Biomedical subjects
Publications and source records attributed to J F Osborn.
Inorganical materials are being increasingly tried out in surgery and periodontal surgery for reconstructing bone defects. This paper discusses the biocompatibility and biofunctionality of different implant materials and presents a new hydroxyapatite ceramic material, of which a good bioactive behaviour is expected.
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OBJECTIVES: The salivary level of Streptococcus mutans related to filled teeth was compared with the levels related to decayed and sound teeth, in order to establish whether the presence of restorations may increase the risk of infection of other teeth by Streptococcus mutans. METHODS: The sound, decayed and filled teeth were recorded in 809, 6-7-year-old school-children. Salivary Streptococcus mutans detection (i.e. more than 1 x 10(4) CFU/ml) and counts were evaluated. Streptococcus mutans log count means and prevalence values of subjects with only sound teeth (group 1), with filled, without decayed teeth (group 2), with decayed, without filled teeth (group 3), were calculated and compared using the Student's t-test and the chi-square test. The effect of filled, decayed and sound teeth on Streptococcus mutans level was also evaluated using logistic regression. RESULTS: Log count means and prevalence values of group 2 subjects were significantly lower than values of group 3 subjects (means, 0.92 vs 1.66: prevalence, 73.17% vs 94.63%) and statistically not-different from values of group 1 subjects (mean. 0.75: prevalence, 70.06%). The logistic regression analysis showed that the factors significantly increasing the risk of Streptococcus mutans being detected in saliva were only primary and/or permanent decayed teeth. The risk of Streptococcus mutans being detected in saliva was not affected by filled teeth more than sound teeth. CONCLUSIONS: In the present study population, the salivary Streptococcus mutans level attributable to filled teeth was low; this suggests that treatment of a carious lesion would cause a lowering of Streptococcus mutans concentration to the same levels as those shown by healthy subjects, thus reducing the risk of infection to other teeth.
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The use of hospital discharge abstracts in estimating the outcome of hospital care represents an ongoing interest in public health. However standardized methodologies are still not available. We carried out a retrospective study to estimate the association between demographic and clinical characteristics and in-hospital mortality after stroke by using administrative data from the Hospital Information System in Lazio Region. We also assessed the relationship between the presence of neurology services and the outcome. We found 12,781 incident episodes of stroke (main diagnosis ICD-9: 430-431-434-436) (49.3% male, mean age = 74 years) admitted in 126 hospitals in the Lazio region for the period 1999-2000. From the hospital discharge abstracts we collected patient demographic and clinical data. The hospitals were classified in centres with and without neurology services. Admissions to hospitals with neurology services were evaluated as predictors of in-hospital mortality after adjustment for gender, age, residence, education, source of admission, type of stroke, heart disease, kidney disease and history of atrial fibrillation. In-hospital mortality (within 30 day) was 25.1%. Female gender, advanced age, residence in Rome, urgent transport, kidney disease and history of atrial fibrillation were associated with an increased risk. Hemorrhagic stroke (ICD-9 = 430-431) had a worse outcome than ischemic stroke (ICD-9 = 434) and acute undefined cerebrovascular disease (ICD-9 = 436). Patients admitted to hospitals with neurology services showed a significantly decreased risk (OR = 0.88, IC95% = 0.79-0.98), particularly in occlusion of cerebral artery (ICD-9 = 434) and in undefined cerebrovascular disease (ICD-9 = 436). Demographic and clinical variables are associated with the outcome of hospitalised stroke patients. Admissions of acute stroke patients in specialized hospitals seem to play a role in reducing the risk of in-hospital mortality.
Records from 6820 deliveries of three year (1980, 1985 and 1988) were reviewed in order to collect informations on cesarean section trend and its indications in a public hospital of Milan, Italy. Data show the magnitude of the phenomenon in the wards considered and an evident increase of cesarean section proportion from 1980 (18.6%) to 1988 (26.9%). The frequencies of major indications has not changed much apart from dystocia which has decreased and previous cesarean section which has increased. A logistic regression model was performed to evaluate cesarean section risk factors. Distribution of cesarean section during the days of the week show higher (about 30%) cesarean section proportion Monday through Thursday compared with low proportion (20% or less) on Fridays and weekend-days; this suggesting a possible high proportion of pre-programmed cesarean section.
This paper has outlined analyses of data for which the chi 2 test is commonly applied and has shown that on its own, a chi 2 test provides very little information about the interpretation of the data. In goodness to fit tests, at best, the chi 2 test is a mere first step in the interpretation of the data and much more information can be gleaned from the deviations between the observed and theoretical distributions, and graphical methods are more sensitive for assessing Normality. Similarly, the chi 2 test as the analysis of a 2 x 2 contingency table misses the most important features of the data. A chi 2 value and associated p value should not be presented without an estimation of the effect and its confidence interval. The use of NS, (not significant), after a chi 2 value (or any other test statistic) is particularly meaningless as it does not even specify a level of significance. The analysis of 2 x 2 contingency tables should specify a measure of the effect such as the difference between two proportions, their ratio or the odds ratio. Confidence intervals should be calculated and least importantly, statistical significance assessed by the Standard Normal Deviate. Chi 2 has no useful role to play in the analysis of 2 x 2 contingency tables. In fact, even with larger two dimensional tables, although chi 2 can be used to test the significance of associations between the rows and columns, such results are seldom of much interest as they give no indication of where in the table associations may exist. They are insensitive particularly if the categories of the row or column variables are quantitative since chi 2 takes no account of the ordering of the rows and columns. Although simple analyses of such tables are inefficient the advent of desk-top computers means that more sophisticated techniques such as logistic regression for proportions and Poisson regression for larger or multidimensional contingency tables can be applied. Although these methods may involve chi 2 tests for testing the significance of including or excluding variables, they are always associated with estimates of effects as measured by regression coefficients. The use of chi 2 for the simple analysis of contingency tables has no place in the interpretation of medical research data.
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