Purpose: Recent studies and anecdotal evidence suggest that patient safety may be compromised on weekends. Our objective was to determine whether rates of complications in hospitals are higher on weekends than on weekdays.

Methods: We examined records from 4,967,114 admissions to acute care hospitals in 3 states and analyzed complication rates using the Patient Safety Indicators. We selected 8 indicators that could be assigned to a single day: complications of anesthesia, retained foreign bodies, postoperative hemorrhage, accidental cuts and lacerations during procedures, birth trauma, obstetric trauma during vaginal deliveries with and without instrumentation, and obstetric trauma during cesarean delivery. Odds ratios (ORs) comparing weekends versus weekdays were adjusted for demographics, type of admission, and admission route. In a subgroup analysis of surgical complications, we restricted the population to patients who underwent cardiac or vascular procedures.

Results: Four of the 8 complications occurred more frequently on weekends: postoperative hemorrhage (OR 1.07, 95% confidence interval [CI], 1.01-1.14), newborn trauma (OR 1.06, 95% CI, 1.03-1.10), vaginal deliveries without instrumentation (OR 1.03, 95% CI, 1.02-1.04), and obstetric trauma during cesarean sections (OR 1.36, 95% CI, 1.29-1.44). Complications related to anesthesia occurred less frequently on weekends (OR 0.86). Among patients undergoing vascular procedures, surgical complications occurred more frequently on weekends (OR 1.46, 95% CI, 1.16-1.85).

Conclusions: Rates of complications are marginally higher on weekends than on weekdays for some surgical and newborn complications, but more significantly for obstetric trauma and for surgical complications involving patients undergoing vascular procedures. Hospitals should work toward increasing the robustness of safeguards on weekends.

Context: Hospitals are under pressure to increase revenue and lower costs, and at the same time, they face dramatic variation in clinical demand.

Objective: We sought to determine the relationship between peak hospital workload and rates of adverse events (AEs).

Methods: A random sample of 24,676 adult patients discharged from the medical/surgical services at 4 US hospitals (2 urban and 2 suburban teaching hospitals) from October 2000 to September 2001 were screened using administrative data, leaving 6841 cases to be reviewed for the presence of AEs. Daily workload for each hospital was characterized by volume, throughput (admissions and discharges), intensity (aggregate DRG weight), and staffing (patient-to-nurse ratios). For volume, we calculated an "enhanced" occupancy rate that accounted for same-day bed occupancy by more than 1 patient. We used Poisson regressions to predict the likelihood of an AE, with control for workload and individual patient complexity, and the effects of clustering.

Results: One urban teaching hospital had enhanced occupancy rates more than 100% for much of the year. At that hospital, admissions and patients per nurse were significantly related to the likelihood of an AE (P 0.05); occupancy rate, discharges, and DRG-weighted census were significant at P 0.10. For example, a 0.1% increase in the patient-to-nurse ratio led to a 28% increase in the AE rate. Results at the other 3 hospitals varied and were mainly non significant.

Conclusions: Hospitals that operate at or over capacity may experience heightened rates of patient safety events and might consider re-engineering the structures of care to respond better during periods of high stress.

Objective: To describe the development of an instrument for assessing workforce perceptions of hospital safety culture and to assess its reliability and validity.

Data Sources/Study Setting: Primary data collected between March 2004 and May 2005. Personnel from 105 U.S. hospitals completed a 38-item paper and pencil survey. We received 21,496 completed questionnaires, representing a 51 percent response rate.

Study Design: Based on review of existing safety climate surveys, we developed a list of key topics pertinent to maintaining a culture of safety in high-reliability organizations. We developed a draft questionnaire to address these topics and pilot tested it in four preliminary studies of hospital personnel. We modified the questionnaire based on experience and respondent feedback, and distributed the revised version to 42,249 hospital workers.

Data Collection: We randomly divided respondents into derivation and validation samples. We applied exploratory factor analysis to responses in the derivation sample. We used those results to create scales in the validation sample, which we subjected to multitrait analysis (MTA).

Principal Findings: We identified nine constructs, three organizational factors, two unit factors, three individual factors, and one additional factor. Constructs demonstrated substantial convergent and discriminant validity in the MTA. Cronbach's  coefficients ranged from 0.50 to 0.89.

Conclusions: It is possible to measure key salient features of hospital safety climate using a valid and reliable 38-item survey and appropriate hospital sample sizes. This instrument may be used in further studies to better understand the impact of safety climate on patient safety outcomes.

Background: While trauma systems improve the outcome of injury in children, there is a paucity of information regarding trauma regionalization system function amid dramatic changes in the financial structure of health care.

Objective: To describe the distribution of acute hospitalization of children with severe trauma by level of hospital trauma care designation in California.

Methods: Retrospective observational study of a population-based cohort from 1998 to 2004. The California Office of Statewide Health Planning and Development (OSHPD) patient Discharge Data Set 1998-2004 was used. Patients were included if: age 0-19 years, trauma International Classification of Diseases, 9th Edition (ICD-9) diagnostic codes, and e-codes (n = 127,841). Differential rates of hospitalization in trauma-designated hospitals vs. non-trauma-designated hospitals were calculated for death and injury severity score. Injury severity scores (ISSs) were calculated from ICD-9 codes. Primary outcomes were hospitalization in a trauma center and death.

Results: From 1998 to 2004, 55%-60% of children 0-14 years and 55%-70% of children 15-19 years with trauma requiring hospitalization were discharged from trauma-designated hospitals. Children with severe injury were consistently hospitalized in trauma-designated hospitals (70%-78%) at a rate higher than children with moderate (60%-70%) and mild (50%-60%) injury. Trends for hospitalization in trauma-designated hospitals increased over the time span of the study (p 0.05). Approximately 20% of hospitalized children who died (I = 1,426) died 2 or more days after injury in non-trauma-designated hospitals.

Conclusions: A majority of children with trauma were cared for in trauma-designated hospitals over the study period. However, 20% of children with severe injuries and 20% of pediatric deaths greater than 2 days after injury were cared for in non-trauma-designated hospitals. Further investigation is warranted in order to enhance clinical protocols and policies that ensure access to appropriate regional trauma care for all children in need.

Objective: Despite evidence and recommendations encouraging the delivery of high-risk newborns in hospitals with subspecialty or high-level NICUs, increasing numbers are being delivered in other facilities. Causes for this are unknown. We sought to explore the impact of diffusion of specialty or midlevel NICUs on the types of hospitals in which low birth weight newborns are born.

Design: We used birth certificate, death certificate, and hospital discharge data for essentially all low birth weight, singleton California newborns born between 1993 and 2000. We identified areas likely to have been affected by the opening of a new nearby midlevel unit, analyzed changes over time in the share of births that took place in midlevel NICU hospitals, and compared patterns in areas that were and were not likely affected by the opening of a new midlevel unit. We also tracked the corresponding changes in the share of births in high-level hospitals and in those without NICU facilities (low-level).

Results: The probability of a 500- to 1499-g infant being born in a midlevel unit increased by 17 percentage points after the opening of a new nearby unit. More than three quarters of this increase was accounted for by reductions in the probability of birth in a hospital with a high-level unit (15 points), and the other portion was resulting from reductions in the share of newborns delivered in hospitals with low-level centers (2 points). Similar patterns were observed in 1500- to 2499-g newborns.

Conclusions: The introduction of new midlevel units was associated with significant shifts of births from both high-level and low-level hospitals to midlevel hospitals. In areas in which new midlevel units opened, the majority of the increase in midlevel deliveries was attributable to shifts from high-level unit births. Continued proliferation of midlevel units should be carefully assessed.

We investigated the determinants of inpatient rehabilitation costs in the Department of Veterans Affairs (VA) and examined the relationship between length of stay (LOS) and discharge costs using data from VA and community rehabilitation hospitals. We estimated regression models to identify patient characteristics associated with specialized inpatient rehabilitation costs. VA data included 3,535 patients discharged from 63 facilities in fiscal year 2001. We compared VA costs to community rehabilitation hospitals using a sample from the Uniform Data System for Medical Rehabilitation of 190,112 patients discharged in 1999 from 697 facilities. LOS was a strong predictor of cost for VA and non-VA hospitals. Functional status, measured by Functional Independence Measure (FIM) scores at admission, was statistically significant but added little explanatory value after controlling for LOS. Although FIM scores were associated with LOS, FIM scores accounted for little variance in cost after controlling for LOS. These results are most applicable to researchers conducting cost-effectiveness analyses.

This issue of CHP/PCOR's quarterly newsletter, which covers news from the summer 2006 quarter, includes articles about:

• research by CHP/PCOR investigators that influenced the Centers for Disease Control and Prevention to recommend widespread voluntary HIV screening for all Americans ages 13 to 64 -- a significant change from the CDC's previous HIV screening guidelines;
• a CHP/PCOR study on patient safety culture in U.S. hospitals -- the largest effort to date to measure hospitals' safety culture and seek to improve it through an intervention that gets hospital executives out of their offices and on to the hospital floors;
• an early-stage project in which CHP/PCOR is collaborating with the Center on Democracy, Development and the Rule of Law to study the relationship between health interventions, governance and development;
• an evidence report examining the challenges of diagnosing and treating anthrax in children, prepared by the Stanford-UCSF Evidence-based Practice Center; and
• a study by CHP/PCOR fellow Kate Bundorf which found that depending on the definition of "affordability" that is used, health insurance is "affordable" to between one-quarter and three-quarters of the uninsured -- and many of those who can't afford insurance purchase it anyway.

Many states have "prudent layperson" mandates that require health plans to reimburse hospitals for emergency department (ED) care delivered to patients who believe that they have symptoms warranting emergency treatment. Increased, and possibly unnecessary, ED use has often been attributed to these policies. We use data from thirty-five states to study relationships between passage of prudent layperson policies in the late 1990s and ED use among the privately insured. None of the analyses show evidence that the mandates are associated with increased use. We conclude that prudent layperson mandates are not associated with increases in ED visits among privately insured patients.

Does quality of care systematically differ among government-owned, private not-for-profit, and for-profit hospitals? A large empirical literature provides conflicting evidence. Through quantitative review of 46 studies since 1990, we find that several study features that can explain divergent results: analytic methods, disease studied, and data sources. For unprofitable care, how studies handle market competition and regional differences account for substantial variation. Policymakers should be aware that differences in results appear to arise predominantly from differences between studies' analytic methods. Moreover, conventional methods of meta-analytic synthesis should be applied with great caution given the considerable overlap among studied hospitals.

This issue of CHP/PCOR's quarterly newsletter, which covers news from the winter 2006 quarter, includes articles about:

• a comprehensive review of worldwide anthrax cases from 1900 to 2005, conducted by CHP/PCOR researchers, which found that timely diagnosis and antibiotic treatment, along with pleural fluid drainage, are key to anthrax patients' survival;
• an early-stage research project in which CHP/PCOR core faculty member Grant Miller is collaborating with an NGO in Bangladesh to study whether villagers' traditional cooking practices are contributing to life-threatening respiratory infections;
• assertions by two CHP/PCOR health policy experts that health-savings accounts -- the cornerstone of President Bush's healthcare agenda -- won't save much money and won't address the fundamental problems of the U.S. healthcare system;
• the Agency for Healthcare Research and Quality's release of the Pediatric Quality Indicators, developed by CHP/PCOR researchers and collaborators. This is the first set of data-analysis tools specifically designed to help hospitals monitor their quality of care for hospitalized children; and
• a roundup of CHP/PCOR's 7th annual retreat, which featured panel discussions on improving healthcare quality, conducting health services research in developing countries, and health systems comparisons across industrialized nations.