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H Krakauer

Publications and source records attributed to H Krakauer.

At least 37 records · Page 2Linked to original sources
PubMed1994

Serum levels of alpha and gamma interferons in hemorrhagic fever with renal syndrome.

Hemorrhagic fever with renal syndrome is an acute viral disease caused by Hantavirus. On the basis of clinical observation, the illness is divided into five sequential stages: febrile, hypotensive, oliguric, diuretic, and convalescent. Because interferons can be induced by viruses, and because their stimulating effects on immune cells can alter the course of viral infections, we examined the presence of alpha interferon (IFN-alpha) and gamma interferon (IFN-gamma) in 276 serum samples collected from 110 patients during the Korean Conflict. We tested these sera for IFN-alpha by bioassay with bovine kidney MDBK cells, and for IFN-gamma by a sandwich ELISA with antibodies specific for human IFN-gamma. We found variable, but persistently elevated levels of IFN-gamma throughout the various phases of the disease, which suggested persistent immune activation through convalescence. Moderate levels of IFN-alpha were found in all stages of infection.

Animals↗
PubMed1994

Severity of illness measures derived from the Uniform Clinical Data Set (UCDSS).

The Health Care Financing Administration (HCFA) plans to use the Uniform Clinical Data Set System (UCDSS) to collect data on hospitalized Medicare patients. This study examined the value of UCDSS data for creating severity of illness measures. UCDSS data were obtained from a study hospital and from a national data set for patients with pneumonia (n = 528) and stroke (n = 565). Models to predict length of stay or an adverse event were derived for each condition using HCFA claims data alone, UCDSS data alone, and UCDSS data supplemented with additional information also abstracted from charts. The models were derived from one set of patients and validated on another. The R2 for predicting length of stay in the validation data for the UCDSS model was 0.29 for pneumonia and 0.19 for stroke compared to R2 values from the claims model of 0.09 for stroke and 0.06 for pneumonia. UCDSS models also were better than claims models for predicting adverse events. The best UCDSS models included International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes and other information requiring clinical judgment, and were improved by adding more information on patient functional status. Some findings were more strongly associated with outcome for the study hospital than for the national data. These results suggest that UCDSS models will predict outcome much better than the claims based models currently used by HCFA for the analysis of hospitalization-related mortality; more functional status information should be added to UCDSS; and despite an extensive objective database, the most predictive UCDSS models require clinician-assigned diagnostic codes.

Aged↗
PubMed1994

The relationship of hospital ownership and teaching status to 30- and 180-day adjusted mortality rates.

Hospital characteristics have been shown previously to be associated with variations in the probability of death within 30 days of admission. In the current study, the authors extend the examination of the relationship between hospital type to both short-term and long-term adjusted mortality. Observed and predicted 1988 hospital mortality rates were obtained from the Health Care Financing Administration (HCFA). A total of 3,782 acute care hospitals were divided into six mutually exclusive groups on the basis of their status as osteopathic, private for-profit, public teaching, public nonteaching, private teaching, and private nonteaching hospitals. After adjusting for the HCFA predicted mortality, Medicaid admissions, and emergency visits, 30-day and 30-to-180-day patient mortality rates were compared for these hospital types. Separate comparisons also were performed after stratifying hospitals into three groups defined by community size. The risk-adjusted 30-day mortality per 1,000 patients was 91.5, ranging from 85.4 for private teaching hospitals to 95.3 for nonteaching public hospitals, and 97.4 for osteopathic hospitals. The adjusted 30-to-180-day mortality was 84.7, ranging from 82.6 for nonteaching public hospitals to 87.4 and 88.2, respectively for public teaching and osteopathic hospitals. Differences among hospital types were minimal for small communities and increased with community size. In the large communities, the types of hospitals with high 30-day mortality also had higher mortality after 30 days. There was a strong association of hospital type with adjusted 30-day mortality, which should depend on the quality of hospital care, and a much weaker association with post-30-day mortality, which may be more dependent on patient risk. There was no evidence that types of hospitals with low 30-day mortality were postponing rather than preventing mortality.

Acute Disease↗
PubMed1994

The role of risk adjustment in the assessment of medical practices in managed care.

As reliance on managed care to control the cost of health care in the United States grows, clinicians and managers will come under increasing competitive and regulatory pressure to identify and adopt the strategies and interventions that are not only most economical but that also best improve the health of the populations served. Explicit criteria will be embodied in public performance reports. Clearly, in comparing the performance of firms and of individuals who provide health care, disparities in risk among the patient populations will have to be compensated.

Actuarial Analysis↗
PubMed1993

An analysis of liver transplant experience from 37 transplant centers as reported to Medicare.

Analysis of 5180 liver transplant cases from 37 liver transplant centers in the United States (1982-1991) shows an overall one-year survival rate of 79.4 +/- 0.6% and a five-year survival rate of 69.2 +/- 0.9%. There was marked improvement in the one-year survival rate after liver transplantation from 36.0 +/- 9.6% in 1982 to 85.0 +/- 1.8% in 1991. One-year survival rates after liver transplantation for postnecrotic cirrhosis, primary biliary cirrhosis, alcoholic cirrhosis, primary sclerosing cholangitis, alpha-1-antitrypsin deficiency, and Wilson's disease ranged from 78.4 +/- 1.0% to 84.2 +/- 1.5% and five-year survival rates from 68.6 +/- 3.8% to 79.2 +/- 5.3%. Survival rates after liver transplantation for hemochromatosis were poor--a one-year survival rate of 53.8 +/- 6.8% and a five year survival rate of 43.1 +/- 11%. One- and five-year survival rates for the 0-13 years age group were 74.6 +/- 2.8% and 66.7 +/- 3.4%; for the 14-37 years age group, 83.3 +/- 1.2% and 73.8 +/- 1.8%; for the 38-54 years age group, 79.6 +/- 0.8% and 69.7 +/- 1.3%; for the 55-63 years age group, 76.0 +/- 1.4% and 63.0 +/- 3.1%; and for the 64-77 years age group, 76.5 +/- 3.0% and 65.4 +/- 4.6%.

Adolescent↗
PubMed1993

Predicting the course of disease.

The ability to predict the course of disease and the effect of interventions is critical to effective medical practice and health care management. In this analysis, we sought to test whether available clinical data and analytic methodologies can be used to accurately predict the time course of the probability of death after hospital admission and the probability of readmission following discharge for patients with acute myocardial infarction or pulmonary disease. We grouped patients by selected physiologic characteristics and made time-to-event predictions using multiple regression models. These predictions were compared with observed probabilities calculated using the actuarial or life-table method. Predictions made with the Bailey-Makeham model generally replicated observed experience. They accurately accounted for substantial differences in the patterns of death and readmission and accurately delineated the effects of therapies, after adjustment for patient risk. These results were validated by analyses of resampled populations that differed in case mix from the source population. We believe that using such models to project the course of disease and the effects of treatment on that course in defined classes of patients should facilitate the development of practice guidelines for patient care and the management of health care resources.

Disease↗
PubMed1993

Data about mortality.

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Data Interpretation, Statistical↗
PubMed1992

Mortality after coronary angioplasty and coronary artery bypass surgery (the national Medicare experience).

Mortality rates for Medicare patients who underwent coronary artery bypass surgery were compared with those who had angioplasty or angioplasty and bypass surgery. Two data sets were used for this study: The first contained information on demographic factors, co-morbidities and subsequent mortality on all 96,666 Medicare patients who had bypass surgery or angioplasty in 1985; the second contained additional detailed clinical data collected using the MedisGroups method on a random sample of 2,931 revascularization patients from 6 states. From the national data set 30-day and 1-year mortality rates were 3.8 and 8.2% for 25,423 angioplasty patients and 6.4 and 11.8% for 71,243 bypass surgery patients (p less than 0.001 for both time periods). Mortality rates for the MedisGroups data were 4.4 and 8.5% for the angioplasty patients and 6.5 and 11.9% for the bypass surgery patients. After eliminating patients admitted with a myocardial infarction, mortality rates were 1.9 and 6.0% for 632 angioplasty patients and 5.1 and 10.8% for 1,730 bypass surgery patients. The risk-adjusted relative risk of mortality for bypass surgery versus angioplasty was 1.72 (p = 0.001) for all patients, 2.15 (p less than 0.001) for low-risk patients and 0.90 (p = not significant) for high-risk patients. Results suggest that low-risk patients have better survival with angioplasty because of lower short-term mortality.

Angioplasty, Balloon, Coronary↗
PubMed1992

Racial and community factors influencing coronary artery bypass graft surgery rates for all 1986 Medicare patients.

OBJECTIVE: This study examines the differences in the rates of coronary artery bypass grafting (CABG) between white and black Medicare patients. DESIGN: This is a cross-sectional study with data from the 1986 Health Care Financing Administration hospital claims records on all Medicare patients, the 1988 update of the Bureau of Health Professions area resource file, and the 1985 Census Bureau's county population estimates file. SETTING: Data are from all Medicare patients in the United States in 1986. MAIN OUTCOME MEASURES: Sex- and age-adjusted CABG rates for whites and blacks over the age of 65 years were computed for each of 50 states and 305 Standard Metropolitan Statistical Areas (SMSAs). RESULTS: Nationally the CABG rate was 27.1 per 10,000 for whites (40.4 for white men and 16.2 for white women), but only 7.6 for blacks (9.3 for black men and 6.4 for black women). Racial differences were greater in the Southeast, particularly in nonmetropolitan areas, than in other regions. Neither white nor black SMSA rates were associated with the rate of admission for acute myocardial infarction (an indication of the amount of coronary artery disease). White rates, but not black rates, were associated with the number of thoracic surgeons per 100,000 people. CONCLUSIONS: For patients insured by Medicare, race is strongly associated with CABG rates, and this association is greater for men than for women and greater in the Southeast than in other parts of the country. Physician supply may relate to the CABG rates for whites.

Black or African American↗
PubMed1992

Analysis of the heterogeneity of the biological responses to native and mutant human interleukin-6.

The structure-function relationships of the biological activities of mutant varieties of the pleiotropic cytokine interleukin-6 (human) were measured by three assays: induction of immunoglobulin M (IgM) secretion from an Epstein-Barr virus-transformed human B cell line and induction of fibrinogen secretion from either a human hepatoma cell line or a rat hepatoma cell line. The biological effects of the cytokine were characterized by three parameters as determined by a novel analysis: effectiveness (the maximal response attainable), efficiency (the concentration yielding a half-maximal response), and complexity (a measure of heterogeneity and feedback control). Substitution of serine for cysteine was associated with a reduction in the effectiveness of interleukin-6 in both fibrinogen secretion assays. In the assay with human hepatoma cells, there was also a profound reduction in efficiency. Serine substitution in the human IgM synthesis assay appears mainly to reduce the efficiency. Deletion of amino acids 4 to 23 increased the efficiency in the rat hepatoma assay. The complexity parameter suggests the presence of multiple receptor classes or negative feedback in all three assays. Use of the proposed sequential approach to the analysis of dose-response relations in bioassays provides a more useful quantitative assessment of activities as well as more insight into the complexity of the reactions.

Animals↗
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↗
PubMed1992

Evaluation of the HCFA model for the analysis of mortality following hospitalization.

From 1987 through 1990, the Health Care Financing Administration (HCFA) evaluated variations in the mortality rates experienced by patients admitted to hospitals participating in the Medicare program. This study was conducted to evaluate the adequacy of the model used for that purpose. Detailed clinical data were gathered on 42,773 patients admitted to 84 statistically selected hospitals. The effect of risk adjustment using the HCFA model, which is based on claims data, was compared to a risk-adjustment model based on physiologic and clinical data. Models that include claims data were markedly superior to those containing only demographic characteristics in predicting the probability of patient death, and the addition of clinical data resulted in further improvement. The correlation of ranks of hospitals based on a model that uses only the claims data and on one that uses, in addition, clinical data, was .91. As a screen for the identification of "high (mortality) outlier" hospitals, the claims model had moderate sensitivity (81 percent) and specificity (79 percent), a high negative predictive value (90 percent), and a low positive predictive value (64 percent) when compared to the clinical model. The two mortality models gave similar results when used to determine which structural characteristics of hospitals were related to mortality rates: hospitals with a higher proportion of registered nurses or board-certified physician specialists, or with a greater level of access to high-technology equipment had lower risk-adjusted mortality rates. These data suggest that the current claims-based risk-adjustment procedure may satisfactorily be used to characterize variations in mortality rates associated with hospitalization. The procedure could also be used as a basis for further epidemiological analyses of factors that affect the probability of patient death. However, it does not positively identify outlier hospitals as providers of problematic care.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed1991

Undertreatment of glaucoma among black Americans.

BACKGROUND: Cross-sectional studies and those using national data sets estimate that glaucoma-related blindness is between six and eight times more common among black Americans than among whites. Community-based studies have found that glaucoma is four to six times more prevalent among blacks. It is not known why blacks with glaucoma are more likely to become blind than whites with glaucoma. METHODS: To investigate the possibility that undertreatment of glaucoma is an important factor contributing to this higher rate of blindness, we studied the population-based rates of incisional and laser surgery for open-angle glaucoma among blacks and whites in a 5 percent random sample of Medicare claims for 1986 through 1988. RESULTS: For all U.S. census divisions combined, the rate of surgery for glaucoma among black Medicare beneficiaries was 2.2 times higher than the rate among white beneficiaries (95 percent confidence interval, 2.1 to 2.3). We calculated an expected rate of treatment among blacks on the basis of the rate of treatment among whites and the assumption that glaucoma is four times more prevalent among blacks--a conservative estimate. The observed rate of glaucoma surgery among blacks was 45 percent lower than the expected rate we calculated, which may in part account for the excess rate of blindness among blacks. The magnitude of this difference in treatment rates varied from 29 percent in the Middle Atlantic states to 50 percent in the South Atlantic states. CONCLUSIONS: Older black Americans are not receiving potentially sight-saving care for open-angle glaucoma at the same rate as older white Americans.

Black or African American↗