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Biomedical subjects

R C Bailey

Publications and source records attributed to R C Bailey.

At least 55 records · Page 3Linked to original sources
PubMed1991

Using clinical variables to estimate the risk of patient mortality.

The Health Care Financing Administration (HCFA) uses information from hospital bills, such as age, sex, and diagnoses, to estimate statistical models for the probability, or risk, of death during and after hospital stays. The average risk estimates (expected death rates) are compared with the actual death rates to identify potentially poor quality of care. However, the methods have been criticized as inadequate and an often cited reason is the failure to incorporate risk factors for mortality that are known from clinical research. This hypothesis was tested using a stratified, random sample of 41,963 Medicare patients in 84 hospitals. Many clinical measurements were abstracted for testing as possible risk factors, and a few (26) were identified as useful predictors of death using logistic regression. The estimated regressions accounted for 39% of the variation in mortality, a standard severity classification accounted for 29%, and a relatively simple classification of patients into 17 groups, based on diagnoses, accounted for 17%. The logistic regressions yielded more accurate estimated mortality rates than the severity classification, which in turn was superior to the estimation methods used by HCFA. The HCFA methods were found to be biased in identifying outlier hospitals and this bias can be removed or ameliorated by using clinical risk factors to predict mortality. It is possible to estimate the risk of death more accurately using clinical risk factors and to measure the quality of care.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed1989

Hospital characteristics and mortality rates.

The Health Care Financing Administration (HCFA) publishes hospital mortality rates each year. We undertook a study to identify characteristics of hospitals associated with variations in these rates. To do so, we obtained data on 3100 hospitals from the 1986 HCFA mortality study and the American Hospital Association's 1986 annual survey of hospitals. The mortality rates were adjusted for each hospital's case mix and other characteristics of its patients. The mortality rate for all hospitalizations was 116 per 1000 patients. Adjusted mortality rates were significantly higher for for-profit hospitals (121 per 1000) and public hospitals (120 per 1000) than for private not-for-profit hospitals (114 per 1000; P less than 0.0001 for both comparisons). Osteopathic hospitals also had an adjusted mortality rate that was significantly higher than average (129 per 1000; P less than 0.0001). Private teaching hospitals had a significantly lower adjusted mortality rate (108 per 1000) than private nonteaching hospitals (116 per 1000; P less than 0.0001). Adjusted mortality rates were also compared for hospitals in the upper and lower fourths of the sample in terms of certain hospital characteristics. The mortality rates were 112 and 121 per 1000 for the hospitals in the upper and lower fourths, respectively, in terms of the percentage of physicians who were board-certified specialists (P less than 0.0001), 112 and 120 per 1000 for occupancy rate (P less than 0.0001), 113 and 120 per 1000 for payroll expenses per hospital bed (P less than 0.0001), and 113 and 119 per 1000 for the percentage of nurses who were registered (P less than 0.0001).

Centers for Medicare and Medicaid Services, U.S.↗
PubMed1989

Nutritional status of Efe pygmies and Lese horticulturists.

We assessed the nutritional status of 90 pygmies (Efe) and 211 members of a neighboring horticultural Lese in the Ituri forest in northeast Zaire. Clinical signs of iron and iodine deficiency were highly prevalent, but the frequency of these and other clinical signs of nutritional deficiency did not differ between the two groups. Infectious diseases such as yaws, cellulitis, and filiariasis were common. Absolute heights and weights of both Efe males and females aged 2-18 years were less than the 5th percentile of the National Center for Health Statistics standards. Weights for height of both groups were within the normal range. Weights and heights, expressed as percentages of the 50th percentile for age and sex, were significantly lower (P less than .001) in Efe males and females than among Lese males and females, but weights for height did not differ significantly. Z-Scores of height and weight were also significantly lower in Efe males and females than among their Lese counterparts. The differences in weight and height, expressed either as a percentage of the 50th percentile or as Z-scores, were most apparent in older adolescents and persisted among adults. The normal weight for height among both populations indicated that acute undernutrition did not exist at the time of the survey. Despite comparable levels of adult fatness, measured by triceps skinfold thickness, heights of Efe males and females were lower than those of the Lese. These observations support the hypothesis that genetic differences account for the short stature of the Ituri pygmy. However, because the environments shared by the two groups are not identical and because other practices differ, nutritional effects cannot be excluded.

Adolescent↗
PubMed1985

Effects of acidification on metal availability to aquatic biota, with special reference to filamentous algae.

A survey of 34 shield lakes in Ontario and Quebec, pH 4.4 to 7.1, was made to evaluate which metals should be considered of concern as a risk to aquatic biota or consumers when lakes are acid stressed. A set of predictions, concerning the mobilization by man, the mobility, the chemical speciation, and the toxicity or bioaccumulation of metals in acid-stressed waters, were used as a basis for designing the study and organizing the results. Attached algae were used as biomonitors to assess metal bioavailability. The study concluded that zinc, lead, aluminum, and mercury were of concern in acid-stressed lakes, while the situation for manganese was unresolved, and cadmium was not studied. Nickel and copper were of concern only when a point source was involved. The study also concluded that the attached algal community had some value as a biomonitor, for metals in acid-stressed as well as metal-polluted surface waters.

Acids↗
PubMed1983

Assessment of prognostic factors and projection of outcomes in renal transplantation.

Analysis of data on renal transplantation collected in two large multicenter observational studies resulted in the concordant identification of five factors that correlated highly and at a substantial level of statistical significance with the outcome of unrelated cadaveric donor transplantation (i.e., they were associated with differences in one-year graft survivals of 0.07-0.21 and P values less than 0.05). These factors were: blood transfusions prior to the transplant, race of the recipient (white or black), prior failure in transplantation, level of sensitization to lymphocyte alloantigens, and diabetes as the cause of end-stage renal failure. Multivariate analysis with a mathematical survival model confirmed the importance and independence of these prognostic factors. Matching of HLA antigens appeared to be beneficial in both studies, but failed to attain high statistical significance in one. Systematic differences in the use of pretransplant splenectomy and, probably, in the nature of the antilymphocyte serum or globulin led to discordance in assessment of the importance of these factors in the two studies. Although advanced age (greater than 45 years) of the recipient was associated with reduced graft survival in both studies, analysis by means of the model failed to detect a significant correlation between the recipient's age and the outcome in one of the studies because the relation was not monotonic. In an illustration of their utility in the detailed assessment of performance, the prognostic factors were found to substantially account for the markedly superior results at one center and partly for lower graft survivals at another. These prognostic factors may be used to predict probable outcomes for populations and for individual patients subjected to particular arrays of conditioning strategies.

Analysis of Variance↗
PubMed1981

Long-term d-amphetamine in rats: lack of change in post-synaptic dopamine receptor sensitivity.

Treatment of rats with d-amphetamine (5 mg/kg) once daily for 25 days did not change locomotor responses, on day 7 of withdrawal, to dopamine (DA) or d-amphetamine into the nucleus accumbens. Nor was there a change in 3H-spiperone binding of caudate nucleus membranes. There was no effect of treatment on the locomotor response of rats to 1.0, 1.5 or 2.0 mg/kg d-amphetamine IP. However, d-amphetamine-treated rats were significantly less sensitive to 0.5 mg d-amphetamine. Although 1, 2 or 3 mg/kg apomorphine produced in same degree of stereotypy in both treatment groups, there was a significant difference in the response of the two groups to 0.5 mg apomorphine, d-amphetamine-treated animals being less sensitive than vehicle-treated animals. No change was found in brain DA levels with or without synthesis inhibition. The present data do not support the hypothesis that chronic treatment of rats with d-amphetamine can produce supersensitive post-synaptic DA receptors.

Animals↗
PubMed1981

Comparison of bone graft materials. Part I. New bone formation with autografts and allografts determined by Strontium-85.

The purpose of this study was to obtain a direct comparison of the bone forming abilities of autogenous osseous coagulum, autogenous bone blend, freeze-dried bone allograft, and decalcified freeze-dried bone allograft. Defects were created in the calvaria of 35 guinea pigs. The graft materials were placed in porous nylon chambers and implanted into the defects. Empty nylon chambers served as the controls. Three days prior to sacrifice, each animal received an injection of 85Sr. The animals were killed in groups of five at 3, 7, 14, 21 28, 35, and 42 days. At sacrifice, a small section of ilium was removed from each animal. The samples were recovered, weighed, and the uptake of 85Sr into new bone determined. An osteogenic index was obtained by dividing cpm/mg for each sample by cpm/mg of ilium. It was concluded that in this model system decalcified freeze-dried bone allograft is a graft material of high osteogenic potential while autogenous bone blend and osseous coagulum were of less potential, and freeze-dried bone allograft even less.

Animals↗
PubMed1980

Dose-responses of guinea pigs to diazepam at recompression depths.

Dose-responses to diazepam were studied in guinea pigs at the recompression pressures used for the treatment of gas embolism and decompression sickness. The conditions and the doses were randomly assigned. Sufficient exposure to 6 ATA air, 3 ATA oxygen, or 1 ATA air was allowed in the hyperbaric chamber before diazepam was administered intravenously. Loss of righting reflex and its return were the end points for sleep and awakening, respectively. The data were analyzed with a mathematical model for dose-response and duration of effect. Results were: (1) in 1 ATA air, widely varying doses induced sleep of long duration; (2) in 6 ATA air, sleep was induced with small doses; and (3) in 3 ATA oxygen, sleep was induced with large doses. The duration of sleep under hyperbaric conditions was shorter than at sea level pressure. The null hypothesis, which assumed similar dose-responses and durations of sleep under these three conditions, was rejected. The dose and duration of diazepam's effect during recompression apparently depend on the pressure and the gas composition used.

Animals↗
PubMed1979

Ketamine and thiopental sleep responses in guinea pigs in hyperbaric helium-oxygen.

One-hundred twenty three guinea pigs, randomly divided into four groups, were exposed to the following normoxic environments: Group I, 1 atmosphere absolute (ATA) air; Group II, 1 ATA helium-oxygen (heliox); Group III, 20 ATA heliox; and Group IV, 31 ATA heliox. Each group was divided into five subgroups; each subgroup received a different and graduated intravenous dose of ketamine in one of these environments. An additional 172 guinea pigs were exposed either to 1 ATA air or 31 ATA heliox and given thiopental. The duration of sleep, determined by failure of the animals to right themselves, was then used to construct dose-response curves for the two drugs in the hyperbaric environments. Results demonstrated less pressure antagonism of anesthesia with ketamine than with thiopental. For both drugs, pressure not only increased the dose required to induce sleep but also decreased the duration of sleep, when it occurred, by as much as 50% compared to effects of the same doses at surface pressure.

Anesthesia↗
PubMed1977

Computations for a best match strategy for kidney transplantation.

In some cases success or failure of a proposed innovation in transplantation may be better judged if we consider the average survival time of the graft rather than the actuarial survival at a point in time. It is suggested that HLA matching may be an example of such a case and that the possible clinical benefits of modest improvements in matching may have been underestimated. Calculations are made that show that transplanting to the best match available in a pool of 100 patients might increase the expected graft survival time by more than 1 year.

Graft Survival↗
PubMed1977

A proposal for the analysis of kidney graft survival.

A survival analysis using a model provides numerous advantages over other approaches. The effectiveness of concomitant variables in describing the data can be evaluated whether the variables are continuous or dichotomized. We can evaluate the effectiveness of such variables in describing either short- or long-term components of the risk. The expected life span of the graft may be computed with the model and complements the insight obtained from the more commonly displayed survival curves.

Age Factors↗