Performance tiers: Implementing comparative effectiveness analysis in the health care setting through operations research and spatial methods

This dissertation develops and tests a comparative effectiveness methodology utilizing a novel approach to the application of Data Envelopment Analysis (DEA) in health studies. The concept of performance tiers (PerT) is introduced as terminology to express a relative risk class for individuals within a peer group and the PerT calculation is implemented with operations research (DEA) and spatial algorithms. The analysis results in the discrimination of the individual data observations into a relative risk classification by the DEA-PerT methodology. The performance of two distance measures, kNN (k-nearest neighbor) and Mahalanobis, was subsequently tested to classify new entrants into the appropriate tier. The methods were applied to subject data for the 14 year old cohort in the Project HeartBeat! study.^ The concepts presented herein represent a paradigm shift in the potential for public health applications to identify and respond to individual health status. The resultant classification scheme provides descriptive, and potentially prescriptive, guidance to assess and implement treatments and strategies to improve the delivery and performance of health systems. ^

A computerized statistical framework for coalescent analysis

Coalescent theory represents the most significant progress in theoretical population genetics in the past three decades. The coalescent theory states that all genes or alleles in a given population are ultimately inherited from a single ancestor shared by all members of the population, known as the most recent common ancestor. It is now widely recognized as a cornerstone for rigorous statistical analyses of molecular data from population [1]. The scientists have developed a large number of coalescent models and methods[2,3,4,5,6], which are not only applied in coalescent analysis and process, but also in today’s population genetics and genome studies, even public health. The thesis aims at completing a statistical framework based on computers for coalescent analysis. This framework provides a large number of coalescent models and statistic methods to assist students and researchers in coalescent analysis, whose results are presented in various formats as texts, graphics and printed pages. In particular, it also supports to create new coalescent models and statistical methods. ^

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.^

Identifying characteristics of mentally ill homeless individuals who are successfully linked to health and social services post-incarceration via the jail inreach project

Healthcare for the Homeless—Houston (HHH) received a research grant from The Medallion Foundation, Inc. in March 2006 to pilot The Jail Inreach Project, an intensive “inreach” initiative to assess the impact of providing continuity of mental and primary health care services for homeless individuals who suffer from mental illness and/or substance abuse being released from jail. This pilot project was initiated by HHH, in collaboration with the Harris County Sheriff’s Office and the Mental Health Mental Retardation Authority of Harris County (MHMRA). Those who are flagged as “frequent flyers” and who are diagnosed with a mental illness are referred to the Jail Inreach Project. In order to maximize the effectiveness of the discharge plan, case managers offer the option of meeting the client at the time of release and bring them to the HHH clinic located four blocks from the jail. Participation in both the program and the option for direct release to the care of a case manager are voluntary.^ The purpose of this study is to determine the outcomes of the Jail Inreach Project and addresses the following objectives: (1) to evaluate the characteristics of inmates that chose to be released from jail to the direct care of an HHH case manager versus those who opt for self release and (2) to determine the number and percent of inmates that are linked to services and relationship with type of release (direct versus indirect), (3) to determine if there is a relationship between outcomes and characteristics and (4) to determine what outcomes are a function of release, controlling for characteristics. Statistical analysis, including frequencies, cross tabulations, chi-square and logistical regression, found that those who opt for self release are six times less likely to be successfully linked to services and that gender is the most significant predictor of choosing self release. Men are far more likely to opt for self release than women engaged in this program. These findings help inform policy and program design and development that addresses the difference in service utilization and successful linkage to services post-incarceration. Successful linkage to services, thus continuity of and access to care, further impact the effects of the revolving door phenomenon of mentally ill homeless individuals cycling between the streets, jails and hospital emergency centers.^

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.^

Cancer perceptions: Implications from the 2007 Health Information National Trends Survey

Background. Research has demonstrated associations between sociodemographic characteristics and illness perceptions; however, the impact of cancer exposure through personal or family diagnoses is not well-studied. The purposes of this study were to examine the prevalence of different cancer beliefs and the disparity in cancer beliefs across groups of individuals with distinct cancer histories; and to identify whether, when adjusted for sociodemographic characteristics, cancer history predicts a set of cancer beliefs.^ Methods. Using Leventhal’s Common Sense Model and data from the 2007 Health Information National Trends Survey (N=7172), we constructed multivariable logistic regressions to evaluate the effect of different stimuli, including cancer experience, on cancer perceptions (e.g., risk, worry, causation, outcome).^ Results. Findings indicate significant associations between cancer history and cancer perceptions. Individuals with family and personal cancer histories were more likely than individuals without any cancer history to worry about getting cancer (OR=3.55, P<0.01), agree they will develop cancer in the future (OR=8.81, P<0.01), and disagree that cancer is most often caused by a person’s behavior or lifestyle (OR=1.24, P=0.03). Additionally, results support education’s role in forming cancer perceptions. Individuals with high levels of education were more likely to endorse cancer prevention (OR=1.68, P<0.01) and higher 5-year survival rates (OR=1.41, P<0.01). ^ Conclusions. Results indicate cancer history affects cancer perceptions throughout the cancer continuum. Additionally, cancer history may influence coping behaviors and outcomes related to cancer.^ Impact. Cancer education and survivorship programs should assess important variables (e.g., cancer history) to more effectively tailor services and monitor evolving needs throughout cancer care.^

HPV vaccine coverage in Texas counties: An application of multilevel, small area estimation

Health departments, research institutions, policy-makers, and healthcare providers are often interested in knowing the health status of their clients/constituents. Without the resources, financially or administratively, to go out into the community and conduct health assessments directly, these entities frequently rely on data from population-based surveys to supply the information they need. Unfortunately, these surveys are ill-equipped for the job due to sample size and privacy concerns. Small area estimation (SAE) techniques have excellent potential in such circumstances, but have been underutilized in public health due to lack of awareness and confidence in applying its methods. The goal of this research is to make model-based SAE accessible to a broad readership using clear, example-based learning. Specifically, we applied the principles of multilevel, unit-level SAE to describe the geographic distribution of HPV vaccine coverage among females aged 11-26 in Texas.^ Multilevel (3 level: individual, county, public health region) random-intercept logit models of HPV vaccination (receipt of ≥ 1 dose Gardasil® ) were fit to data from the 2008 Behavioral Risk Factor Surveillance System (outcome and level 1 covariates) and a number of secondary sources (group-level covariates). Sampling weights were scaled (level 1) or constructed (levels 2 & 3), and incorporated at every level. Using the regression coefficients (and standard errors) from the final models, I simulated 10,000 datasets for each regression coefficient from the normal distribution and applied them to the logit model to estimate HPV vaccine coverage in each county and respective demographic subgroup. For simplicity, I only provide coverage estimates (and 95% confidence intervals) for counties.^ County-level coverage among females aged 11-17 varied from 6.8-29.0%. For females aged 18-26, coverage varied from 1.9%-23.8%. Aggregated to the state level, these values translate to indirect state estimates of 15.5% and 11.4%, respectively; both of which fall within the confidence intervals for the direct estimates of HPV vaccine coverage in Texas (Females 11-17: 17.7%, 95% CI: 13.6, 21.9; Females 18-26: 12.0%, 95% CI: 6.2, 17.7).^ Small area estimation has great potential for informing policy, program development and evaluation, and the provision of health services. Harnessing the flexibility of multilevel, unit-level SAE to estimate HPV vaccine coverage among females aged 11-26 in Texas counties, I have provided (1) practical guidance on how to conceptualize and conduct modelbased SAE, (2) a robust framework that can be applied to other health outcomes or geographic levels of aggregation, and (3) HPV vaccine coverage data that may inform the development of health education programs, the provision of health services, the planning of additional research studies, and the creation of local health policies.^

Analysis of participation in the federally mandated coal workers' health surveillance program

The Federal Coal Mine Health and Safety Act of 1969 required that periodic chest radiographs be offered to underground coal miners to protect the miners from the development of Coal Workers' Pneumoconiosis (CWP) and progression of the disease to progressive massive fibrosis (PMF). These examinations are administered by the National Institute for Occupational Safety and Health (NIOSH) through the Coal Workers' Health Surveillance Program (CWHSP). The mine operator is required to provide each miner with the opportunity to have the chest radiograph at no cost to the miner.^ Three rounds of examinations have been conducted since 1969 and the fourth is underway. The decrease in participation over rounds is of great concern if the incidence and progression of CWP are to be understood and controlled.^ This study developed rates of participation for each of 558 West Virginia underground coal mines who submitted or had NIOSH assigned plans for making chest radiographs available during the third round, July 1978 through December 1980. These rates were analyzed in relation to desired levels of participation and to reinforcing, predisposing and enabling factors presumed to affect rates of participation in disease prevention and surveillance programs.^ Two reinforcing factors, size of mine and inclusion of the mine in the National Coal Study (NCS) epidemiology research program, and the enabling factor, use of an on-site radiograph facility, demonstrated highly significant relationships to participation rates.^ The major findings of the study were: (1) Participation in the CWHSP is even lower than previously estimated; (2) CWHSP program evaluation is not systematic and program data base is not complete and comprehensive; and (3) NIOSH program policy is not clear and administration of the CWHSP is fragmented and lacks adequate fiscal and personnel resources. ^

Social network size and perceived network sufficiency as predictors of perceived health status

This study focused on the relationship between social network size (number of friends and relatives), perceived sufficiency of the network and self-rated health utilizing data from the National Survey of Personal Health Practices and Consequences, 1979. For men neither perceived sufficiency nor number of relatives were associated with self-rated health status. The number of friends was positively associated with health status. For women perceived network sufficiency was positively and significantly related to health status, independent of network size. The number of friends and relatives was not associated with self-rated health status. The sociodemographic variables accounted for most of the explained variance in health status for both males and females. Social networks may hold different meanings for women and men, and may require qualitative as well as quantitative analysis. There may have been insufficient variance in the major variables to produce meaningful results. ^

Factors associated with home health care costs

Characteristics of Medicare-certified home health agencies in Texas and the contributions of selected agency characteristics on home health care costs were examined. Cost models were developed and estimated for both nursing and total visit costs using multiple regression procedures. The models included home health agency size, profit status, control, hospital-based affiliation, contract-cost ratio, service provision, competition, urban-rural input-price differences, and selected measures of patient case-mix. The study population comprised 314 home health agencies in Texas that had been certified at least one year on July, 1, 1986. Data for the analysis were obtained from Medicare Cost Reports for fiscal year ending between July 1, 1985 to June 30, 1986.^ Home health agency size, as measured by the logs of nursing and total visits, has a statistically significant negative linear relationship with nursing visit and total visit costs. Nursing and total visit costs decrease at a declining rate as size increases. The size-cost relationship is not altered when controlling for any other agency characteristic. The number of visits per patient per year, a measure of patient case-mix, is also negatively related to costs, suggesting that costs decline with care of chronic patients. Hospital-based affiliation and urban location are positively associated with costs. Together, the four characteristics explain 19 percent of the variance in nursing visit costs and 24 percent of the variance in total visit costs.^ Profit status and control, although correlated with other agency characteristics, exhibit no observable effect on costs. Although no relationship was found between costs and competition, contract cost ratio, or the provision on non-reimburseable services, no conclusions can be made due to problems with measurement of these variables. ^

Social support, health status and health services utilization among the noninstitutionalized elderly: An analysis of the Supplement on Aging to the 1984 national health interview survey

The association between Social Support, Health Status, and Health Services Utilization of the elderly, was explored based on the analysis of data from the Supplement on Aging to the National Health Interview Survey, 1984 (N = 11,497) using a modified framework of Aday and Andersen's Expanded Behavioral Model. The results suggested that Social Support as operationalized in this study was an independent determinant of the use of health services. The quantity of social activities and the use of community services were the two most consistent determinants across different types of health services use.^ The effects of social support on the use of health services were broken down into three components to facilitate explanations of the mechanisms through which social support operated. The Predisposing and Enabling component of Social Support had independent, although not uniform, effects on the use of health services. Only slight substitute effects of social support were detected. These included the substitution of the use of senior centers for longer stay in the hospital and the substitution of help with IADL problems for the use of formal home care services.^ The effect of financial support on the use of health services was found to be different for middle and low income populations. This differential effect was also found for the presence of intimate networks, the frequencies of interaction with children and the perceived availability of support among urban/rural, male/female and white/non-white subgroups.^ The study also suggested that the selection of appropriate Health Status measures should be based on the type of Health Services Utilization in which a researcher is interested. The level of physical function limitation and role activity limitation were the two most consistent predictors of the volume of physician visits, number of hospital days, and average length of stay in the hospital during the past year.^ Some alternative hypotheses were also raised and evaluated, when possible. The impacts of the complex sample design, the reliability and validity of the measures and other limitations of this analysis were also discussed. Finally, a revised framework was proposed and discussed based on the analysis. Some policy implications and suggestions for future study were also presented. ^

Determinants of participation in worksite health risk appraisal (HRA) programs

The purpose of this study was to apply the Behavioral Model of Health Services Utilization to examine an existing worksite HRA program to identify and examine the roles of determinants of participation in HRA programs. The program consisted of three activities: questionnaire, physical examination, and group interpretation sessions. All of the 1821 employees were eligible for the program; 523 (29%) participated in at least one activity. Results from bivariate analyses suggest that being female, being white, having fewer dependents, and having higher medical claims for the past year were positively associated with participation. Results of logistic regression suggest that Age, Sex, Race, Marital, Number of Dependents, Job Title, Months with the Company, and a log transformed value of Employee's Total Medical Claims were all significant determinants of participation. Applications of the logistic regression models, other factors that should be investigated in future studies, and the limitations of the study were discussed. ^

A study of the determinants of the utilization of preventive health care service among Chicanos

This study examines the individual and health care system determinants of two types of preventive health care practice behaviors, having a routine physical exam or a preventive dental exam, in the past year among Chicanos in the Southwestern United States. The study utilizes the Health System Model, developed by Aday and Andersen in 1974, to analyze the relative effect of education, income and occupation on the use of discretionary health care, controlling for other individual and health care system determinants.^ The study is based on a sample of 4,111 Mexican origin adults, drawn from the Hispanic Health and Nutrition Examination Survey (HHANES). This sample is representative of Mexican American residing in the Southwestern United States.^ The study tests the hypothesis that education is the most important social class predictor of preventive health care practice behavior. The fully elaborated model tests the hypothesis that individual determinants alone are insufficient to explain the use of preventive health care services among Chicanos.^ The study found that education and income are statistically significant social class indicators only as it relates to having a preventive dental exam. Education is not the most important social class predictor of either preventive health care practice behavior. Health care system determinants are key predictors of both behaviors. Need, as measured by self-perceived health status of teeth and gender, is as important a determinant as having dental insurance coverage as it relates to having a preventive dental exam. Implications for health programs to effectively reach Chicano target groups and remove access barriers to their use of discretionary health care services are discussed. ^

Bayesian inference and its application to meta-analysis of epidemiologic data

In Part One, the foundations of Bayesian inference are reviewed, and the technicalities of the Bayesian method are illustrated. Part Two applies the Bayesian meta-analysis program, the Confidence Profile Method (CPM), to clinical trial data and evaluates the merits of using Bayesian meta-analysis for overviews of clinical trials.^ The Bayesian method of meta-analysis produced similar results to the classical results because of the large sample size, along with the input of a non-preferential prior probability distribution. These results were anticipated through explanations in Part One of the mechanics of the Bayesian approach. ^

Mitral valve prolapse and its relationship with stroke

The purpose of this study was to elucidate the relationship between mitral valve prolapse and stroke. A population-based historical cohort investigation was conducted among residents of Olmsted County, Minnesota who had an initial echocardiographic diagnosis of mitral valve prolapse from 1975 through 1989. This cohort (N = 1085) was followed for stroke outcomes using the resources of an operational medical record linkage system. There was an overall two-fold increase in the incidence of stroke among individuals with mitral valve prolapse relative to a standard population (standardized morbidity ratio = 2.12, 95% confidence limits = 1.33-3.21). When the data were partitioned by duration of follow-up from the diagnosis of mitral valve prolapse, or by the calendar years at echocardiographic diagnosis, respectively, the association between mitral valve prolapse and stroke was not modified. Mitral valve prolapse subjects 85 years and older were at highest increased risk of developing strokes relative to the general population (standardized morbidity ratio = 5.47, 95% confidence limits = 2.20-11.24). Coronary heart disease, atrial fibrillation, diabetes mellitus and hypertension, were unlikely to have confounded the association between mitral valve prolapse and stroke.^ The cumulative risk of first stroke among individuals initially diagnosed with mitral valve prolapse age 15 to 64 years, given survival to 15.2 years of follow-up, was 4.0%. The cumulative risk of first stroke among individuals initially diagnosed with mitral valve prolapse age 65 to 74 years, given survival to 11.2 years of follow-up, was 13.2%. The cumulative risk of first stroke among individuals initially diagnosed with mitral valve prolapse age 75 years and older, given survival to 6.7 years of follow-up, was 30.6%.^ Among individuals with mitral valve prolapse, age, diabetes, and atrial fibrillation were associated with an increased risk of stroke. Atrial fibrillation was associated with a four-fold rate of stroke and diabetes associated with a seven-fold rate of stroke.^ Findings from this research support the hypothesis that mitral valvular heart prolapse is linked with a stroke sequela. ^