Impact of hypertension information on high blood pressure control between 1973 and 1978.

To determine whether the immense multifocal efforts in the United States over the past 7 years to detect and treat high blood pressure (BP), had affected the status of hypertension, data from a national household survey in 1973-74 were compared with data obtained in 1977-78 from a second non-overlapping population in the same three communities. The impact of hypertension programs was measured by assessing change over the 5-year period in BP distribution, degree of awareness, and level of treatment in the population. Our data show that a substantial improvement in the status of high BP detection, treatment, and control has occurred since the early 1970s for all age, sex, and race groups studied.

Pediatric brain injuries: the nature, clinical course, and early outcomes in a defined United States' population.

Acute brain injury is the cause of approximately 100,000 pediatric hospital admissions per year in the United States. This report examines the nature of the brain injury, clinical diagnosis, hospital course, and discharge outcome of all pediatric cases in the population of San Diego County, California, for 1981 (N = 709). Brain-injured children were identified from hospital records, death certificates, and coroners' records. Severity of injury was determined using the Abbreviated Injury Scale and the Glasgow Coma Scale. Three percent of brain-injured children died at the accident site; an additional 3% died in the hospital. All in-hospital deaths occurred among the 5% of children with Glascow Coma Scale scores of 8 or less, and in this group the case fatality rate was 59%. Fractures of the skull, present in 23% of cases, seemed to be associated with excess mortality even after type of lesion was considered. Type of lesion, but not presence or absence of a skull fracture, had some predictive power for disability among survivors. Concussion was the most frequent diagnosis. Mildly brain-injured children accounted for 93% of all cases and about 90% of all hospital days.

Chronic fetal hypoxia and sudden infant death syndrome: interaction between maternal smoking and low hematocrit during pregnancy.

To investigate the hypothesis that chronic fetal hypoxia contributes to the etiology of sudden infant death syndrome (SIDS), a possible interaction between the effect of maternal cigarette smoking and low hematocrit during pregnancy on the risk of SIDS was studied using the US Collaborative Perinatal Project cohort. The 193 SIDS cases identified in the cohort were analyzed with 1930 controls randomly selected from infants who survived the first year of life. After adjustment for maternal age, infants born to mothers who smoked 10 or more cigarettes per day and who were anemic (hematocrit less than 30%) during pregnancy were at a much higher risk of SIDS than infants born to mothers who did not smoke and were not anemic (odds ratio = 4.0; 95% confidence limits, 2.1 and 7.4). Smoking 10 or more cigarettes per day vs none increased the risk of SIDS by 70% among women with hematocrit at or above 30% but increased risk threefold among women with hematocrit below 30%. After adjustment for more potential confounders in a logistic regression model, the effect of smoking on SIDS continued to increase with lower levels of hematocrit during pregnancy. Birth weight accounted for very little of these associations. Low hematocrit was not a risk factor for SIDS among nonsmokers but became an important predictor among heavy smokers. These findings are in agreement with the hypothesis that chronic fetal hypoxia may predispose to SIDS, possibly by impairing the normal development of the fetal central nervous system.

Effect of immediate resuscitation on children with submersion injury.

STUDY OBJECTIVE: To determine the effect of immediate resuscitative efforts on the neurological outcome of children with submersion injury. DESIGN: A case-control study was designed to determine if immediate resuscitation by rescuers or bystanders reduces the frequency of severe neurological damage or death in children with a documented submersion event. Logistic regression was used calculate an adjusted odds ratio. PARTICIPANTS: The study group consisted of 166 children, aged zero to 14 years, having a submersion event during May 1984 through August 1992, and admitted through various emergency departments to Huntington Memorial Hospital in Pasadena, California. MEASUREMENTS AND MAIN RESULTS: All study subjects had an observed and documented episode of apnea at the time of submersion. Outcomes were evaluated on the basis of neurological impairment or death. Exposure was verified from historical accounts of postsubmersion events provided by family, friends, and/or paramedical personnel. The study factors included age and gender, duration of submersion, hypothermia, presence of apnea, resuscitative efforts, and clinical outcome. Children with a good outcome were 4.75 (adjusted odds ratio (OR)) times more likely to have a history of immediate resuscitation than children with poor outcome (95% confidence interval: 3.44 < OR < 6.06, P = .0001). Various types of resuscitative efforts and potential confounding factors were also evaluated. CPR and mouth-to-mouth resuscitation were the most effective types for the prevention of death or severe anoxic encephalopathy. CONCLUSION: Immediate resuscitation before the arrival of paramedical personnel is associated with a significantly better neurological outcome in children with submersion injury.

Standard definitions for childhood injury research: excerpts of a conference report.

As awareness of the huge human and other costs of injury has grown, research has expanded. There has not been any standard set of terminology for use in this research. As a result, research and surveillance data are too often difficult to interpret and compare. To overcome this impediment to gains in needed knowledge about childhood injuries, a conference was held in 1989 by the National Institute of Child Health and Human Development to develop a set of standard definitions. The full conference report is available from the US Government Printing Office. This report presents excerpts, emphasizing those--core--variables likely to be of use to the largest number of investigators. The conference recommendations presented address cross-cutting factors (age, race/ethnicity, location, socioeconomic status, and biopsychosocial development), effect modifiers (exposure, medical risk factors, substance abuse, time, injury severity, and social risk factors), and specific injuries (motor vehicle injuries, central nervous system injuries, falls, fire/burns, drowning, and violence). It is expected that childhood injury investigators will strive to meet the recommendations of this conference and that use of these definitions will lead to improvements in research and, ultimately, to revision of the definitions.

GIS mapping of earthquake-related deaths and hospital admissions from the 1994 Northridge, California, Earthquake.

PURPOSE: Earthquakes pose a persistent but unpredictable health threat. Although knowledge of geologic earthquake hazards for buildings has increased, spatial relations between injuries and seismic activity have not been explained. METHODS: Fatal and hospital-admitted earthquake injuries due to the 1994 Northridge Earthquake were identified. Geographical Information Systems software was used to map all injury locations. Injuries were analyzed with regard to distance from the earthquake epicenter, the Modified Mercalli Intensity Index, peak ground acceleration, and proportion of damaged residential buildings. RESULTS: Injury severity was inversely related to distance from the epicenter and increased with increasing ground motion and building damage. However, injury incidence and severity were not completely predicted by seismic hazard and building damage, and injuries of all severities occurred in a large geographic area. Average distance to the epicenter was smallest for injuries related to falling building parts and largest for cutting/piercing injuries and falls. CONCLUSIONS: The injuries from the Northridge Earthquake extended beyond the areas of highest environmental activity. Factors such as age and activity during the earthquake may be equally important in predicting injury from earthquakes as seismic features.

Risk factors for sudden infant death syndrome in the US Collaborative Perinatal Project.

Risk factors for sudden infant death syndrome (SIDS) were studied among infants born to the nearly 56,000 women enrolled in the US Collaborative Perinatal Project from 1959 through 1966. The 193 SIDS cases identified in the cohort were compared with 1930 controls randomly selected from infants who survived the first year of life. The previously documented excess risk associated with black race disappeared after adjusting for maternal education and family income. Maternal smoking, maternal anaemia during pregnancy, and lack of early prenatal care were all positively associated with SIDS. After adjustment for gestational age, infants with low weight and length at birth were still at increased SIDS risk, suggesting that intrauterine growth retardation may be a risk factor. Neurological abnormalities diagnosed before death were associated with SIDS, but much of the association was removed by adjusting for birthweight. The negative association of breastfeeding with SIDS was much reduced upon adjustment by maternal education and birthweight. These findings may have important implications in our understanding of the epidemiology of SIDS.

Cross-national comparison of injury mortality: Los Angeles County, California and Mexico City, Mexico.

BACKGROUND: Cross-national comparisons of injury mortality can suggest possible causal explanations for injuries across different countries and cultures. This study identifies differences in injury mortality between Los Angeles (LA) County, California and Mexico City DF, Mexico. METHODS: Using LA County and Mexico City death certificate data for 1994 and 1995, injury deaths were classified according to the International Classification of Diseases Ninth Revision-Clinical Modification external cause of injury codes. Crude, gender-, and age-adjusted annual fatality rates were calculated and comparisons were made between the two regions. RESULTS: Overall and age-adjusted injury death rates were higher for Mexico City than for LA County. Injury death rates were found to be higher for young adults in LA County and for elderly residents of Mexico City. Death rates for motor vehicle crashes, falls, and undetermined causes were higher in Mexico City, and relatively high rates of poisoning, homicide, and suicide were found for LA County. Motor vehicle crash and fall death rates in Mexico City increased beginning at about age 55, while homicide death rates were dramatically higher among young adults in LA County. The largest proportion of motor vehicle crash deaths was to motor vehicle occupants in LA County and to pedestrians in Mexico City. CONCLUSIONS: These findings illustrate the importance of primary injury prevention in countries having underdeveloped trauma care systems and should aid in setting priorities for future work. The high frequency of pedestrian fatalities in Mexico City may be related to migration of rural populations, differing vehicle characteristics and traffic patterns, and lack of safety knowledge. Mexico City's higher rate of fall-related deaths may be due to concurrent morbidity from chronic conditions, high-risk environments, and delay in seeking medical treatment.

Recall bias in a case-control study of sudden infant death syndrome.

Case-control differences in the accuracy of maternal recall may create spurious associations between suspected risk factors and perinatal conditions. We examined case-control differences in the accuracy of maternal recall and evaluated the impact of maternal reporting errors on observed measures of association. We compared interview information with information recorded on medical records for the mothers of 226 cases of Sudden Infant Death Syndrome (SIDS) and the mothers of 226 living controls. We found that having a child die from SIDS increased the sensitivity of recall for less than half of the 25 study variables. However, for 18 of the 25 variables, the mothers of SIDS cases were more likely than the mothers of living controls to report events that could not be confirmed on medical records. Case-control differences in recall accuracy did not appear to create spurious associations with SIDS or to bias most associations away from the null value.

The application of a modified follow-up life table technique to the study of outpatient clinic services for sickle-cell patients.

A cohort of 60 matched pairs of sickle-cell anaemia (SS) patients from Ibadan, Nigeria and Oakland, California, were compared in a follow-up study. The null hypothesis tested was that there was no significant difference in the morbidity associated with sickle-cell anaemia among Ibadan SS patients receiving antimalarial prophylaxis and Oakland SS patients. Proportions of all clinic visits during which the patients had crises or infections associated with sickle cell anaemia (SSINF) were used as measures of morbidity. A modification of the follow-up life table was used for the analysis. Plots of PX and its confidence bands against frequency of clinic visits due to crises and SSINF were drawn. The Kruskal Wallis test was used to determine any significant differences in the probability of SS patients from either of the two centres visiting the clinic because of crises or SSINF. The results showed no significant differences in these probabilities.

Fatal and hospitalized injuries resulting from the 1994 Northridge earthquake.

BACKGROUND: The Northridge earthquake struck Los Angeles on 17 January 1994, originating from a previously unknown thrust fault. The earthquake measured 6.7 on the Richter scale and caused extensive damage to buildings, utilities and roadways. This report describes injuries occurring in the Northridge earthquake which resulted in death or hospital admission. METHODS: Earthquake-related deaths were identified by the Los Angeles Department of the Coroner. All 78 hospitals in Los Angeles County were screened for earthquake-related admissions and were found in 16 of them. Coroner's records and medical records from the 16 hospitals were individually reviewed to identify earthquake-related injuries and to obtain information about the injury. RESULTS: A total of 171 earthquake-related injuries was identified in Los Angeles County, 33 were fatal and 138 required hospital admission. Injury rates were approximately equal by gender and increased significantly with increasing age. Most of the fatalities were due to building collapse, and most of the hospital-admitted injuries were caused by falls or being hit by objects. Motor vehicle injuries and burns were also common causes of injury. Head and chest injuries were common among fatalities, and extremity injuries were the most common among those admitted to a hospital. CONCLUSION: Earthquakes cause injuries through many mechanisms, and a clearer understanding of these pathways can help focus prevention strategies. Research combining comprehensive surveillance with risk factor assessment can help identify behaviours and circumstances increasing the risk of injury in an earthquake.

The impact of two related prevention strategies on head injury reduction among nonfatally injured motorcycle riders, California, 1991-1993.

Although the traumatic injury death rate in the United States decreased during the last 20 years, the percent of all injury deaths attributable to brain injuries has remained steady. Head injuries are a leading cause of injury among motorcycle riders in crashes, and the helmet is an effective measure to reduce these injuries. To reduce the burden and cost of motorcycle injuries, many states have increased helmet use by introducing mandatory helmet legislation. This report presents evidence on the effects of the motorcycle helmet and helmet use legislation--two interrelated prevention strategies which decrease traumatic brain injury among motorcycle riders. Nonfatally injured motorcyclists were included if they crashed between January 1, 1991 and December 31, 1993 and were treated in one of 18 hospitals in 10 California counties. Medical records for all injured motorcyclists admitted to these 18 hospitals and those treated in the emergency department and released in eight of these hospitals were individually reviewed. Complete lists of injury diagnoses for each rider were coded according to the 1990 Abbreviated Injury Severity Scale by trained clinical staff. Before the universal helmet law was introduced (when only a third of injured riders wore helmets) 38.2% of riders sustained head injuries. When helmet use increased to over 85% of injured riders following the law, less than 25% of riders sustained head injuries. Both the severity and the number of head injuries per individual rider decreased after the mandatory helmet use law led to increased helmet use. Riders wearing helmets suffered fewer skull fractures, fewer intracranial injuries, had less frequent and shorter periods of loss of consciousness, more favorable GCS scores, and shorter hospital stays. Mandatory motorcycle helmet use laws are an effective mechanism to increase helmet use among riders and thus prevent head and brain injuries resulting from motorcycle crashes.

The specific deterrence of administrative per se laws in reducing drunk driving recidivism.

OBJECTIVE: To determine if administrative per se laws are more effective than other forms of sanction against drunk drivers. SEARCH STRATEGIES: The overall goal of the search strategy was to identify all relevant research concerning the specific effects of administrative per se laws in reducing drunk driving recidivism, traffic crashes, and other alcohol-related driving offenses by those drivers with suspended licenses. Known review articles and MEDLINE reviews formed the reference bibliography; numerous databases were searched from 1966 to the present, using such terms as alcohol, driver's license, recidivism, deterrence, and legislation. SELECTION CRITERIA: To be selected the study had to be designed to test the presence of an administrative per se license revocation or restriction in a defined cohort, have a suitable comparison cohort whose sanctions for drunk driving were not administrative per se, and provide relevant data that lead to an objective assessment of recidivism. Types of studies included were randomized controlled trials, nonrandomized controlled trials, other specialized cohort studies, and case-control studies. Three studies were identified; all met inclusion criteria. DATA COLLECTION AND ANALYSIS: One of the studies provided Kaplan-Meier survival curves for failure times defined as days to new conviction following the initial arrest. Odds ratios and 99% confidence intervals were extracted from two of the studies and additional information was supplied by the author of one of the studies. MAIN RESULTS: One study found that one state in the United States experienced a reduction of about one third in repeat arrests for drunk driving over a 3-year period among those who were arrested under administrative per se, relative to recidivism seen in a comparison cohort of drivers prior to administrative per se. Two other states did not experience any change in recidivism. The second study found that drivers whose licenses were suspended under administrative per se were 39% less likely during the first year following suspension to be rearrested on the charge of driving while intoxicated compared with a comparison cohort. This differential persisted into the second year of follow-up, but disappeared by the third year. The third study found both first offenders and repeat offenders arrested under administrative per se were 34% less likely to be involved during the year following their arrest in a subsequent motor vehicle crash compared with those in the comparison cohort. Drivers with administrative per se suspensions were 21% less likely to be involved in additional drunk driving offenses, and 27% less likely to be involved in reckless driving offenses related to alcohol. CONCLUSIONS: Administrative per se laws governing license restriction for drivers have been shown to be effective in some states but not others in decreasing the rates at which these same drivers are subsequently involved in a motor vehicle crash or in another alcohol-related offense, compared with drivers who were sanctioned through other conventional judicial processes. Replications are needed in other states or large driver populations using improved methodology.

The expected impact of a smoking cessation program for pregnant women on infant mortality among Native Americans.

To quantify the expected impact of a smoking cessation program for pregnant women on infant mortality among Native Americans, we estimated the proportional reduction (impact fraction) and the absolute reduction (impact risk) in neonatal and postneonatal mortality as a result of the intervention program. The estimated attributable fraction due to maternal smoking was 16.6% of infant deaths in the Aberdeen Indian Health Service (IHS) Area, 16.2% in the Alaska IHS Area, and 5.2% in the Navajo IHS Area. Under the assumptions that 14% of the smokers participating in a smoking cessation program would quit and that the intervention would have 60% relative efficacy in preventing infant deaths attributable to smoking, the impact fraction was estimated to be 0.9% of all infant deaths in the Aberdeen Area, 1.0% in the Alaska Area, and 0.3% in the Navajo Area. Under the "best" model assumptions (28% cessation rate and 90% relative efficacy), 2.6% of all infant deaths, 3.7% of postneonatal deaths, and 1.2% of neonatal deaths would be prevented by a smoking cessation program in the Aberdeen Area. When applied to 1984-1986 infant mortality data, the impact risk per 100,000 live births under the "best" model assumptions was 10 neonatal deaths and 41 postneonatal deaths in the Aberdeen Area, 10 neonatal and 34 postneonatal deaths in Alaska, and 2 neonatal and 8 postneonatal deaths in the Navajo Area. This report points to the need to develop effective smoking cessation programs for Native Americans, targeted in particular to women of reproductive age.

The epidemiology of drowning in adulthood: implications for prevention.

Previous epidemiological studies of drowning in the United States have dealt primarily with children. The epidemiology and prevention of drowning in adulthood may be very different. To test this general hypothesis, we analyzed the 293 drownings occurring among Sacramento County residents 20 years of age and above during 1974 to 1985. Drowning rates were highest for men 20-29 years of age (11.5 per 100,000 population) and blacks (7.5 per 100,000 population). Swimmers, boaters, and motor vehicle occupants were most frequently represented. Alcohol use was involved in 48% of cases overall and 77% of those involving motor vehicle occupants. A history of seizure disorder was another contributing factor. Important differences do exist in drowning epidemiology between children and adults. Our results suggest that preventing drowning will be more problematic among adults than among children. The study was also used to test the sensitivity of two commonly used methods of case ascertainment for cases in Sacramento County. A manual review of coroner's records had a sensitivity of 96%. A computerized review of death certificate data from the state's vital statistics data base had a sensitivity of 79%. The sources and implications of these differences are discussed.

The occurrence and epidemiologic features of alcohol-related occupational injuries.

This paper presents a review of published literature on alcohol-related occupational injuries. Based on the information presented the true magnitude of the problem of alcohol- and work-related injuries has not been accurately assessed and the epidemiologic features of this problem have not been properly evaluated. There is some evidence, albeit incomplete, that alcohol contributes to work-related injuries, but the extent is not known. Further, the risk of injury by specific industry and occupation has not yet been elucidated. Analytic studies which include control groups and which assess confounding variables are needed so as to aid in the design of effective countermeasure strategies. Even when alcohol is detected, its role in the causal pathway from the worker-energy interaction to injury onset (or exacerbation) has not been studied.

Injury to the head and spinal cord. The epidemiological relevance of the medical literature published from 1960 to 1978.

This article reviews the English language medical literature published from January, 1960, through June, 1978, on selected morbidity measures and economic costs of injury to the head or spinal cord. Most of the reports discussed here come from outside the United States. Regardless of the source of the report, however, one of the most conspicuous shortcomings in the published reports was the lack of uniformity of terms, definitions, and research methods used. Because of severe variations as to source of data, year of study, and methods of investigation, general observations about the occurrence of injury to the head or spinal cord in the United States are limited, and must be regarded with caution.

A comparison of recent studies on the extent of the head and spinal cord injury problem in the United States.

Several recent studies that provide estimates on the occurrence of new cases and the frequency of existing cases of injury to the head or spinal cord in the United States are compared. These studies include the National Head and Spinal Cord Injury Survey, the Health Interview Survey, the Hospital Discharge Survey, and separate investigations of spinal cord injury in Northern California and Connecticut. The comparison made of methodological approaches between the studies will enable the reader to better understand the estimates and why they differ.

Cerebral hyperglycolysis following severe traumatic brain injury in humans: a positron emission tomography study.

Experimental traumatic brain injury studies have shown that cerebral hyperglycolysis is a pathophysiological response to injury-induced ionic and neurochemical cascades. This finding has important implications regarding cellular viability, vulnerability to secondary insults, and the functional capability of affected regions. Prior to this study, posttraumatic hyperglycolysis had not been detected in humans. The characteristics and incidence of cerebral hyperglycolysis were determined in 28 severely head injured patients using [18F]fluorodeoxyglucose-positron emission tomography (FDG-PET). The local cerebral metabolic rate of glucose (CMRG) was calculated using a standard compartmental model. In six of the 28 patients, the global cerebral metabolic rate of oxygen (CMRO2) was determined by the simultaneous measurements of arteriovenous differences of oxygen and cerebral blood flow (xenon-133). Hyperglycolysis, defined as an increase in glucose utilization that measures two standard deviations above expected levels, was documented in all six patients in whom both FDG-PET and CMRO2 determinations were made within 8 days of injury. Five additional patients were found to have localized areas of hyperglycolysis adjacent to focal mass lesions. Within the 1st week following the injury, 56% of patients studied had presumptive evidence of hyperglycolysis. The results of this study indicate that the metabolic state of the traumatically injured brain should be defined differentially in terms of glucose and oxygen metabolism. The use of FDG-PET demonstrates that hyperglycolysis occurs both regionally and globally following severe head injury in humans. The results of this clinical study directly complement those previously reported in experimental brain-injury studies, indicating the capability of imaging a fundamental component of cellular pathophysiology characteristic of head injury.