THE RELATIONSHIP BETWEEN OBESITY AND PSYCHOLOGICAL GENERAL WELL-BEING IN UNITED STATES WOMEN

While clinical studies have shown a negative relationship between obesity and mental health in women, population studies have not shown a consistent association. However, many of these studies can be criticized regarding fatness level criteria, lack of control variables, and validity of the psychological variables.^ The purpose of this research was to elucidate the relationship between fatness level and mental health in United States women using data from the First National Health and Nutrition Examination Survey (NHANES I), which was conducted on a national probability sample from 1971 to 1974. Mental health was measured by the General Well-Being Schedule (GWB), and fatness level was determined by the sum of the triceps and subscapular skinfolds. Women were categorized as lean (15th percentile or less), normal (16th to 84th percentiles), or obese (85th percentile or greater).^ A conceptual framework was developed which identified the variables of age, race, marital status, socioeconomic status (education), employment status, number of births, physical health, weight history, and perception of body image as important to the fatness level-GWB relationship. Multiple regression analyses were performed separately for whites and blacks with GWB as the response variable, and fatness level, age, education, employment status, number of births, marital status, and health perception as predictor variables. In addition, 2- and 3-way interaction terms for leanness, obesity and age were included as predictor variables. Variables related to weight history and perception of body image were not collected in NHANES I, and thus were not included in this study.^ The results indicated that obesity was a statistically significant predictor of lower GWB in white women even when the other predictor variables were controlled. The full regression model identified the young, more educated, obese female as a subgroup with lower GWB, especially in blacks. These findings were not consistent with the previous non-clinical studies which found that obesity was associated with better mental health. The social stigma of being obese and the preoccupation of women with being lean may have contributed to the lower GWB in these women. ^

Multiple imputation for missing continuous and dichotomous data: The effects of patterns of missingness and variable correlations on type I error with small samples

The purpose of this study is to investigate the effects of predictor variable correlations and patterns of missingness with dichotomous and/or continuous data in small samples when missing data is multiply imputed. Missing data of predictor variables is multiply imputed under three different multivariate models: the multivariate normal model for continuous data, the multinomial model for dichotomous data and the general location model for mixed dichotomous and continuous data. Subsequent to the multiple imputation process, Type I error rates of the regression coefficients obtained with logistic regression analysis are estimated under various conditions of correlation structure, sample size, type of data and patterns of missing data. The distributional properties of average mean, variance and correlations among the predictor variables are assessed after the multiple imputation process. ^ For continuous predictor data under the multivariate normal model, Type I error rates are generally within the nominal values with samples of size n = 100. Smaller samples of size n = 50 resulted in more conservative estimates (i.e., lower than the nominal value). Correlation and variance estimates of the original data are retained after multiple imputation with less than 50% missing continuous predictor data. For dichotomous predictor data under the multinomial model, Type I error rates are generally conservative, which in part is due to the sparseness of the data. The correlation structure for the predictor variables is not well retained on multiply-imputed data from small samples with more than 50% missing data with this model. For mixed continuous and dichotomous predictor data, the results are similar to those found under the multivariate normal model for continuous data and under the multinomial model for dichotomous data. With all data types, a fully-observed variable included with variables subject to missingness in the multiple imputation process and subsequent statistical analysis provided liberal (larger than nominal values) Type I error rates under a specific pattern of missing data. It is suggested that future studies focus on the effects of multiple imputation in multivariate settings with more realistic data characteristics and a variety of multivariate analyses, assessing both Type I error and power. ^

Molecular markers of human papillomavirus (HPV) infection and epidemiologic risk factors for squamous intraepithelial lesions (SIL) of the cervix

Infection with certain types of HPV is a necessary event in the development of cervical carcinoma; however, not all women who become infected will progress. While much is known about the molecular influence of HPV E6 and E7 proteins on the malignant transformation, little is known about the additional factors needed to drive the process. Currently, conventional cervical screening is insufficient at identifying women who are likely to progress from premalignant lesions to carcinoma. Aneuploidy and chromatin texture from image cytometry have been suggested as quantitative measures of nuclear damage in premalignant lesions and cancer, and traditional epidemiologic studies have identified potential factors to aid in the discrimination of those lesions likely to progress. ^ In the current study, real-time PCR was used to quantitate mRNA expression of the E7 gene in women exhibiting normal epithelium, LSIL, and HSIL. Quantitative cytometry was used to gather information about the DNA index and chromatin features of cells from the same women. Logistic regression modeling was used to establish predictor variables for histologic grade based on the traditional epidemiologic risk factors and molecular markers. ^ Prevalence of mRNA transcripts was lower among women with normal histology (27%) than for women with LSIL (40%) and HSIL (37%) with mean levels ranging from 2.0 to 4.2. The transcriptional activity of HPV 18 was higher than that of HPV 16 and increased with increasing level of dysplasia, reinforcing the more aggressive nature of HPV 18. DNA index and mRNA level increased with increasing histological grade. Chromatin score was not correlated with histology but was higher for HPV 18 samples and those with both HPV 18 and HPV 16. However, chromatin score and DNA index were not correlated with mRNA levels. The most predictive variables in the regression modeling were mRNA level, DNA index, parity, and age, and the ROC curves for LSIL and HSIL indicated excellent discrimination. ^ Real-time PCR of viral transcripts could provide a more efficient method to analyze the oncogenic potential within cells from cervical swabs. Epidemiological modeling of malignant progression in the cervix should include molecular markers, as well as the traditional epidemiological risk factors. ^

Interrelationships between the structural and functional aspects of social relationships, comorbidity and health related quality of life in breast cancer survivors

It is widely acknowledged in theoretical and empirical literature that social relationships, comprising of structural measures (social networks) and functional measures (perceived social support) have an undeniable effect on health outcomes. However, the actual mechanism of this effect has yet to be clearly understood or explicated. In addition, comorbidity is found to adversely affect social relationships and health related quality of life (a valued outcome measure in cancer patients and survivors). ^ This cross sectional study uses selected baseline data (N=3088) from the Women's Healthy Eating and Living (WHEL) study. Lisrel 8.72 was used for the latent variable structural equation modeling. Due to the ordinal nature of the data, Weighted Least Squares (WLS) method of estimation using Asymptotic Distribution Free covariance matrices was chosen for this analysis. The primary exogenous predictor variables are Social Networks and Comorbidity; Perceived Social Support is the endogenous predictor variable. Three dimensions of HRQoL, physical, mental and satisfaction with current quality of life were the outcome variables. ^ This study hypothesizes and tests the mechanism and pathways between comorbidity, social relationships and HRQoL using latent variable structural equation modeling. After testing the measurement models of social networks and perceived social support, a structural model hypothesizing associations between the latent exogenous and endogenous variables was tested. The results of the study after listwise deletion (N=2131) mostly confirmed the hypothesized relationships (TLI, CFI >0.95, RMSEA = 0.05, p=0.15). Comorbidity was adversely associated with all three HRQoL outcomes. Strong ties were negatively associated with perceived social support; social network had a strong positive association with perceived social support, which served as a mediator between social networks and HRQoL. Mental health quality of life was the most adversely affected by the predictor variables. ^ This study is a preliminary look at the integration of structural and functional measures of social relationships, comorbidity and three HRQoL indicators using LVSEM. Developing stronger social networks and forming supportive relationships is beneficial for health outcomes such as HRQoL of cancer survivors. Thus, the medical community treating cancer survivors as well as the survivor's social networks need to be informed and cognizant of these possible relationships. ^

Racial/ethnic disparities in colorectal cancer screening and survival in a large nationwide population-based cohort

Background. Colorectal cancer (CRC) is the third most commonly diagnosed cancer (excluding skin cancer) in both men and women in the United States, with an estimated 148,810 new cases and 49,960 deaths in 2008 (1). Racial/ethnic disparities have been reported across the CRC care continuum. Studies have documented racial/ethnic disparities in CRC screening (2-9), but only a few studies have looked at these differences in CRC screening over time (9-11). No studies have compared these trends in a population with CRC and without cancer. Additionally, although there is evidence suggesting that hospital factors (e.g. teaching hospital status and NCI designation) are associated with CRC survival (12-16), no studies have sought to explain the racial/ethnic differences in survival by looking at differences in socio-demographics, tumor characteristics, screening, co-morbidities, treatment, as well as hospital characteristics. ^ Objectives and Methods. The overall goals of this dissertation were to describe the patterns and trends of racial/ethnic disparities in CRC screening (i.e. fecal occult blood test (FOBT), sigmoidoscopy (SIG) and colonoscopy (COL)) and to determine if racial/ethnic disparities in CRC survival are explained by differences in socio-demographic, tumor characteristics, screening, co-morbidities, treatment, and hospital factors. These goals were accomplished in a two-paper format.^ In Paper 1, "Racial/Ethnic Disparities and Trends in Colorectal Cancer Screening in Medicare Beneficiaries with Colorectal Cancer and without Cancer in SEER Areas, 1992-2002", the study population consisted of 50,186 Medicare beneficiaries diagnosed with CRC from 1992 to 2002 and 62,917 Medicare beneficiaries without cancer during the same time period. Both cohorts were aged 67 to 89 years and resided in 16 Surveillance, Epidemiology and End Results (SEER) regions of the United States. Screening procedures between 6 months and 3 years prior to the date of diagnosis for CRC patients and prior to the index date for persons without cancer were identified in Medicare claims. The crude and age-gender-adjusted percentages and odds ratios of receiving FOBT, SIG, or COL were calculated. Multivariable logistic regression was used to assess race/ethnicity on the odds of receiving CRC screening over time.^ Paper 2, "Racial/Ethnic Disparities in Colorectal Cancer Survival: To what extent are racial/ethnic disparities in survival explained by racial differences in socio-demographics, screening, co-morbidities, treatment, tumor or hospital characteristics", included a cohort of 50,186 Medicare beneficiaries diagnosed with CRC from 1992 to 2002 and residing in 16 SEER regions of the United States which were identified in the SEER-Medicare linked database. Survival was estimated using the Kaplan-Meier method. Cox proportional hazard modeling was used to estimate hazard ratios (HR) of mortality and 95% confidence intervals (95% CI).^ Results. The screening analysis demonstrated racial/ethnic disparities in screening over time among the cohort without cancer. From 1992 to 1995, Blacks and Hispanics were less likely than Whites to receive FOBT (OR=0.75, 95% CI: 0.65-0.87; OR=0.50, 95% CI: 0.34-0.72, respectively) but their odds of screening increased from 2000 to 2002 (OR=0.79, 95% CI: 0.72-0.85; OR=0.67, 95% CI: 0.54-0.75, respectively). Blacks and Hispanics were less likely than Whites to receive SIG from 1992 to 1995 (OR=0.75, 95% CI: 0.57-0.98; OR=0.29, 95% CI: 0.12-0.71, respectively), but their odds of screening increased from 2000 to 2002 (OR=0.79, 95% CI: 0.68-0.93; OR=0.50, 95% CI: 0.35-0.72, respectively).^ The survival analysis showed that Blacks had worse CRC-specific survival than Whites (HR: 1.33, 95% CI: 1.23-1.44), but this was reduced for stages I-III disease after full adjustment for socio-demographic, tumor characteristics, screening, co-morbidities, treatment and hospital characteristics (aHR=1.24, 95% CI: 1.14-1.35). Socioeconomic status, tumor characteristics, treatment and co-morbidities contributed to the reduction in hazard ratios between Blacks and Whites with stage I-III disease. Asians had better survival than Whites before (HR: 0.73, 95% CI: 0.64-0.82) and after (aHR: 0.80, 95% CI: 0.70-0.92) adjusting for all predictors for stage I-III disease. For stage IV, both Asians and Hispanics had better survival than Whites, and after full adjustment, survival improved (aHR=0.73, 95% CI: 0.63-0.84; aHR=0.74, 95% CI: 0.61-0.92, respectively).^ Conclusion. Screening disparities remain between Blacks and Whites, and Hispanics and Whites, but have decreased in recent years. Future studies should explore other factors that may contribute to screening disparities, such as physician recommendations and language/cultural barriers in this and younger populations.^ There were substantial racial/ethnic differences in CRC survival among older Whites, Blacks, Asians and Hispanics. Co-morbidities, SES, tumor characteristics, treatment and other predictor variables contributed to, but did not fully explain the CRC survival differences between Blacks and Whites. Future research should examine the role of quality of care, particularly the benefit of treatment and post-treatment surveillance, in racial disparities in survival.^

Improving the Quality of Life of spousal caregivers of stroke survivors: A cost effectiveness analysis

Back ground and Purpose. There is a growing consensus among health care researchers that Quality of Life (QoL) is an important outcome and, within the field of family caregiving, cost effectiveness research is needed to determine which programs have the greatest benefit for family members. This study uses a multidimensional approach to measure the cost effectiveness of a multicomponent intervention designed to improve the quality of life of spousal caregivers of stroke survivors. Methods. The CAReS study (Committed to Assisting with Recovery after Stroke) was a 5-year prospective, longitudinal intervention study for 159 stroke survivors and their spousal caregivers upon discharge of the stroke survivor from inpatient rehabilitation to their home. CAReS cost data were analyzed to determine the incremental cost of the intervention per caregiver. The mean values of the quality-of-life predictor variables of the intervention group of caregivers were compared to the mean values of usual care groups found in the literature. Significant differences were then divided into the cost of the intervention per caregiver to calculate the incremental cost effectiveness ratio for each predictor variable. Results. The cost of the intervention per caregiver was approximately $2,500. Statistically significant differences were found between the mean scores for the Perceived Stress and Satisfaction with Life scales. Statistically significant differences were not found between the mean scores for the Self Reported Health Status, Mutuality, and Preparedness scales. Conclusions. This study provides a prototype cost effectiveness analysis on which researchers can build. Using a multidimensional approach to measure QoL, as used in this analysis, incorporates both the subjective and objective components of QoL. Some of the QoL predictor variable scores were significantly different between the intervention and comparison groups, indicating a significant impact of the intervention. The estimated cost of the impact was also examined. In future studies, a scale that takes into account both the dimensions and the weighting each person places on the dimensions of QoL should be used to provide a single QoL score per participant. With participant level cost and outcome data, uncertainty around each cost-effectiveness ratio can be calculated using the bias-corrected percentile bootstrapping method and plotted to calculate the cost-effectiveness acceptability curves.^

LONGITUDINAL GROWTH PARAMETERS AND THEIR ECOLOGICAL DETERMINANTS (SEASONALITY)

The growth patterns of weight from birth through the first twelve months of life among rural Taiwanese infants were investigated with the following objectives: (i) compare each of the parameters of the Count model estimated for infants who were nutritionally at risk with those for a reference population from the United States; and (ii) within the Taiwanese infants, account for the variance in the growth patterns in the first and second six months of life on the basis of selected ecological factors.^ The significance between group differences were observed in the patterns of the weight growth in both linear growth and in the timing and the direction of velocity changes. A significant decline in growth velocity was observed among Taiwanese infants at about the fourth month of life. The decline is in keeping with a recent proposal made by J. C. Waterlow regarding the timing of change in growth velocity among nutritionally at risk populations in developing countries. The growth course of a nutritionally at risk infant during the first three months is apparently protected by the nurturance of the mother and innate biological properties of the infant.^ A highly significant portion of the growth variance in the second six months of life was accounted for by exogenous factors and biological factors related to the infant. Conversely, none of the growth variance in the first six months of life was accounted for by predictor variables. The most potent determinant of growth in the second six months of life was seasonality which represents a multiple environmental event.^ The model parameters estimated from the Count model represent different aspect of physical growth; yet the correlation coefficients between parameters b and c are high (r > .80). Clearly, the biological interpretation of the model parameters requires analysis of the whole function in the specific context of a given age period. ^

Correlates of post-diagnosis weight management among female breast cancer survivors: An Internet survey

Objective. Weight gain after cancer treatment is associated with breast cancer recurrence. In order to prolong cancer-free survivorship, interventions to manage post-diagnosis weight are sometimes conducted. However, little is known about what factors are associated with weight management behaviors among cancer survivors. In this study, we examined associations of demographic, clinical, and psychosocial variables with weight management behaviors in female breast cancer survivors. We also examined whether knowledge about post-diagnosis weight gain and its risk is associated with weight management behaviors. ^ Methods. 251 female breast cancer survivors completed an internet survey. They reported current performance of three weight management behaviors (general weight management, physical activity, and healthy diet). We also measured attitude, elf-efficacy, knowledge and social support regarding these behaviors along with demographic and clinical characteristics. ^ Results. Multiple regression models for the weight management behaviors explained 17% of the variance in general weight management, 45% in physical activity and 34% in healthy dieting. The models had 9–14 predictor variables which differed in each model. The variables associated with all three behaviors were social support and self-efficacy. Self-efficacy showed the strongest contribution in all models. The knowledge about weight gain and its risks was not associated with any weight management behaviors. However, women who obtained the knowledge during cancer treatment were more likely to engage in physical activity and healthy dieting. ^ Conclusions. The findings suggest that an intervention designed to increase their self-efficacy to manage weight, to be physically active, to eat healthy will effectively promote survivors to engage in these behaviors. Knowledge may motivate women to manage post-diagnosis weight about risk if information is provided during cancer treatment.^

Data quality in trauma transfusion studies and the impact of missing data on predicting massive transfusion

Maximizing data quality may be especially difficult in trauma-related clinical research. Strategies are needed to improve data quality and assess the impact of data quality on clinical predictive models. This study had two objectives. The first was to compare missing data between two multi-center trauma transfusion studies: a retrospective study (RS) using medical chart data with minimal data quality review and the PRospective Observational Multi-center Major Trauma Transfusion (PROMMTT) study with standardized quality assurance. The second objective was to assess the impact of missing data on clinical prediction algorithms by evaluating blood transfusion prediction models using PROMMTT data. RS (2005-06) and PROMMTT (2009-10) investigated trauma patients receiving ≥ 1 unit of red blood cells (RBC) from ten Level I trauma centers. Missing data were compared for 33 variables collected in both studies using mixed effects logistic regression (including random intercepts for study site). Massive transfusion (MT) patients received ≥ 10 RBC units within 24h of admission. Correct classification percentages for three MT prediction models were evaluated using complete case analysis and multiple imputation based on the multivariate normal distribution. A sensitivity analysis for missing data was conducted to estimate the upper and lower bounds of correct classification using assumptions about missing data under best and worst case scenarios. Most variables (17/33=52%) had <1% missing data in RS and PROMMTT. Of the remaining variables, 50% demonstrated less missingness in PROMMTT, 25% had less missingness in RS, and 25% were similar between studies. Missing percentages for MT prediction variables in PROMMTT ranged from 2.2% (heart rate) to 45% (respiratory rate). For variables missing >1%, study site was associated with missingness (all p≤0.021). Survival time predicted missingness for 50% of RS and 60% of PROMMTT variables. MT models complete case proportions ranged from 41% to 88%. Complete case analysis and multiple imputation demonstrated similar correct classification results. Sensitivity analysis upper-lower bound ranges for the three MT models were 59-63%, 36-46%, and 46-58%. Prospective collection of ten-fold more variables with data quality assurance reduced overall missing data. Study site and patient survival were associated with missingness, suggesting that data were not missing completely at random, and complete case analysis may lead to biased results. Evaluating clinical prediction model accuracy may be misleading in the presence of missing data, especially with many predictor variables. The proposed sensitivity analysis estimating correct classification under upper (best case scenario)/lower (worst case scenario) bounds may be more informative than multiple imputation, which provided results similar to complete case analysis.^

Anthropometric measures as a predictor of cephalopelvic disproportion

This study compared three body measurements, height, hip width (bitrochanteric) and foot length, in 120 Hispanic women who had their first birth by cesarean section (N = 60) or by spontaneous vaginal delivery (N = 60). The objective of the study was to see if there were differences in these measurements that could be useful in predicting cephalopelvic disproportion. Data were collected from two public hospitals in Houston Texas over a 10 month period from December 1994 to October 1995. The statistical technique used to evaluate the measures was discriminant analysis.^ Women who delivered by cesarean section were older, shorter, had shorter feet and delivered heavier infants. There were no differences in the bitrochanteric widths of the women or in the mean gestational age or Apgar scores of the infants.^ Significantly more of the mothers and infants were ill following cesarean section delivery. Maternal illness was usually infection; infant illness was primarily infection or respiratory difficulties.^ Discriminant analysis is a technique which allows for classification and prediction to which group a particular entity will belong given a certain set of variables. Using discriminant analysis, with a probability of cesarean section 50 percent, the best combination to classify who would have a cesarean section was height and hip width, correctly classifying 74.2 percent of those who needed surgery. When the probability of cesarean section was 10 percent and probability of vaginal delivery was 90 percent, the best predictor of who would need operative delivery was height, hip width and age, correctly classifying 56.2 percent. In the population from which the study participants were selected the incidence of cephalopelvic disproportion was low, approximately 1 percent.^ With the technologic assistance available in most of the developed world, it is likely that the further pursuit of different measures and their use would not be of much benefit in attempting to predict and diagnose disproportion. However, in areas of the world where much of obstetrics is "hands on", the availability of technology extremely limited, and the incidence of disproportion larger, the use of anthropometric measures might be useful and of some potential benefit. ^

BLOOD PRESSURE CHANGES IN RELATION TO DEMOGRAPHIC, ANTHROPOMETRIC, AND SEXUAL MATURATION VARIABLES IN U.S. HEALTH EXAMINATION SURVEY OF CHILDREN AND YOUTHS (UNITED STATES)

The determinants of change in blood pressure during childhood and adolescence were studied in a cohort of U.S. national probability sample of 2146 children examined on two occasions during the Health Examination Survey. Significant negative correlations between the initial level and the subsequent changes in blood pressure were observed. The multiple regression analyses showed that the major determinants of systolic blood pressure (SBP) change were change in weight, baseline SBP, and baseline upper arm girth. Race, time interval between examinations, baseline age, and height change were also significant determinants in SBP change. For the change in diastolic blood pressure (DBP), baseline DBP, baseline weight, and weight change were the major determinants. Baseline SBP, time interval and race were also significant determinants. Sexual maturation variables were also considered in the subgroup analysis for girls. Weight change was the most important predictor of the change in SBP for the group of girls who were still in the pre-menarchal or pre-breast maturation status at the time of the follow-up examination, and who had started to menstruate or to develop breast maturation at sometime between the two examinations. Baseline triceps skinfold thickness or initial SBP were more important variables than weight change for the group of girls who had already experienced menarche or breast maturation at the time of the initial survey. For the total group, pubic hair maturation was found to be a significant predictor of SBP change at the 5% significance level. The importance of weight change and baseline weight for the changes in blood pressure warrants further study. ^

Baseline quality of life as a predictor of exercise intervention adherence among endometrial cancer survivors

Background: The objective of this analysis is to test whether baseline quality of life (QOL) measurements, body mass index (BMI) and prior exercise behavior are significantly associated with (1) telephone counseling adherence, and (2) activity at the final assessment, in a physical activity promoting intervention among endometrial cancer survivors.^ Methods: One hundred endometrial cancer survivors not currently meeting physical activity guidelines completed baseline QOL and anthropometric assessments to measure general physical and mental health [Medical Outcomes Survey (SF-36)], sleep patterns and sleep quality [Pittsburgh Sleep Quality Index (PSQI)], perceived stress [Perceived Stress Scale (PSS)], cancer-specific concerns of long-term survivors [Quality of Life in Adult Cancer Survivors (QLACS)], and psychological distress [Brief Symptom Inventory-18 (BSI-18)]. Survivors were counseled by telephone during the 6-month intervention and their completion rate determined their adherence. The primary variables of interest included age, baseline BMI, baseline activity level, time since diagnosis, education, treatment received, and the SF-36 physical and mental component scores.^ Results: Final activity was most closely linked with baseline activity (p<.001) and less invasive surgery, being leaner and older, and experiencing less pain and more vitality. Telephone counseling was also predicted well by baseline activity, working less and having better overall cancer-related functioning.^ Conclusion: Above and beyond the QOL measures, baseline activity was the strongest predictor of both final activity and telephone counseling adherence. While education, surgery treatment type and bodily pain were important predictors for final exercise and employment status and cancer-related quality of life were important predictors for telephone counseling adherence, considering adaptive exercise interventions that focus heavily on engaging inactive participants may be a way to produce better exercise-related outcomes in the endometrial cancer survivor population.^