Health outcomes, quality improvement and cost-effectiveness of the Community Diabetes Education (CoDE) program: Results of a randomized controlled trial

The objectives of this dissertation were to evaluate health outcomes, quality improvement measures, and the long-term cost-effectiveness and impact on diabetes-related microvascular and macrovascular complications of a community health worker-led culturally tailored diabetes education and management intervention provided to uninsured Mexican Americans in an urban faith-based clinic. A prospective, randomized controlled repeated measures design was employed to compare the intervention effects between: (1) an intervention group (n=90) that participated in the Community Diabetes Education (CoDE) program along with usual medical care; and (2) a wait-listed comparison group (n=90) that received only usual medical care. Changes in hemoglobin A1c (HbA1c) and secondary outcomes (lipid status, blood pressure and body mass index) were assessed using linear mixed-models and an intention-to-treat approach. The CoDE group experienced greater reduction in HbA1c (-1.6%, p<.001) than the control group (-.9%, p<.001) over the 12 month study period. After adjusting for group-by-time interaction, antidiabetic medication use at baseline, changes made to the antidiabetic regime over the study period, duration of diabetes and baseline HbA1c, a statistically significant intervention effect on HbA1c (-.7%, p=.02) was observed for CoDE participants. Process and outcome quality measures were evaluated using multiple mixed-effects logistic regression models. Assessment of quality indicators revealed that the CoDE intervention group was significantly more likely to have received a dilated retinal examination than the control group, and 53% achieved a HbA1c below 7% compared with 38% of control group subjects. Long-term cost-effectiveness and impact on diabetes-related health outcomes were estimated through simulation modeling using the rigorously validated Archimedes Model. Over a 20 year time horizon, CoDE participants were forecasted to have less proliferative diabetic retinopathy, fewer foot ulcers, and reduced numbers of foot amputations than control group subjects who received usual medical care. An incremental cost-effectiveness ratio of $355 per quality-adjusted life-year gained was estimated for CoDE intervention participants over the same time period. The results from the three areas of program evaluation: impact on short-term health outcomes, quantification of improvement in quality of diabetes care, and projection of long-term cost-effectiveness and impact on diabetes-related health outcomes provide evidence that a community health worker can be a valuable resource to reduce diabetes disparities for uninsured Mexican Americans. This evidence supports formal integration of community health workers as members of the diabetes care team.^

PREDICTIVE VARIABLES FOR WEIGHT CHANGE 2 YEARS FOLLOWING PARTICIPATION IN A WEIGHT LOSS INTERVENTION PROGRAM

A historical prospective study was designed to assess the man weight status of subjects who participated in a behavioral weight reduction program in 1983 and to determine whether there was an association between the dependent variable weight change and any of 31 independent variables after a 2 year follow-up period. Data was obtained by abstracting the subjects records and from a follow-up questionnaire administered 2 years following program participation. Five hundred nine subjects (386 females and 123 males) of 1460 subjects who participated in the program, completed and returned the questionnaire. Results showed that mean weight was significantly different (p < 0.001) between the measurement at baseline and after a 2 year follow-up period. The mean weight loss of the group was 5.8 pounds, 10.7 pounds for males and 4.2 pounds for females after a 2 year follow-up period. A total of 63.9% of the group, 69.9% of males and 61.9% of females were still below their initial weight after the 2 year follow-up period. Sixteen of the 31 variables assessed utilizing bivariate analyses were found to be significantly (p (LESSTHEQ) 0.05) associated with weight change after a 2 year follow-up period. These variables were then entered into a multivariate linear regression model. A total of 37.9% of the variance of the dependent variable, weight change, was accounted for by all 16 variables. Eight of these variables were found to be significantly (p (LESSTHEQ) 0.05) predictive of weight change in the stepwise multivariate process accounting for 37.1% of the variance. These variables included: Two baseline variables (percent over ideal body weight at enrollment and occupation) and six follow-up variables (feeling in control of eating habits, percent of body weight lost during treatment, frequency of weight measurement, physical activity, eating in response to emotions, and number of pounds of weight gain needed to resume a diet). It was concluded that a greater amount of emphasis should be placed on the six follow-up variables by clinicians involved in the treatment of obesity, and by the subjects themselves to enhance their chances of success at long-term weight loss. ^

Tracking of plasma lipids and lipoproteins, within-person and year-to-year variability in plasma cholesterol levels among participants from age 8 to 18 in Project HeartBeat!

Coronary heart disease remains the leading cause of death in the United States and increased blood cholesterol level has been found to be a major risk factor with roots in childhood. Tracking of cholesterol, i.e., the tendency to maintain a particular cholesterol level relative to the rest of the population, and variability in blood lipid levels with increase in age have implications for cholesterol screening and assessment of lipid levels in children for possible prevention of further rise to prevent adulthood heart disease. In this study the pattern of change in plasma lipids, over time, and their tracking were investigated. Also, within-person variance and retest reliability defined as the square root of within-person variance for plasma total cholesterol, HDL-cholesterol, LDL-cholesterol, and triglycerides and their relation to age, sex and body mass index among participants from age 8 to 18 years were investigated. ^ In Project HeartBeat!, 678 healthy children aged 8, 11 and 14 years at baseline were enrolled and examined at 4-monthly intervals for up to 4 years. We examined the relationship between repeated observations by Pearson's correlations. Age- and sex-specific quintiles were calculated and the probability of participants to remain in the uppermost quintile of their respective distribution was evaluated with life table methods. Plasma total cholesterol, HDL-C and LDL-C at baseline were strongly and significantly correlated with measurements at subsequent visits across the sex and age groups. Plasma triglyceride at baseline was also significantly correlated with subsequent measurements but less strongly than was the case for other plasma lipids. The probability to remain in the upper quintile was also high (60 to 70%) for plasma total cholesterol, HDL-C and LDL-C. ^ We used a mixed longitudinal, or synthetic cohort design with continuous observations from age 8 to 18 years to estimate within person variance of plasma total cholesterol, HDL-C, LDL-C and triglycerides. A total of 5809 measurements were available for both cholesterol and triglycerides. A multilevel linear model was used. Within-person variance among repeated measures over up to four years of follow-up was estimated for total cholesterol, HDL-C, LDL-C and triglycerides separately. The relationship of within-person and inter-individual variance with age, sex, and body mass index was evaluated. Likelihood ratio tests were conducted by calculating the deviation of −2log (likelihood) within the basic model and alternative models. The square root of within-person variance provided the retest reliability (within person standard deviation) for plasma total cholesterol, HDL-C, LDL-C and triglycerides. We found 13.6 percent retest reliability for plasma cholesterol, 6.1 percent for HDL-cholesterol, 11.9 percent for LDL-cholesterol and 32.4 percent for triglycerides. Retest reliability of plasma lipids was significantly related with age and body mass index. It increased with increase in body mass index and age. These findings have implications for screening guidelines, as participants in the uppermost quintile tended to maintain their status in each of the age groups during a four-year follow-up. The magnitude of within-person variability of plasma lipids influences the ability to classify children into risk categories recommended by the National Cholesterol Education Program. ^

Evaluation of the city of Houston HIV/STD prevention program in Houston Independent School District (HISD) high schools

This cross-sectional study was undertaken to evaluate the impact in terms of HIV/STD knowledge and sexual behavior that the City of Houston HIV/STD prevention program in HISD high schools has had on students who have participated in it by comparing them with their peers who have not, based on self reports. The study further evaluated the program cost-effectiveness for averting future HIV infections by computing Cost-Utility Ratios based on reported sexual behavior. ^ Mixed results were obtained, indicating a statistically significant difference in knowledge with the intervention group having scored higher (p-value 0.001) but not for any of the behaviors assessed. The knowledge score outcome's overall p-value after adjusting for each stratifying variable (age, grade, gender and ethnicity) was statistically significant. The Odds Ratio of intervention group participants aged 15 years or more scoring 70% or higher was 1.86 times; that of intervention group female participants was 2.29 times; and that of intervention group Black/African American participants was 2.47 times relative to their comparison group counterparts. The knowledge score results remained statistically significant in the logistic regression model, which controlled for age, grade level, gender and ethnicity. The Odds Ratio in this case was 1.74. ^ Three scenarios based on the difference in the risk of HIV infection between the intervention and comparison group were used for computation of Cost-Utility Ratios: Base, worst and best-case scenario. The best-case scenario yielded cost-effective results for male participants and cost-saving results for female participants when using ethnicity-adjusted HIV prevalence. The scenario remained cost-effective for female participants when using the unadjusted HIV prevalence. ^ The challenge to the program is to devise approaches that can enhance benefits for male participants. If it is a threshold problem implying that male participants require more intensive programs for behavioral change, then programs should first be piloted among boys before being implemented across the board. If it is a reflection of gender differences, then we might have to go back to the drawing board and engage boys in focus group discussions that will help formulate more effective programs. Gender-blind approaches currently in vogue do not seem to be working. ^

Impact of oral contraceptives on weight, body composition, and cardiovascular disease risk factors in women age 18--30 years participating in a 15-week exercise program

Objective. To assess differences in body weight, body composition, total cholesterol, blood pressure, and blood glucose between OC users and non-users age 18-30 y before and after a 15-week cardiovascular exercise program in Houston, TX from 2003 to 2007.^ Study Design. Secondary analysis of prospective data. ^ Study Subjects. 453 Non-Hispanic white (NHW), Hispanic, and African American (AA) women age 18-30 y with no previous live birth, a history of menstruating, no use of other hormonal contraceptives or medications, no menopause or hysterectomy, and no current pregnancies.^ Measurements. Demographic data, medication use, and menstrual history were assessed via self-administered questionnaires at baseline. Anthropometric and laboratory measures were taken at baseline and 15-weeks. ^ Data Analysis. Linear regression assessed the association between OC use and study variables at baseline, and the change in study variables from baseline to 15-weeks. Logistic regression assessed the association between OC use and CVD risk. Each analysis was also stratified by race/ethnicity. ^ Results. At baseline, OC users had higher total cholesterol (p<.0005) and were above cholesterol risk cut points for CVD (OR=4.3, 95% CI=2.4-7.7) compared to non-users. At baseline, OC use was also associated with higher diastolic blood pressure (p=.018) compared to non-users, primarily in non-Hispanic whites (p=.007). OC use was associated with lower blood glucose compared to non-users in Hispanics only (p=.008). OC use was associated with absolute change in diastolic blood pressure (p=.044) and total cholesterol (p=.003). There was evidence that OC use may affect individuals differently based on race/ethnicity for certain obesity and CVD risk factors.^ Conclusions. OC users and non-users responded similarly to a 15-week cardiovascular exercise program. Exceptions included a greater change in diastolic blood pressure and total cholesterol among NHW and Hispanic OC users compared to non-users after exercise intervention. At baseline, OC use was associated with diastolic blood pressure and was most strongly associated with increased levels of total cholesterol. OC users were at greater risk of having total cholesterol above CVD risk cut points than non-users.^

Development and evaluation of a nutrition education program designed to increase fruit and vegetable consumption in girls, ages 9--12

The purpose of this study is to evaluate the theory-based Eat 5 nutrition badge. It is designed to increase fruit and vegetable (F&V) intake in 4th-6th grade junior Girl Scouts. Twenty-two troops were recruited and randomized by grade level (4th, 5th, 6th, or mixed) into either the intervention or control conditions. The leaders in the intervention condition received a brief training and the materials and conducted the program with their troops during four meetings. The Girl Scouts in the intervention condition completed 1-day Food Frequency Questionnaires and Nutrition Questionnaires both before and after completing the Eat 5 badge, and a third measurement of F&V intake three months after the posttest. Girl Scouts in the control condition were only evaluated at the three time periods.^ The primary hypotheses were that the Girl Scouts in the intervention condition would increase their daily intake of fruits and vegetables at both the posttest and three months later, compared to the Girl Scouts in the control condition. Other study questions investigated the impact of the Eat 5 program on intervening variables such as knowledge, self-efficacy, barriers, norms, F&V preference, and F&V selection and preparation skills.^ A nested ANOVA, with troop as the unit of analysis nested within condition, was used to assess the effects of the program. Pretest F&V intake and grade level were used as covariates. Pretest mean F&V intake for the total sample of 210 girls was 2.50 servings per day; 3.0 for the intervention group (n = 101). Significant increases in F&V intake (to 3.4 servings per day), knowledge, and fruit and vegetable preference were found for the intervention condition troops compared to the troops in the control condition. Three months later, the mean F&V intake had returned to pretest levels.^ This study indicates that social groups such as Girl Scouts can provide a channel for nutrition education. Long term effects were not sustained by the intervention; a possible cause was the lack of change in self-efficacy. Therefore, additional interventions are recommended such as booster lessons to maintain increased F&V intake by Girl Scouts. ^

Improving adherence in African American women with uncontrolled primary hypertension

Background and Objectives: African American (AA) women are disproportionately affected with hypertension (HTN). The aim of this randomized controlled trial was to evaluate the effectiveness of a 6-week culturally-tailored educational intervention for AA women with primary HTN who lived in rural Northeast Texas. ^ Methods: Sixty AA women, 29 to 86 years (M 57.98 ±12.37) with primary HTN were recruited from four rural locations and randomized to intervention (n =30) and wait-list control groups ( n =30) to determine the effectiveness of the intervention on knowledge, attitudes, beliefs, social support, adherence to a hypertension regimen, and blood pressure (BP) control. Survey and BP measurements were collected at baseline, 3 weeks, 6 weeks (post intervention) and 6 months post intervention. Culturally-tailored educational classes were provided for 90 minutes once a week for 6 weeks in two local churches and a community center. The wait-list control group received usual care and were offered education at the conclusion of the data collection six months post-intervention. Linear mixed models were used to test for differences between the groups. ^ Results: A significant overall main effect (Time) was found for systolic blood pressure, F(3, 174) =11.104, p=.000, and diastolic blood pressure. F(3, 174) =4.781, p=.003 for both groups. Age was a significant covariate for diastolic blood pressure. F(1, 56) =6.798 p=.012. Participants 57 years or older (n=30) had lower diastolic BPS than participants younger than 57 (n=30). No significant differences were found between groups on knowledge, adherence, or attitudes. Participants with lower incomes had significantly less knowledge about HBP Prevention (r=.036, p=.006). ^ Conclusion: AA women who participated in a 6 week intervention program demonstrated a significant decrease in BP over a 6 month period regardless of whether they were in the intervention or control group. These rural AA women had a relatively good knowledge of HTN and reported an average level of compliance, compared to other populations. Satisfaction with the program was high and there was no attrition, suggesting that AA women will participate in research studies that are culturally tailored to them, held in familiar community locations, and conducted by a trusted person with whom they can identify. Future studies using a different program with larger sample sizes are warranted to try to decrease the high level of HTN-related complications in AA women. ^

Statistical issues on studies of mixed longitudinal design

Mixed longitudinal designs are important study designs for many areas of medical research. Mixed longitudinal studies have several advantages over cross-sectional or pure longitudinal studies, including shorter study completion time and ability to separate time and age effects, thus are an attractive choice. Statistical methodology used in general longitudinal studies has been rapidly developing within the last few decades. Common approaches for statistical modeling in studies with mixed longitudinal designs have been the linear mixed-effects model incorporating an age or time effect. The general linear mixed-effects model is considered an appropriate choice to analyze repeated measurements data in longitudinal studies. However, common use of linear mixed-effects model on mixed longitudinal studies often incorporates age as the only random-effect but fails to take into consideration the cohort effect in conducting statistical inferences on age-related trajectories of outcome measurements. We believe special attention should be paid to cohort effects when analyzing data in mixed longitudinal designs with multiple overlapping cohorts. Thus, this has become an important statistical issue to address. ^ This research aims to address statistical issues related to mixed longitudinal studies. The proposed study examined the existing statistical analysis methods for the mixed longitudinal designs and developed an alternative analytic method to incorporate effects from multiple overlapping cohorts as well as from different aged subjects. The proposed study used simulation to evaluate the performance of the proposed analytic method by comparing it with the commonly-used model. Finally, the study applied the proposed analytic method to the data collected by an existing study Project HeartBeat!, which had been evaluated using traditional analytic techniques. Project HeartBeat! is a longitudinal study of cardiovascular disease (CVD) risk factors in childhood and adolescence using a mixed longitudinal design. The proposed model was used to evaluate four blood lipids adjusting for age, gender, race/ethnicity, and endocrine hormones. The result of this dissertation suggest the proposed analytic model could be a more flexible and reliable choice than the traditional model in terms of fitting data to provide more accurate estimates in mixed longitudinal studies. Conceptually, the proposed model described in this study has useful features, including consideration of effects from multiple overlapping cohorts, and is an attractive approach for analyzing data in mixed longitudinal design studies.^

Anal warts and their predictors among HIV-infected women

Human papillomavirus (HPV) is a necessary cause of cervical cancer and is also strongly associated with anal cancer. While different factors such as CD4+ cell count, HIV RNA viral load, smoking status, and cytological screening results have been identified as risk factors for the infection of HPV high-risk types and associated cancers, much less is known about the association between those risk factors and the infection of HPV low-risk types and anogential warts. In this dissertation, a public dataset (release P09) obtained from the Women's Interagency HIV Study (WIHS) was used to examine the effects of those risk factors on the size of the largest anal warts in HIV-infected women in the United States. Linear mixed modeling was used to address this research question. ^ The prevalence of anal warts at baseline for WIHS participants was higher than other populations. Incidence of anal warts in HIV-infected women was significantly higher than that of HIV-uninfected women [4.15 cases per 100 person-years (95% CI: 3.83–4.77) vs. 1.30 cases per 100 person-years (95% CI: 1.00–1.58), respectively]. There appeared to be an inverse association between the size of the largest anal wart and CD4+ cell count at baseline visit, however it was not statistically significant. There was no association between size of the largest anal wart and CD4+ cell count or HIV RNA viral load over time among HIV-infected women. There was also no association between the size of the largest anal wart and current smoking over time in HIV-infected women, even though smokers had larger warts at baseline than non-smokers. Finally, even though a woman with Pap smear results of ASCUS/LGSIL was found to have an anal wart larger than a woman with normal cervical Pap smear results the relationship between the size of the largest anal wart with cervical Pap smear results over time remains unclear. ^ Although the associations between these risk factors and the size of the largest anal wart over time in HIV-infected women could not be firmly established, this dissertation poses several questions concerning anal wart development for further exploration: (1) the role of immune function (i.e., CD4+ cell count), (2) the role of smoking status and the interaction between smoking status with other risk factors (e.g., CD4+ cell count or HIV RNA viral load), (3) the molecular mechanism of smoking on anal warts over time, (4) the potential for development of a screening program using anal Pap smear in HIV-infected women, and (5) how cost-effective and efficacious would an anal Pap smear screening program be in this high-risk population. ^