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Biomedical subjects

R F Woolson

Publications and source records attributed to R F Woolson.

At least 73 records · Page 4Linked to original sources
PubMed1988

Hospital-acquired candidemia. The attributable mortality and excess length of stay.

Between 1977 and 1984, estimates of hospital-acquired bloodstream infections caused by Candida species increased in the United States from 0.5 to 1.5 per 10,000 admissions (National Nosocomial Infection Study data). We examined crude and attributable mortality rates and excess length of stay in 88 closely matched pairs of cases and controls with illnesses occurring between July 1983 and December 1986. The crude mortality rates for cases and controls were 57% and 19%, respectively; thus the attributable mortality rate was 38% with a 95% confidence interval of 26% to 49%. The risk ratio was 2.94 with a 95% confidence interval of 1.95 to 4.43. The median length of stay was 48 days for all cases and 40 days for all controls. An analysis of the length of stay for the 34 matched pairs that survived showed a median of 70 days for cases and 40 days for controls. Candida bloodstream infections represented 10% of all nosocomial bloodstream infections in the period studied at our University Hospital; they are associated with a significant medical and economic burden well above that expected of the underlying diseases alone.

Adolescent↗
PubMed1988

Statistics for hospital epidemiology. General design and analysis questions.

In this first article of the series, we have listed a number of issues for the design and analysis of epidemiologic studies. In subsequent papers, we shall discuss methods appropriate for a variety of data from both retrospective and prospective studies. Methods of analysis will be described that will permit adequate control for stratification variables and adjustment for factors related to both disease and risk factor. When possible, we shall describe computer packages that will be helpful in carrying out the analysis. Our emphasis, however, will be on interpretation of the methods we describe.

Data Interpretation, Statistical↗
PubMed1988

Implications of acquired oxacillin resistance in the management and control of Staphylococcus aureus infections.

Refinements in testing for resistance to penicillinase-resistant penicillins (PRP) in Staphylococcus aureus have resulted in confusion in classifying isolates as PRP susceptible or resistant. Specifically, a group of organisms has been identified that produce large amounts of beta-lactamase and appear borderline resistant. These organisms have been called "occult resistant" or "acquired oxacillin-resistant" S. aureus (AORSA). A retrospective study was conducted to evaluate the implication of this in vitro phenomenon in managing patients with AORSA infections. Among 134 patients with S. aureus infections, 89 were infected with oxacillin-susceptible S. aureus (OSSA), 26 with AORSA, and 19 with oxacillin-resistant S. aureus (ORSA). There were no significant differences in outcomes when OSSA and AORSA infections were treated with PRP (chi 2MH = .990; P = .32). These results do not suppor the contention that AORSA infections should be managed differently from OSSA infections. Identifying AORSA may not be helpful in guiding antimicrobial therapy or predicting the outcome of infections with AORSA.

Adult↗
PubMed1986

Fundus lesions in malignant hypertension. III. Arterial blood pressure, biochemical, and fundus changes.

Malignant (accelerated) renovascular arterial hypertension was produced in 57 adult rhesus monkeys by clamping the renal artery (one-kidney model in 25 animals and two-kidney model in 32). The animals were investigated before renal artery clamping and serially thereafter by recording systolic arterial blood pressure (BP), biochemical changes, and changes in the fundus of the eye; the latter was evaluated by ophthalmoscopy, stereoscopic color fundus photography, and fluorescein fundus angiography. All of the animals developed arterial hypertension. The data on BP, biochemical, and fundus findings were analyzed and correlated. The findings of this study clearly showed that the various fundus lesions seen in these hypertensive animals fall into three distinct categories: (1) hypertensive retinopathy, (2) hypertensive choroidopathy, and (3) hypertensive optic neuropathy. The appearance of the retinopathy was significantly earlier than that of the choroidopathy or optic neuropathy (P less than 0.01), but the difference between the times of appearance of the choroidopathy and neuropathy was not significant. There was no significance in the order in which the three types of fundus changes reached their maximum severity. There was no significant difference between the mean BPs when the retinopathy, choroidopathy, or optic neuropathy first appeared, nor between the BPs at the time of their appearance and at the time when they were most marked. In monkeys of the one-kidney model, the rise in BP developed significantly (P = 0.01) faster and the fundus lesions appeared significantly (P = 0.00001) earlier than in those with the two-kidney model.

Animals↗
PubMed1986

Changes in ponderosity and blood pressure in childhood: the Muscatine Study.

This paper describes the association between longitudinal changes in blood pressure and changes in measures of ponderosity. Between 1971 and 1981, 2,925 Muscatine, Iowa schoolchildren were measured at least once between ages 6 and 15 years and again between ages 15 and 18. The study shows that change in ponderosity is associated with change in blood pressures; children whose ponderosity decreases relative to their peers usually exhibit a similar drop in their systolic and diastolic blood pressures, while children who gain in ponderosity show a similar gain in their blood pressures. The magnitude of change in blood pressure is related to amount of ponderosity gain or loss and does not depend on initial blood pressure. These data suggest that for obese children weight loss might be an effective method for reducing their blood pressure.

Adolescent↗
PubMed1986

Interocular differences of the visual field in normal subjects.

One way of judging if a visual field is abnormal, particularly when a patient has unilateral or asymmetric disease, is to compare the suspicious visual field to that of the normal eye. This assumes that in normal individuals the two visual fields are symmetrical. To determine the extent of normal symmetry, the authors examined the central visual fields of both eyes of 20 normal subjects with program 30-2 of the Humphrey perimeter. The inter-ocular sensitivity difference at single pairs of locations ranged from 0 to 9 decibels with large differences occurring most frequently in the upper field. Confidence intervals constructed from this set of normal data predict that asymmetry exceeding 6 decibels should occur in fewer than 1% of test locations and that asymmetry of overall mean sensitivity exceeding 1.4 decibels should occur in fewer than 1% of normal subjects.

Adult↗
PubMed1986

Sample size for case-control studies using Cochran's statistic.

Sample size determination for case-control studies of chronic disease are often based on the simple 2 X 2 tabular cross-classification of exposure and disease, thereby ignoring stratification which may be considered in the analysis. One consequence of this approach is that the sample size may be inadequate to attain a specified power and size when performing a statistical analysis on J 2 X 2 tables using Cochran's (1954, Biometrics 10, 417-451) statistic or the Mantel-Haenszel (1959, Journal of the National Cancer Institute 22, 719-748) statistic. A sample size formula is derived from Cochran's statistic and it is compared with the corresponding one derived when the data are treated as unstratified, and also with two other formulas proposed for stratified data analysis. The formula developed yields values slightly higher than one recently proposed by Muñoz and Rosner (1984, Biometrics 40, 995-1004), which assumes that both margins of each 2 X 2 table are fixed, while the present study considers only the case-control margin to be fixed.

Biometry↗
PubMed1985

Bladder cancer risk among auto and truck mechanics and chemically related occupations.

Male participants in the NCI National Bladder Cancer study were evaluated for risks in auto and truck mechanic and in chemically related exposure occupations compared with those who had never worked in these areas. In nonsmokers the adjusted rate ratios (RR) for mechanics equalled 1.33, (95% CI 0.77, 2.31). The adjusted RR in the nonsmoker chemically related group was 1.53 (95% CI 1.13, 2.07). Duration of exposure as a mechanic was not clearly associated with bladder cancer risk regardless of smoking status.

Adult↗
PubMed1983

Ocular neovascularization with retinal vascular occlusion-III. Incidence of ocular neovascularization with retinal vein occlusion.

A prospective natural history study was conducted in 721 eyes with various types of retinal vein occlusion (RVO) to determine the incidence of various types of ocular neovascularization (NV) and the factors that influence the development of ocular NV. The material was 360 eyes with central retinal vein occlusion (CRVO), 97 eyes with hemi-CRVO, and 264 eyes with branch retinal vein occlusion (BRVO); these cases were further subdivided into six groups for logical data analysis: nonischemic CRVO (venous stasis retinopathy-VSR, 282 eyes), ischemic CRVO (hemorrhagic retinopathy-HR, 78 eyes), hemi-VSR (66 eyes), hemi-HR (31 eyes), major BRVO (191 eyes) and macular BRVO (73 eyes). Ocular NV attributable to RVO was seen only in HR, hemi-HR, and major BRVO. In HR the anterior segment was the major site of NV, with iris and angle NV and neovascular glaucoma (NVG), while in hemi-HR and major BRVO the retina and optic disc were the major sites of NV. The principal factor influencing the development of ocular NV in RVO seems to be the severity and extent of retinal ischemia, while duration of follow-up since onset also plays an important role in determining the incidence of ocular NV. The findings and subject of ocular NV in RVO are discussed in detail along with a review of the pertinent literature.

Adult↗
PubMed1983

Rank analysis of covariance with right-censored data.

A modification of the rank analysis of covariance, suitable for randomly right-censored dependent variate observations, is proposed and studied. The test suggested is based on an appropriate permutation distribution of the rank scores, and for large samples may be conducted by using the chi square distribution. The principal assumptions are that both censoring and covariate distributions do not depend on the treatment group.

Carcinoma, Squamous Cell↗
PubMed1982

Regression analysis of matched case-control data.

A regression methodology is outlined for the logistic analysis of matched pair case-control data. This weighted least squares technique is applicable to the problem of analyzing multiple, but categorical, risk factors. Estimates of odds ratios and statistics for hypothesis testing are directly produced with the procedure. The proposed methodology may be viewed as an alternative to that described by Holford et al. (Am J Epidemiol 1978;107:245-56). The required computations may be performed with standard programs for least squares categorical data analysis.

Accidents, Traffic↗
PubMed1982

The efficacy of isoproterenol inhalation for predicting the response to orally administered theophylline in chronic obstructive pulmonary disease.

Orally administered theophylline is commonly prescribed for patients with chronic obstructive pulmonary disease (COPD). It would be advantageous to predict those patients who will or will not respond to this methylxanthine. Forty men with COPD received placebo and theophylline orally, each for 1 month in a double-blind, single cross-over fashion. The acute response of the forced expiratory volume in one second (FEV1) to isoproterenol inhalation (015 mg) during placebo therapy was determined. The subjective and objective responses after 1 month of therapeutic theophylline concentrations (15.1 +/- 4.2 microgram/ml), mean +/- SD) in these clinically stable subjects also were measured. The sensitivity and specificity of isoproterenol aerosolization for predicting an objective response to theophylline was 75 and 96%, respectively. We conclude that isoproterenol inhalation can predict the response to orally administered theophylline in patients with COPD.

Administration, Intranasal↗
PubMed1981

Analysis of the presenting features of adult acute leukemia: the French-American-British classification.

The authors have performed a clinical and statistical analysis of the presenting features of adult acute leukemia classified according to the French-American-British (FAB) hematopathologic criteria. Observations were made on 70 variables of history, physical examination, and laboratory examination recorded for 195 patients seen during a recent six year interval. The incidence of each category as determined by consensus of three observers was L1, 9%; L2, 17%; L3, 3%; M1, 21%; M2, 22%; M3, 5%; M4, 21%; M5, 4%; and M6 1%. there were recurring features of each FAB category and for aggregated categories (myeloid, lymphoid). Some groups such as L1, M3, M4, and M5 were characterized by many distinctive characteristics. In contrast, the L2, M1, and M2 categories had few distinctive characteristics, although L3 shared many features with the other lymphoid groups. The distinctness of the categories was quantitated by stepwise discriminant analysis. Using only a few computer-selected clinical variables, the authors classified patients into the correct FAB category with an accuracy of over 65% for some groups. The accuracy in discriminating between lymphoid and myeloid groups, the important therapeutic distinction, was 82%. This study demonstrates that many of the categories defined by the FAB criteria have characteristic clinical features at presentation.

Adult↗
PubMed1981

Stability of psychiatric diagnosis. Schizophrenia and affective disorders followed up over a 30- to 40-year period.

Stability of diagnosis in schizophrenia and affective disorders is high. Patients selected according to research criteria for schizophrenia and affective disorders were followed up in a historical prospective study to evaluate their diagnostic stability over a 30- to 40-year period. Our follow-up, lifetime diagnosis, based on blind diagnostic assessment, showed that 92.5% of the personally interviewed schizophrenics were given the follow-up diagnosis of schizophrenia, which was significantly higher than the 78.3% found in affective disorders. However, no significant difference exists when assessment was made on available records of those who died or refused to be interviewed. These stability coefficients are discussed in light of the methodological assumptions involved in a long-term follow-up study. We concluded that the diagnostic stability in schizophrenia and affective disorders were very high and that rigorous diagnostic criteria should be maintained.

Adult↗