The risk of seizures after receipt of whole-cell pertussis or measles, mumps, and rubella vaccine.

BACKGROUND: The administration of the diphtheria and tetanus toxoids and whole-cell pertussis (DTP) vaccine and measles, mumps, and rubella (MMR) vaccine has been associated with adverse neurologic events, including seizures. We studied the relation between these vaccinations and the risk of a first seizure, subsequent seizures, and neurodevelopmental disability in children. METHODS: This cohort study was conducted at four large health maintenance organizations and included reviews of the medical records of children with seizures. We calculated the relative risks of febrile and nonfebrile seizures among 679,942 children after 340,386 vaccinations with DTP vaccine, 137,457 vaccinations with MMR vaccine, or no recent vaccination. Children who had febrile seizures after vaccination were followed to identify the risk of subsequent seizures and other neurologic disabilities. RESULTS: Receipt of DTP vaccine was associated with an increased risk of febrile seizures only on the day of vaccination (adjusted relative risk, 5.70; 95 percent confidence interval, 1.98 to 16.42). Receipt of MMR vaccine was associated with an increased risk of febrile seizures 8 to 14 days after vaccination (relative risk, 2.83; 95 percent confidence interval, 1.44 to 5.55). Neither vaccination was associated with an increased risk of nonfebrile seizures. Analyses of automated data alone gave results similar to the analyses of the data from medical-record reviews. The number of febrile seizures attributable to the administration of DTP and MMR vaccines was estimated to be 6 to 9 and 25 to 34 per 100,000 children, respectively. As compared with other children with febrile seizures that were not associated with vaccination, the children who had febrile seizures after vaccination were not found to be at higher risk for subsequent seizures or neurodevelopmental disabilities. CONCLUSIONS: There are significantly elevated risks of febrile seizures on the day of receipt of DTP vaccine and 8 to 14 days after the receipt of MMR vaccine, but these risks do not appear to be associated with any long-term, adverse consequences.

Clinical assessment of HIV-associated lipodystrophy in an ambulatory population.

OBJECTIVE: To identify clinical factors associated with prevalence of fat atrophy (lipoatrophy) and fat accumulation (lipoaccumulation) in HIV-1 infected patients. DESIGN: Evaluation of HIV-1 infected patients seen for routine care between 1 October and 31 December 1998 in the eight HIV Outpatient Study (HOPS) clinics. SETTING: Eight clinics specializing in the care of HIV-1 infected patients. PATIENTS: A total of 1077 patients were evaluated for signs of fat maldistribution. INTERVENTIONS: A standardized set of questions and specific clinical signs were assessed. Demographic, clinical and pharmacological data for each patient were also included in the analysis. MAIN OUTCOME MEASURES: Demographic, immunologic, virologic, clinical, laboratory, and drug treatment factors were assessed in stratified and multivariate analyses for their relationship to the presence and severity of fat accumulation and atrophy. RESULTS: Independent factors for moderate/severe lipoatrophy for 171 patients were increasing age, any use of stavudine, use of indinavir for longer than 2 years, body mass index (BMI) loss, and measures of duration and severity of HIV disease. Independent risk factors for moderate/severe fat accumulation for 104 patients were increasing age, BMI gain, measures of amount and duration of immune recovery, and duration of antiretroviral therapy (ART). The number of non-drug risk factors substantially increased the likelihood of lipoatrophy. If non-drug risk factors were absent, lipoatrophy was unusual regardless of the duration of drug use. CONCLUSIONS: HIV-associated lipodystrophy is associated with several host, disease, and drug factors. While prevalence of lipoatrophy increased with the use of stavudine and indinavir, and lipoaccumulation was associated with duration of ART, other non-drug factors were strongly associated with both fat atrophy and accumulation.

The incidence of Kawasaki syndrome in West Coast health maintenance organizations.

BACKGROUND: Kawasaki syndrome (KS) causes an acute vasculitis of unknown etiology. It is a leading cause of acquired heart disease of children in Japan and the United States. METHODS: We examined the incidence of KS in a well-defined population group of children < or =6 years of age, using data collected through the Vaccine Safety Datalink (VSD) project. The VSD database contains information on >1 million children enrolled in four West Coast health maintenance organizations (HMOs). RESULTS: During 1993 through 1996 a total of 234 physician-diagnosed KS patients were reported in the 4 HMOs; 152 (65.0%) were boys and 195 (83.3%) were <5 years of age. The incidence of KS among children <5 years of age in the HMOs ranged from 9.0 to 19.1 per 100,000 person years. KS incidence was higher among boys in 3 of the sites. In the 2 sites with the highest number of KS patients, a seasonal occurrence of KS in winter and early spring was observed. Overall 226 (96.6%) of the KS patients were reported to have been hospitalized; hospitalization rates for children <5 years of age ranged from 9.0 to 16.8 per 100,000 person years. CONCLUSIONS: The incidence of KS in the HMOs was similar to that reported in other population-based studies in the United States and higher than estimates for Australia and several European countries.

Ukraine, 1992: first assessment of diphtheria vaccine effectiveness during the recent resurgence of diphtheria in the Former Soviet Union.

A case-control study in Ukraine provided the first data on the field effectiveness of Russian-produced vaccine during the 1990 diphtheria resurgence in the former Soviet Union. For each of 262 diphtheria cases <15 years of age who were reported from January through October 1992, 2 controls, matched by age and clinic, were selected. The effectiveness of three doses of diphtheria vaccine was 98.2% (95% confidence interval: 90.3-99.9). Among controls, 84% had received three or more vaccinations by 2 years of age. These results suggest that the following five hypothesized causes of the outbreak appeared unlikely: appearance of a new "mutant" diphtheria strain, low potency of the Russian-produced diphtheria vaccine, inadequate cold chain, poor host immunogenicity due to radiation exposure from Chernobyl, and low routine childhood vaccination coverage. It is concluded that initial priority for scarce resources for controlling this outbreak should be placed on vaccination of persons susceptible to diphtheria (e.g., adults) rather than revaccination of children.

HIV-1 seroprevalence among childbearing women in northern Thailand: monitoring a rapidly evolving epidemic.

OBJECTIVES: To describe trends in prevalence of HIV-1 infection among women giving birth at Chiang Rai Hospital (CRH) and to assess risk factors associated with HIV infection in this population. DESIGN: Analysis of hospital registry data for all deliveries at CRH from 1990 to mid-1997. METHODS: From 1990 to mid-1997, women giving birth at CRH were tested for HIV-1 infection using enzyme immunoassay (EIA); positive sera were confirmed using a different manufacturer's EIA. Demographic and clinical data were abstracted from delivery-ward log books. RESULTS: Data from 40723 deliveries indicated that overall HIV-1 seroprevalence increased sharply, from 1.3% in 1990 to a peak of 6.4% in 1994, and then declined to 4.6% in the first 6 months of 1997. Prevalence was highest, at 7.0%, among young (age < or = 24 years) primigravidas, compared with 2.4% among older (age > or = 25 years) multigravidas. When we controlled for age, prevalence declined 40% from 1994 to 1997 among young primigravidas (95% confidence interval for percentage reduction, 16-57). Amongst older multigravid women, prevalence was consistently lower but increased steadily from 2.7% in 1994 to 3.4% in 1997. CONCLUSIONS: A rapid rise in HIV prevalence in childbearing women was followed by a sharp decline among young primigravidas. In each year, the prevalence was highest among young primigravidas. They may be the best subgroup of pregnant women for monitoring HIV epidemic trends, but they also represent a challenging prevention priority that will require its own targeted interventions.

Risk of diphtheria among schoolchildren in the Russian Federation in relation to time since last vaccination.

BACKGROUND: Between 1990 and 1996, more than 110,000 cases and 2900 deaths from diphtheria were reported in the Russian Federation. In 1994, because disease rates were high among children aged 7-10 years, the age of administration of the second booster dose of diphtheria vaccine was lowered from 9 years to 6 years, the age of school entry. To assess the impact of this policy change, we did a matched case-control study in three Russian cities. METHODS: Children aged 6-8 years who had diphtheria between September, 1994, and December, 1996, were each matched with five to seven children acting as controls who were within 3 months of age of the case and were from the same class at school. We did a matched analysis using conditional logistic regression. FINDINGS: We analysed the immunisation records of 58 cases and 306 controls. All but one case and all controls had received at least three doses of diphtheria-toxoid vaccine. 19 (33%) cases and 144 (47%) controls had received a booster dose of diphtheria toxoid within the previous 2 years. Cases were more likely than were controls to have received only four doses rather than five (odds ratio 2.8 [95% CI 1.2-6.5]) and to have a time since the last dose of diphtheria toxoid of 3-4 years (3.1 [1.1-9.1]) or 5-7 years (15.0 [2.5-89.0]), compared with children for whom it was 2 years or less. On multivariate analysis only a time since the last dose of 5-7 years remained significantly associated with disease (matched odds ratio adjusted for total number of doses 10.9 [1.6-75.1]). CONCLUSION: A booster dose of diphtheria-toxoid vaccine given to children in the Russian Federation at 6-8 years of age reduced the interval since the last dose of diphtheria toxoid and improved protection against diphtheria.

PIP: More than 110,000 cases and 2900 deaths from diphtheria were reported in the Russian Federation in 1990-96. In response to the high disease rates in children 7-10 years of age, the timing of the second booster dose of diphtheria vaccine was lowered in 1994 from 9 to 6 years of age--the age of school entry. The impact of this change was assessed in a matched, retrospective, case-control study conducted in three Russian cities. 58 children 6-8 years old who had diphtheria between September 1994 and December 1996 were matched with 306 controls within 3 months of age and from the same school class. All but one case and all controls had received at least three doses of diphtheria toxoid vaccine and 19 cases (33%) and 144 controls (47%) had received a booster dose of the vaccine within the previous 2 years. Cases were more likely than controls to have received 4 rather than 5 doses (odds ratio (OR), 2.8; 95% confidence interval (CI), 1.2-6.5) and to have an interval since the last vaccine dose of 3-4 years (OR, 3.1; 95% CI, 1.1-9.1) or 5-7 years (OR, 15.0; 95% CI, 2.5-89.0) compared with children for whom it was 2 years or less since the last dose. In the multivariate analysis, only time since the last vaccine dose of 5-7 years was significantly associated with disease (matched OR adjusted for total number of doses, 10.9; 95% CI, 1.6-75.1). These findings indicate that a booster dose of diphtheria toxoid at the age of school entry is effective in preventing diphtheria among school-aged children. This evidence should be considered in the development of routine childhood immunization schedules in countries where diphtheria remains endemic.

Epidemiology of diarrheal disease among children enrolled in four West Coast health maintenance organizations. Vaccine Safety Datalink Team.

BACKGROUND: We used information from the Vaccine Safety Datalink (VSD) about approximately 1 million children enrolled in four health maintenance organizations to assess the morbidity from diarrhea and estimate the disease burden of rotavirus. METHODS: We examined trends of diarrhea-associated hospitalizations and emergency room (ER) visits among VSD children ages 1 month through 4 years during October, 1992, through September, 1994 (two rotavirus seasons) and estimated the morbidity from rotavirus on the basis of characteristic patterns of age and seasonality. RESULTS: Overall diarrhea was associated with 6.3% of hospitalizations and 4% of ER visits. During a child's first 5 years of life, we estimated that 1 in 57 was hospitalized and 1 in 21 required an ER visit because of diarrhea. Each year the number of diarrhea-associated hospitalizations and ER visits was greatest in winter among children ages 4 to 23 months and peaked in November in California and during February in Oregon and Washington. The winter seasonality of diarrhea-associated hospitalizations reflected the trends for diarrhea of presumed noninfectious and viral etiologies, which together accounted for most (92.9%) hospitalizations. CONCLUSIONS: Diarrhea is an important cause of morbidity among VSD children. The epidemiologic patterns of diarrhea-associated hospitalizations and ER visits resembled those reported previously for rotavirus diarrhea, suggesting that rotavirus may be a major contributor to the overall morbidity from diarrhea. Enhanced surveillance by screening for rotavirus in a sample of children with diarrhea will permit a more accurate assessment of the disease burden of this pathogen and the cost effectiveness of a rotavirus immunization program.

The interruption of transmission of indigenous measles in the United States during 1993.

BACKGROUND: The United States has a goal to eliminate all indigenous cases of measles by the year 2000. Initial interruption of indigenous measles transmission would be expected during a period of very low measles incidence as occurred during late 1993. METHODS: Indigenous measles cases (i.e. cases acquired in the United States and not traceable to any imported case) from 1993 were investigated to determine their source of infection. The probability of sustained undetected measles transmission between isolated indigenous cases was estimated. RESULTS: Of the 312 measles cases reported for 1993, only 25 (8%) occurred after September 19. Of these only 4 cases (16%) could be classified as indigenous. The estimated probability that any of these 4 cases resulted from indigenous measles transmission in theirs or any adjoining counties was 0.05 or less. CONCLUSIONS: Interruption of indigenous measles transmission appears to have occurred for the first time throughout the United States in 1993. This event provides strong support for the current national strategy for measles elimination. However, complete elimination of indigenous measles will require maintaining high population immunity to prevent spread from imported cases and attaining global measles control to prevent the importation of measles.

Vaccine Safety Datalink project: a new tool for improving vaccine safety monitoring in the United States. The Vaccine Safety Datalink Team.

OBJECTIVE: To fill the large "gaps and limitations" in current scientific knowledge of rare vaccine adverse events identified in recent reviews of the Institute of Medicine. METHODS: Computerized information on immunization, medical outcomes, and potential confounders on more than 500 000 children 0 to 6 years of age is linked annually at several health maintenance organizations to create a large cohort for multiple epidemiologic studies of vaccine safety. RESULTS: Analysis of 3 years of follow-up data shows that 549 488 doses of diphtheria-tetanus-pertussis (DTP) and 310 618 doses of measles-mumps-rubella (MMR) vaccines have been administered to children in the study cohort. Analyses for associations between vaccines and 34 medical outcomes are underway. Screening of automated data shows that seizures are associated with receipt of DTP on the same day (relative risk [RR], 2.1; 95% confidence interval [CI], 1.1 to 4.0) and 8 to 14 days after receipt of MMR (RR, 3.0; 95% CI, 2.1 to 4.2). The diversity of vaccination exposures in this large cohort permits us to show that an apparent association of seizures 8 to 14 days after Haemophilus influenzae type b vaccine (RR, 1.6; 95% CI, 1.2 to 2.1) was attributable to confounding by simultaneous MMR vaccination; the association disappears with appropriate adjustment (RR, 1.0; 95% CI, 0.7 to 1.4). CONCLUSION: Preliminary design, data collection, and analytic capability of the Vaccine Safety Datalink project has been validated by replication of previous known associations between seizures and DTP and MMR vaccines. The diversity in vaccine administration schedules permits potential disentangling of effects of simultaneous and combined vaccinations. The project provides a model of public health-managed care collaborations in addition to an excellent infrastructure for safety and other studies of vaccines.

The risk of Guillain-Barré syndrome after tetanus-toxoid-containing vaccines in adults and children in the United States.

OBJECTIVES: This study examined whether there is a risk that tetanus-toxoid-containing vaccines could cause Guillain-Barré syndrome and, if so, how large the risk is. METHODS: This study was based on previous active surveillance epidemiological studies of Guillain-Barré syndrome and vaccination history. RESULTS: A background rate of 0.3 cases of Guillain-Barré syndrome per million person-weeks has been estimated. By chance, 2.2 people with the syndrome would have received tetanus-toxoid-containing vaccine within the 6 weeks before onset, yet only 1 person had done so. Data on children show similar results. CONCLUSIONS: If an association exists, it must be extremely rare and not of public health significance.

Influenza vaccination programs for elderly persons: cost-effectiveness in a health maintenance organization.

OBJECTIVE: To estimate the cost-effectiveness and net medical care costs of programs for annual influenza vaccinations for the elderly in a health maintenance organization (HMO). DESIGN: Population-based, case-control study. SETTING: The Northwest Region of Kaiser Permanente, a prepaid group practice HMO in Portland, Oregon. PARTICIPANTS: Kaiser Permanente members 65 years of age and older who had at least 1 month of HMO eligibility during any of nine influenza seasons in the 1980s. MEASUREMENTS: The HMO's costs for providing medical care and conducting vaccination programs were estimated using accounting data. RESULTS: 32% of high-risk elderly persons and 22% of non-high-risk elderly persons received influenza vaccinations. Aggregate vaccine effectiveness in preventing pneumonia and influenza hospitalizations was 30% (95% CI, 17% to 42%) for high-risk and 40% (CI, 1% to 64%) for non-high-risk elderly persons. The net savings to the HMO per vaccination was $6.11 for high-risk elderly persons and $1.10 for all elderly persons. The HMO incurred a net cost of $4.82 per vaccination for non-high-risk elderly persons. CONCLUSIONS: Influenza vaccination rates in this HMO were relatively low for high-risk elderly persons. The medical care costs saved by preventing pneumonia and influenza through vaccination of high-risk elderly persons provide a compelling rationale to increase compliance with recommendations for annual influenza vaccination. Indirect benefits, such as prevention of suffering, incapacity, and lost wages, are likely to compensate for the small net cost of vaccinating non-high-risk elderly persons.

Immunogenicity of a supplemental dose of oral versus inactivated poliovirus vaccine.

In many developing countries, the immunogenicity of three doses of live, attenuated, oral poliovirus vaccine (OPV) is lower than that in industrialised countries. We evaluated serum neutralising antibody responses in 368 children aged 6 months and 346 children aged 9 months in Côte d'Ivoire who had previously received three doses of OPV at 2, 3, and 4 months of age, and who were then randomised to receive a supplemental dose of OPV or enhanced-potency inactivated poliovirus vaccine (IPV) at the time of measles vaccination. Although both vaccines increased seroconversion to all three poliovirus types, antibody responses were greater in the IPV group. Among children with no detectable antibody at baseline, IPV was 2 to 14 times more likely than OPV to induce seroconversion (type 1, 80% vs 40% at 6 months [p < 0.001] and 81% vs 14% at 9 months [p < 0.001]; type 3, 76% vs 22% at 6 months [p < 0.001], and 67% vs 5% at 9 months [p < 0.001]. Among children with detectable antibody at baseline, IPV was 1.4 to 7 times more likely than OPV to elicit 4-fold or more rises in antibody titre (p < 0.01). Geometric mean titres (GMTs) to all three poliovirus types were also consistently higher among IPV recipients than in OPV recipients when measured 4-6 weeks and 13-17 months after vaccination. Administration of a supplemental dose of IPV or OPV, which requires no additional visits or changes in the existing immunisation schedule, might improve protection against paralytic poliomyelitis in communities with suboptimum seroconversion rates after three doses of OPV.

Preterm delivery among black and white enlisted women in the United States Army.

OBJECTIVE: To examine black-white differences in preterm delivery in a healthy population who had unrestricted access to prenatal care. METHODS: We conducted a retrospective cohort study of 842 black and 1026 white enlisted servicewomen who delivered a singleton infant of 20 or more weeks' gestation from July 1, 1987 through September 30, 1990 at four Army Medical Centers in the United States. Data were collected by reviewing maternal and newborn records. We used logistic and proportional hazards regression models to analyze outcomes defined by length of gestation, cause of preterm delivery, and jointly by length and cause. RESULTS: Black enlisted women had a cumulative probability of preterm delivery (13.5%) that was higher than that for white enlisted women (10.5%) (hazard ratio 1.31, 95% confidence interval [CI] 1.002-1.70). However, the ratio of black-to-white hazards was not uniform. Black-white differences were small and nonsignificant from 33-36 weeks' gestation, when most preterm deliveries occur. The differences were also small and nonsignificant for deliveries related to spontaneous rupture of membranes or idiopathic preterm labor, the most common causes of preterm delivery. The black-to-white hazard ratios were greatest for all deliveries before 33 weeks' gestation and for medically indicated preterm deliveries. CONCLUSIONS: Efforts to reduce black-white differences in preterm delivery must go beyond providing prenatal care and eliminating recreational drug use. Future studies should consider black-white differences in environments during the mother's own development and in psychosocial and physical stresses during pregnancy.

Identification of nonfatal family and intimate assault incidents in police data.

We examined different strategies for identifying nonfatal family and intimate assaults (FIAs) in police data. Police most often classify such incidents in the "assault" category, but they also use other crime categories. We estimated that, during 1984, 3300 FIAs (or 837 per 100,000 population) occurred in Atlanta. Of those, 77% were classified as assaults; 23% were classified in nonassault categories. Research measuring the magnitude of FIAs should take into account incidents classified in nonassault crime categories.

Weapon involvement and injury outcomes in family and intimate assaults.

OBJECTIVE: To compare the risk of death and the risk of nonfatal injury during firearm-associated family and intimate assaults (FIAs) with the risks during non-firearm-associated FIAs. DESIGN: Records review of police incident reports of FIAs that occurred in 1984. Victim outcomes (death, nonfatal injury, no injury) and weapon involvement were examined for incidents involving only one perpetrator. SETTING: City of Atlanta, Ga, within Fulton County. PARTICIPANTS: Stratified sample (n = 142) of victims of nonfatal FIAs, drawn from seven nonfatal crime categories, plus all fatal victims (n = 23) of FIAs. MAIN OUTCOME MEASURES: Risk of death (vs nonfatal injury or no injury) during FIAs involving firearms, relative to other types of weapons; risk of nonfatal injury (vs all other outcomes, including death) during FIAs involving firearms, relative to other types of weapons. RESULTS: Firearm-associated FIAs were 3.0 times (95% confidence interval, 0.9 to 10.0) more likely to result in death than FIAs involving knives or other cutting instruments and 23.4 times (95% confidence interval, 7.0 to 78.6) more likely to result in death than FIAs involving other weapons or bodily force. Overall, firearm-associated FIAs were 12.0 times (95% confidence interval, 4.6 to 31.5) more likely to result in death than non-firearm-associated FIAs. CONCLUSIONS: Strategies for limiting the number of deaths and injuries resulting from FIAs include reducing the access of potential FIA assailants to firearms, modifying firearm lethality through redesign, and establishing programs for primary prevention of violence among intimates.

Survival of hemophilic males with acquired immunodeficiency syndrome with and without risk factors for AIDS other than hemophilia.

Between January 1, 1981, and June 30, 1990, 1,514 hemophilia-associated acquired immunodeficiency syndrome (AIDS) cases in males were diagnosed in the United States. In 1,394, hemophilia was reported as the sole risk factor. For an additional 120, other risk factors were reported: of 101 of these, 40 had homosexual/bisexual activity, 53 had a history of intravenous drug use, and 8 had both of these risk factors. We examined the demographic data and the survival data of two principal groups: males for whom hemophilia was the sole reported risk factor for human immunodeficiency virus (HIV) exposure, and hemophilic males for whom homosexual/bisexual activity, intravenous drug use, or both of these additional risk factors were reported. The survival curves showed marginal differences between the hemophilia-only and the multiple risk groups; the median survival times were 13.1 and 14.6 months, with the cumulative probability of survival at 1 year as 52.7% and 54.0%, respectively. Kaposi's sarcoma was among AIDS indicator diseases more commonly found in the multiple risk factor group. Pneumocystis carinii pneumonia was the sole reported diagnosis indicative of AIDS for 34.4% of those in the hemophilia-only group, compared with 20.8% of those with multiple risk factors. The principal demographic difference between the two groups was the age distribution; those in the multiple risk factor group were primarily between 20 and 44 years of age. Restricting the analysis to those between 20 and 44 years resulted in a slightly longer survival time in the hemophilia-only group and no appreciable difference between the disease distributions and survival curves of the two groups.

Another look at the black-white gap in gestation-specific perinatal mortality.

In the US, black infants born near or at term experience higher mortality than white infants. To extend our understanding of black-white differences in the relative advantages of growth (measured by birthweight) for gestational age, we compared race-specific rates of perinatal mortality by deviation in grams from the median birthweight for four categories of gestation (35-36, 37-38, 39-41, and 42-43 weeks). We also used race-specific standards to examine the difference between the median birthweight and the optimum birthweight (i.e. birthweight with the lowest mortality). The data, which were derived from vital records for singletons delivered in the US from 1983-1984, comprised 24,626 fetal and neonatal deaths among 5,157,197 white infants and 5973 fetal and neonatal deaths among 926,678 black infants. At all deviations from the median birthweight, black infants had relatively better survival at 35-36 weeks of gestation. This advantage was reversed among infants with gestations of 39-41 and 42-43 weeks. The optimum birthweight for black infants with gestations greater than or equal to 37 weeks was closer to their median birthweight than was that for white infants. For black infants with gestations of 39-41 weeks, the optimum birthweight was 187g (95% confidence interval (CI): 150-234) greater than the median birthweight (3289g); for comparable white infants the optimum birthweight was 397g (95% CI: 366-431) greater than the median birthweight (3487g). To reduce the black-white gap in perinatal mortality, we need a better understanding of aetiological relations between gestation, growth, and mortality.

Postneonatal deaths from infections and injuries: race, maternal risk, and age at death.

Most infants with birthweights greater than or equal to 2,500 g who survive the first 27 days of life have a reasonable opportunity to grow into healthy children. However, some of these infants succumb to two potentially preventable causes of death: infections and injuries. Although the relationship between maternal attributes and risk of death from these causes has been described, little is known about how maternal attributes relate to postneonatal age at death. To examine this relationship, we analyzed postneonatal deaths from infections and injuries among 3,116,391 white and 638,915 black neonatal survivors with birthweights greater than or equal to 2,500 g. We grouped postneonates by maternal race and risk status. Infants of mothers greater than or equal to 20 years of age who started prenatal care in the first trimester were considered low risk; all others were high risk. For each category of infection death (respiratory, central nervous system, and other bacterial--including sepsis), neither race nor maternal risk status was related to age at death. The same was true for three categories of injury death (motor vehicle, fire, and homicide), but not for injury deaths in the category of choking, drowning, or suffocation. Among blacks, these deaths occurred at younger ages, regardless of maternal risk status. Thus, efforts to prevent deaths from choking, drowning, or suffocation among blacks should focus on early infancy.

Electrohydrodynamic effects in continuous flow electrophoresis.

We demonstrate experimentally and theoretically the importance of electrohydrodynamic (EHD) flows in continuous-flow electrophoresis (CFE) separations. These flows are associated with variations in the conductivity or dielectric constant, and are quadratic in the field strength. They appear to be the main cause of extraneous and undesired flows in CFE which have degraded separation performance and have until now not been explained. We discuss the importance of EHD flows relative to other effects. We also describe possible techniques for reducing the associated degradation of CFE separations.

Are race and length of gestation related to age at death in the sudden infant death syndrome?

Although race and preterm delivery are known to be associated with sudden infant death syndrome (SIDS), the relationships between age at death from SIDS and these factors have not been well described. To examine these relationships, we used linked infant birth and death records for the cohort of 1,204,375 White and 283,776 Black postneonates who were born from 1979 to 1981 in five states: California, Georgia, Missouri, South Carolina and Tennessee. Deaths attributable to SIDS occurred to 1404 White postneonates and to 696 Black postneonates. Although postneonatal SIDS rate among Black infants was twice that of White infants, the relative risk was smaller among infants with gestations of less than 35 weeks. For White postneonates, the median postneonatal age at death sharply declined for gestations from 28-29 weeks to 36-37 weeks and levelled off for longer gestations. For Black postneonates, the results do not support an association between length of gestation and age at death. The findings suggest that practitioners investigating approaches to avert SIDS need to maintain their interventions to an older age among White preterm infants. Researchers investigating the causes of SIDS need to consider the relationship between length of gestation and age at death from SIDS as well as possible developmental differences between White and Black preterm infants.