A day in the life of PubMed: analysis of a typical day's query log.

OBJECTIVE: To characterize PubMed usage over a typical day and compare it to previous studies of user behavior on Web search engines. DESIGN: We performed a lexical and semantic analysis of 2,689,166 queries issued on PubMed over 24 consecutive hours on a typical day. MEASUREMENTS: We measured the number of queries, number of distinct users, queries per user, terms per query, common terms, Boolean operator use, common phrases, result set size, MeSH categories, used semantic measurements to group queries into sessions, and studied the addition and removal of terms from consecutive queries to gauge search strategies. RESULTS: The size of the result sets from a sample of queries showed a bimodal distribution, with peaks at approximately 3 and 100 results, suggesting that a large group of queries was tightly focused and another was broad. Like Web search engine sessions, most PubMed sessions consisted of a single query. However, PubMed queries contained more terms. CONCLUSION: PubMed's usage profile should be considered when educating users, building user interfaces, and developing future biomedical information retrieval systems.

Health care policy analysis of Medicaid's early and periodic screening, diagnosis, and treatment (EPSDT) benefit in Colorado

The purpose of this thesis is to identify "best practice" recommendations for successful implementation of the EPSDT outreach program at Memorial Health System's Hospital for Children in Colorado Springs through a policy analysis of Medicaid EPSDT services in Colorado. A successful program at Memorial will increase education and awareness of EPSDT services, enrollment, and access to and utilization of health care services for eligible children. Methodology utilized in this study included questionnaires designed for the EPSDT contract administrator and outreach coordinators/workers; analysis of current federal and state policies; and studies conducted at the federal and state level, and by various advocacy groups. The need for this analysis of EPSDT came about in part through an awareness of increasingly high numbers of children in poverty and who are uninsured. Though the percentage of children living in poverty in Colorado is slightly below the national average (see Table 2), according to data analyzed by The Annie E. Casey Foundation, the percentage of children (0-18) living in poverty in Colorado increased from 10% in 2000 to 16% in 2006, a dramatic increase of 60% surpassed by only one other state in the nation (The Annie E. Casey Foundation, 2008). By comparison, the U.S. percentage of children in poverty during the same time frame rose from 17% to 18% (The Annie E. Casey Foundation, 2008). What kind of health care services are available to this vulnerable and growing group of Coloradans, and what are the barriers that affect their enrollment in, access to and utilization of these health care services? Barriers identified included difficulty with the application process; system and process issues; a lack of providers; and a lack of awareness and knowledge of EPSDT. Fiscal restraints and legislation at the federal and state level are also barriers to increasing enrollment and access to services. Outreach services are a critical component of providing EPSDT services, and there were several recommendations regarding outreach and case management that will benefit the program in the future. Through this analysis and identification of a broad range of barriers, a clearer picture emerged of current challenges within the EPSDT program as well as a broad range of strategies and recommendations to address these challenges. Through increased education and advocacy for EPSDT and the services it encompasses; stronger collaboration and cooperation between all groups involved, including providing a Medical Home for all eligible children; and new legislation putting more money and focus on comprehensive health care for low-income uninsured children; enrollment, access to and utilization of developmentally appropriate and quality health care services can be achieved. ^

Effect of patient accrual patterns on power and size of log-rank test for time-to-event outcome in clinical trials

The determination of size as well as power of a test is a vital part of a Clinical Trial Design. This research focuses on the simulation of clinical trial data with time-to-event as the primary outcome. It investigates the impact of different recruitment patterns, and time dependent hazard structures on size and power of the log-rank test. A non-homogeneous Poisson process is used to simulate entry times according to the different accrual patterns. A Weibull distribution is employed to simulate survival times according to the different hazard structures. The current study utilizes simulation methods to evaluate the effect of different recruitment patterns on size and power estimates of the log-rank test. The size of the log-rank test is estimated by simulating survival times with identical hazard rates between the treatment and the control arm of the study resulting in a hazard ratio of one. Powers of the log-rank test at specific values of hazard ratio (≠1) are estimated by simulating survival times with different, but proportional hazard rates for the two arms of the study. Different shapes (constant, decreasing, or increasing) of the hazard function of the Weibull distribution are also considered to assess the effect of hazard structure on the size and power of the log-rank test. ^