The application of latent variable models to the assessment of determinants of HIV risk behavior

Studies on the relationship between psychosocial determinants and HIV risk behaviors have produced little evidence to support hypotheses based on theoretical relationships. One limitation inherent in many articles in the literature is the method of measurement of the determinants and the analytic approach selected. ^ To reduce the misclassification associated with unit scaling of measures specific to internalized homonegativity, I evaluated the psychometric properties of the Reactions to Homosexuality scale in a confirmatory factor analytic framework. In addition, I assessed the measurement invariance of the scale across racial/ethnic classifications in a sample of men who have sex with men. The resulting measure contained eight items loading on three first-order factors. Invariance assessment identified metric and partial strong invariance between racial/ethnic groups in the sample. ^ Application of the updated measure to a structural model allowed for the exploration of direct and indirect effects of internalized homonegativity on unprotected anal intercourse. Pathways identified in the model show that drug and alcohol use at last sexual encounter, the number of sexual partners in the previous three months and sexual compulsivity all contribute directly to risk behavior. Internalized homonegativity reduced the likelihood of exposure to drugs, alcohol or higher numbers of partners. For men who developed compulsive sexual behavior as a coping strategy for internalized homonegativity, there was an increase in the prevalence odds of risk behavior. ^ In the final stage of the analysis, I conducted a latent profile analysis of the items in the updated Reactions to Homosexuality scale. This analysis identified five distinct profiles, which suggested that the construct was not homogeneous in samples of men who have sex with men. Lack of prior consideration of these distinct manifestations of internalized homonegativity may have contributed to the analytic difficulty in identifying a relationship between the trait and high-risk sexual practices. ^

Comparing experience of diabetes care with chronic illness care in the primary care clinic using the Patient Assessment of Chronic Illness Care (PACIC)

Purpose. The overall purpose of the study was to evaluate the patient experience relevant to the Chronic Care Model as measured by the PACIC. Chronic illness care of patients with diabetes was compared to those with other chronic illnesses. In addition, chronic illness care of Hispanics was compared to those of other race/ethnicity. ^ Methods. The setting of this study was 20 primary care practices located in San Antonio, TX. The subjects in this study were consecutive adult patients age >18 yrs. Data was collected via a survey (PACIC) administered to 40-60 consecutive adult patients in each primary care clinic who presented for a scheduled appointment. ^ Results. Patient experience of the Chronic Care Model is different among those with diabetes than those with other chronic diseases: those with diabetes report a higher PACIC score. (P = 0.012) Although Hispanic patients report a higher PACIC score, patient experience of the Chronic Care Model among Hispanic patients is not significantly different than that of patients of other race/ethnicity regardless of chronic disease. (P = 0.053) After controlling for the patient characteristics of age, education, health status, and race/ethnicity, the diabetes status of the patient remains significantly associated with the outcome, the PACIC score. (P = 0.033) ^ Conclusions. Diabetes is associated with a greater experience of the Chronic Care model. Contributing factors to diabetes patients’ greater experience of the Chronic Care Model include the greater heath care use and higher self-care needs unique to individuals with diabetes. Special consideration must be given to the specific needs diabetic patients to ensure effective interventions, higher patient education, greater patient compliance, and lower health care costs. ^

Assessment of the performance of 3m 3500 organic vapor monitors over extended sampling durations

The purpose of this study was to assess the accuracy and precision of airborne volatile organic compound (VOC) concentrations measured using passive air samplers (3M 3500 organic vapor monitors) over extended sampling durations (9 and 15 days). A total of forty-five organic vapor monitor samples were collected at a State of Texas air monitoring site during two different sampling periods (July/August and November 2008). The results of this study indicate that for most of the tested compounds, there was no significant difference between long-term (9 or 15 days) sample concentrations and the means of parallel consecutive short-term (3 days) sample concentrations. Biases of 9 or 15-day measurements vs. consecutive 3-day measurements showed considerable variability. Those compounds that had percent bias values of <10% are suggested as acceptable for long-term sampling (9 and 15 days). Of the twenty-one compounds examined, 10 compounds are classified as acceptable for long-term sampling; these include m,p-xylene, 1,2,4-trimethylbenzene, n-hexane, ethylbenzene, benzene, toluene, o-xylene, d-limonene, dimethylpentane and methyl tertbutyl ether. The ratio of sampling procedure variability relative to variability within days was approximately 1.89 for both sampling periods for the 3-day vs. 9-day comparisons and approximately 2.19 for both sampling periods for the 3-day vs. 15-day comparisons. Considerably higher concentrations of most VOCs were measured during the November sampling period compared to the July/August period. These differences may be a result of varying meteorological conditions during these two time periods, e.g., the differences in wind direction, and wind speed. Further studies are suggested to further evaluate the accuracy and precision of 3M 3500 organic vapor monitors over extended sampling durations. ^

A community-based assessment of the spatiotemporal distribution of influenza in a U.S.-Mexico border county during the spring 2009 novel H1N1 swine-origin influenza A pandemic

This study retrospectively evaluated the spatial and temporal disease patterns associated with influenza-like illness (ILI), positive rapid influenza antigen detection tests (RIDT), and confirmed H1N1 S-OIV cases reported to the Cameron County Department of Health and Human Services between April 26 and May 13, 2009 using the space-time permutation scan statistic software SaTScan in conjunction with geographical information system (GIS) software ArcGIS 9.3. The rate and age-adjusted relative risk of each influenza measure was calculated and a cluster analysis was conducted to determine the geographic regions with statistically higher incidence of disease. A Poisson distribution model was developed to identify the effect that socioeconomic status, population density, and certain population attributes of a census block-group had on that area's frequency of S-OIV confirmed cases over the entire outbreak. Predominant among the spatiotemporal analyses of ILI, RIDT and S-OIV cases in Cameron County is the consistent pattern of a high concentration of cases along the southern border with Mexico. These findings in conjunction with the slight northward space-time shifts of ILI and RIDT cluster centers highlight the southern border as the primary site for public health interventions. Finally, the community-based multiple regression model revealed that three factors—percentage of the population under age 15, average household size, and the number of high school graduates over age 25—were significantly associated with laboratory-confirmed S-OIV in the Lower Rio Grande Valley. Together, these findings underscore the need for community-based surveillance, improve our understanding of the distribution of the burden of influenza within the community, and have implications for vaccination and community outreach initiatives.^

Prospective gated 64 slice computed tomography in assessment of coronary artery disease: A single center experience and relationship of body mass index to outcomes

Coronary artery disease (CAD) is the most common cause of morbidity and mortality in the United States. While Coronary Angiography (CA) is the gold standard test to investigate coronary artery disease, Prospective gated-64 Slice Computed Tomography (Prosp-64CT) is a new non-invasive technology that uses the 64Slice computed tomography (64CT) with electrocardiographic gating to investigate coronary artery disease. The aim of the current study was to investigate the role of Body Mass Index (BMI) as a factor affecting occurrence of CA after a Prosp-64CT, as well as the quality of the Prosp-64CT. Demographic and clinical characteristics of the study population were described. A secondary analysis of data on patients who underwent a Prosp-64CT for evaluation of coronary artery disease was performed. Seventy seven patients who underwent Prosp-64CT for evaluation for coronary artery disease were included. Fifteen patients were excluded because they had missing data regarding BMI, quality of the Prosp-64CT or CA. Thus, a total of 62 patients were included in the final analysis. The mean age was 56.2 years. The mean BMI was 31.3 kg/m 2. Eight (13%) patients underwent a CA within one month of Prosp-64CT. Eight (13%) patients had a poor quality Prosp-64CT. There was significant association of higher BMI as a factor for occurrence of CA post Prosp-64CT (P<0.05). There was a trend, but no statistical significance was observed for the association of being obese and occurrence of CA (P=0.06). BMI, as well as obesity, were not found to be significantly associated with poor quality of Prosp-64CT (P=0.19 and P=0.76, respectively). In conclusion, BMI was significantly associated with occurrence of CA within one month of Prosp-64CT. Thus, in patients with a higher BMI, diagnostic investigation with both tests could be avoided; rather, only a CA could be performed. However, the relationship of BMI to quality of Prosp-64CT needs to be further investigated since the sample size of the current study was small.^

Secondary data analysis of a pilot study of use of an instructional video for dietary assessment

Introduction. Food frequency questionnaires (FFQ) are used study the association between dietary intake and disease. An instructional video may potentially offer a low cost, practical method of dietary assessment training for participants thereby reducing recall bias in FFQs. There is little evidence in the literature of the effect of using instructional videos on FFQ-based intake. Objective. This analysis compared the reported energy and macronutrient intake of two groups that were randomized either to watch an instructional video before completing an FFQ or to view the same instructional video after completing the same FFQ. Methods. In the parent study, a diverse group of students, faculty and staff from Houston Community College were randomized to two groups, stratified by ethnicity, and completed an FFQ. The "video before" group watched an instructional video about completing the FFQ prior to answering the FFQ. The "video after" group watched the instructional video after completing the FFQ. The two groups were compared on mean daily energy (Kcal/day), fat (g/day), protein (g/day), carbohydrate (g/day) and fiber (g/day) intakes using descriptive statistics and one-way ANOVA. Demographic, height, and weight information was collected. Dietary intakes were adjusted for total energy intake before the comparative analysis. BMI and age were ruled out as potential confounders. Results. There were no significant differences between the two groups in mean daily dietary intakes of energy, total fat, protein, carbohydrates and fiber. However, a pattern of higher energy intake and lower fiber intake was reported in the group that viewed the instructional video before completing the FFQ compared to those who viewed the video after. Discussion. Analysis of the difference between reported intake of energy and macronutrients showed an overall pattern, albeit not statistically significant, of higher intake in the video before versus the video after group. Application of instructional videos for dietary assessment may require further research to address the validity of reported dietary intakes in those who are randomized to watch an instructional video before reporting diet compared to a control groups that does not view a video.^

ASSESSMENT OF SKELETAL MUSCLE BLOOD FLOW AND GLUCOSE METABOLISM WITH POSITRON EMITTING RADIONUCLIDES

In order to evaluate factors regulating substrate metabolism in vivo positron emitting radionuclides were used for the assessment of skeletal muscle blood flow and glucose utilization. The potassium analog, Rb-82 was used to measure skeletal muscle blood flow and the glucose analog, 18-F-2-deoxy-2-fluoro-D-glucose (FDG) was used to examine the kinetics of skeletal muscle transport and phosphorylation.^ New Zealand white rabbits' blood flow ranged from 1.0-70 ml/min/100g with the lowest flows occurring under baseline conditions and the highest flows were measured immediately after exercise. Elevated plasma glucose had no effect on increasing blood flow, whereas high physiologic to pharmacologic levels of insulin doubled flow as measured by the radiolabeled microspheres, but a proportionate increase was not detected by Rb-82. The data suggest that skeletal muscle blood flow can be measured using the positron emitting K+ analog Rb-82 under low flow and high flow conditions but not when insulin levels in the plasma are elevated. This may be due to the fact that insulin induces an increase in the Na+/K+-ATPase activity of the cell indirectly through a direct increase in the Na+/H+pump activity. This suggests that the increased cation pump activity counteracts the normal decrease in extraction seen at higher flows resulting in an underestimation of flow as measured by rubidium-82.^ Glucose uptake as measured by FDG employed a three compartment mathematical model describing the rates of transport, countertransport and phosphorylation of hexose. The absolute values for the metabolic rate of FDG were found to be an order of magnitude higher than those reported by other investigators. Changes noted in the rate constant for transport (k1) were found to disagree with the a priori information on the effects of insulin on skeletal muscle hexose transport. Glucose metabolism was however, found to increase above control levels with administration of insulin and electrical stimulation. The data indicate that valid measurements of skeletal muscle glucose transport and phosphorylation using the positron emitting glucose analog FDG requires further model application and biochemical validation. (Abstract shortened with permission of author.) ^

The assessment of standardized training programs in public health preparedness

The Texas Bioterrorism Continuing Education Consortium (BCE) provided National Disaster Life Support (NDLS) training courses throughout the state of Texas in 2005, to help improve knowledge and skills pertaining to bioterrorism and other public health emergencies. The NDLS training courses include curriculum in Basic Disaster Life Support (BDLS) and Core Disaster Life Support (CDLS). A course evaluation which included items assessing ability and willingness of training participants, role of responders, and other variables was mailed to all NDLS participants who provided contact information. An analysis was conducted to determine whether the survey respondents participated in the Hurricanes Katrina and/or Rita relief efforts, as well as to evaluate the impact of the NDLS training courses on the participant's ability and willingness to respond during a disaster. The study population (n = 2150) consisted mostly of nurses (50%) (n=1074). A chi-square test of analysis indicated the following results. Among the survey respondents who took the CDLS course, there was no statically significant difference by occupation pertaining to ability or willingness to respond (x2 [df = 5] = 4.02, p= 0.546); (x2 [df = 5] = 2.45, p = .783). However, there was a statistically significant difference among those respondents who took the BDLS course with respect to ability, and a slightly significant difference with respect to willingness (x2 [df = 5] = 13.35, p = .020 and (x2 = [df = 5] = 10.299, p = .067). These findings are similar to previous studies assessing willingness to respond to a disaster.^ A second analysis was conducted with these survey data to evaluate the implications for disaster response training for the NDLS courses. Results indicated that the majority of disaster responders served in the role for which they were professionally trained (Physicians=68%; Nurses = 50.4%). Nurses, EMT, and Fire professionals served in multiple roles. These results suggest the importance of developing training programs that will prepare professionals to serve in multiple roles. The development of standardized evaluation methods would fill an important gap in assessing impact of national training programs. ^

Houston Rescue and Restore Coalition human trafficking needs assessment

Background. Human trafficking, or "modern day slavery", is a complex public health issue that we must understand more fully before it can be effectively tackled. There have been very few empirical studies on human trafficking and estimates of global and national human trafficking victims vary widely. Free the Slaves, a non-profit organization, estimates that there are at least 27 million people in the world at any given time that can be classified as victims of human trafficking. Houston, Texas has been identified as a place where human trafficking may be more likely to exist due to its close proximity to Mexico and due to economic and population factors. Houston Rescue and Restore Coalition (HRRC) is a local organization that exists to raise awareness of human trafficking in Houston, Texas. To better serve victims of human trafficking, HRRC commissioned a community assessment of the services available to victims of human trafficking in the greater Houston metropolitan area.^ Purpose. The current study assessed the capacity of organizations and agencies within the greater Houston metropolitan area to deal with human trafficking issues; in particular, knowledge regarding human trafficking issues among these organizations and agencies was evaluated.^ Methods. A cross-sectional study design was used to conduct surveys with key informants/stakeholders from organizations and agencies within the greater Houston metropolitan area. The survey instrument included 41 items in three parts, and consisted of multiple choice questions, open-ended essay questions, and closed-ended 5 point Likert questions.^ Results. The findings from this study indicate that efforts must be made to increase comprehensive awareness of the issue of human trafficking, including the federal and state laws that have been enacted to combat this problem. The data also indicate that there are limited services provided to human trafficking victims within the greater Houston metropolitan area.^ Conclusion. The results of the survey will provide Houston Rescue and Restore Coalition with information that will assist them in targeting their efforts to combat human trafficking in Houston, Texas.^

Concordance between medical records and personal interview in ascertaining breast cancer and diabetes status: Analysis of the south Texas women's health project

Accurate ascertainment of risk factors and disease status is vital in public health research for proper classification of research subjects. The two most common ways of obtaining this data is by self-report and review of medical records (MRs). South Texas Women’s Health Project was a case-control study looking at interrelationships between hormones, diet, and body size and breast cancer among Hispanic women 30-79 years of age. History of breast cancer, diabetes mellitus (DM) and use of DM medications was ascertained from a personal interview. At the time of interview, the subject identified her major health care providers and signed the medical records release form, which was sent to the designated providers. The MRs were reviewed to confirm information obtained from the interview.^ Aim of this study was to determine the sensitivity and specificity between MRs and personal interview in diagnosis of breast cancer, DM and DM treatment. We also wanted to assess how successful our low-cost approach was in obtaining pertinent MRs and what factors influenced the quality of MR or interview data. Study sample was 721 women with both self-report and MR data available by June 2007. Overall response rate for MR requests was 74.5%. MRs were 80.9% sensitive and 100% specific in confirming breast cancer status. Prevalence of DM was 22.7% from the interviews and 16% from MRs. MRs did not provide definite information about DM status of 53.6% subjects. Sensitivity and specificity of MRs for DM status was 88.9% and 90.4% respectively. Disagreement on DM status from the two sources was seen in 15.9% subjects. This discordance was more common among older subjects, those who were married and were predominantly Spanish speaking. Income and level of education did not have a statistically significantly association with this disagreement.^ Both self-report and MRs underestimate the prevalence of DM. Relying solely on MRs leads to greater misclassification than relying on self-report data. MRs have good to excellent specificity and thus serve as a good tool to confirm information obtained from self-report. Self-report and MRs should be used in a complementary manner for accurate assessment of DM and breast cancer status.^

Assessment of the effect on statistical power of regression model misspecification by using techniques of mathematical statistics and simulation study

Objectives. This paper seeks to assess the effect on statistical power of regression model misspecification in a variety of situations. ^ Methods and results. The effect of misspecification in regression can be approximated by evaluating the correlation between the correct specification and the misspecification of the outcome variable (Harris 2010).In this paper, three misspecified models (linear, categorical and fractional polynomial) were considered. In the first section, the mathematical method of calculating the correlation between correct and misspecified models with simple mathematical forms was derived and demonstrated. In the second section, data from the National Health and Nutrition Examination Survey (NHANES 2007-2008) were used to examine such correlations. Our study shows that comparing to linear or categorical models, the fractional polynomial models, with the higher correlations, provided a better approximation of the true relationship, which was illustrated by LOESS regression. In the third section, we present the results of simulation studies that demonstrate overall misspecification in regression can produce marked decreases in power with small sample sizes. However, the categorical model had greatest power, ranging from 0.877 to 0.936 depending on sample size and outcome variable used. The power of fractional polynomial model was close to that of linear model, which ranged from 0.69 to 0.83, and appeared to be affected by the increased degrees of freedom of this model.^ Conclusion. Correlations between alternative model specifications can be used to provide a good approximation of the effect on statistical power of misspecification when the sample size is large. When model specifications have known simple mathematical forms, such correlations can be calculated mathematically. Actual public health data from NHANES 2007-2008 were used as examples to demonstrate the situations with unknown or complex correct model specification. Simulation of power for misspecified models confirmed the results based on correlation methods but also illustrated the effect of model degrees of freedom on power.^

Air Force Web Preventive Health Assessment (AF WEBPHA) mental health screening effectiveness

The U.S. Air Force assesses Active Duty Air Force (ADAF) health annually using the Air Force Web-based Preventative Health Assessment (AF WebPHA). The assessment is based on a self-administered survey used to determine the overall Air Force health and readiness, as well as, the individual health of each airman. Individual survey responses as well as groups of responses generate further computer generated assessment and result in a classification of 'Critical', 'Priority', or 'Routine', depending on the need and urgency for further evaluation by a health care provider. The importance of the 'Priority' and 'Critical' classifications is to provide timely intervention to prevent or limit unfavorable outcomes that may threaten an airman. Though the USAF has been transitioning from a paper form to the online WebPHA survey for the last three years it was not made mandatory for all airmen until 2009. The survey covers many health aspects including family history, tobacco use, exercise, alcohol use, and mental health. ^ Military stressors such as deployment, change of station, and the trauma of war can aggravate and intensify the common baseline worries experienced by the general population and place airmen at additional risks for mental health concerns and illness. This study assesses the effectiveness of the AF WebPHA mental health screening questions in predicting a mental health disorder diagnosis according to International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes generated by physicians or their surrogates. In order to assess the sensitivity, specificity, and positive predictive value of the AF WebPHA as a screening tool for mental health, survey results were compared to ascertain if they generated any mental health disorder related diagnosis for the period from January 1, 2009 to March 31, 2010. ^ Statistical analysis of the AF WebPHA mental health responses when compared with matching ICD-9-CM codes found that the sensitivity for 'Critical' or 'Priority' responses was only 3.4% and that it would correctly predict those who had the selected mental health diagnosis 9% of the time.^

Improving the transitional experience of previously incarcerated women a nutritional needs assessment at a transitional home in Houston, Texas

Transitional homes present a window of opportunity to address the nutrition-related chronic diseases of previously incarcerated women. However, few transitional facilities offer nutrition education programs. This study assesses the nutritional status of 9 previously incarcerated women living at a transitional home in Houston, Texas and makes recommendations for effective nutrition education programs. Data was collected through individual interviews, questionnaires and a 24-hour dietary recall. Participants differed significantly from national nutrition recommendations when comparing BMI values and fruit, vegetable and fiber intake. Qualitative interview themes concerned key barriers to healthful dietary intake such as inadequate food storage and inconvenient cooking environment. Nutrition education programs at transitional homes should focus on healthy meals and snacks that can be quickly prepared and easily stored in small spaces. ^

A methodologic study of pain assessment in Anglo and Hispanic children with cancer

There is growing clinical evidence that even young children experience pain and accompanying anxiety. Few instruments have been validated to assess pain characteristics in children. The study of related demographic, illness, psychologic and parental factors in children has also been limited. This study examines the reliability and validity of pain assessment tools in an outpatient pediatric cancer population. A total of 78 children from three to fifteen years of age were observed and interviewed about the pain of invasive procedures. The effect of cultural factors and the stress of acculturation were examined by comparing data from two cultural groups, Anglo and Hispanic.^ Spielberger State-Trait Anxiety Scales were administered to children and parents prior to an invasive procedure. The Procedure Behavioral Checklist (PBCL) was used for observation of the child's response during the procedure. The Children's Procedural Interview (CPI) which contains items on the PBCL and visual analogues (scales of faces indicating varying degrees of pain and anxiety) was administered following the procedure.^ Reliability coefficients for Anglos were.78 on the PBCL,.79 on the CPI and.85 on the visual analogue scales. For Hispanics, the reliability for the PBCL was.54, while the CPI had a reliability of.72 and the visual analogue scales,.87. Construct validity was demonstrated by high correlations between the PBCL and CPI scores for both ethnic groups (.66 for Anglos and.64 for Hispanics) and by the significant correlation of State anxiety scores with both PBCL and CPI scores. Age was inversely correlated with PBCL and CPI scores for both ethnic groups. Hispanic parents' anxiety scores were higher than Anglo parents, but were not highly correlated with their child's PBCL, CPI or State-Trait anxiety scores. Caregivers' ratings were correlated with the PBCL scores for Anglos but not for Hispanics.^ The findings of this study indicate that pain responses may be reliably assessed using both observational and self-report methods in children, though differences in Anglo and Hispanic cultures exist. Differences in pain symptomatology and assessment in the two cultural groups warrant further study. ^

Assessment of cancer incidence in Titus County, Texas, 1977--1984

The purpose of this study was to determine the incidence of cancer in Titus County, Texas, through the identification of all cases of cancer that occurred in residents of the county during the period from 1977 to 1984. Data gathered from Texas Cancer Registry, hospital records, and death certificates were analyzed with regard to anatomic site, race, sex, age, city of residence, and place of birth. Adjustment of incidence rates by sex and race allowed comparisons with U.S. rates provided by the Surveillance, Epidemiology, and End Results Program (SEER).^ Seven hundred sixty-six (766) cancer cases were identified for the eight year period during 171,536 person-years of observation. In whites, statistically significant standardized incidence ratios (SIR) were found for leukemia (males SIR = 2.70 and females SIR = 2.26), melanoma (males SIR = 1.90 and females SIR = 2.25), lung (males SIR = 1.45) and for multiple myeloma (both sexes combined SIR = 1.86). In blacks, significant excess numbers of cases were found for Hodgkin's disease (males SIR = 8.33 and females SIR = 13.3) and for esophagus and bone considering both sexes together (SIR = 2.68 and 12.54, respectively). Rates for blacks were based on a small population and therefore unstable. A statistically significant excess number of cases for all sites combined was found in Mount Pleasant residents (age-adjusted incidence rate = 563.6 per 100,000 per year).^ A review of possible environmental risk factors in the area: hazardous waste disposal site, lignite deposits, and petrochemical and poultry industries are presented. A need for further epidemiological and environmental studies to identify etiological factors that could be responsible for the excess number of leukemia cases are recommended. For melanoma, a public health educational program to teach the population methods of protection from sun exposure is also suggested. ^