Search PubMed⌕ Search

Biomedical subjects

P Duca

Publications and source records attributed to P Duca.

14 recordsLinked to original sources
PubMed1992

Statistical aspects of the estimation of reference limits.

This paper deals with some basic statistical issues arising from biological monitoring. Data description, Gaussianity tests, outlier identification, parametric and non-parametric estimates of fractiles and their standard errors, and parametric estimate of the one tail upper side tolerance interval are treated and exemplified using two data sets. Sample size and power determination are considered in terms of the cut-off point of the diagnostic quantitative test.

Biometry↗
PubMed1992

Precision of gestational age assessment in the neonate.

The precision of the Ballard scale for assessing gestational age (GA) was evaluated in a consecutive sample of 227 preterm and/or low-birth-weight neonates. Each newborn was rated independently by two neonatologists and the difference in GA estimation between them was computed. The estimated precision was not high, the 95% tolerance interval estimate being as large as 7.4 weeks. The precision of the neurologic and physical parts of the scale was poorer than that of the complete scale (95% of differences less than 10.5 and 9.2 weeks respectively), and more influenced by the type of delivery. These findings are not unexpected from statistical theory, and cast doubts on the use of only the physical part of the Ballard scale in assessing GA, since greater accuracy could be accompanied by reduced precision.

Anthropometry↗
PubMed1991

Reproducibility of histologic classification of gastric cancer.

A panel review of histologic specimens was carried out as part of a multi-centre case-control study of gastric cancer (GC) and diet. Comparisons of diagnoses of 100 GCs by six pathologists revealed agreement in histologic classification for about 70-80% of the cancers. Concordance was somewhat higher when using the Lauren rather than the Ming or World Health Organization classification systems. Histologic types from reading biopsy tissue agreed with those derived from surgical specimens for 65-75% of the 100 tumours. Intra-observer agreement in histologic classification, assessed by repeat readings up to 3 years apart by one pathologist, was 95%. The findings indicate that, although overall concordance was good, it is important to standardise diagnoses in multi-centre epidemiologic studies of GC by histologic type.

Case-Control Studies↗
PubMed1991

[Cigarette smoking among high school students in Brescia: analysis of relations between smoking habit and knowledge, attitudes socioeconomic and behavioral factors].

A sample of high school students in grade 9 and 13 (14-15 and 18-19 years old respectively) in Brescia, North Italy, were interviewed to assess the relationship of smoking habit with attitudes, knowledge, behavioural and socio-environmental factors among adolescents. The associations between smoking habit, considered as a dichotomous response variable, and the other variables were assessed by estimating the prevalence ratios. The following variables were found to be associated with the students' smoking: best friend and/or partner smoking, sibling smoking, alcohol drinking and the students' judgement of the health risks of smoking. Although no conclusion can be drawn on the causal relationship of these associations due to the cross-sectional design of the survey, these findings suggest that social environment influences adolescents' smoking more than family life does. Furthermore, the knowledge of the health risks of smoking was not associated to adolescents' smoking.

Adolescent↗
PubMed1990

Significance and validity of a shortened lead chelation test.

We evaluated the chelation test in 38 subjects exposed to lead or with suspected lead exposure, comparing the values of lead excretion at the 3rd h (PbU EDTA/3-h) and at the 24th h (PbU EDTA/24-h) after EDTA administration. Good correlation exists between PbU EDTA/3-h and PbU EDTA/24-h (r = .86) and between them and the main biological indicators of dose and effect of lead. When a second chelation test was performed in 15 subjects, a slightly better r coefficient (.93) was observed between the two tests, without reaching statistical significance. It seems difficult, in terms of the type of exposure that we considered, to use the 3-h test, on an individual basis, to predict the PbU EDTA/24-h values.

Adult↗
PubMed1990

[Several risk indicators in industrial accidents].

Since the 1986, the National Institute for Occupational Accident Insurance (INAIL) provides each single Region with the occupational accident data on magnetic support. This strengthens the need to critically evaluate the most commonly used risk indicators. In this paper we discuss advantages and limits of the usual frequency and severity measures; the formulae for the standard errors are also given. A method proposed by I. Bross (1958), the RIDIT Analysis, is considered and exemplified. The appealing properties of this method ask for a more extensive application in this field.

Accidents, Occupational↗
PubMed1989

[The anatomo-pathologist as a necroscopy physician in the field: a balance-sheet of 4 years' experience].

The quality of the certificates of death for 2429 cases, all the residents died at home in the USL 70 during the period 1.8.83-31.12.87, was evaluated thanks to the necroscopic activity of the Legnano's Hospital pathologist. All the information, oral or written, available about each case was used to check the family doctor's certificate. Any correction to the certificate was discussed with the certifier. During the period a gradual and progressive reduction of error in the statement of the underlying cause of death was shown. The improvement comes out using different quality indicators.

Autopsy↗
PubMed1988

Intralaboratory reproducibility of interpretation of Pap smears: results of an experiment.

One hundred and twenty Pap-smears were examined by 3 cytotechnologists on two occasions in the Legnano Hospital Cytologic Center. A 10-category classification system was used. Chance-adjusted overall and category-specific agreement was estimated (Cohen's unweighted kappa-statistics) within and between cytotechnologists. Mean K for the Center, weighted for precision, was 0.432, S.E. 0.029 (between cytotechnologists). The most reproducible categories (between cytotechnologists) were "9: malignant cells" (K = 0.683) and "1: normal" (K = 0.533); the least reproducible categories were "4: endocervical metaplastic cells" (K = 0.024) and "8: severe squamous dysplasia CIN III" (K = 0.227).

Female↗
PubMed1977

Improved survival after coronary bypass surgery in patients with poor left ventricular function: role of intraaortic balloon counterpulsation.

The operative mortality rate of aortocoronary bypass surgery in 23 patients with poor left ventricular function (ejection fraction 0.30 or less) operated on in 1973-74 was 34.7 percent. The incidence rate of operative myocardial infarction was 30.4 percent. In an attempt to improve survival, intraaortic balloon counterpulsation was used therafter in 25 similar patients. Counterpulsation was instituted preoperatively and continued intra- and postoperatively for 2 to 5 days. Preoperative studies revealed an "unloading" effect of the left ventricle, with significant reductions of systolic arterial blood pressure, end-diastolic pulmonary arterial pressure and end-diastolic left ventricular volume and pressure. Metabolic improvement was demonstrated by the lesser production of myocardial lactate after pacing-induced tachycardia when the ventricle was balloon-assisted. Intraoperatively, blood flow through the vein graft was found to increase with counterpulsation. The rate of operative myocardial infarction was reduced to 4 percent and the mortality rate to 8 percent. In patients who have sustained a significant loss of functioning myocardium, the beneficial hemodynamic and metabolic effects of intraaortic balloon counterpulsation appear to prevent furhter, possibly critical, myocardial damage in the perioperative period.

Assisted Circulation↗
PubMedDate not supplied

[Reference values and tolerance intervals].

Statistical aspects of tolerance intervals estimation are considered and tolerance coefficients for unilateral and central intervals are derived for normally distributed biological variables. The difference between confidence and tolerance interval is explained and application to biological and environmental monitoring, as well as applications to reference values estimation, are exemplified. Tables of unilateral and central coefficients are also produced and reported for different sample dimensions, confidence, and tolerance levels.

Environmental Monitoring↗
PubMedDate not supplied

[Numerical synthesis of statistical data].

The paper describes the methods currently used for numerical synthesis of statistical data. A review is made of the main properties of the various statistical indices required to describe the central tendency, dispersion and shape of distribution of values. Mode, median, arithmetic mean, harmonic and geometric mean, range, quantiles and standard deviation, asymmetry and kurtosis indices are described and discussed using data drawn from practical experience. Special attention is paid to the errors most frequently incurred using these methods. An appendix supplies details of some of the mathematical properties of the operators described.

Statistics as Topic↗
PubMedDate not supplied

[Elements of probability calculation. I].

This is the first of a series of articles on probability calculation, consisting of a simple introduction to the definitions of probability. A brief historical background explains some of the reasons for the delay in the development of probability calculation and recalls the main problems that had to be faced, the solution of which marked the birth of the theory of probability. Classical, frequentist and subjective approaches are addressed and their relative merits and weaknesses are discussed.

Probability↗
PubMedDate not supplied

[Elements of probability calculation--II].

This is the second part of an introduction to probability calculation and covers basic concepts such as conditional and simple probabilities and independent events and also a definition of two fundamental laws, those of addition and multiplication, which permit a correct combination of probabilities. Explanation of probability concepts and ideas is illustrated with the aid of examples from the field of screening tests. Bayes theorem is derived by applying the addition and multiplication laws to conditional and simple probabilities.

Bayes Theorem↗