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S V Williams

Publications and source records attributed to S V Williams.

At least 37 records · Page 2Linked to original sources
PubMed1995

Evaluation of the complication rate as a measure of quality of care in coronary artery bypass graft surgery.

OBJECTIVE: To determine whether hospital rankings based on complication rates provide the same information as hospital rankings based on mortality rates. DESIGN: A retrospective study of in-hospital death, complication, and death following complication (failure to rescue). Hospitals were ranked using residuals based on the difference between the observed and the expected number of events (from logistic regression models); rankings were compared using Spearman rank correlations. SETTING: Hospitals performing coronary artery bypass graft (CABG) surgery in the 1991 and 1992 MedisGroups National Comparative Data Bases. PATIENTS AND DATA SETS: Record abstraction data for 16,673 patients who underwent CABG procedures at 57 hospitals, linked with data from the 1991 American Hospital Association Annual Survey. RESULTS: After adjusting for patient admission severity of illness, there were low correlations between hospital rankings based on death or failure to rescue and those rankings based on complication (death vs complication, r = 0.07, P = .58; failure to rescue vs complication, r = -0.22, P = .11). In addition, many hospital characteristics that are generally associated with a higher quality of care were associated with higher complication rates but with expected or lower-than-expected mortality rates. CONCLUSIONS: Hospital rankings based on complication rates provide different information than those based on mortality rates. Until more is known about these differences, complication rates should not be used to judge hospital quality of care in CABG surgery.

Coronary Artery Bypass↗
PubMed1995

Morphine-augmented hepatobiliary scintigraphy: a meta-analysis.

The aim of this study was to compare the sensitivity and specificity of morphine-augmented hepatobiliary scintigraphy (MA-HBS) with that of conventional hepatobiliary scintigraphy (C-HBS) for acute cholecystitis. The results of most MA-HBS studies cannot be compared with C-HBS estimates, since articles describing C-HBS often include non-candidates for MA-HBS. However, using meta-analytic techniques to combine data from eligible studies (4 for C-HBS and 5 for MA-HBS), the specificity of MA-HBS (0.84; 95% CI = 0.75-0.94) was significantly greater (P = 0.008) than that of C-HBS (0.68; 95% CI = 0.61-0.75); there were no differences in sensitivity (MA-HBS; 0.96, 95% CI = 0.92-0.99; C-HBS: 0.97, 95% CI = 0.97-0.99).

Acute Disease↗
PubMed1994

A case-mix classification system for medical rehabilitation.

Dissatisfaction with Medicare's current system of paying for rehabilitation care has led to proposals for a rehabilitation prospective payment system, but first a classification system for rehabilitation patients must be created. Data for 36,980 patients admitted to and discharged from 125 rehabilitation facilities between January 1, 1990, and April 19, 1991, were provided by the Uniform Data System for Medical Rehabilitation. Classification rules were formed using clinical judgment and a recursive partitioning algorithm. The Functional Independence Measure version of the Function Related Groups (FIM-FRGs) uses four predictor variables: diagnosis leading to disability, admission scores for motor and cognitive functional status subscales as measured by the Functional Independence Measure, and patient age. The system contains 53 FRGs and explains 31.3% of the variance in the natural logarithm length of stay for patients in a validation sample. The FIM-FRG classification system is conceptually simple and stable when tested on a validation sample. The classification system contains a manageable number of groups, and may represent a solution to the problem of classifying medical rehabilitation patients for payment, facility planning, and research on the outcomes, quality, and cost of rehabilitation.

Activities of Daily Living↗
PubMed1994

Four methods for characterizing disability in the formation of function related groups.

The Functional Independence Measure-Function Related Groups (FIM-FRGs) were developed to classify medical rehabilitation inpatients into homogeneous groups based on length of stay (LOS). Patients are first grouped into clinically relevant rehabilitation impairment categories, then by functional status, as expressed by the FIM, and in certain cases by patient age. The statistical approach used to form the final groupings was a recursive partitioning algorithm applied to the FIM scores and patient age within impairment category. This analysis compares four FIM-FRG classification schemes developed from four scale sets that combine FIM items differently: (1) use of the 18 FIM items as separate variables, (2) the combination of FIM items into six clinical subscales, (3) the combination of the six clinical subscales into motor and cognitive subscales, and (4) the combination of all FIM items into a single scale. The FIM-FRG schemes explain similar amounts of variance in the logarithm of LOS and contain approximately equal numbers of FRGs. The motor and cognitive subscale scheme is recommended for use in payment, however, this scheme and the other schemes have additional uses. Each FRG scheme provides different insight into the clinical relationship between disability and LOS.

Activities of Daily Living↗
PubMed1993

Variation in physicians' decision-making thresholds in management of a sexually transmitted disease.

OBJECTIVE: To gain insight into the variation in physicians' clinical decisions and further understand the factors that influence physicians' thresholds for testing and treating. DESIGN: Written clinical scenarios were mailed to two groups of physicians who were asked to provide probability estimates of syphilis, how these estimates might change with new information, and when a diagnostic test would be ordered or treatment begun. A model was then used to calculate the probabilities at which physicians ordered tests or initiated treatment. PARTICIPANTS: Group 1 comprised 126 board-certified internists from metropolitan Philadelphia responding from a sample of 360 such physicians randomly selected from a directory. Group 2 consisted of 31 experts in sexually transmitted disease responding from a sample of 50 experts selected by the authors. MEASUREMENTS AND MAIN RESULTS: Experts were willing to obtain a serologic screening test at a lower likelihood of syphilis (0.013%) than were internists (0.034%), and they were willing to obtain a lumbar puncture at a lower likelihood of neurosyphilis (0.165%) than were internists (0.393%). The difference in the groups' thresholds to begin neurosyphilis treatment was not significant. A multivariate model showed that group differences were created by individual characteristics (years in practice, subspecialty board certification, and full-time nonacademic practice) that were associated with higher thresholds for serologic screening. CONCLUSIONS: There are differences in the diagnostic testing practices for syphilis between national experts and internists. Although status in one of these groups alone did not predict the threshold for obtaining syphilis tests, certain individual characteristics were predictive. Examination of physician characteristics helps to explain the variation observed in their practice patterns, and determination of physicians' thresholds aids in analyzing these variations.

Clinical Laboratory Techniques↗
PubMed1993

Applying quantitative methods to the prediction of full functional recovery in adult rehabilitation patients.

The purpose of this project was to construct a pilot prognostic index for use in research and clinical practice that would predict functional recovery in adult rehabilitation patients at discharge using clinical characteristics at admission to rehabilitation (independent performance of seven activities of daily living and three basic mobility tasks). We constructed the index from retrospectively collected data on 1,020 adult rehabilitation patients who underwent rehabilitation between 1980 and 1986. Adjusting for patient characteristics, the odds of recovering independent function doubled for each ten-point increase in the 100-point functional status score measured at admission to rehabilitation (odds ratio = 2.1, 95% confidence interval [CI] = 1.9 to 2.4). The odds increased by a factor of 1.9 (95% CI = 1.1 to 3.2) in patients with an impairment considered more functionally reversible and by a factor of 2.1 (95% CI = 1.3 to 3.4) in patients transferred from an acute hospital. The odds of functional recovery decreased in those over 79 years of age, in those who were unemployed before hospitalization, and as the number of comorbid conditions increased. Our findings demonstrate the feasibility of developing quantitative estimates of functional prognosis. Prior to use, the index should be externally validated in different rehabilitation facilities.

Activities of Daily Living↗
PubMed1992

Appearance of Ph negative recipient clones in chronic myeloid leukemia patients following bone marrow transplantation.

Seven patients were studied following bone marrow transplantation for chronic myeloid leukemia. Cytogenetic heteromorphisms were used to determine the origin of cells present post-BMT. Differences were found between results from blood and bone marrow samples, and between karyotype and interphase Y-body studies on the same samples. Philadelphia negative (Ph-) hematopoietic chimerism was found in 6 of 7 patients, all of whom had been Ph+ before BMT. One patient also demonstrated hematopoietic chimerism with Ph+ recipient cells following clinical evidence of relapse. In two patients who had received T-cell depleted grafts, cytogenetically rearranged Ph- clones of recipient cells were prominent in PHA-stimulated blood. In one case two clones had appeared only 1 month post BMT. The appearance of these clones so soon after transplant suggests very rapid clonal expansion, or that they were already present pre-BMT but at levels too low to have been detected. In the second patient, clones were not observed until more than 12 months post-BMT, after which four were found. These collectively expanded to occupy an increasing proportion of the total cells. These two patients with clones both remain in good health 44 and 51 months post-BMT. Further studies are needed to determine the true frequency and the significance of such findings.

Adult↗
PubMed1992

Hospital and patient characteristics associated with death after surgery. A study of adverse occurrence and failure to rescue.

We asked if the factors that predict overall mortality following two common surgical procedures are different from those that predict adverse occurrences (complications) during the hospitalization or death after an adverse occurrence, which we refer to as "failure to rescue." We examined 5,972 Medicare patients undergoing elective cholecystectomy or transurethral prostatectomy using three outcome measures: 1) the death rate (number of deaths/number of patients); 2) the adverse occurrence rate (number of patients who developed an adverse occurrence/number of patients); and 3) the failure rate (number of deaths in patients who developed an adverse occurrence/number of patients with an adverse occurrence). The death rate was associated with both hospital and patient characteristics. The adverse occurrence rate was associated primarily with patient characteristics. In contrast, failure to rescue was associated more with hospital characteristics, and was less influenced by patient admission severity of illness as measured by the MedisGroups score. We concluded that factors associated with hospital failure to rescue are different from factors associated with adverse occurrences or death. Understanding the reasons behind variation in mortality rates across hospitals should improve our ability to use mortality statistics to help hospitals upgrade the quality of care.

Age Factors↗
PubMed1991

Gene amplification accompanied by the loss of a chromosome containing the native allele and the appearance of the amplified DNA at a new chromosomal location.

The organization of amplified DNA in mammalian cells in the form of inverted repeats rather than tandem repeats was first observed and studied in the 3B rat cell line. The structure and chromosomal location of the amplified inverted duplications in this cell line have been further analyzed by cloning, long-range mapping, and fluorescence in situ hybridization. The amplification unit is at least 450 kilobases in size and all of the amplicons are located in a single chromosomal location of approximately 10 or 11 megabases. No heterogeneity in either size or molecular structure is detected between the 3B amplicons, indicating that the 20- to 40-fold amplification occurred in a single event and not through a series of events, which would result in heterogeneity among the amplicons. Thus the amplification in 3B cells may reflect more closely the situation seen in tumors containing amplified oncogenes/protooncogenes than the amplifications present in cell lines after multiple selections with cytotoxic drugs. The progenitor Rat-2 cell line contains three alleles of the region of DNA that is amplified in 3B cells; two are located on the two normal homologues of rat chromosome 2 and the third is at the equivalent position on a marker chromosome, der(3)t(2;3). 3B cells contain only one of the two normal homologues of chromosome 2 in addition to chromosome der(3)t(2;3). All of the amplified DNA is located on a new marker chromosome, M2, whose amplified DNA region does not resemble chromosome 2. These results are consistent with the amplification model proposed by Passananti et al. [Passananti, C., Davies, B., Ford, M. & Fried, M. (1987) EMBO J. 6, 1697-1703], in which the excision from a chromosome of the DNA to be amplified results in the loss of rearrangement of that chromosome. In this model the excised DNA can be amplified extrachromosomally during a single S phase before becoming stabilized by integration into a chromosome, probably at a different location to that of its unamplified allele.

Alleles↗
PubMed1991

Differences in mortality from coronary artery bypass graft surgery at five teaching hospitals.

OBJECTIVE: To measure hospital- and surgeon-specific mortality rates for patients with coronary artery bypass graft (CABG) surgery and to examine possible reasons for any differences. DESIGN: Cohort study using hospital discharge abstracts and itemized bills. SETTING: Five major teaching hospitals in Philadelphia, Pa. PATIENTS: Consecutive sample of all 4613 patients over a 30-month period. MAIN OUTCOME MEASURE: In hospital mortality rates. RESULTS: We observed differences in hospital mortality rates for patients who underwent coronary artery catheterization and CABG surgery during the same admission (diagnosis related group 106) but not for patients who underwent only CABG surgery during the admission (diagnosis related group 107). There were threefold differences in surgeon-specific mortality rates. The hospital mortality rates for coronary artery catheterization and CABG surgery during the same admission changed during the study and coincided with moves of surgeons among study hospitals. Our measures of illness severity did identify patients who were more likely to die, but differences in severity of illness did not explain differences in hospital- or surgeon-specific mortality rates. Patient mortality rates were not associated with the volume of procedures performed by individual surgeons. We found inconclusive evidence for an association with surgeons' clinical skills, and to a lesser extent, with the hospital's volume of procedures and the hospital's organization and staffing. A greater intensity of hospital services was not necessary for a lower mortality rate. CONCLUSIONS: We conclude that studies of CABG mortality should examine mortality rates by diagnosis related group, collect data from more than 1 year, examine associations with surgeons' clinical skills, include information on hospital organization and staffing, and cautiously explore more efficient ways of providing care.

Age Factors↗
PubMed1991

Molecular cloning and analysis of the fragile X region in man.

The fragile X syndrome (FraX), the most common inherited form of mental retardation, has been located to Xq27.3. As a step in the molecular analysis of this mutation, we have cloned a contiguous 1.8 Mb region containing the entire fragile X region in YAC and cosmid clones. The cloned area defines a region of 50 kb containing a CpG island, found to be selectively methylated in patients expressing the fragile X phenotype. In this 50kb area we have localised the breakpoints of four somatic cell hybrids selected to break at the position of the fragile site. Fluorescence in-situ hybridisation of cosmids flanking this area shows that the breakpoints, the CpG island and the fragile site coincide.

Chromosomes, Fungal↗
PubMed1991

Fine mapping of probes in the adenomatous polyposis coli region of chromosome 5 by in situ hybridization.

The gene for adenomatous polyposis coli has been localized to 5q21-22. We have mapped six probes from this region using isotopic or nonisotopic in situ hybridization. Using tritium-labeled probes we localized II227 (D5S37) to 5q14-15 and ECB27 (D5S98) to 5q21. Following hybridization with biotin-labeled probes, the positions of signals along the chromosomes were measured as fractional length relative to the length of the chromosome arm from centromere to qter (FLcen-qter). Ninety-five percent confidence limits, compared with standard karyotypes, provided the corresponding band localization. By this method we localized Cllpll (D5S71) to FLcen-qter 0.407-0.452 (5q21.1-21.3), ECB27 to FLcen-qter 0.426-0.473 (5q21.3), YN5.48 (D5S81) to FLcen-qter 0.459-0.496 (5q21.3-22.2), and ECB134 (D5S97) to FLcen-qter 0.509-0.533 (5q22.3-23.1). ECB220 had three sites of hybridization, a major site at FLcen-qter 0.460-0.492 (5q21.3-22.1) and minor sites at FLcen-qter 0.299-0.339 (5q14.3-15) and FLcen-qter 0.629-0.691 (5q23.3-31.2). We have shown that the chromosome 5 breakpoint in a t(5;15) translocation from a patient with Gardner's syndrome (GM03314) is between Cllpll and ECB27. Linkage data are presented suggesting that ECB27 is located on the same side of the APC locus as II227. These and published results including data on several constitutional deletions (M, SD, and brothers PW and ND) give a probable order of [cen] - [II227, proximal SD breakpoint] - [Cllpll] - [proximal PW/ND, M breakpoint(s), GM03314 breakpoint] - [ECB27] - [APC] - [YN5.48] - [distal PW/ND breakpoint] - [ECB134] - [distal M breakpoint] - [qter]. The major site of ECB220 appears to be between ECB27 and the distal PW/ND breakpoint; the distal SD breakpoint is distal to YN5.48.

Adenomatous Polyposis Coli↗
PubMed1990

Expansion of the medical intensive care unit: clinical consequences in a large urban hospital.

We examined how a permanent expansion of the medical ICU (MICU) affected resource utilization and severity of illness for intensive care admissions within a 700-bed urban teaching hospital. On our 162-bed medical service, construction of a separate cardiac care unit and the expansion of the MICU increased the number of core intensive care beds by 100%. We prospectively analyzed noncardiology MICU admissions 2 months before, immediately after, and 4 months after MICU expansion. Although the volume of MICU patients increased by 51% after MICU expansion, the severity of illness as determined by the Acute Physiology and Chronic Health Evaluation (APACHE II) score and types of admission diagnoses remained the same. Moreover, there was no change in MICU occupancy and length of stay, hospital or MICU mortality, or MICU readmission rate. The increased MICU patient volume came from the ED, transfers from other hospitals, and from other ICUs within our hospital. In contrast, the volume and severity of illness of MICU transfers from the inpatient medical floor service were constant in all time periods. These results suggest that, while MICU expansion increased patient volume, physician utilization of the MICU resources was unchanged. Our physicians used high-intensity ICU beds in a consistent fashion in response to external factors, such as ED activity, intramural ICU transfers, and referrals from other hospitals.

Bed Occupancy↗
PubMed1990

Predicting inpatient rehabilitation length of stay.

Using standardized forms and predefined criteria, information was collected on all 1,238 patients admitted to the inpatient rehabilitation facility at our university hospital between August 1, 1980 and December 30, 1986. Data from 96% of these patients were used retrospectively to create a mathematic model, based on multiple linear regression, that predicts the patient's total rehabilitation length of stay (LOS). The model requires only information about the patient's admitting diagnosis, referral source, admission functional status, and date of admission. The model compared favorably with prospective estimates of LOS made independently by attending physicians at admission to rehabilitation. We conclude that such models could be used to facilitate management of rehabilitation units, forecast patient census, schedule unit personnel, set interim goals for LOS, and facilitate discharge planning. The delivery of rehabilitation services, like the delivery of other medical services, can be defined in part by objective, measurable patient characteristics.

Adult↗