INFANT MORTALITY IN THE MEXICAN AMERICAN COMMUNITY: AN ANALYSIS OF DIFFERENTIALS IN INFANT, NEONATAL, AND POSTNEONATAL MORTALITY BY ETHNICITY AND PARENTAL NATIVITY, 1974-75 SINGLE LIVE BIRTH COHORT, HARRIS COUNTY, TEXAS

The paradoxically low infant mortality rates for Mexican Americans in Texas have been attributed to inaccuracies in vital registration and idiosyncracies in Mexican migration in rural areas along the U.S.-Mexico border. This study examined infant (IMR), neonatal (NMR), and postneonatal (PNMR) mortality rates of Mexican Americans in an urban, non-border setting, using linked birth and death records of the 1974-75 single live birth cohort (N = 68,584) in Harris County, Texas, which includes the city of Houston and is reported to have nearly complete birth and death registration. The use of parental nativity with the traditional Spanish surname criterion made it possible to distinguish infants of Mexican-born immigrants from those of Blacks, Anglos, other Hispanics, and later-generation, more Anglicized Mexican Americans. Mortality rates were analyzed by ethnicity, parental nativity, and cause of death, with respect to birth weight, birth order, maternal age, legitimacy status, and time of first prenatal care.^ While overall IMRs showed Spanish surname rates slightly higher than Anglo rates, infants of Mexican-born immigrants had much lower NMRs than did Anglos, even for moderately low birth weight infants. However, among infants under 1500 grams, presumably unable to be discharged home in the neonatal period, Mexican Americans had the highest NMR. The inconsistency suggested unreported deaths for Mexican American low birth weight infants after hospital discharge. The PNMR of infants of Mexican immigrants was also lower than for Anglos, and the usual mortality differentials were reversed: high-risk categories of high birth order, high maternal age, and late/no prenatal care had the lowest PNMRs. Since these groups' characteristics are congruent with those of low-income migrants, the data suggested the possibility of migration losses. Cause of death analysis suggested that prematurity and birth injuries are greater problems than heretofore recognized among Mexican Americans, and that home births and "shoebox burials" may be unrecorded even in an urban setting.^ Caution is advised in the interpretation of infant mortality rates for a Spanish surname population of Mexican origin, even in an urban, non-border area with reportedly excellent birth and death registration. ^

ENVIRONMENTAL EXPOSURES AND LUNG CANCER RISK AMONG WOMEN IN HARRIS COUNTY, TEXAS, 1977-1980 (OCCUPATION, SMOKING, BYSTANDER)

Excessively high, accelerating lung cancer rates among women in Harris County, Texas, prompted this case-comparison study. Objectives were to compare patterns of employment, indirect exposures, and sociodemographic variables of lung cancer cases with comparison subjects (compeers) after standardizing for possible confounders, such as age and cigarette smoking. Lung cancer cases were microscopically confirmed, white, Harris County residents. Compeers, chosen from Medicare records and Texas Department of Public Safety records, were matched on gender, race, age, resident and vital status. Personal interviews were conducted with study subjects or next-of-kin. Industries and occupations were categorized as high risk, based on previous studies.^ Almost all cases (95.0%) and 60.0% of compeers smoked cigarettes. The odds ratio for lung cancer and smoking is 13.9. Stopping smoking between ages 30-50 years carries a lower risk than stopping at age 58 or more years. Women's employment in a high risk industry or occupation results in consistently elevated, smoking-adjusted odds ratios. Frequency and duration of employment demonstrate a moderate dose-response effect. A temporal association exists with employment in a high risk occupation during 1940-1949.^ No increased risk appeared with passive smoking. Husband's employment in a construction industry or a structural occupation significantly increased the smoking-adjusted odds ratios among cases and compeers (O.R. = 2.9, 2.2). Smoking-adjusted odds ratios increased significantly when women had resided with persons employed in cement (O.R. = 3.2) or insulation (O.R. = 5.5) manufacturing, or a high rise construction industry (O.R. = 2.4). A family history of lung cancer resulted in a two-fold increase in smoking-adjusted odds ratios. Vital status of compeers affected the odds ratios.^ Work-related exposures appear to increase the risk of lung cancer in women although cigarette smoking has the single highest odds ratio. Indirect exposure to certain employment also plays a significant role in lung cancer in women. Investigations of specific direct and indirect hazardous exposures in the workplace and home are needed. Cigarette smoking is as hazardous for women as for men. Smoking should be prevented and eliminated. ^

Spatial analysis of pertussis cases in Harris County from 2005-2010

Objective: This study examined the recent trends and characteristics of reported pertussis in Harris County from 2005-2010. ^ Methods: The study population included surveillance data from all reported pertussis cases from January 1, 2005 to December 31, 2010 to Harris County Public Health and Environmental Services (HCPHES). We calculated incidence and attack rates for varying age groups, race/ethnicity, and gender. Spatial analyses were conducted of hot spot and cluster of incident cases in Harris County census tracts. Maps were constructed using geographic information system. ^ Results: Age-specific incidence rates of reported cases of pertussis were highest among infants under a year of age and lowest among adults age 20 and older. Hispanics represented the most cases reported compared to any other race or ethnic group (42% of 483 cases). Age-adjusted rates were highest in 2009 at 9.81 cases per 100,000 population. Only 31.2% of people received at least four of the recommended five doses of vaccine. Spatial analyses revealed statistically significant clusters within the northeast region of Harris County. ^ Conclusions: Hispanic infants are the most at risk group for pertussis. Although 70% of cases had a history of immunization, 41.8% of infants were appropriately vaccinated for their age. Increased vaccination coverage may decrease the incidence of pertussis.^

A screening for anti-West Nile immunoglobulin-G and immunoglobulin-M in the Cameron County Hispanic cohort

This study is designed to be a cross-sectional, retrospective analysis of the seroprevalence of anti-WNV antibodies in 1,006 plasma samples collected from February 2, 2006 to June 18, 2007 originally for The Cameron County Hispanic Cohort: Extreme obesity and uncontrolled diabetes on the U.S.-Mexico border, major concerns for populations with health disparities. The aim of this thesis research is to give a more up-to-date picture of Flavivirus activity in south Texas, which can potentially contribute to the surveillance objective of arboviral control in this area. A West Nile virus (WNV) seroprevalence study in humans in this particular area has never before been completed. Plasma samples were tested using immunoglobulin-G (IgG) and immunoglobulin-M (IgM) WNV enzyme linked immunosorbent assays (ELISA). Estimated seroprevalence for this particular population was 0.98% or 9.8 cases of West Nile disease per 1,000 citizens. After IgG testing, seroprevalence in the study population was found to be 15.4%. Specimens tested for WNV IgG were compared with a subset of specimens (N=803) tested for history of primary dengue virus (DENV) infection. Of the 803 specimens tested for IgG to DENV, 308 were positive. Of the 132 positive WNV IgG specimens in the subset, 131 (99.2%) tested also tested positive for DENV IgG. It would be helpful to use standard plaque reduction neutralization testing to determine if the seroprevalence is in fact lower because of cross-reaction to DENV on testing. Regardless of the possibility of other Flavivirus activity occurring prior to the introduction of WNV into the United States and the potential for cross-reactivity, Texas has ranked in the top 5 states with the highest, laboratory confirmed incidence of infection with WNV since 2003. Indicating that climate factors and the presence of suitable vectors makes Texas a hotspot for WNV activity. ^ A description of the study population by age, gender, and income was done indicating a statistically significant income difference with a mean household income per year being $13,413.55 for a case and $20,268.80 for non-cases (p=0.001). Lower income neighborhoods should be targeted for education and prevention of vector-borne diseases during the summer months in Cameron County. With respect to gender, being male has been noted in the literature to be a risk factor for infection with WNV (25). In this study, females comprised approximately 68% of the study population, they also made up 66.5% of the positive IgG specimens. An odds ratio of 0.91 indicates that women are less likely to be IgG positive for WNV as compared to men; however, this was not found to be significant based on the 95% confidence interval, but is consistent with the literature. When looking at age difference between positive and negative/equivocal cases, there was no statistical difference found between the two groups. ^ We concluded that this study will enable us to understand the epidemiology of WNV transmission since its introduction into the United States and hopefully to maintain or improve the current measures we have in place to prevent infections that are seen annually with WNV.^

Burden of invasive pneumococcal disease in Harris County, Texas (2003--2010) and the implication for enhanced public health surveillance of isolates

Invasive pneumococcal disease (IPD) causes significant health burden in the US, is responsible for the majority of bacterial meningitis, and causes more deaths than any other vaccine preventable bacterial disease in the US. The estimated National IPD rate is 14.3 cases per 100,000 population with a case-fatality rate of 1.5 cases per 100,000 population. Although cases of IPD are routinely reported to the local health department in Harris County Texas, the incidence (IR) and case-fatality (CFR) rates have not been reported. Additionally, it is important to know which serotypes of S. pneumoniae are circulating in Harris County Texas and to determine if ‘replacement disease’ is occurring. ^ This study reported incidence and case-fatality rates from 2003 to 2009, and described the trends in IPD, including the IPD serotypes circulating in Harris County Texas during the study period, particularly in 2008 and 2010. Annual incidence rates were calculated and reported for 2003 to 2009, using complete surveillance-year data. ^ Geographic information system (GIS) software was used to create a series of maps of the data reported during the study period. Cluster and outlier analysis and hot spot analysis were conducted using both case counts by census tract and disease rate by census tract. ^ IPD age- and race-adjusted IR for Harris County Texas and their 95% confidence intervals (CIs) were 1.40 (95% CI 1.0, 1.8), 1.71 (95% CI 1.24, 2.17), 3.13 (95% CI 2.48, 3.78), 3.08 (95% CI 2.43, 3.74), 5.61 (95% CI 4.79, 6.43), 8.11 (95% CI 7.11, 9.1), and 7.65 (95% CI 6.69, 8.61) for the years 2003 to 2009, respectively (rates were age- and race-adjusted to each year's midyear US population estimates). A Poisson regression model demonstrated a statistically significant increasing trend of about 32 percent per year in the IPD rates over the course of the study period. IPD age- and race-adjusted case-fatality rates (CFR) for Harris County Texas were also calculated and reported. A Poisson regression model demonstrated a statistically significant increasing trend of about 26 percent per year in the IPD case-fatality rates from 2003 through 2009. A logistic regression model associated the risk of dying from IPD to alcohol abuse (OR 4.69, 95% CI 2.57, 8.56) and to meningitis (OR 2.42, 95% CI 1.46, 4.03). ^ The prevalence of non-vaccine serotypes (NVT) among IPD cases with serotyped isolates was 98.2 percent. In 2008, the year with the sample more geographically representative of all areas of Harris County Texas, the prevalence was 96 percent. Given these findings, it is reasonable to conclude that ‘replacement disease’ is occurring in Harris County Texas, meaning that, the majority of IPD is caused by serotypes not included in the PCV7 vaccine. Also in conclusion, IPD rates increased during the study period in Harris County Texas.^

A comparison of two statistical methods for analysis of day of the week effect on births from 2005-2007 in Harris County of Texas

The pattern of the births during the week has been reported by many studies. The births occurred in weekends are found consistently less then births occurred in weekdays. This study employed two statistical methods, two-way ANOVA and two-way Friedman's test to analyse the daily variations in amount of births of 222,735 births from 2005-2007 in Harris County, Texas. The two methods were compared on their assumptions, procedures and results. Both of the tests showed a significant result which indicated that the births through the week are not uniformly distributed. The result of multiple comparison demonstrated the births occurring on weekends were significantly different than the births occurring on weekdays with least amount on Sundays.^

Spatial analysis of cardiovascular disease mortality and air pollution in Harris County, Texas

The association between fine particulate matter air pollution (PM2.5) and cardiovascular disease (CVD) mortality was spatially analyzed for Harris County, Texas, at the census tract level. The objective was to assess how increased PM2.5 exposure related to CVD mortality in this area while controlling for race, income, education, and age. An estimated exposure raster was created for Harris County using Kriging to estimate the PM2.5 exposure at the census tract level. The PM2.5 exposure and the CVD mortality rates were analyzed in an Ordinary Least Squares (OLS) regression model and the residuals were subsequently assessed for spatial autocorrelation. Race, median household income, and age were all found to be significant (p<0.05) predictors in the model. This study found that for every one μg/m3 increase in PM2.5 exposure, holding age and education variables constant, an increase of 16.57 CVD deaths per 100,000 would be predicted for increased minimum exposure values and an increase of 14.47 CVD deaths per 100,000 would be predicted for increased maximum exposure values. This finding supports previous studies associating PM2.5 exposure with CVD mortality. This study further identified the areas of greatest PM2.5 exposure in Harris County as being the geographical locations of populations with the highest risk of CVD (i.e., predominantly older, low-income populations with a predominance of African Americans). The magnitude of the effect of PM2.5 exposure on CVD mortality rates in the study region indicates a need for further community-level studies in Harris County, and suggests that reducing excess PM2.5 exposure would reduce CVD mortality.^

Cross-sectional study examining the role of acculturation in self-reported hypertension among Mexican Americans in Harris County, Texas

The objective of this secondary analysis was to examine the role of acculturation and self-reported hypertension in a Mexican-American cohort from Harris County, Texas. Specifically, we examined the acculturation measures of language-based Bidimensional Acculturation Scale (BAS), nativity, and length of United States (U.S) residency. Of 6,229 participants aged 40 and older, 38.0% self-reported hypertension at baseline. ^ Multiple logistic regression was used to estimate the prevalence odds ratios (pOR) for the association of each acculturation measure and hypertension while controlling for confounding. When adjusted for age, gender, body mass index, number of comorbidities, and family history of hypertension, U.S.-born participants were 1.37 times more likely to report having hypertension compared to Mexico-born participants (95% CI: 1.21, 1.55). Similarly, immigrants residing in the U.S. for more than 20 years had an adjusted pOR of 1.40 (95% CI: 1.16, 1.70) as compared to immigrants living in the U.S. for less than 10 years. ^ In conclusion, individuals who were born in the U.S. or emigrated to the U.S. over 20 years ago were more likely to report having hypertension compared to individuals born in Mexico or compared to those who emigrated more recently to the U.S. This study will contribute to the literature in demonstrating the need for more initiatives in prevention of cardiovascular disease, specifically hypertension, in the acculturating Mexican American population.^

Prevalence of symptoms of neurotoxicity and potential occupational pesticide and solvent exposures among high school students in Starr County, Texas: A pilot study

Numerous harmful occupational exposures affect working teens in the United States. Teens working in agriculture and other heavy-labor industries may be at risk for occupational exposures to pesticides and solvents. The neurotoxicity of pesticides and solvents at high doses is well-known; however, the long term effects of these substances at low doses on occupationally exposed adolescents have not been well-studied. To address this research gap, a secondary analysis of cross-sectional data was completed in order to estimate the prevalence of self-reported symptoms of neurotoxicity among a cohort of high school students from Starr County, Texas, a rural area along the Texas-Mexico border. Multivariable linear regression was used to estimate the association between work status (i.e., no work, farm work, and non-farm work) and symptoms of neurotoxicity, while controlling for age, gender, Spanish speaking preference, inhalant use, tobacco use, and alcohol use. The sample included 1,208 students. Of these, the majority (85.84%) did not report having worked during the prior nine months compared to 4.80% who did only farm work, 6.21% who did only non-farm work, and 3.15% who did both types of work. On average, students reported 3.26 symptoms with a range from 0-16. The most commonly endorsed items across work status were those related to memory impairment. Adolescents employed in non-farm work jobs reported more neurotoxicity symptoms than those who reported that they did not work (Mean 4.31; SD 3.97). In the adjusted multivariable regression model, adolescents reporting non-farm work status reported an average of 0.77 more neurotoxicity symptoms on the Q16 than those who did not work (P = 0.031). The confounding variables included in the final model were all found to be factors significantly associated with report of neurotoxicity symptoms. Future research should examine the relationship between these variables and self-report of symptoms of neurotoxicity.^

Pre-pregnancy obesity on the border and pregnancy complications: A secondary analysis comparing post-natal adult women in Matamoros, Mexico and Cameron County, Texas

Obesity during pregnancy is a serious health concern which has been associated with many adverse health outcomes for both the mother and the infant. In addition, data on the prevalence of obesity and its effects on pregnant women living in the border region are limited. This goal of this study was to examine the prevalence of preconception obesity among women living on each side of the Brownsville-Matamoros border who have just given birth, the relationship between obesity and pregnancy complications for the total population, and these associations by location. Study participants were drawn from a sample (n=947) from the Brownsville-Matamoros Sister City Project which included women from 10 border region hospitals (6 in Matamoros, 4 in Cameron County) who were recruited based on hospital log records indicating they had given birth to a live infant. De-identified data from verbal questionnaires administered within twenty-four hours after birth were analyzed to determine prevalence of preconception obesity on both sides of the border, and associated pregnancy outcomes for women residing in the United States and those in Mexico. Participants with missing height or weight data were excluded from analyses in this study, resulting in a final sample of 727 women. Significant associations were found between pre-pregnancy obesity and adverse pregnancy outcomes (OR=1.85, CI=1.30–2.64), hypertensive conditions (OR=2.76, CI=1.72–4.43), and macrosomia (OR=6.77, CI=1.13–40.57) using the total sample. Comparisons between the United States and Mexico sides of the border showed differences; associations between preconception obesity and adverse pregnancy outcomes were marginally significant among women in the United States (p=0.05), but failed to reach significance within this group for each individual complication. However, significant associations were found between obesity and preeclampsia (OR=3.61, CI=2.14–6.10), as well as obesity and the presence of one or more adverse pregnancy outcome (OR=2.29, CI=1.30–4.02), among women in Mexico. The results from this analysis provide new information specific to women on the Texas and Mexico border, a region that had not previously been studied. These significant associations between preconception obesity and adverse birth outcomes indicate that efforts to prevent obesity should focus on women of childbearing age, especially in Mexico.^

Effect of primary care availability and health insurance coverage on risk and cost of Preventable Hospitalizations in Harris County

Preventable Hospitalizations (PHs) are hospitalizations that can be avoided with appropriate and timely care in the ambulatory setting and hence are closely associated with primary care access in a community. Increased primary care availability and health insurance coverage may increase primary care access, and consequently may be significantly associated with risks and costs of PHs. Objective. To estimate the risk and cost of preventable hospitalizations (PHs); to determine the association of primary care availability and health insurance coverage with the risk and costs of PHs, first alone and then simultaneously; and finally, to estimate the impact of expansions in primary care availability and health insurance coverage on the burden of PHs among non-elderly adult residents of Harris County. Methods. The study population was residents of Harris County, age 18 to 64, who had at least one hospital discharge in a Texas hospital in 2008. The primary independent variables were availability of primary care physicians, availability of primary care safety net clinics and health insurance coverage. The primary dependent variables were PHs and associated hospitalization costs. The Texas Health Care Information Collection (THCIC) Inpatient Discharge data was used to obtain information on the number and costs of PHs in the study population. Risk of PHs in the study population, as well as average and total costs of PHs were calculated. Multivariable logistic regression models and two-step Heckman regression models with log-transformed costs were used to determine the association of primary care availability and health insurance coverage with the risk and costs of PHs respectively, while controlling for individual predisposing, enabling and need characteristics. Predicted PH risk and cost were used to calculate the predicted burden of PHs in the study population and the impact of expansions in primary care availability and health insurance coverage on the predicted burden. Results. In 2008, hospitalized non-elderly adults in Harris County had 11,313 PHs and a corresponding PH risk of 8.02%. Congestive heart failure was the most common PH. PHs imposed a total economic burden of $84 billion at an average of $7,449 per PH. Higher primary care safety net availability was significantly associated with the lower risk of PHs in the final risk model, but only in the uninsured. A unit increase in safety net availability led to a 23% decline in PH odds in the uninsured, compared to only a 4% decline in the insured. Higher primary care physician availability was associated with increased PH costs in the final cost model (β=0.0020; p<0.05). Lack of health insurance coverage increased the risk of PH, with the uninsured having 30% higher odds of PHs (OR=1.299; p<0.05), but reduced the cost of a PH by 7% (β=-0.0668; p<0.05). Expansions in primary care availability and health insurance coverage were associated with a reduction of about $1.6 million in PH burden at the highest level of expansion. Conclusions. Availability of primary care resources and health insurance coverage in hospitalized non-elderly adults in Harris County are significantly associated with the risk and costs of PHs. Expansions in these primary care access factors can be expected to produce significant reductions in the burden of PHs in Harris County.^

Addressing teenage pregnancy in rural areas: A case study from Liberty County, Texas

This study explores the issue of teenage pregnancy in a case study of Liberty County, a rural area in Texas with no public health department. It also describes the decision-making process and barriers faced in the beginning phases of adopting a sexual education program, and sets forth an implementation plan for two school districts on disseminating an evidence-based, comprehensive curriculum. Methods include a review of epidemiological data surrounding teenage pregnancy on the national, state, and county level; a literature review of factors related to teenage pregnancy and past interventions implemented in a rural community; a policy review of past and current bills in Legislature; and an analysis of barriers and decision making in implementing an evidence based program through qualitative observations, discussions with community members during meetings, presentations, and discussions. Results of this study indicate that there is a lack of research conducted in rural areas in the field of teenage pregnancy prevention and sexual education programs. Barriers experienced in Liberty County are shown to be consistent in scientific literature such as funding, logistical issues, and problems approaching the School Board in adopting a comprehensive sexual education program. This study fills a large gap in the literature on rural adolescents and attempts to analyze the process of decision-making in a rural area related to adoption of sexual education programming. In order to relieve this health disparity, further research should focus on rural areas to gain insight on the attitudes and behaviors of rural adolescents and beliefs among community stakeholders.^

Lifetime prevalence and risk factors for cancer in a Mexican American population with severe health disparities: The Cameron County Hispanic Cohort

Retrospective data from the Cameron Country Hispanic Cohort (1) were analyzed to assess the burden of cancer in the Mexican American population living in Brownsville TX. Data provided by the study participants for themselves and their parents and other extended relatives on cancer and related risk factors were used to determine both the prevalence of cancer and these risk factors as well as any associations between them. Lifetime incidence of cancer among the study participants was of 2.8%. Lifetime incidence of cancer among the parents of the study population was calculated for cancer in general and for specific cancer sites to determine the ranking of occurrence of each type of cancer. Some cancer types in this population were ranked higher than what would be expected when compared with national data from Hispanics in the U.S, these were: Liver cancer (3rd vs. 7th nationally in males and 6th vs. 13th nationally in females), stomach cancer (4th vs. 8th nationally in males and 5th vs. 11th nationally in females) and ovarian cancer (3rd vs. 8th nationally in females). A significant association with cancer was found for being born in the United States compared to being born elsewhere (O.R. 1.62, 95% C.I. 1.01–2.60) among study participants and the same association was also found between birth of parents in the United States regardless of gender for cancers in general (O.R. 1.38 95% C.I. 1.12–1.70), stomach cancer (O.R. 1.92 95% C.I. 1.01–3.67) and colorectal cancer (O.R. 2.93 95% C.I. 1.28–6.72). Having been born in the United States and having a family history of cancer was also found to be significantly associated with other risk factors for cancer such as obesity, diabetes and insulin resistance, both among the parents and the participant population, suggesting these interactions are complex. These high rates of cancer and particular prominence of less usual cancer such as liver and ovary in health disparities warrant evaluation of early detection strategies.^

Disparities in foodborne illness in Harris County, Texas, 2005--2010

Using a retrospective cross-sectional approach, this study quantitatively analyzed foodborne illness data, restaurant inspection data, and census-derived socioeconomic and demographic data within Harris County, Texas between 2005 and 2010. The main research question investigated involved determining the extent to which contextual and regulatory conditions distinguish outbreak and non-outbreak establishments within Harris County. Two groups of Harris County establishments were analyzed: outbreak and non-outbreak restaurants. STATA 11 was employed to determine the average profiles of each category across both the regulatory and socioeconomic (contextual) variables. Cross tabulations of all of the non-quantitative variables were also performed, and finally, a discriminant analysis was conducted to assess how well the variables were able to allocate the restaurants into their respective categories. Contextual and regulatory conditions were found to be minimally associated with the occurrence of foodborne outbreaks within Harris County. Across both the categories (outbreak and non-outbreak establishments), variables included were extremely similar in means, and when possible to observe, distributions. The variables analyzed in this study, both regulatory and contextual, were not found to significantly allocate the establishments into their correct outbreak or non-outbreak categories. The implications of these findings are that regulatory processes and guidelines in place in Harris County do not effectively to distinguish outbreak from non-outbreak restaurants. Additionally, no socioeconomic or racial/ethnic patterns are apparent in the incidence of foodborne disease in the county. ^

HIV prevalence and contextual risk-factors among injection drug users in Harris County, Texas

Injection drug use is the third most frequent risk factor for new HIV infections in the United States. A dual mode of exposure: unsafe drug using practices and risky sexual behaviors underlies injection drug users' (IDUs) risk for HIV infection. This research study aims to characterize patterns of drug use and sexual behaviors and to examine the social contexts associated with risk behaviors among a sample of injection drug users. ^ This cross-sectional study includes 523 eligible injection drug users from Houston, Texas, recruited into the 2009 National HIV Behavioral Surveillance project. Three separate set of analyses were carried out. First, using latent class analysis (LCA) and maximum likelihood we identified classes of behavior describing levels of HIV risk, from nine drug and sexual behaviors. Second, eight separate multivariable regression models were built to examine the odds of reporting a given risk behavior. We constructed the most parsimonious multivariable model using a manual backward stepwise process. Third, we examined whether HIV serostatus knowledge (self-reported positive, negative, or unknown serostatus) is associated with drug use and sexual HIV risk behaviors. ^ Participants were mostly male, older, and non-Hispanic Black. Forty-two percent of our sample had behaviors putting them at high risk, 25% at moderate risk, and 33% at low risk for HIV infection. Individuals in the High-risk group had the highest probability of risky behaviors, categorized as almost always sharing needles (0.93), seldom using condoms (0.10), reporting recent exchange sex partners (0.90), and practicing anal sex (0.34). We observed that unsafe injecting practices were associated with high risk sexual behaviors. IDUs who shared needles had higher odds of having anal sex (OR=2.89, 95%CI: 1.69-4.92) and unprotected sex (OR=2.66, 95%CI: 1.38-5.10) at last sex. Additionally, homelessness was associated with needle sharing (OR=2.24, 95% CI: 1.34-3.76) and cocaine use was associated with multiple sex partners (OR=1.82, 95% CI: 1.07-3.11). Furthermore, twenty-one percent of the sample was unaware of their HIV serostatus. The three groups were not different from each other in terms of drug-use behaviors: always using a new sterile needle, or in sharing needles or drug preparation equipment. However, IDUs unaware of their HIV serostatus were 33% more likely to report having more than three sexual partners in the past 12 months; 45% more likely to report to have unprotected sex and 85% more likely to use drug and or alcohol during or before at last sex compared to HIV-positive IDUs. ^ This analysis underscores the merit of LCA approach to empirically categorize injection drug users into distinct classes and identify their risk pattern using multiple indicators and our results show considerable overlap of high risk sexual and drug use behaviors among the high-risk class members. The observed clustering pattern of drug and sexual risk behavior among this population confirms that injection drug users do not represent a homogeneous population in terms of HIV risk. These findings will help develop tailored prevention programs.^