Carolina Reyes

Variations in the Incidence of Postpartum Hemorrhage Across Hospitals in California

Objective: Because postpartum hemorrhage may result from factors related to obstetrical practice patterns, we examined the variability of postpartum hemorrhage and related risk factors (obstetrical trauma, chorioamnionitis, and protracted labor) across hospital types and hospitals in California. Methods: Linked birth certificate and hospital discharge data from 507,410 births in California in 1997 were analyzed. Cases were identified using International Classification of Diseases, Ninth Edition, Clinical Modification (ICD-9-CM) codes. Comparisons were made across hospital types and individual hospitals. Risk adjustments were made using 1) sample restriction to a subset of 324,671 low-risk women, and 2) Bayesian hierarchical logistic regression model to simultaneously quantify the effects of patient-level and hospital-level risk factors. Results: Postpartum hemorrhage complicated 2.4% of live births. The incidence ranged from 1.6% for corporate hospitals to 4.9% for university hospitals in the full sample, and from 1.4% for corporate hospitals to 3.9% for university hospitals in the low-risk sample. Low-risk women who delivered at government, HMO and university hospitals had two- to threefold increased odds (odds ratios 1.98 to 2.71; 95% confidence sets ranged from 1.52 to 4.62) of having postpartum hemorrhage compared to women who delivered at corporate hospitals, irrespective of patient-level characteristics. They also had significantly higher rates of obstetrical trauma and chorioamnionitis. Greater variations were observed across individual hospitals. Conclusion: The incidence of postpartum hemorrhage and related risk factors varied substantially across hospital types and hospitals in California. Further studies using primary data sources are needed to determine whether these variations are related to the processesof care.

Innovative Strategies to Reduce Disparities in the Quality of Prenatal Care in Underresourced Settings

This study examined what innovative strategies, including the use of health information technology (health IT), have been or can be used to reduce disparities in prenatal care quality in underresourced settings. Based on literature review and key informant interviews, the authors identified 17 strategies that have been or can be used to (a) increase access to timely prenatal care, (b) improve the content of prenatal care, and (c) enhance the organization and delivery of prenatal care. Health IT can be used to (a) increase consumer awareness about the importance of preconception and early prenatal care, facilitate spatial mapping of access gaps, and improve continuity of patient records; (b) support collaborative quality improvement, facilitate performance measurement, enhance health promotion, assist with care coordination, reduce clinical errors, improve delivery of preventive health services, provide decision support, and encourage completeness of documentation; and (c) support data integration and engineer collaborative innovation.

Hospital Rates of Maternal and Neonatal Infection in a Low-Risk Population

Background: In 2003, the Agency for Healthcare Quality and Research (AHRQ) published its Quality Indicators for healthcare, and set out methodological criteria for the evaluation of potential candidates. Objectives: Because perinatal infections may result from poor obstetrical practices, we intended to describe the variability of maternal and congenital neonatal infections across different types of hospital ownership (e.g., not for profit, government), and to assess whether rates of these infections meet criteria as quality indicators. Research Design: Population-based cohort study. Subjects: All laboring women without maternal, fetal, or placental complications who delivered in California in 1997, and their neonates, as reported through hospital discharge data. Measures: A Bayesian hierarchical logistic regression model was used to quantify the effects of both “patient-level” risk factors such as parity and prior cesarean history, and “hospital-level” risk factors such as ownership and teaching status. Results: The 308,841 mother–newborn pairs in this low-risk study population delivered at 281 hospitals; 0.39% had uterine infections and 1.3% had neonatal infections. Hospital ownership and teaching status were strongly associated with perinatal infection. Secondly, methods used to estimate and analyze hospital-specific infection rates identified hospitals with exceptionally high rates. Twenty-eight hospitals had neonatal infection rates that ranged from 3% to 28%. Conclusions: The methods presented here were consistent with AHRQ methods and criteria for potential Quality Indicators. They also identified hospitals with exceptionally high rates of infectious morbidity. The relationship between hospital ownership and obstetrical practice patterns, and the feasibility of practice improvement, remain to be studied.

Chapter 6:Nucleic acid structure and dynamics: perspectives from site-directed spin labeling

The technique of site-directed spin labeling (SDSL) provides information on bio-molecular systems by monitoring the behaviors of a stable radical tag (i.e., spin label) using electron paramagnetic resonance (EPR) spectroscopy. SDSL studies of nucleic acids and protein–nucleic acid complexes have yielded unique information that is difficult to derive from other methods. In this chapter, we describe strategies used in nucleic acid SDSL investigations, and summarize advancements with a focus on those reported during the past five years.

Nucleic Acid-Dependent Conformational Changes in CRISPR–Cas9 Revealed by Site-Directed Spin Labeling

In a type II clustered regularly interspaced short palindromic repeats (CRISPR) system, RNAs that are encoded at the CRISPR locus complex with the CRISPR-associated (Cas) protein Cas9 to form an RNA-guided nuclease that cleaves double-stranded DNAs at specific sites. In recent years, the CRISPR–Cas9 system has been successfully adapted for genome engineering in a wide range of organisms. Studies have indicated that a series of conformational changes in Cas9, coordinated by the RNA and the target DNA, direct the protein into its active conformation, yet details on these conformational changes, as well as their roles in the mechanism of function of Cas9, remain to be elucidated. Here, nucleic acid-dependent conformational changes in Streptococcus pyogenes Cas9 (SpyCas9) were investigated using the method of site-directed spin labeling (SDSL). Single nitroxide spin labels were attached, one at a time, at one of the two native cysteine residues (Cys80 and Cys574) of SpyCas9, and the spin-labeled proteins were shown to maintain their function. X-band continuous-wave electron paramagnetic resonance spectra of the nitroxide attached at Cys80 revealed conformational changes of SpyCas9 that are consistent with a large-scale domain re-arrangement upon binding to its RNA partner. The results demonstrate the use of SDSL to monitor conformational changes in CRISPR–Cas9, which will provide key information for understanding the mechanism of CRISPR function.

CRISPR–Cas9 Mediated DNA Unwinding Detected Using Site-Directed Spin Labeling

The RNA-guided CRISPR-Cas9 nuclease has revolutionized genome engineering, yet its mechanism for DNA target selection is not fully understood. A crucial step in Cas9 target recognition involves unwinding of the DNA duplex to form a three-stranded R-loop structure. Work reported here demonstrates direct detection of Cas9-mediated DNA unwinding by a combination of site-directed spin labeling and molecular dynamics simulations. The results support a model in which the unwound nontarget strand is stabilized by a positively charged patch located between the two nuclease domains of Cas9 and reveal uneven increases in flexibility along the unwound nontarget strand upon scissions of the DNA backbone. This work establishes the synergistic combination of spin-labeling and molecular dynamics to directly monitor Cas9-mediated DNA conformational changes and yields information on the target DNA in different stages of Cas9 function, thus advancing mechanistic understanding of CRISPR-Cas9 and aiding future technological development.