There are currently thousands of Jamaican citizens that lack access to basic health care. In order to improve the health-care system, I collect and analyze data from two clinics in remote locations of the island. This report analyzes data collected from Clarendon Parish, Jamaica. In order to create a descriptive analysis, I use SAS^® Studio 9.4. A few of the procedures I use include: PROC IMPORT, PROC MEANS, PROC FREQ, and PROC GCHART. After conducting the aforementioned procedures, I am able to produce a descriptive analysis of the health issues plaguing the island.

Read the paper (PDF) | View the e-poster or slides (PDF)

It is common for hundreds or even thousands of clinical endpoints to be collected from individual subjects, but events from the majority of clinical endpoints are rare. The challenge of analyzing high dimensional sparse data is in balancing analytical consideration for statistical inference and clinical interpretation with precise meaningful outcomes of interest at intra-categorical and inter-categorical levels. Lumping or grouping similar rare events into a composite category has the statistical advantage of increasing testing power, reducing multiplicity size, and avoiding competing risk problems. However, too much or inappropriate lumping would jeopardize the clinical meaning of interest and external validity, whereas splitting or keeping each individual event at its basic clinical meaningful category can overcome the drawbacks of lumping. This practice might create analytical issues of increasing type II errors, multiplicity size, competing risks, and having a large proportion of endpoints with rare events. It seems that lumping and splitting are diametrically opposite approaches, but in fact, they are complementary. Both are essential for high dimensional data analysis. This paper describes the steps required for the lumping and splitting analysis and presents SAS^® code that can be used to implement each step.

While cardiac revascularization procedures like cardiac catheterization, percutaneous transluminal angioplasty, and cardiac artery bypass surgery have become standard practices in restorative cardiology, the practice is not evenly prescribed or subscribed to. We analyzed Florida hospital discharge records for the period 1992 to 2010 to determine the odds of receipt of any of these procedures by Hispanics and non-Hispanic Whites. Covariates (potential confounders) were age, insurance type, gender, and year of discharge. Additional covariates considered included comorbidities such as hypertension, diabetes, obesity, and depression. The results indicated that even after adjusting for covariates, Hispanics in Florida during the time period 1992 to 2010 were consistently less likely to receive these procedures than their White counterparts. Reasons for this phenomenon are discussed.

This paper presents the use of latent class analysis (LCA) to base the identification of a set of mutually exclusive latent classes of individuals on responses to a set of categorical, observed variables. The LCA procedure, a user-defined SAS^® procedure for conducting LCA and LCA with covariates, is demonstrated using follow-up data on substance use from Monitoring the Future panel data, a nationally representative sample of high school seniors who are followed at selected time points during adulthood. The demonstration includes guidance on data management prior to analysis, PROC LCA syntax requirements and options, and interpretation of output.

The Oklahoma State Department of Health (OSDH) conducts home visiting programs with families that need parental support. Domestic violence is one of the many screenings performed on these visits. The home visiting personnel are trained to do initial screenings; however, they do not have the extensive information required to treat or serve the participants in this arena. Understanding how demographics such as age, level of education, and household income among others, are related to domestic violence might help home visiting personnel better serve their clients by modifying their questions based on these demographics. The objective of this study is to better understand the demographic characteristics of those in the home visiting programs who are identified with domestic violence. We also developed predictive models such as logistic regression and decision trees based on understanding the influence of demographics on domestic violence. The study population consists of all the women who participated in the Children First Program of the OSDH from 2012 to 2014. The data set contains 1,750 observations collected during screening by the home visiting personnel over the two-year period. In addition, they must have completed the Demographic form as well as the Relationship Assessment form at the time of intake. Univariate and multivariate analysis has been performed to discover the influence that age, education, and household income have on domestic violence. From the initial analysis, we can see that women who are younger than 25 years old, who haven't completed high school, and who are somewhat dependent on their husbands or partners for money are most vulnerable. We have even segmented the clients based on the likelihood of domestic violence.

Disease prevalence is one of the most basic measures of the burden of disease in the field of epidemiology. As an estimate of the total number of cases of disease in a given population, prevalence is a standard in public health analysis. The prevalence of diseases in a given area is also frequently at the core of governmental policy decisions, charitable organization funding initiatives, and countless other aspects of everyday life. However, all too often, prevalence estimates are restricted to descriptive estimates of population characteristics when they could have a much wider application through the use of inferential statistics. As an estimate based on a sample from a population, disease prevalence can vary based on random fluctuations in that sample rather than true differences in the population characteristic. Statistical inference uses a known distribution of this sampling variation to perform hypothesis tests, calculate confidence intervals, and perform other advanced statistical methods. However, there is no agreed-upon sampling distribution of the prevalence estimate. In cases where the sampling distribution of an estimate is unknown, statisticians frequently rely on the bootstrap re-sampling procedure first given by Efron in 1979. This procedure relies on the computational power of software to generate repeated pseudo-samples similar in structure to an original, real data set. These multiple samples allow for the construction of confidence intervals and statistical tests to make statistical determinations and comparisons using the estimated prevalence. In this paper, we use the bootstrapping capabilities of SAS^® 9.4 to compare statistically the difference between two given prevalence rates. We create a bootstrap analog to the two-sample t test to compare prevalence rates from two states despite the fact that the sampling distribution of these estimates is unknown using SAS^®.

Administrative health databases, including hospital and physician records, are frequently used to estimate the prevalence of chronic diseases. Disease-surveillance information is used by policy makers and researchers to compare the health of populations and develop projections about disease burden. However, not all cases are captured by administrative health databases, which can result in biased estimates. Capture-recapture (CR) models, originally developed to estimate the sizes of animal populations, have been adapted for use by epidemiologists to estimate the total sizes of disease populations for such conditions as cancer, diabetes, and arthritis. Estimates of the number of cases are produced by assessing the degree of overlap among incomplete lists of disease cases captured in different sources. Two- and three-source CR models are most commonly used, often with covariates. Two important assumptions--independence of capture in each data source and homogeneity of capture probabilities, which underlie conventional CR models--are unlikely to hold in epidemiological studies. Failure to satisfy these assumptions bias the model results. Log-linear, multinomial logistic regression, and conditional logistic regression models, if used properly, can incorporate dependency among sources and covariates to model the effect of heterogeneity in capture probabilities. However, none of these models is optimal, and researchers might be unfamiliar with how to use them in practice. This paper demonstrates how to use SAS^® to implement the log-linear, multinomial logistic regression, and conditional logistic regression CR models. Methods to address the assumptions of independence between sources and homogeneity of capture probabilities for a three-source CR model are provided. The paper uses a real numeric data set about Parkinson's disease involving physician claims, hospital abstract, and prescription drug records from one Canadian province. Advantages and disadvantages of each model are discus sed.

An important strength of observational studies is the ability to estimate a key behavior's or treatment's effect on a specific health outcome. This is a crucial strength as most health outcomes research studies are unable to use experimental designs due to ethical and other constraints. Keeping this in mind, one drawback of observational studies (that experimental studies naturally control for) is that they lack the ability to randomize their participants into treatment groups. This can result in the unwanted inclusion of a selection bias. One way to adjust for a selection bias is through the use of a propensity score analysis. In this study, we provide an example of how to use these types of analyses. Our concern is whether recent substance abuse has an effect on an adolescent's identification of suicidal thoughts. In order to conduct this analysis, a selection bias was identified and adjustment was sought through three common forms of propensity scoring: stratification, matching, and regression adjustment. Each form is separately conducted, reviewed, and assessed as to its effectiveness in improving the model. Data for this study was gathered through the Youth Risk Behavior Surveillance System, an ongoing nation-wide project of the Centers for Disease Control and Prevention. This presentation is designed for any level of statistician, SAS^® programmer, or data analyst with an interest in controlling for selection bias, as well as for anyone who has an interest in the effects of substance abuse on mental illness.

The increasing popularity and affordability of wearable devices, together with their ability to provide granular physical activity data down to the minute, have enabled researchers to conduct advanced studies on the effects of physical activity on health and disease. This provides statistical programmers the challenge of processing data and translating it into analyzable measures. One such measure is the number of time-specific bouts of moderate to vigorous physical activity (MVPA) (similar to exercise), which is needed to determine whether the participant meets current physical activity guidelines (for example, 150 minutes of MVPA per week performed in bouts of at least 20 minutes). In this paper, we illustrate how we used SAS^® arrays to calculate the number of 20-minute bouts of MVPA per day. We provide working code on how we processed Fitbit Flex data from 63 healthy volunteers whose physical activities were monitored daily for a period of 12 months.

Read the paper (PDF) | Download the data file (ZIP)

In health care and epidemiological research, there is a growing need for basic graphical output that is clear, easy to interpret, and easy to create. SAS^® 9.3 has a very clear and customizable graphic called a Radar Graph, yet it can only display the unique responses of one variable and would not be useful for multiple binary variables. In this paper we describe a way to display multiple binary variables for a single population on a single radar graph. Then we convert our method into a macro with as few parameters as possible to make this procedure available for everyday users.

Read the paper (PDF) | Download the data file (ZIP)