Biomedical subjects
Publications and source records attributed to R L Munasinghe.
Of 836 medical admissions evaluated over a 1-month period, 89 (10.7%) had a urinary catheter placed within 24 hours; 34 placements (38%) had no justifiable indication. Risk for inappropriate catheterization was independent of age, gender, functional status, and mental status at admission. Preventive measures should focus on increasing awareness among healthcare providers.
Daily counts of diagnosed gastroenteritis (gastrointestinal events) in Milwaukee County, Wisconsin, from January 1992 through April 1993 were compared with reported daily turbidity from the two drinking water treatment plants serving the county. Turbidity in both plants was associated with an increased number of gastrointestinal events even after exclusion of a major documented outbreak of cryptosporidiosis. During the 434-day period prior to the outbreak, an increase in turbidity of 0.5 nephelometric turbidity units at one of the plants was associated with relative risks for gastrointestinal events of 2.35 among children (95% confidence interval [CI] = 1.34, 4.12) and 1.17 among adults (95% CI = 0.91, 1.52).
OBJECTIVES: Preexisting data sets were used to investigate the association between hospital admissions for congestive heart failure and air pollutants. METHODS: Medicare hospital admissions data, ambient air pollution monitoring data, and meteorological data were used to create daily values of hospital admissions for congestive heart failure, maximum hourly temperature, and maximum hourly levels of carbon monoxide, nitrogen dioxide, sulfur dioxide, and ozone. Data were compiled for each of seven cities (Chicago, Detroit, Houston, Los Angeles, Milwaukee, New York, and Philadelphia) for 1986 through 1989. Single-pollutant and multipollutant models with adjustments for temperature, seasonal effects, and weekly cycles were used in conducting negative binomial regression analyses. RESULTS: Ambient carbon monoxide levels were positively associated with hospital admissions for congestive heart failure in the single-pollutant and multipollutant models for each of the seven cities. The relative risk of hospital admission for congestive heart failure associated with an increase of 10 ppm in carbon monoxide ranged from 1.10 in New York to 1.37 in Los Angeles. CONCLUSIONS: Hospital admissions for congestive heart failure exhibited a consistent association with daily variations in ambient carbon monoxide. This association was independent of season, temperature, and other major gaseous pollutants.
BACKGROUND: The elderly represent a susceptible subpopulation that experiences disproportionate levels of morbidity and mortality from respiratory disease. As a consequence, they are frequently hospitalized for these conditions. Evaluating the geographic distributions of these hospital admissions can provide useful insights concerning patterns in incidence and medical care for respiratory diseases. METHODS: All hospital admissions for pneumonia, acute respiratory infections, asthma, and chronic obstructive pulmonary disease from the United States for a 6-year period (1984 through 1989) were identified using Medicare admissions records. Age-, race-, and sex-standardized annual admission rates were calculated for each county and spatial clustering of disease specific rates was evaluated using Moran's I statistic. Ecologic analyses were conducted using multiple regression procedures with county-specific measures of average annual temperature, average income, household crowding, median educational level, population density, physicians per capita, and hospital beds per capita together with surrogate measures of cigarette consumption and occupational exposures as predictor variables. RESULTS: Hospital admission rates in the elderly for all four categories of respiratory disease showed marked regional elevations (p < 0.0001), particularly in the southeast and the northern plains states. Low median education level, low per capita income, and household crowding were all associated with elevated hospital admission rates. Surrogate measures of cigarette consumption were strongly associated with hospital admissions in all four disease groups. Hospital beds per capita demonstrated positive associations with hospital admissions, but the number of physicians per capita exhibited consistent inverse relationships with hospital admissions. CONCLUSIONS: Hospital admission rates for respiratory diseases among the elderly show marked geographic variation and are associated with regional indicators of socioeconomic status, availability of medical resources, occupational lung disease rates, and smoking.
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The availability of large data sets together with the growth in power and storage capabilities of computers have made the analysis of the spatial distribution of disease rates an increasingly important tool in public health research. Use of existing geographic divisions or groupings tends to result either in unstable estimates of disease rates if the corresponding populations are small or in loss of spatial resolution if the areas are unnecessarily large. This paper describes a computer algorithm for combining existing geographic areas into regions with populations large enough to diminish spurious variability in disease rates while limiting the loss in resolution. The method is demonstrated using Medicare hospital admissions data for pneumonia and central nervous system cancer. Disease rates were calculated for both predefined regions and those generated by the algorithm and their frequency distributions were compared. The algorithm produces more stable rates over a variety of diseases and provides substantially more flexibility than the use of predefined aggregations.
Maps of disease rates are often used to identify regions with elevated disease rates. The goal of this study was to develop and evaluate a regional measure of spatial autocorrelation for localization of these clusters. A regional spatial autocorrelation coefficient (RSAC) was defined and a theoretical mean and standard deviation was derived for its probability distribution. The RSAC was used to identify spatial units that belong to disease clusters. The sensitivity and specificity of the RSAC method in detecting simulated disease clusters was evaluated. For comparison the simulated data were also used to evaluate methods employed by the National Cancer Institute (NCI) for mapping cancer mortality in the United States. The distribution of pancreatic cancer among the elderly white male population in the United States was also evaluated. Within a simulated disease cluster with a relative risk of 2, the RSAC method detected between 75 per cent and 91 per cent of the units depending on the size of the spatial unit used for the analysis. The corresponding sensitivities of the NCI method ranged from 9 per cent to 68 per cent. The RSAC map of pancreatic cancer demonstrated an area of positive clustering (clustering of high rates) in the south central United States. The RSAC method localized disease clusters with greater sensitivity than the NCI method, particularly when geographic units were small. The RSAC method is an effective tool for the identification of regional disease clusters.
OBJECTIVE: This paper describes a pilot project to develop and implement a low-cost system for ongoing surveillance of childhood asthma in Milwaukee County, Wisconsin. METHODS: The authors organized a planning workshop to solicit information and ideas for an asthma surveillance system, bringing together national experts with Milwaukee professionals and community representatives involved in the prevention and treatment of asthma. Based on recommendations from the workshop, a pilot surveillance project was implemented in Milwaukee County using records of emergency room visits and hospital admissions for asthma abstracted from the computerized billing records of the Children's Hospital of Wisconsin (CHW), retrospectively for 1993 and prospectively for 1994. Retrospective data were also sought from the other hospital emergency departments in Milwaukee County to evaluate the representativeness of the CHW data. Surveillance data were used to evaluate utilization of care by patient subgroups and to describe temporal patterns in emergency room visits. RESULTS: Of the emergency department visits for asthma in Milwaukee County in 1993, CHW accounted for 94% among infants less than 1 year of age, 89% among children ages 1 through 5 years, and only 59% among children between the ages of 6 and 18 years. In 1994, the 7% of asthmatic children with repeat hospital admissions accounted for 38% of all hospital admissions for asthma and the 20% with repeat emergency department visits accounted for 50% of all emergency visits. Emergency visits for asthma showed clear seasonality, with a peak in the fall and a smaller peak in the spring. CONCLUSIONS: Computerized medical billing data provide an opportunity for asthma surveillance at a relatively low cost. The data obtained are useful for tracking trends in exacerbations of asthma and the use of medical services for asthma care and should prove valuable in targeting interventions.