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PubMed1998

Hospitalizations for back and neck problems: a comparison between the Province of Ontario and Washington State.

OBJECTIVE: To examine back and neck hospitalizations in the Province of Ontario and Washington State. Because of their different organization and financing, there has been considerable interest in comparing healthcare systems in Canada and the United States. Features of healthcare systems might be expected to result in greater variations in care for elective than urgent conditions. DATA SOURCE: Automated hospital discharge databases. STUDY DESIGN: Previously developed algorithms were used to identify surgical and nonsurgical hospitalizations for back and neck problems in the administrative databases. We compared overall rates of hospitalization and lengths of hospital stay in Ontario and Washington as well as small area variations within the province and state. PRINCIPAL FINDINGS: Surgical back and neck hospitalizations were three times as common in Washington, but medical hospitalizations were twice as common in Ontario. Provincial lengths of stay were longer for both surgical and nonsurgical hospitalizations. Admission rates varied substantially and significantly among small areas in both Washington and Ontario. Variations in hospital length of stay were greater in Ontario, particularly for nonsurgical back and neck hospitalizations. CONCLUSION: The two jurisdictions had very different patterns of hospital utilization for one of the most common health problems seen by physicians. Our results suggest that the global controls on hospital budgets and access to technology in Ontario were associated with lower rates of surgery, higher rates of hospital-based medical care, and longer lengths of stay. They also indicate that the utilization review process in Washington was associated with lower small area variation rates for medical back care.

Adult↗
PubMed1995

Small-area variations in utilization of abortion services in Ontario from 1985 to 1992.

OBJECTIVE: To assess interregional differences in the utilization of abortion services in Ontario from 1985 to 1992. DESIGN: Retrospective analysis of provincial therapeutic abortion database. SETTING: All hospitals conducting abortions between 1985 and 1992 and all free-standing abortion clinics conducting abortions between 1990 and 1992. POPULATION: All women in Ontario aged 15 to 44 years who underwent a therapeutic abortion in Ontario during the study period. OUTCOME MEASURES: Utilization of abortion services by county and age-specific abortion rates by county of residence. RESULTS: From 1985 to 1989, when only hospital data were gathered, the mean therapeutic abortion rate increased by 11.2%. From 1990 to 1992, when data from hospitals and free-standing clinics were collected, the mean rate increased by 26.5%. Logistic regression analysis showed significant variation in the age-standardized abortion rates between counties in each study year (p < 0.0001). The counties with age-standardized rates below the 25th percentile had the highest proportions of women who sought abortion services outside their county of residence; in some of these counties no abortions were performed in local facilities. CONCLUSION: There are interregional variations in the utilization of abortion services in Ontario. These disparities raise questions about the accessibility of abortion services and need to be further investigated.

Abortion, Therapeutic↗
PubMed1995

Spatial statistical methods in environmental epidemiology: a critique.

Despite recent advances in the available statistical methods for geographical analysis, there are many constraints to their application in environmental epidemiology. These include problems of data availability and quality, especially the lack in most situations of environmental exposure measurements. Methods for disease 'cluster' investigation, point source exposures, small-area disease mapping and ecological correlation studies are critically reviewed, with the emphasis on practical applications and epidemiological interpretation. It is shown that, unless dealing with rare diseases, high specificity exposures and high relative risks, cluster investigation is unlikely to be fruitful, and is often complicated by the post hoc nature of such studies. However, it is recognized that in these circumstances proper assessment of the available data is often required as part of the public health response. Newly available methods, particularly in Bayesian statistics, offer an appropriate framework for geographical analysis and disease mapping. Again, it is uncertain whether they will give important clues as to aetiology, although they do give valuable description. Perhaps the most satisfactory approach is to test a priori hypotheses using a geographical database, although problems of interpretation remain.

Adult↗
PubMed1998

Perinatal mortality in an English health region: geographical distribution and association with socio-economic factors.

Although the international and regional variability of perinatal mortality rates have been widely studied, less is known about the variability at the small-area level. The geographical distribution of perinatal mortality in the former North-West Thames Health Region, England, during 1981-90, and its association with small-area socio-economic factors, as measured by the Carstairs index of deprivation, were studied. Recently developed methods of analysis, including use of Bayesian statistics, were applied to obtain descriptive results and maps, and for fitting regression models that allowed for the presence of unmeasured risk factors. Significant heterogeneity (P < 0.001) of perinatal mortality across census wards and districts was found. The 5% of wards with the highest mortality experienced a risk more than 1.7 times that of the 5% with lowest mortality. Significant, positive association between deprivation and perinatal mortality was also found. Assuming causality, social differentials at the small-area level accounted for between 1.3% and 14.1% of all perinatal deaths, depending on which level of the Carstairs index was selected as reference. Although a proportion of such variability might be explained by social characteristics, a better understanding of the nature of the association is necessary.

England↗
PubMed1990

Changes in Connecticut hospital use rates: have small-area variations been affected?

This paper examines the extent to which changes (prospective payment, alternative delivery systems, etc.) in the hospital environment and the general decline in hospital days affect small-area variations in hospital use rates for 18 selected diagnoses in nine hospital service areas in Connecticut. After adjusting for coding changes between DRGs, we found that variation across the service areas did not, in general, differ for any one of the years 1981-86. In one instance (cardiac catheterization), however, we found that a DRG-specific change in knowledge and technology decreased the extent of small-area variation for that diagnosis.

Analysis of Variance↗
PubMed1989

Colour measurements of all ceramic crown systems.

The objectives of this study were: (i) to determine variability among colour parameters of five different ceramic crown systems; and (ii) to measure the effect of using coloured luting agents on restoration colour. The crown systems studied were Cerestore, Dicor, Hi-Ceram, Renaissance, and Vitadur-N. Five crowns for each system were made according to manufacturer's instructions with the same nominal shade (Vita Lumin Vacuum A2) to fit an Ivorine central incisor tooth. Restoration thickness was adjusted to within +/- 0.1 mm (+/- 0.05 mm in the mid-facial area where colour measurements were to be made) with the aid of a dial calliper prior to glazing or, in the case of Dicor, surface staining. Where a core was part of the system this was fabricated to the minimum recommended thickness. The crowns were cemented using luting agents of five different colours in a randomly chosen sequence. The colour of each restoration/cement combination was measured three times using a small-area colorimeter (Minolta CR-121). The variance of each colour parameter (L*, a*, b*) was statistically compared for each crown system using an analysis of variance procedure, as was the effect of the cement. Observed differences were related to visual perception by using the colour difference formula. There were statistically significant differences among the variances of the crown systems and the cements, with significant interactions between crown systems and direction of colour and between cement and direction of colour. Restorations made with different ceramic crown systems had noticeably different colour despite having the same nominal shade. Changing the shade of the luting agent had a perceivable effect on Dicor crowns and, to a lesser extent, on Vitadur-N crowns but not on the other systems due, presumably, to the opacity of their core materials.

Color↗
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↗