > or = 25 months were more likely to be infected with HIV. Prevention programs need to emphasize strategies to protect the health of shooting gallery clients and, in particular, shooting gallery managers. Additional studies are required to determine effective strategies for reducing the risk of HIV and TB infection in shooting galleries.

A Comparative Study of Mortality Among Puerto Rican Injection Drug Users in East Harlem, New York, and Bayamon, Puerto Rico

Drug users have been found to be at high risk of mortality but the mortality experience of Hispanic drug users remains understudied. This study assessed mortality among Puerto Rican injection drug users (IDUs) in New York City (NY), and in Puerto Rico (PR). Study subjects were 637 IDUs from NY and 319 IDUs from PR. Mortality was ascertained using data from the National Death Index. Annual mortality rate of the NY cohort was 1.3 per 100 person years compared to the PR cohort with a rate of 4.8. Compared to the Hispanic population of New York City, the standardized mortality ratio (SMR) of the NY cohort was 4.4. Compared to the population of Puerto Rico, the SMR of the PR cohort was 16.2. The four principal causes of death were: NY—HIV/AIDS (50.0%), drug overdoses (13.3%), cardiovascular conditions (13.3%), and pulmonary conditions (10.0%); PR—HIV/AIDS (37.0%), drug overdoses (24.1%), sepsis (13.0%), and homicide (11.1%). Modeling time to death using Cox proportional hazards regression, the relative risk of mortality of the PR cohort as compared to the NY cohort was 9.2. The other covariates found to be significantly associated with time to death were age, gender, education, social isolation, intoxication with alcohol, and HIV seropositivity. The large disparity in mortality rates found in this study suggests that health disparities research should be expanded to identify intra-group disparities. Furthermore, these results point to an urgent need to reduce excess mortality among IDUs in Puerto Rico.

Problems and challenges of teaching biostatistics to medical students and professionals

The problems and challenges encountered in teaching biostatistics to medical students and professionals are considered. Some suggestions and tips, which may help to overcome some of these problems and enhance certain aspects of biostatistics teaching and learning, are presented.

What is a census

A census is a total process of collecting and publishing demographic, socioeconomic, and other pertinent data for all persons in a given country or region. The article presents a general overview of various aspects—both conceptual and operational—of a demographic census, including controversy surrounding the statistical adjustment of census counts.

Design-based Sample and Probability Law-Assumed Sample: Their Role in Scientific Investigation.

Students in statistics service courses are frequently exposed to dogmatic approaches for evaluating the role of randomization in statistical designs, and inferential data analysis in experimental, observational and survey studies. In order to provide an overview for understanding the inference process, in this work some key statistical concepts in probabilistic and nonprobabilistic sampling are discussed. The statistical model constituting the basis of statistical inference is postulated and a brief review of the finite population descriptive inference and a quota sampling inferential theory are provided. Some comments on distinct approaches for conducting inferences in probabilistic and nonprobabilistic samples are adduced.

Two-Way Nested Classification

In the preceding two chapters, we have considered experimental situations where the levels of two factors are crossed. In this and the following chapter we onsider experiments where the levels of one of the factors are nested within the levels of the other factor. The data for a two-way nested classification are similar hat of a single factor classification except that now replications are grouped into different sets arising from the levels of the nested factor for a given level of the main factor. Suppose the main factor A has a levels and the nested factor B has ab levels which are grouped into a sets of b levels each, and n observations are made at each level of the factor B giving a total of abn observations. The nested or hierarchical designs of this type are very important in many industrial and genetic investigations. For example, suppose an experiment is designed to investigate the variability of a certain material by randomly selecting a batches, b samples are made from each batch, and finally n analyses are performed on each sample. The purpose of the investigation may be to make inferences about the relative contribution of each source of variation to the total variance or to make inferences about the variance components individually. For another example, suppose in a breeding experiment a random sample of a sires is taken, each sire is mated to a sample of b dams, and finally n offspring are produced from each sire-dam mating. Again, the purpose of the investigation may be to study the relative magnitude of the variance components or to make inferences about them individually.