HIV incidence estimates and HIV/AIDS concurrent diagnosis in Houston/Harris County

The purpose of this dissertation was to estimate HIV incidence among the individuals who had HIV tests performed at the Houston Department of Health and Human Services (HDHHS) public health laboratory, and to examine the prevalence of HIV and AIDS concurrent diagnoses among HIV cases reported between 2000 and 2007 in Houston/Harris County. ^ The first study in this dissertation estimated the cumulative HIV incidence among the individuals testing at Houston public health laboratory using Serologic Testing Algorithms for Recent HIV Seroconversion (STARHS) during the two year study period (June 1, 2005 to May 31, 2007). The HIV incidence was estimated using two independently developed statistical imputation methods, one developed by the Centers for Disease Control and Prevention (CDC), and the other developed by HDHHS. Among the 54,394 persons who tested for HIV during the study period, 942 tested HIV positive (positivity rate=1.7%). Of these HIV positives, 448 (48%) were newly reported to the Houston HIV/AIDS Reporting System (HARS) and 417 of these 448 blood specimens (93%) were available for STARHS testing. The STARHS results showed 139 (33%) out of the 417 specimens were newly infected with HIV. Using both the CDC and HDHHS methods, the estimated cumulative HIV incidences over the two-year study period were similar: 862 per 100,000 persons (95% CI: 655-1,070) by CDC method, and 925 per 100,000 persons (95% CI: 908-943) by HDHHS method. Consistent with the national finding, this study found African Americans, and men who have sex with men (MSM) accounted for most of the new HIV infections among the individuals testing at Houston public health laboratory. Using CDC statistical method, this study also found the highest cumulative HIV incidence (2,176 per 100,000 persons [95%CI: 1,536-2,798]) was among those who tested in the HIV counseling and testing sites, compared to the sexually transmitted disease clinics (1,242 per 100,000 persons [95%CI: 871-1,608]) and city health clinics (215 per 100,000 persons [95%CI: 80-353]. This finding suggested the HIV counseling and testing sites in Houston were successful in reaching high risk populations and testing them early for HIV. In addition, older age groups had higher cumulative HIV incidence, but accounted for smaller proportions of new HIV infections. The incidence in the 30-39 age group (994 per 100,000 persons [95%CI: 625-1,363]) was 1.5 times the incidence in 13-29 age group (645 per 100,000 persons [95%CI: 447-840]); the incidences in 40-49 age group (1,371 per 100,000 persons [95%CI: 765-1,977]) and 50 or above age groups (1,369 per 100,000 persons [95%CI: 318-2,415]) were 2.1 times compared to the youngest 13-29 age group. The increased HIV incidence in older age groups suggested that persons 40 or above were still at risk to contract HIV infections. HIV prevention programs should encourage more people who are age 40 and above to test for HIV. ^ The second study investigated concurrent diagnoses of HIV and AIDS in Houston. Concurrent HIV/AIDS diagnosis is defined as AIDS diagnosis within three months of HIV diagnosis. This study found about one-third of the HIV cases were diagnosed with HIV and AIDS concurrently (within three months) in Houston/Harris County. Using multivariable logistic regression analysis, this study found being male, Hispanic, older, and diagnosed in the private sector of care were positively associated with concurrent HIV and AIDS diagnoses. By contrast, men who had sex with men and also used injection drugs (MSM/IDU) were 0.64 times (95% CI: 0.44-0.93) less likely to have concurrent HIV and AIDS diagnoses. A sensitivity analysis comparing difference durations of elapsed time for concurrent HIV and AIDS diagnosis definitions (1-month, 3-month, and 12-month cut-offs) affected the effect size of the odds ratios, but not the direction. ^ The results of these two studies, one describing characteristics of the individuals who were newly infected with HIV, and the other study describing persons who were diagnosed with HIV and AIDS concurrently, can be used as a reference for HIV prevention program planning in Houston/Harris County. ^

Evaluation of epidemiological and clinical factors in survival of patients with de novo myelodysplastic syndrome at the University of Texas MD Anderson cancer center

Little is known about epidemiological markers that are associated with survival of patients with myelodysplastic syndromes (MDS). We conducted a secondary case-based analysis of 465 de novo MDS patients from the University of Texas MD Anderson Cancer Center (UTMDACC). We investigated the association between demographic as well as occupational exposure markers and survival while incorporating known clinical markers of prognosis. In our patient population, 60.6% were men and the majority were white (93.1%). The distribution of MDS subtypes by the French–American–British (FAB) classification was 81 (19%) refractory anemia (RA), 46 (9.9%) refractory anemia with ringed sideroblasts (RARS), 57 (12.3%) chronic myelomonocytic leukemia (CMML), 173 (37.2%) RA with excess blasts (RAEB), and 86 (18.5%) RAEB in transformation (RAEBT). We found that those older at diagnosis (> 60 years of age) (HR = 1.68, CI = 1.26-2.25) were at a higher risk of dying compared to younger patients. Similarly, high pack years of smoking (>= 30 pack years of smoking) (HR = 1.34, CI = 1.02-1.74), and agricultural chemical exposure (HR = 1.61, CI = 1.05-2.46) were significantly associated with overall lower survival when compared to patients with none or medium exposures. Among clinical markers, greater than 5% bone marrow blasts (HR = 1.81 CI = 1.27-2.56), poor cytogenetics (HR = 3.20, CI = 2.37-4.33)), and platelet cytopenias (<100000/ul) (HR = 1.46, CI = 1.11-1.92) were also significantly associated with overall MDS survival.^ The identification of epidemiological markers could help physicians stratify patients and customize treatment strategies to improve the outcome of MDS based on patient lifestyle information such as smoking exposure and agrochemical exposure. We hope that this study highlights the impact of these exposures in MDS prognosis.^

If we call them, will they change? Feasibility of a telephone adaptation of motivational interviewing aimed at parents to reduce television time among 2nd and 4th grade children

Television viewing is a sedentary behavior that is modifiable. Reducing media-related behaviors via parent-focused interventions may hold promise for decreasing childhood obesity. This feasibility study examines a novel parent-centered brief telephone-delivered Motivational Enhancement Interview (MEI) to encourage parents of 2nd and 4th graders to set a rules limiting TV time or remove the TV from the child's bedroom. This quasi-experimental sub-study was part of the larger CATCH: En Vivo pilot study conducted in a Hispanic population in the Texas Rio Grande Valley. Parents in the MEI condition were contacted via telephone and encouraged to meet the American Academy of Pediatrics (AAP) recommended 2 hours per day or less of TV. Unconditional logistic regression was used to analyze the data. At post-test, 85% of parents of 4th graders in the MEI group (compared to 71% at pre-test) reported having a rule limiting TV time. The adjusted odds ratio for the MEI group compared to the control group was 3.88, 95% CI (0.72-20.99). At pre-test, 63.16% of 2nd graders had a television in their bedrooms. The 2nd grade MEI intervention reduced that number to 41.03% (OR=0.25, 95%CI (0.08-0.82)). This first look at using MEI to target parents of children to modify TV behavior presents evidence on a promising strategy for modifying children's home media environment and warrants further investigation. ^

Ethnic differences in tumor characteristics, treatment and survival in glioma patients

Purpose. A descriptive analysis of glioma patients by race was carried out in order to better elucidate potential differences between races in demographics, treatment, characteristics, prognosis and survival. ^ Patients and Methods. Among 1,967 patients ≥ 18 years diagnosed with glioma seen between July 2000 and September 2006 at The University of Texas M.D. Anderson Cancer Center (UTMDACC). Data were collated from the UTMDACC Patient History Database (PHDB) and the UTMDACC Tumor Registry Database (TRDB). Chi-square analysis, uni- /multivariate Cox proportional hazards modeling and survival analysis were used to analyze differences by race. ^ Results. Demographic, treatment and histologic differences exist between races. Though risk differences were seen between races, race was not found to be a significant predictor in multivariate regression analysis after accounting for age, surgery, chemotherapy, radiation, tumor type as stratified by WHO tumor grade. Age was the most consistent predictor in risk for death. Overall survival by race was significantly different (p=0.0049) only in low-grade gliomas after adjustment for age although survival differences were very slight. ^ Conclusion. Among this cohort of glioma patients, age was the strongest predictor for survival. It is likely that survival is more influenced by age, time to treatment, tumor grade and surgical expertise rather than racial differences. However, age at diagnosis, gender ratios, histology and history of cancer differed significantly between race and genetic differences to this effect cannot be excluded. ^

Sleep quality and quantity and associated factors among high school students from south Texas

Background. Insufficient and poor quality sleep among adolescents affects not only the cognitive functioning, but overall health of the individual. Existing research suggests that adolescents from varying ethnic groups exhibit differing sleep patterns. However, little research focuses on sleep patterns and associated factors (i.e. tobacco use, mental health indicators) among Hispanic youth. ^ Methods. The study population (n=2,536) included students in grades 9-12 who attended one of the three public high schools along the Texas-Mexico border in 2003. This was a cross sectional study using secondary data collected via a web-based, confidential, self-administered survey. Separate logistic regression models were estimated to identify factors associated with reduced (<9 hours/night) and poor quality sleep on average during weeknights. ^ Results. Of participants, 49.5% reported reduced sleep while 12.8% reported poor quality sleep. Factors significantly (p<0.05) associated with poor quality sleep were: often feeling stressed or anxious (OR=5.49), being born in Mexico (OR=0.65), using a computer/playing video games 15+ hours per week (OR=2.29), working (OR=1.37), being a current smoker (OR=2.16), and being a current alcohol user (OR=1.64). Factors significantly associated with reduced quantity of sleep were: often feeling stressed or anxious (OR=2.74), often having headaches/stomachaches (OR=1.77), being a current marijuana user (OR=1.70), being a current methamphetamine user (OR=4.92), and being a current alcohol user (OR=1.27). ^ Discussion. Previous research suggests that there are several factors that can influence sleep quality and quantity in adolescents. This paper discusses these factors (i.e. work, smoking, alcohol, etc.) found to be associated with poor sleep quality and reduced sleep quantity in the Hispanic adolescent population. A reduced quantity of sleep (81.20% of the participants) and a poor quality of sleep (12.80% of the participants) were also found in high school students from South Texas. ^

The relationship between physical activity and perceived built environment factors among adult Mexican Americans living in Brownsville, Texas

Background. Physical Activity (PA) is a central part in the fight to reduce obesity rates that are higher in Mexican Americans in the United States than any other ethnic groups. More than half of all Americans do not meet the daily PA recommendations and 48% of Mexican Americans do not exercise. The built environment is believed to affect participation in physical activity. The influence of the built environmental on physical activity levels in low-income Mexican Americans living along the Texas-Mexico border has not been investigated. ^ Purpose. The purpose of this secondary data analysis was trifold: (1) to determine the levels of self-reported PA in adults living in Brownsville, Texas; (2) to characterize the perceptions of this population regarding the built environment; and (3) to determine the association between self-reported PA and the built environment in Mexican Americans living in Brownsville, Texas. ^ Methods. 400 participants from the Tu Salud ¡Sí Cuenta! (TSSC) community-wide campaign were included in this secondary data analysis. Percentages for level of physical activity and the built environment were calculated using SPSS. Perceptions of the built environment were assessed by 14 items. Logistic regression analysis was used to assess the relationship between physical activity and built environment. All models were adjusted for age, gender, and level of education. ^ Results. The majority of men (41.97%) and women (59%), combined (56.7%)did not meet the 2008 PA Guidelines for Americans. We analyzed 14 built environment variables to characterize participants’ perceptions of the built environment. We conducted odds ratio (OR) to find if those who met PA levels associated the built environment such as neighborhood shops ([OR:1.806], CI:1.074,3.038 ]) bus stops ([OR:1.436], CI:.806,2.558) unattended stray dogs ([OR: 1.806], CI:1. 074,3.038), sidewalk access ([OR: .858],CI:.437,1.686), access to free parks ([OR:.549],CI:.335,.900) heavy traffic in neighborhood ([OR:.802], CI:.501,1.285), crime rate ([OR:.779], CI:.494,1.228) ranked the highest by mean score. The association between physical activity and the perceived built environment factors for Mexican Americans participating in the TSSCStudy were weakly associated. ^ Conclusions. This study provides evidence that PA levels are low in this Mexican American population. The built environment factors assessed in this study characterized the need for further studies of the variables that are seen as important to the Mexican American population. Lastly, the association of PA levels to the built environment was weak overall and further studies are recommended of the built environment.^

The association of internet use and depression among spinal cord injury population

The purpose of this study was to exam the relationship between internet use and depression among a population of individuals who have sustained spinal cord injury. This was cross-sectional survey design conducted among spinal cord injury (SCI) patients in the Model Spinal Cord Injury System. We included a total of 1,011 SCI-patients who were interviewed face-to-face or by telephone interview over approximately a three year time period (2004–2006). All data were collected through a telephone survey which included the Patient Health Questionnaire-9 (PHQ-9) to assess depression. We examined various scales of this survey, included a reduced 3-item scale (items 1, 2 and 6) to avoid the presence of somatic symptoms among SCI patients from influencing classification of depression. The frequency of internet usage was grouped as daily/weekly/monthly/non user. Covariates examined as possible confounders included demographic characteristics, occupational status, educational level, injury type, daily function of living, pain level, self-perceived health status and satisfaction with life. We observed a negative association between the frequency of internet use and the level of depression. Daily use of internet was associated with lower PHQ-9 score and depression; however this association did not reach statistical significance after for the mentioned covariates. In conclusion, the factors related to lower depression in SCI patients who use the internet are complicated. Daily internet usage was associated with lower levels of depression. The accuracy of 3-item scale needs further validation and investigation. Further study of internet usage pattern in SCI patient is recommended. ^

Birth prevalence of isolated congenital limb reduction defects in Texas 1999--2001

Objective. Congenital limb defects are common birth defects occurring in approximately 2-7/10,000 live births. Because congenital limb defects are pervasive throughout all populations, and the conditions profoundly affect quality of life, they represent a significant public health concern. Currently there is a paucity of etiologic information in the literature regarding congenital limb reduction defects which represents a major limitation in developing treatment strategies as well as identifying high risk pregnancies. ^ Additionally, despite the fact that the majority of congenital limb reduction defects are isolated, most previous studies have not separated them from those occurring as part of a known syndrome or with multiple additional congenital anomalies of unknown etiology. It stands to reason that factors responsible for multiple congenital anomalies that happen to include congenital limb reduction defects may be quite different from those factors leading to an isolated congenital limb reduction defect. ^ As a first step toward gaining etiologic understanding, this cross-sectional study was undertaken to determine the birth prevalence and obtain demographic information about non-syndromic (isolated) congenital limb reduction defects that occurred in Texas from 1999-2001. ^ Methods. The study population included all infants/fetuses with isolated congenital limb reduction defects born in Texas during 1999-2001; the comparison population was all infants who were born to mothers who were residents of Texas during the same period of time. The overall birth prevalence of limb reduction defects was determined and adjusted for ethnicity, gender, site of defect (upper limb versus lower limb), county of residence, maternal age and maternal education. ^ Results. In Texas, the overall birth prevalence of isolated CLRDs was 2.1/10,000 live births (1.5 and 0.6/10,000 live births for upper limb and lower limb, respectively). ^ The risk of isolated lower limb CLRDs in Texas was significantly lower in females when gender was examined individually (crude prevalence odds ratio of 0.57, 95% CI of 0.36-0.91) as well as in relation to all other variables used in the analysis (adjusted prevalence odds ratio of 0.58, 95% CI of 0.36-0.93). ^ Harris County (which includes the Houston metropolitan area) had significantly lower risks of all (upper limb and lower limb combined) isolated CLRDs when examined in relation to other counties in Texas, with a crude prevalence odds ratio of 0.4 (95% CI: 0.29-0.72) and an adjusted prevalence odds ratio of 0.50 (95% CI: 0.31-0.80). The risk of isolated upper limb CLRDs was significantly lower in Harris County (crude prevalence odds ratio of 0.45, CI of 0.26-0.76 and adjusted prevalence odds ratio of 0.49, CI of 0.28-0.84). This trend toward decreased risk in Harris County was not observed for isolated lower limb reduction defects (adjusted prevalence odds ratio of 0.50, 95% confidence interval: 0.22-1.12). ^ Conclusions. The birth prevalence of isolated congenital limb reduction defects in Texas is in the lower limits of the range of rates that have been reported by other authors for other states (Alabama, Arkansas, California, Georgia, Hawaii, Iowa, Maryland, Massachusetts, North Carolina, Oklahoma, Utah, Washington) and other countries (Argentina, Australia, Austria, Bolivia, Brazil, Canada, Chile, China, Colombia, Costa Rica, Croatia, Denmark, Ecuador, England, Finland, France, Germany, Hungary, Ireland, Israel, Italy, Lithuania, Mexico, Norway, Paraguay, Peru, Spain, Scotland, Sweden, Switzerland, Uruguay, and Venezuela). In Texas, the birth prevalence of isolated congenital lower limb reduction defects was greater for males than females, while the birth prevalence of isolated congenital upper limb reduction defects was not significantly different between males and females. The reduced rates of limb reduction defects in Harris County warrant further investigation. This study has provided an important first step toward gaining etiologic understanding in the study of isolated congenital limb reduction defects. ^

Evaluation of association between childhood obesity and depression: A systematic literature review

Obesity has become a major public health concern throughout the world. Both developing as well as developed countries have been facing the consequences of obesity. [1, 2] According to World Health Organization, worldwide prevalence of overweight among adults was 1.6 billion and that of obesity was 400 million by the end of year 2005. At the same time, around 20 million children of less than 5 years of age were overweight worldwide. [3] ^ From amongst the obese children, around 15% of children manifest symptoms of depression before 18 years of age as compared to non-obese children of the same age group. Approximately 3-5% of these obese individuals develop major depressive disorders (MDD). [4, 5] The incidence of depression increases markedly as the child reaches puberty. The risk of persistent depression in childhood as well as in adulthood is two to four times higher if the child is obese as compared to those depressed adult individuals who are not obese in their childhood. [6, 7] ^ This paper will review the scientific literature concerning the association between childhood obesity and depression. ^

Risk factors for encephalitis and death from West Nile virus infection: An analysis of hospitalized cases in Houston, Texas from 2002--2008

We conducted a nested case-control study to determine the significant risk factors for developing encephalitis from West Nile virus (WNV) infection. The purpose of this research project was to expand the previously published Houston study of 2002–2004 patients to include data on Houston patients from four additional years (2005–2008) to determine if there were any differences in risk factors shown to be associated with developing the more severe outcomes of WNV infection, encephalitis and death, by having this larger sample size. A re-analysis of the risk factors for encephalitis and death was conducted on all of the patients from 2002–2008 and was the focus of this proposed research. This analysis allowed for the determination to be made that there are differences in the outcome in the risk factors for encephalitis and death with an increased sample size. Retrospective medical chart reviews were completed for the 265 confirmed WNV hospitalized patients; 153 patients had encephalitis (WNE), 112 had either viral syndrome with fever (WNF) or meningitis (WNM); a total of 22 patients died. Univariate logistic regression analyses on demographic, comorbidities, and social risk factors was conducted in a similar manner as in the previously conducted study to determine the risk factors for developing encephalitis from WNV. A multivariate model was developed by using model building strategies for the multivariate logistic regression analysis. The hypothesis of this study was that there would be additional risk factors shown to be significant with the increase in sample size of the dataset. This analysis with a greater sample size and increased power supports the hypothesis in that there were additional risk factors shown to be statistically associated with the more severe outcomes of WNV infection (WNE or death). Based on univariate logistic regression results, these data showed that even though age of 20–44 years was statistically significant as a protecting effect for developing WNE in the original study, the expanded sample lacked significance. This study showed a significant WNE risk factor to be chronic alcohol abuse, when it was not significant in the original analysis. Other WNE risk factors identified in this analysis that showed to be significant but were not significant in the original analysis were cancer not in remission > 5 years, history of stroke, and chronic renal disease. When comparing the two analyses with death as an outcome, two risk factors that were shown to be significant in the original analysis but not in the expanded dataset analysis were diabetes mellitus and immunosuppression. Three risk factors shown to be significant in this expanded analysis but were not significant in the original study were illicit drug use, heroin or opiate use, and injection drug use. However, with the multiple logistic regression models, the same independent risk factors for developing encephalitis of age and history of hypertension including drug induced hypertension were consistent in both studies.^

A retrospective analysis of patients referred for tuberculosis testing at Parkland Hospital, Dallas, TX

Tuberculosis (TB) is an infectious disease of great public health importance, particularly to institutions that provide health care to large numbers of TB patients such as Parkland Hospital in Dallas, TX. The purpose of this retrospective chart review was to analyze differences in TB positive and TB negative patients to better understand whether or not there were variables that could be utilized to develop a predictive model for use in the emergency department to reduce the overall number of suspected TB patients being sent to respiratory isolation for TB testing. This study included patients who presented to the Parkland Hospital emergency department between November 2006 and December 2007 and were isolated and tested for TB. Outcome of TB was defined as a positive sputum AFB test or a positive M. tuberculosis culture result. Data were collected utilizing the UT Southwestern Medical Center computerized database OACIS and included demographic information, TB risk factors, physical symptoms, and clinical results. Only two variables were significantly (P<0.05) related to TB outcome: dyspnea (shortness of breath) (P<0.001) and abnormal x-ray (P<0.001). Marginally significant variables included hemoptysis (P=0.06), weight loss (P=0.11), night sweats (P=0.20), history of homelessness or incarceration (P=0.15), and history of positive skin PPD (P=0.19). Using a combination of significant and marginally significant variables, a predictive model was designed which demonstrated a specificity of 24% and a sensitivity of 70%. In conclusion, a predictive model for TB outcome based on patients who presented to the Parkland Hospital emergency department between November 2006 and December 2007 was unsuccessful given the limited number of variables that differed significantly between TB positive and TB negative patients. It is suggested that a future prospective cohort study should be implemented to collect data on TB positive and TB negative patients. It may be possible that a more thorough prospective collection of data may lead to clearer comparisons between TB positive and TB negative patients and ultimately to the design of a more sensitive predictive model for TB outcome. ^

Determining associations and assessing methodological issues in a case-control study of hazardous air pollutants and neural tube defects

Recent studies have reported positive associations between maternal exposures to air pollutants and several adverse birth outcomes. However, there have been no assessments of the association between environmental hazardous air pollutants (HAPs) such as benzene, toluene, ethylbenzene, and xylene (BTEX) and neural tube defects (NTDs) a common and serious group of congenital malformations. Before examining this association, two important methodological questions must be addressed: (1) is maternal residential movement likely to result in exposure misclassification and (2) is it appropriate to lump defects of the neural tube, such as anencephaly and spina bifida, into a composite disease endpoint (i.e., NTDs). ^ Data from the National Birth Defects Prevention Study and Texas Birth Defects Registry were used to: (1) assess the extent to which change of residence may result in exposure misclassification when exposure is based on the address at delivery; (2) formally assess heterogeneity of the associations between known risk factors for NTDs, using polytomous logistic regression; and (3) conduct a case-control study assessing the association between ambient air levels of BTEX and the risk of NTDs among offspring. ^ Regarding maternal residential mobility, this study suggests address at delivery was not significantly different from using address at conception when assigning quartile of benzene exposure (OR 1.0, 95% CI 0.9, 1.3). On the question of effect heterogeneity among NTDs, the effect estimates for infant sex P = 0.017), maternal body mass index P = 0.016), and folate supplementation P = 0.050) were significantly different for anencephaly and spina bifida, suggesting it is often more appropriate to assess potential risk factors among subgroups of NTDs. For the main study question on the association between environmental HAPs and NTDs, mothers who have offspring with isolated spina bifida are 2.4 times likely to live in areas with the highest benzene levels (95% CI 1.1, 5.0). However, no other significant associations were observed.^ This project is the first to include not only an assessment of the relationship between environmental levels of BTEX and NTDs, but also two separate studies addressing important methodological issues associated with this question. Our results contribute to the growing body of evidence regarding air pollutant exposure and adverse birth outcomes. ^

Suspected outbreak of dengue fever in Houston: Clinical characteristics and determination of autochthonous transmission between 2003 and 2005

Houston, Texas maintains the appropriate climate and mosquito populations to support the circulation of dengue viruses. The city is susceptible to the introduction and subsequent local transmission of dengue virus with its proximity to dengue-endemic Mexico and the high degree of international travel routed through its airports. In 2008, a study at the University of Texas School of Public Health identified 58 suspected dengue fever cases that presented at hospitals and clinics in the Houston area. Serum or CSF samples of the 58 samples tested positive or equivocal for the presence of anti-dengue IgM antibodies (Rodriguez, 2008). Here, we present the results of an investigation aimed to describe the clinical characteristics of the 58 suspected dengue fever cases and to determine if local transmission had occurred. Data from medical record abstractions and personal telephone interviews were used to describe clinical characteristics and travel history of the suspected cases. Our analysis classified six probable dengue fever cases based on the case definition from the World Health Organization. Three of the probable cases for which we were able to obtain travel history had not recently traveled to an endemic area prior to onset of symptoms suggesting the illnesses were locally acquired in Houston. Further analysis led us to hypothesize that additional cases of dengue fever are present in our study population. Fifty-one percent of the study population was diagnosed with meningitis and/or encephalitis. Sixty percent of the individuals who received a lumbar puncture had abnormal CSF. Together these findings indicate viral infection with neurological involvement, which has been reported to occur with dengue fever. Among the individuals who received liver enzyme analysis, 54% had evidence of abnormal liver enzyme levels, a clinical sign commonly observed with dengue. Our results indicate that a suspected outbreak of dengue fever with autochthonous transmission occurred in the Houston area between 2003 and 2005. ^

Systematic review of genetic risk score in coronary heart disease and other diseases

In order to better take advantage of the abundant results from large-scale genomic association studies, investigators are turning to a genetic risk score (GRS) method in order to combine the information from common modest-effect risk alleles into an efficient risk assessment statistic. The statistical properties of these GRSs are poorly understood. As a first step toward a better understanding of GRSs, a systematic analysis of recent investigations using a GRS was undertaken. GRS studies were searched in the areas of coronary heart disease (CHD), cancer, and other common diseases using bibliographic databases and by hand-searching reference lists and journals. Twenty-one independent case-control studies, cohort studies, and simulation studies (12 in CHD, 9 in other diseases) were identified. The underlying statistical assumptions of the GRS using the experience of the Framingham risk score were investigated. Improvements in the construction of a GRS guided by the concept of composite indicators are discussed. The GRS will be a promising risk assessment tool to improve prediction and diagnosis of common diseases.^

Plasma homocysteine levels and Alzheimer's Disease: A systematic review

Objective. To systematically review studies published in English on the relationship between plasma total homocysteine (Hcy) levels and the clinical and/or postmortem diagnosis of Alzheimer's disease (AD) in subjects who are over 60 years old.^ Method. Medline, PubMed, PsycINFO and Academic Search Premier, were searched by using the keywords "homocysteine", "Alzheimer disease" and "dementia", and "cognitive disorders". In addition, relevant articles in PubMed using the "related articles" link and by cross-referencing were identified. The study design, study setting and study population, sample size, the diagnostic criteria of the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS) and the Alzheimer's Disease and Related Disorders Association (ADRDA), and description of how Hcy levels were measured or defined had to have been clearly stated. Empirical investigations reporting quantitative data on the epidemiology of the relationship between plasma total Hcy (exposure factor) and AD (outcome) were included in the systematic review.^ Results. A total of 7 studies, which included a total of 2,989 subjects, out of 388 potential articles met the inclusion criteria: four case control and three cohort studies were identified. All 7 studies had association statistics, such as the odds ratio (OR), the relative rates (RR), and the hazard ratio (HR) of AD, examined using multivariate and logistic regression analyses. Three case - comparison studies: Clarke et al. (1998) (OR: 4.5, 95% CI.: 2.2 - 9.2); McIlroy et al. (2002) (OR: 2.9, 95% CI.: 1.00–8.1); Quadri et al. (2004) (OR: 3.7, 95% CI.: 1.1 - 13.1), and two cohort studies: Seshadri et al. (2002) (RR: 1.8, 95% CI.: 1.3 - 2.5); Ravaglia et al. (2005) (HR: 2.1, 95% CI.: 1.7 - 3.8) found a significant association between serum total Hcy and AD. One case-comparison study, Miller et al. (2002) (OR: 2.2, 95% C.I.: 0.3 -16), and one cohort study, Luchsinger et al. (2004) (HR: 1.4, 95% C.I.: 0.7 - 2.3) failed to reject H0.^ Conclusions. The purpose of this review is to provide a thorough analysis of studies that examined the relationship between Hcy levels and AD. Five studies showed a positive statistically significant association between elevated total Hcy values and AD but the association was not statistically significant in two studies. Further research is needed in order to establish evidence of the strong, consistent association between serum total Hcy and AD as well as the presence of the appropriate temporal relationship. To answer these questions, it is important to conduct more prospective studies that examine the occurrence of AD in individuals with and without elevated Hcy values at baseline. In addition, the international standardization of measurements and cut-off points for plasma Hcy levels across laboratories is a critical issue to be addressed for the conduct of future studies on the topic.^