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PubMedDate not supplied

Asbestos-related mortality in Italy: a geographical approach.

The present contribution describes two studies of asbestos-related cancer mortality in Italy: an analysis of the geographical distribution of mortality from pleural neoplasms and an investigation into the relationship between pleural and lung cancer mortality in an Italian region, Piedmont. Mortality from malignant pleural neoplasms (ICD-IX Revision 163.0-163.9) has been studied in Italy in the 20 regions and the over 8000 municipalities for the years 1988-92: restriction of analysis to municipalities with at least three observed deaths and statistically significant increases led to identification of areas where occupational and/or environmental exposure to asbestos can have occurred. The analysis of pleural and lung cancer mortality was carried out for the years 1980-87 in Piedmont using an empirical Bayes method for small-area disease mapping; the results showed that the proportion of lung cancer mortality attributable to asbestos exposure was 5.6 and 5.7 percent respectively in men and women. While analyses of routinely collected data are no substitute for ad hoc individual based studies, notwithstanding the limitations of geographical approaches to the study of asbestos-related mortality, investigations carried out at the level of small area populations appear to provide informative results, which might be of value in terms of public health.

Asbestos↗
PubMed1997

Analysis of a general principle of crystal nucleation, formation in the different hard tissues.

We have found, at high EM magnification, on ultrathin sections of shock-frozen, freeze-dried, embedded pieces of the developing hard tissues, that the primary crystallites consist of strands composed of nanometer-sized apatitic islands, which rapidly coalesce to needles and afterward to platelets. By small-area electron diffraction, with energy-filtered electrons, it was clarified that these strands are already crystallographically oriented along the bipolar c-axis so that the center-to-center distances between the islands would reflect the distances between crystal-nucleating sites along the matrix. The EM analysis of the cross-cut stained unmineralized and of the unstained mineralized collagen fibers of turkey tibia tendon shows that the staining "nuclei" and the early crystallites, appearing as dark dots, surround "light" round structures, which we interpret as the collagen microfibrils, surrounded by the apatitic crystallites.

Animals↗
PubMed1997

Small-area study of the incidence of neoplasms of the brain and central nervous system among adults in the West Midlands region, 1974-86. Small Area Health Statistics Unit.

This small-area study of incidence of cancers of the brain and central nervous system found evidence of trend (P = 0.02) of cancer risk with deprivation (8% higher risk in affluent areas), but no significant association with urban-rural status. Results were not indicative of a strong geographically determined risk at small-area level.

Adolescent↗
PubMed1998

[Health inequalities in the outlying towns of the urban sprawl of Granada].

OBJECTIVES: 1. To investigate health inequalities in the outlying towns around urban Granada. 2. To classify the towns in homogeneous groups according to their demographic, social and economic, and urban environment features, and to contrast these categories with their health situation. DESIGN: Ecological study using indicators of health and town environment from various sources. SETTING: The 29 towns in the periphery of Granada. MEASUREMENTS AND INTERVENTIONS: The differences in health of the towns were compared among themselves and with the group formed by all of them together. Cluster analysis was employed in order to classify the towns into homogeneous groups. RESULTS: It is noteworthy that only two towns had overall and premature mortality rates above and below the group as a whole. We found marked differences between towns for the other health indicators, with difference ratios up to 6 times greater than the group as a whole, as was the case for incidence of Brucellosis. There were some towns with poorer general conditions on Health and Poverty indexes than the rest. There were 5 clusters or groups of towns with homogeneous characteristics, for which the ratios of all the health indicators of the group with the best conditions were higher than the ratios of the group with the worst conditions. CONCLUSIONS: Better understanding of health inequalities at the small-area level, along with the use of health and poverty indices, help to characterise the place in question and favour the reduction of the inequalities.

Aged↗
PubMed1989

Small-area variation in hospital discharge rates. Do socioeconomic variables matter?

Although numerous studies have been made of the determinants of small-area variation in hospital discharge rates, there is still disagreement about the role of socioeconomic factors. The lack of consensus stems, in part, from the difficulty in comparing results across studies that use different units and methods of analysis. Many of the studies using well-defined hospital service areas did not have the data needed to conduct a controlled analysis of the determinants of hospital utilization. Most of the studies that have performed controlled analyses have relied on larger geopolitical areas, which are not believed to capture self-contained health care systems. The study described here used a consistent set of data, three methods of analysis, and two units of analysis to test the importance of socioeconomic characteristics in explaining the variation in medical and surgical discharge rates in Michigan. Socioeconomic factors are found to be statistically significant determinants of the variation in both medical and surgical discharge rates, whether the method of analysis is simple correlations or multiple regressions, and whether the unit of analysis is the county or a well-designed hospital service area. These results suggest that previous small-area variation studies may have incorrectly concluded that socioeconomic characteristics do not explain differences in utilization rates.

Hospitals↗
PubMed1996

The estimation of caries prevalence in small areas.

National surveys have been effective for the estimation of caries prevalence in broad regions of the US. However, it is unclear if data from such surveys can be used to estimate prevalences in small areas such as states or counties because of small sample sizes within individual areas. In this study, we applied specialized statistical methods to the estimation of small-area caries measures using data from an oral health survey conducted in the State of Washington. Dental exams to assess caries and the presence of sealants and fluorosis were performed on 2921 third-grade students in 84 public schools selected by a stratified random sample from all 39 counties in the state. Statistical methods for small-area estimation were used to estimate disease and sealant utilization measures for each of the counties. Adjustment was made for covariates measured at the school level, including ethnicity and the proportion of children in the Federally sponsored school lunch program. Substantial variability in disease and sealant utilization between counties was found. The estimated number of decayed and filled surfaces per child was 4.7 (inter-county range, 2.4 to 7.4). The estimated number of surfaces of untreated decay was 1.2 per child overall (range, 0.5 to 3.1). Thirty percent of the children had restorative treatment needs (range, 15 to 54%). The prevalence of sealants on one or more permanent molars was estimated to be 34% (range, 19 to 46%). Overall, only 8% of children showed evidence of fluorosis. The results demonstrate the usefulness of small-area estimation methods for oral health surveys.

Child↗
PubMed1989

The new United States Cancer Atlas.

Published in 1975, the Atlas of Cancer Mortality for U.S. Counties: 1950-1969 proved useful in identifying geographic patterns, especially clusters of high-rate areas, that have stimulated further epidemiologic study of specific cancer sites. These data have been updated to include population and mortality statistics through 1980. Our new atlas presents static maps of area-specific mortality rates for each decade from 1950 to 1980 among white males and females for 33 cancer sites, along with dynamic maps illustrating the trends in these rates over time. Although the geographic distribution of mortality rates has become more uniform for most cancer sites, clusters of high-rate areas have persisted for several common tumors. However, some new patterns have appeared, notably the emergence of several high-rate areas for lung cancer among women. Possible explanations for the geographic peculiarities of cancer are considered, based on the results of correlation and analytic studies prompted by the earlier maps. These successive studies indicate the value of monitoring mortality statistics on a small-area scale as a strategy for generating etiologic clues and targeting epidemiologic research, although one must be mindful of geographic fluctuations in diagnostic and reporting practices, survival rates, and migration patterns.

Chronology as Topic↗
PubMed1991

Corrosion pattern of silver points in vivo.

The purpose of this study was to examine the electrochemical behavior of silver points in vivo. The apices of silver points removed from teeth with successful or failed endodontic treatments were subjected to complete surface characterization by small-area ESCA, scanning electron microscopy, and electron probe microanalyzer. Cross-sections of the points near the apex were examined with scanning electron microscopy and electron probe microanalyzer to identify the depth of corrosion involvement. According to the results, all silver points manifested evidence of corrosion attack. Electron probe microanalyzer showed no difference in the elemental distribution found on the points. ESCA analysis of the uppermost 5-nm point layer revealed the presence of N on silver points removed from failed treatments. The examination of cross-sections manifested deep S penetration in the bulk of the points removed from failed treatments. Considering the results of this study, no direct association seems to exist between the extent of the corrosion involvement and the prognosis of the treatment. Handling factors and the presence of bacteria are probably the parameters determining the outcome of a treatment.

Corrosion↗
PubMedDate not supplied

The relationship between elastomer opacity, colorimeter beam size, and measured colorimetric response.

The effect of opacity on the colorimetric responses of large-area and small-area colorimeters was determined using an elastomer intended for maxillofacial prosthetics use and containing various pigments at different concentrations. Opacity was determined by calculating the contrast ratio of 2-mm-thick specimens against black and white backings, using Kubelka-Munk analyses to correct for thickness and backing color variations. The measure of comparison of the two colorimeters was the relative difference in tristimulus reflectance, with the tristimulus reflectance of the large-area colorimeter as the basis of the relative difference. A significant quadratic relationship was found between contrast ratio and the relative difference in tristimulus reflectance. This relationship may be used to describe opacity without the need to make optical observations or measurements of a thin layer of material on contrasting backings. The small-area colorimeter produced color parameters that are a measure of the combined effects of both color and opacity. The importance of beam size considerations of optical measuring devices for translucent natural and prosthetic materials was emphasized.

Color↗
PubMed1996

Randomized clinical trial of the efficacy and safety of a home bleaching procedure.

The safety and efficacy of a home-use carbamide peroxide tooth-whitening procedure were evaluated in a double-blind experimental design. Fifty-two adults were randomly assigned to experimental and control (placebo gel) groups. The products were applied in a custom-fitted tray and used for 5 consecutive nights in accordance with the manufacturer's recommendations. Tooth color changes from baseline were measured with a small-area colorimeter. Concurrently, electric pulp test and periodontal indices were measured. At the end of 6 months, the teeth in the active group had a statistically significant greater mean color change that did the placebo controls. The mean color change differed significantly by tooth type. No statistically significant changes in vitality, sulcus depth, or Gingival Index were found in the treatment group.

Adult↗
PubMedDate not supplied

Colorimetric evaluation of vita shade resin composites.

The shades of several resin composite materials are keyed to the Vita Lumin shade guide. This study was designed to determine whether different composites of the same designated Vita shade were actually similar in color. A small-area colorimeter was used to compare the L*a*b* color parameters of three hybrid resin composites--Pertac-Hybrid, Prisma AP.H, and XRV Herculite. Four Vita shades (A2, B3, C2, and D3) of each material were evaluated. Color differences (delta E values) between composites of the same designated shade ranged from 2.07 for the A2 shades of Herculite and AP.H to 7.64 for the D3 shades of Herculite and Pertac. Color differences in this range are perceptible to many observers under ideal viewing conditions.

Analysis of Variance↗
PubMed1998

Multi-drug resistant tuberculosis in Finland--a forecast.

Since the collapse of the Soviet system, travel between the St Petersburg district and the Baltic states and Finland has increased substantially. Although it is difficult to obtain exact figures on the number of cases of tuberculosis (TB) and multi-drug resistant (MDR) TB in these countries, there is strong evidence of growing epidemics, bringing added epidemiological threat to Finland. The purpose of this study is to produce a short-term "worst case" forecast of the spatial development of a threatened MDR-TB epidemic in Finland. The method applied is a chorological multistep procedure using statistical and geographical methods and a simulation technique. Instead of focusing on populations of carriers and susceptibles, emphasis is placed on identifying the primary influences directing the epidemic as a spatial process. This was done by dividing Finland into small-area units and by assigning the risk of obtaining MDR-TB to each unit based on socioeconomic and structural characteristics of the population. The simulated 6 year cumulative distribution of new MDR-TB cases showed a marked concentration of cases in the capital region and in a cluster of municipalities along the west coast. Although socioeconomic factors are important in explaining the distribution of cases, frequent and widespread international contacts seemed to be equally important at the beginning of the epidemic.

Disease Outbreaks↗
PubMed1995

Tooth color and reflectance as related to light scattering and enamel hardness.

Tooth color is determined by the paths of light inside the tooth and absorption along these paths. This paper tests the hypothesis that, since the paths are determined by scattering, a relation between color and scattering coefficients exists. One hundred and two extracted incisors were fixed in formalin, mounted in a standardized position in brass holders, and pumiced. A facet was prepared near the incisal edge on the labial plane to allow for Knoop hardness measurements with a 500-gram load. Light scattering by the enamel was measured in a 45 degrees/0 degrees geometry; light scattering by both enamel and dentin was measured in a 0 degrees/0 degrees geometry. The reflection spectrum of the tooth was measured from the labial plane with a spectroradiometer in a 45 degrees/0 degrees geometry, with standard illuminant A and standard illuminant D65. To include all volume-reflected light, we used entire-tooth illumination and small-area measurement. CIELAB color coordinates were calculated from the spectra. Neither spectra nor coordinates showed evidence of a contribution of fluorescence to tooth color. Averaged values and standard deviations for L*,a*,b* were 69.9 (4.1), 1.22 (1.4), and 17.9 (2.9), respectively. Both scattering coefficients averaged to 0.6 (0.4) mm-1; Knoop hardness number was, on average, 271 (39) kg/mm2. L* correlated with a* (r = -0.51), with the enamel scattering coefficient (r = 0.60), and slightly with hardness (r = 0.17, p = 0.03). The colors of 28 teeth from which the enamel was removed correlated strongly with the colors of the complete tooth.(ABSTRACT TRUNCATED AT 250 WORDS)

Chemical Phenomena↗
PubMed1997

Clustering of childhood IDDM. Links with age and place of residence.

OBJECTIVE: To improve understanding of the etiology of IDDM by analyzing spatial and space-time distribution of the incidence in children. RESEARCH DESIGN AND METHODS: Statistical tests to detect clustering were applied to a population-based register of 1,490 children (aged 0-16 years) with IDDM in Yorkshire, northern England. The Knox test analyzed clustering in space and time, and the Potthoff-Whittinghill test quantified spatial differences in incidence between small-area census units (electoral wards). The Potthoff-Whittinghill test was conditioned for childhood population density and deprivation (Townsend index). RESULTS: Both tests demonstrated clustering of IDDM in Yorkshire children. Space-time and spatial clustering is strongest in the younger children (0-4 and 5-9 years of age), even after conditioning for known associations. Clustering was more common in the county of Humberside during the years 1982-1985 and in wards of low population density (< 0.26 0- to 16 year-old subjects per hectare). CONCLUSIONS: The study revealed a nonrandom space-time distribution of IDDM in children not accounted for by known covarying demographic factors. The Potthoff-Whittinghill test has not previously been applied to childhood IDDM. The new finding of strong clustering in young children is consistent with early exposure, possibly in utero, to infectious agents or localized environmental sources.

Adolescent↗
PubMed1993

Variation in hysterectomy rates across small geographic areas of Massachusetts.

OBJECTIVE: Our objective was to determine whether small-area variation in hysterectomy rates exists within Massachusetts and, if so, whether regions with persistently high or low rates can be identified. STUDY DESIGN: By examining data derived from standardized hospital discharge forms between 1982 and 1989, we compared hysterectomy rates among 172 small geographic areas within Massachusetts. The ratios of actual to expected number of hysterectomies for each area were also computed. Statistical significance of rate variation was established by a value of p < 0.01 (chi 3 test). RESULTS: The-hysterectomy rate per 1000 women varies fivefold across small-population areas of Massachusetts. Eight areas had persistently high and five had persistently low rates compared with the statewide average. CONCLUSION: Possible explanations for these rate variations include indigenous population factors, supply of health care resources, income, insurance coverage, methodological problems in data analysis, and variation in professional judgment with regard to the indication for hysterectomy. Only a combination of the study of local causes of high and low rates and the study of the clinical outcomes of different treatment decisions will allow physicians to develop an informed consensus on appropriate indications for surgery.

Female↗
PubMed1988

Display of small-area variation in health-related data: a methodology using resistant statistics.

Health care planning requires characterization of the population to be served. Examination of available demographic and epidemiologic data is one early step in this process. However, aggregate data for the entire geographic area of concern often fail to reveal important differences among geographically defined sub-populations--differences that influence the form an effective delivery system should take. We present a methodology based on exploratory data analysis (EDA) techniques that we have found useful in examining health-related data for our ambulatory care catchment area. Our examples use three population characteristics that have major implications for health care planning for the elderly: 1970-1980 change in population aged 65+; the percent of the population aged 65+ below poverty level; and the percent of single-person households among households with one or more persons aged 65+. With these data for the 25 municipalities of Middlesex County, New Jersey, we illustrate a two-step process: (1) the construction of stem-and-leaf displays that permit examination of a data distribution for asymmetry, concentrations around specific values, gaps in values, and outliers; and (2) the use of the median, the fourth-spread, and other information from the stem-and-leaf display in the systematic selection of data value classes to be given distinct shadings on a map of the selected geographic area. Discussion emphasizes the usefulness of graphic display of data in detecting similarities and unusual data values. Comparison of maps based on the EDA techniques and maps based on several traditional methods of value classing for the same data illustrates the influence of classing choices on the interpretation of cartographic displays of health-related data.

Aged↗
PubMed1998

Nitrate in drinking water and the incidence of gastric, esophageal, and brain cancer in Yorkshire, England.

OBJECTIVES: This small-area ecologic study in Yorkshire, northern England, examines the hypothesis that exposure to higher levels of nitrate in drinking water increases the risk of stomach, esophageal, or brain cancer in adults. METHODS: Nitrate levels over the period 1990-95 and numbers of incident cancers from 1975-94 were available for 148 water supply zones, geographically defined areas each supplying water of homogeneous chemical composition to an average population of around 20,000. RESULTS: No relationship was found between nitrate concentrations and the incidence of stomach or esophageal cancers. The incidence of cancer of the brain and central nervous system was found to be higher in areas with higher nitrate levels, with a relative risk of 1.18 (95 percent confidence interval = 1.08-1.30) in the quartile of the population with the highest average levels (mean 29.8 mg/l) compared with the lowest quartile (mean 2.4 mg/l). The increase in risk remained statistically significant (P < 0.01) after allowing for other covariates and for extra-Poisson variation in a regression model. CONCLUSIONS: This study does not support the hypothesis of an increased risk of stomach or esophageal cancer associated with higher nitrate levels in drinking water. The observed relationship with brain cancer requires confirmation in other studies, including those involving data on individuals.

Adolescent↗
PubMed1990

Geographic variations in US asthma mortality: small-area analyses of excess mortality, 1981-1985.

US asthma mortality rates have been increasing during the past 10 years. Little is known about the geographic variation of this infrequent health event. Using US vital records for the 1981-1985 period, small-area variation of excess asthma mortality of young adults was studied. Several geopolitical definitions were used to define populations. A total of 22 single counties, 12 metropolitan statistical areas, 11 health service areas, and 29 state economic areas were identified as having mortality significantly in excess of that expected, based on US race/sex-specific rates. Significant variation in asthma mortality was found at several levels of geopolitical classification of the data. Elevated areas included the central plains states and three large urban metropolitan areas--Chicago, Illinois, New York, New York, and Phoenix, Arizona--as well as a few mostly suburban populations. Areas with excess mortality may provide a useful population base for further epidemiologic investigation into the risk factors associated with the more frequent morbid events of this disease, such as emergency room and hospital utilization.

Adolescent↗