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Biomedical subjects

David E Clark

Publications and source records attributed to David E Clark.

11 recordsLinked to original sources
PubMed2003

Effect of population density on mortality after motor vehicle collisions.

The objective of this study was to evaluate the effect of population density on mortality after traffic crashes. Subjects were the drivers of vehicles requiring towing after collisions, sampled by NASS-GES during 1994-1998. Cases were classified by population of crash location (greater or lesser than 25,000) and by population density of the driver's county of residence (using ZIP code and Census data). Cases were also categorized by age, belt use and vehicle speed. Analytic methods for weighted, stratified survey data were used to estimate effects on mortality. A total of 190,721 cases with a specified crash location were identified in the sample, of which 93.7% had a specified population at the crash location, and 94.1% could be linked to the driver's county data. Mortality was higher in locations with populations less than 25,000 and was inversely proportional to the driver's county population density. Age, belt use, and vehicle speed also affected mortality significantly, but the effect of rural location remained after controlling for these factors (O.R. 2.10, 95% C.I. 1.62-2.73). The excess risk for residents of rural areas to die in traffic crashes can be attributed in part to post-crash factors.

Accidents, Traffic↗
PubMed2003

Trauma system evaluation using the fatality analysis reporting system.

BACKGROUND: The Fatality Analysis Reporting System (FARS) has recorded detailed data on fatal traffic crashes since 1975. At least three prior studies have used declining mortality rates derived from FARS as evidence of regional trauma system effectiveness. METHODS: FARS and census data were obtained at no cost through the Internet. Previously published studies were replicated graphically including data from additional years before and after the previously reported time periods, and with rates also calculated for control populations. RESULTS: The association of trauma system organization with observed decreases in mortality rates was less convincing when all available data were displayed and other potential factors were considered. Death after traffic crashes, and especially death in hospitals, is becoming less frequent throughout the country. CONCLUSION: FARS is an excellent resource available to all injury researchers, but provides little evidence that some regions have decreased traffic mortality more than others because of trauma systems.

Accidents, Traffic↗
PubMed2003

Predicting passive transport in silico--history, hype, hope.

The development of computational tools for the prediction of passive transport is reviewed with particular reference to four diverse approaches: the rule-of-5, polar surface area, Volsurf and Abraham's General Solvation Equation. To illustrate the current state of the art, several examples of the application of in silico methods in drug design projects drawn from the recent medicinal chemistry literature are presented. In conclusion, the current challenges facing practitioners of this discipline are outlined and possible directions towards their resolution are suggested.

Biological Transport↗
PubMed2003

Management of adult splenic injury: a 20-year perspective.

The objective of this study was to identify changes in the management of blunt splenic injury in adults. Hospital discharge abstract data from Maine were used to identify patients > or = 16 years old discharged between January 1, 1981 and December 31, 2000 with International Classification of Diseases (9th revision) codes indicating splenic injury. Incidence of operative intervention and outcomes for trauma hospitals and other hospitals were determined. The number of splenic injuries was about 75 per year for the first 15 years increasing to 96 per year in the last 5-year period. The rate of operative intervention declined from 71 to 41 per cent and was lower at the trauma hospitals during the last two 5-year periods (41% vs 53%). The rate of operative intervention > 24 hours after admission was 2.2 per cent during the last 10 years of study. The rate of splenorrhaphy remained stable at about 12 per cent throughout the study period. Mortality rates were higher at the trauma hospitals as were the numbers of patients with very severe injuries (Injury Severity Score > 25). There has been a marked decrease in rate of operative intervention for splenic injury in adults especially in the last 10 years. Rates of operative intervention were lower at the trauma hospitals despite higher injury severity. Frequency of delayed intervention was low and did not increase with lower operative rate.

Adolescent↗
PubMed2002

Operative technique, paraplegia, and mortality after blunt traumatic aortic injury.

HYPOTHESIS: The use of mechanical circulatory support (MCS) during repair of traumatic aortic injuries is associated with a decreased incidence of postoperative paraplegia and mortality. DESIGN AND SETTING: Historical cohort study with contemporaneous but nonrandomized controls in a tertiary care hospital from July 1, 1988, through December 31, 1999. PATIENTS AND INTERVENTIONS: Consecutive cases undergoing operation for traumatic aortic injuries. Use of MCS (with or without systemic heparinization) determined by surgeon preference. MAIN OUTCOME MEASURES: Incidence of postoperative paraplegia and mortality. RESULTS: Twenty-two patients underwent repair of traumatic aortic injuries using MCS, resulting in no paraplegia but 4 deaths, 3 of them from cerebral ischemia. Thirteen patients had their traumatic aortic injuries repaired using a "clamp-and-sew" or passive shunt technique with no deaths but paraplegia in 2. Compared with an earlier report from our group from January 1, 1975, through June 30, 1988, the annual incidence of traumatic aortic injuries has decreased, whereas the age of patients and proportion of operations using MCS have increased. A review of the recent literature on traumatic aortic injuries reveals an average postoperative paraplegia incidence of 1% with MCS and 16% without MCS. Overall mortality is similar, but others have also reported cases of cerebral ischemia after aortic repair. CONCLUSIONS: The use of MCS during repair of traumatic aortic injuries is associated with a decreased incidence of postoperative paraplegia. The occasional occurrence of cerebral ischemia deserves further study.

Adolescent↗
PubMed2002

Predicted effect of automatic crash notification on traffic mortality.

OBJECTIVE: To estimate the reduction in traffic mortality in the United States that would result from an automatic crash notification (ACN) system. METHODS: 1997 Fatality Analysis Reporting System (FARS) data from 30,875 cases of incapacitating or fatal injury with complete information on emergency medical services (EMS) notification and arrival times were analyzed considering cases at any time to be in one of four states: (1) alive prior to notification; (2) alive after notification; (3) alive after EMS arrival; and (4) dead. For each minute after the crash, transition probabilities were calculated for each possible change of state. These data were used to construct models with (1) number of incapacitating injuries ranging from FARS cases up to an estimated total for the US in 1997; (2) deaths equal to FARS total; (3) transitions to death from other states proportional to FARS totals and rates and (4) other state transitions equal to FARS rates. The outcomes from these models were compared to outcomes from otherwise identical models in which all notification times were set to 1 min. RESULTS: FARS data estimated 12,823 deaths prior to notification, 1800 after notification, and 14,015 between EMS arrival and 6 h. If notification times were all set to 1 min, a model using FARS data only predicted 10,703 deaths prior to notification, 2,306 after notification, and 15,208 after EMS arrival, while a model using an estimated total number of incapacitating injuries for the US predicted 9,569 deaths prior to notification, 2,261 after notification, and 15,134 after arrival. In the first model, overall mortality was reduced from 28,638 to 28,217 (421 per year. or 1.5%), while in the second model mortality was reduced to 26,964 (1,674 per year, or 6%). CONCLUSIONS: Modest but important reduction in traffic mortality should be expected from a fully functional ACN system. Imperfect systems would be less effective.

Accidents, Traffic↗
PubMed2002

Increasing importance of the elderly in a trauma system.

The objectives of the study were to determine age- and sex-related trends in hospitalization after injuries. Statewide hospitalization data from 1980-1999 were evaluated annually by sex and age (0-39, 40-64, 65-99), incidence, mean length of stay (LOS), and disposition. Males 0-39 represented 39.6% of admissions in 1980, but only 20.7% in 1999; females >or=65 are now most frequent. These trends partly reflect population changes, but rates of hospitalization for young men have also declined. For age < 65, LOS has gradually decreased since 1980; for age >or=65, LOS decreased after 1990. However, most elderly patients were formerly discharged home, whereas now most are discharged to skilled nursing facilities (SNF). The proportion of younger patients hospitalized in trauma centers increased significantly, but over age 65 this proportion remained stable. Major changes have occurred in populations served by trauma systems. Preventing injuries in the elderly is increasingly important. Accurate evaluation of cost-effectiveness in the elderly must include outcomes from SNF.

Adolescent↗
PubMed2002

Concurrent prediction of hospital mortality and length of stay from risk factors on admission.

OBJECTIVE: To develop a method for predicting concurrently both hospital survival and length of stay (LOS) for seriously ill or injured patients, with particular attention to the competing risks of death or discharge alive as determinants of LOS. DATA SOURCES: Previously collected 1995-1996 registry data on 2,646 cases of injured patients from three trauma centers in Maine. STUDY DESIGN: Time intervals were determined for which the rates of discharge or death were relatively constant. Poisson regression was used to develop a model for each type of terminal event, with risk factors on admission contributing proportionately to the subsequent rates for each outcome in each interval. Mean LOS and cumulative survival were calculated from a combination of the resulting piecewise exponential models. PRINCIPAL FINDINGS: Age, Glasgow Coma Scale, Abbreviated Injury Scores, and specific mechanisms of injury were significant predictors of the rates of death and discharge, with effects that were variable in different time intervals. Predicted probability of survival and mean LOS from the model were similar to actual values for categorized patient groups. CONCLUSIONS: Piecewise exponential models may be useful in predicting LOS, especially if determinants of mortality are separated from determinants of discharge alive.

Adult↗
PubMed2002

Progress in computational methods for the prediction of ADMET properties.

This review surveys recent progress in the development and application of computational techniques for the prediction of absorption, distribution, metabolism, elimination and toxicity (ADMET) properties, including intestinal permeability, blood-brain barrier penetration, active transport/efflux, aqueous solubility, metabolism and toxicity. While much effort continues to be expended in this field with some success on existing datasets, perhaps the most pressing need at this time is for larger, high-quality sets of experimental data to provide a sound basis for model building.

Absorption↗