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Biomedical subjects

C B Hall

Publications and source records attributed to C B Hall.

At least 19 recordsLinked to original sources
PubMed2005

Identifying seizure clusters in patients with epilepsy.

Clinicians often encounter patients whose neurologic attacks appear to cluster. In a daily diary study, the authors explored whether clustering is a true phenomenon in epilepsy and can be identified in the clinical setting. Nearly half the subjects experienced at least one episode of three or more seizures in 24 hours; 20% also met a statistical clustering criterion. Utilizing the clinical definition of clustering should identify all seizure clusterers, and false positives can be determined with diary data.

Adult↗
PubMed2005

Dementia incidence may increase more slowly after age 90: results from the Bronx Aging Study.

BACKGROUND: Dementia incidence increases dramatically from age 65 to age 85, with many studies reporting a doubling every 5 years. The incidence beyond age 85 is not established. OBJECTIVE: To estimate the incidence of dementia as a function of age, with a particular focus on persons aged 85 and over. METHODS: The Bronx Aging Study began in 1980 with 488 healthy, nondemented community-dwelling individuals, age 75 to 85. Persons in the study received clinical examinations and cognitive testing approximately every 12 months until death or loss to follow-up. The diagnosis of dementia was made using Diagnostic and Statistical Manual of Mental Disorders-III-R at diagnostic case conferences. Dementia incidence rates were calculated for 5-year age bands using person-time of follow-up as the denominator. RESULTS: The relative incidence rate ratios of dementia for age 80 to 84 vs 75 to 79 was 2.32 (95% CI 1.23 to 4.37), the relative rate for age 85 to 89 vs 80 to 84 was 1.89 (95% CI 1.26 to 2.83), the relative rate for age 90 to 94 vs 85 to 89 was 1.49 (95% CI 0.86 to 2.58), while the relative rate for age 95 to 99 vs 90 to 94 was 1.31 (95% CI 0.38 to 4.46). Similar results were seen for men and women considered separately. Had the rate of increase from age 75 to 89 continued into the 90s, the study would have had 73% power to detect a significant difference between the rates for age 90 to 94 and 85 to 89 given the amount of observed follow-up time. CONCLUSIONS: Whereas dementia incidence continues to increase beyond age 85, the rate of increase appears to slow relative to that of 65- to 85-year-olds. These results suggest that dementia in the oldest old might be related not to the aging process itself but with age-associated risk factors.

Age Distribution↗
PubMed2003

Low blood pressure and the risk of dementia in very old individuals.

BACKGROUND: The role of blood pressure (BP) as a risk factor for dementia is complex and may be age dependent. In very old individuals, low BP might increase risk for dementia, perhaps by reducing cerebral perfusion pressure. METHODS: The association between BP and dementia was examined in the Bronx Aging Study, a prospective study of 488 community-dwelling elderly individuals over age 75, dementia-free at baseline (1980 to 1983) and followed at 12- to 18-month intervals. Subjects with baseline BP and with at least one follow-up visit were included (n = 406). Incident dementia was diagnosed using the criteria of the Diagnostic and Statistical Manual of Mental Disorders (3rd rev. ed.). RESULTS: Over 21 years (median 6.7 years), 122 subjects developed dementia (65 Alzheimer's disease [AD], 28 vascular dementia, 29 other dementias). Relative risk of dementia increased for each 10-mm Hg decrement in diastolic (hazard ratio [HR] 1.20, 95% CI 1.03 to 1.40) and mean arterial (HR 1.16, 95% CI 1.02 to 1.32) pressure, adjusted for age, sex, and education. Low diastolic BP significantly influenced risk of developing AD but not vascular dementia. Upon examination of groups defined by BP, mildly to moderately raised systolic BP (140 to 179 mm Hg) was associated with reduced risk for AD (HR vs normal systolic BP group 0.55, 95% CI 0.32 to 0.96), whereas low diastolic BP (<or=70 mm Hg) was associated with increased risk of AD (HR vs normal diastolic BP group 1.91, 95% CI 1.05 to 3.48). Subjects with persistent low BP over 2 years had higher risk of developing dementia (HR 2.19, 95% CI 1.27 to 3.77). CONCLUSIONS: Low diastolic pressure is associated with higher risk of dementia in elderly individuals over age 75. Dementia risk was higher in subjects with persistently low BP.

Age Factors↗
PubMed2001

Estimation of bivariate measurements having different change points, with application to cognitive ageing.

Longitudinal studies of ageing make repeated observations of multiple measurements on each subject. Change point models are often used to model longitudinal data. We demonstrate the use of Bayesian and profile likelihood methods to simultaneously estimate different change points in the longitudinal course of two different measurements of cognitive function in subjects in the Bronx Aging Study who developed Alzheimer's disease (AD). Analyses show that accelerated memory decline, as measured by Buschke Selective Reminding, begins between seven and eight years before diagnosis of AD, while decline in performance on speeded tasks as measured by WAIS Performance IQ begins slightly more than two years before diagnosis, significantly after the decline in memory.

Aged↗
PubMed2001

Respiratory syncytial virus infections in previously healthy working adults.

During 1975-1995, a total of 2960 healthy adults, 18-60 years of age, were prospectively evaluated for respiratory virus infections. Of these subjects, 211 (7%) acquired respiratory syncytial virus (RSV) infection. The infections were symptomatic in 84% of subjects, involved only the upper respiratory tract in 74%, and included lower respiratory tract symptoms in 26%. Overall, 40% of the subjects were febrile. Lower respiratory tract signs developed in 26%. RSV illnesses were more prolonged than non-RSV respiratory illnesses. Compared with influenza, RSV infections were less frequently associated with fever and headache, but were associated significantly more often with nasal congestion, ear and sinus involvement, and productive cough. Absence from work during the acute phase of the illness resulted from 38% of RSV infections and 66% of influenza cases. The mean duration of RSV illness (9.5 days), however, was significantly longer than that of influenza (6.8 days). The occurrence of annual epidemics of RSV, the virus' potential to reinfect all age groups, and the morbidity associated with these reinfections suggest that RSV infections in working adults may result in appreciable costs for medical visits and absence from work.

Adolescent↗
PubMed2001

Diagnosing pediatric asthma: validating the Easy Breathing Survey.

OBJECTIVE: To determine the sensitivity, specificity, and predictive value of a simple, self-administered questionnaire for the diagnosis of asthma in children. STUDY DESIGN: A questionnaire specifically designed to assist primary care providers in making a diagnosis of asthma in children was developed and administered in 4 different primary care and subspecialty clinics, validated, and then used as part of an asthma management program called Easy Breathing. Asthma diagnoses were made according to recommended National Asthma Expert Panel Guidelines. RESULTS: Four questions on the survey were shown to be sensitive and specific for asthma. The sensitivity was greater for all levels (mild, moderate, and severe) of persistent asthma than for mild, intermittent asthma. A positive response to any 1 of the 4 questions was over 94% sensitive for asthma; a negative response to all 4 questions was 55% specific for ruling out asthma. CONCLUSIONS: Patient responses to 4 specific respiratory symptom questions can assist primary care providers in diagnosing asthma in children. Primary care providers serving pediatric populations at high risk for asthma should consider asking patients or their parents these 4 questions regarding asthma symptoms on a regular basis.

Adolescent↗
PubMed2000

Nosocomial respiratory syncytial virus infections: the "Cold War" has not ended.

Respiratory syncytial virus (RSV) is a major nosocomial hazard on pediatric wards during its annual outbreaks. It produces significant morbidity in young children and is most severe in those with underlying conditions, especially cardiopulmonary and immunosuppressive diseases. In older patients, RSV may exacerbate an underlying condition or pulmonary and cardiac manifestations. On transplant units, of RSV may be occult and is associated with high mortality rates. The manifestations of nosocomial RSV infections may be atypical, especially in neonates and immunosuppressed patients, resulting in delayed or missed diagnosis and adding appreciably to the costs of hospitalization. RSV is primarily spread by close contact with infectious secretions, either by large-particle aerosols or by fomites and subsequent self-inoculation, and medical staff are often instrumental in its transmission. Thus, integral to any infection control program is the education of personnel about the modes of transmission, the manifestations, and the importance of RSV nosocomial infections. Hand washing is probably the most important infection control procedure. The choice of barrier controls should be decided by individual institutions depending on the patients, the type of ward, and the benefit relative to cost.

Adult↗
PubMed2000

Circulation patterns of group A and B human respiratory syncytial virus genotypes in 5 communities in North America.

Human respiratory syncytial virus (HRSV) is a major cause of serious lower respiratory tract illness in infants, young children, and the elderly. To characterize the circulation patterns of HRSV strains, nucleotide sequencing of the C-terminal region of the G protein gene was performed on 34-53 isolates obtained from 5 communities during 1 epidemic year, representing distinct geographical locations in North America. Phylogenetic analysis revealed that 5-7 HRSV genotypes, including 1 or 2 predominant strains, circulated in each community. The patterns of genotypes were distinct between communities, and less diversity was seen between strains of the same genotype within than between communities. These findings are consistent with HRSV outbreaks' being community based in nature, although transmission of viruses between communities may occur. Several strains are probably introduced or circulate endemically in communities each year, and local factors-possibly immunity induced by previous years' strains-determine which strains predominate during an HRSV season.

Child↗
PubMed2000

White matter abnormalities in mobility-impaired older persons.

OBJECTIVE: To investigate the relationship between white matter abnormalities and impairment of gait and balance in older persons. METHODS: Quantitative MRI was used to evaluate the brain tissue compartments of 28 older individuals separated into normal and impaired groups on the basis of mobility performance testing using the Short Physical Performance Battery. In addition, individuals were tested on six indices of gait and balance. For imaging data, segmentation of intracranial volume into four tissue classes was performed using template-driven segmentation, in which signal-intensity-based statistical tissue classification is refined using a digital brain atlas as anatomic template. RESULTS: Both decreased white matter volume, which was age-related, and increased white matter signal abnormalities, which were not age-related, were observed in the mobility-impaired group compared with the control subjects. The average volume of white matter signal abnormalities for impaired individuals was nearly double that of control subjects. CONCLUSIONS: This cross-sectional study suggests that decreased white matter volume is age-related, whereas increased white matter signal abnormalities are most likely to occur as a result of disease. Both of these changes are independently associated with impaired mobility in older persons and therefore likely to be additive factors of motor disability.

Aged↗
PubMed2000

Respiratory syncytial virus and premature infants born at 32 weeks' gestation or earlier: hospitalization and economic implications of prophylaxis.

OBJECTIVES: To assess the risk of hospitalization associated with respiratory syncytial virus (RSV) and to estimate the economic impact of RSV prophylaxis with either RSV immune globulin (RSV-Ig) or RSV monoclonal antibody (palivizumab) on a cohort of preterm infants born at 32 weeks' gestation or earlier. DESIGN: Historical cohort study. SETTING: A 12-county neonatal network served by the regional center in Rochester, NY. PARTICIPANTS: One thousand twenty-nine infants born at 32 weeks' gestation or earlier followed up until 1 year of corrected age. MAIN OUTCOME MEASURES: Rate of hospitalization with an RSV-associated illness; cost per hospitalization prevented resulting from either form of RSV prophylaxis. RESULTS: The probability of hospitalization with an RSV-associated illness for infants born at 32 weeks' gestation or earlier was estimated at 11.2%. The incidence of RSV hospitalization increased with decreasing gestational age (13.9% vs 4.4% for infants born at < or =26 weeks' gestation vs those born at 30-32 weeks' gestation). Infants requiring respiratory support at 36 weeks of postconceptual age (PCA) or older had a higher hospitalization rate (16.8% vs 6.2%), longer hospital stays, and higher hospital charges than infants requiring respiratory support at less than 36 weeks of PCA. For infants requiring respiratory support at less than 36 weeks of PCA, the incidence of RSV hospitalization still increased with decreasing gestational age (10.2% vs 4.3% for infants < or =26 weeks' gestation vs those 30-32 weeks' gestation). Analysis indicated that both forms of RSV prophylaxis would increase the net cost of care for all groups. Palivizumab was more cost-effective than RSV-Ig for preventing RSV hospitalization among infants who required respiratory support at less than 36 weeks of PCA, especially those born at 26 weeks' gestation or earlier. Overall, RSV-Ig was more cost-effective than palivizumab for infants requiring respiratory support at 36 weeks of PCA or older. CONCLUSIONS: This analysis suggests that available forms of RSV prophylaxis would increase the net cost of care not only for the entire cohort but for each of the subgroups studied. However, the RSV hospitalization rate and the cost-effectiveness of prophylaxis varied markedly by subgroup.

Antibodies, Monoclonal↗
PubMed1999

Modelling disease progression in terms of exposure history.

We consider the relationship between accumulating exposure to a putative agent and the associated change in physiologic function. This type of problem is common to prospective studies of cognitive, pulmonary and cardiovascular function. A general model is proposed for data from prospective, observational studies with concurrent measures of exposures and continuous outcome measures. This model permits non-linearity in the relationship between exposure and outcome and is designed to describe outcome in terms of one's entire exposure history. As exposure data are often severely right-skewed, we use regression spline estimation methods which localize the influence of extreme points. We illustrate our methodology using data from a longitudinal epidemiologic investigation of the effects of amateur boxing on neuropsychologic function.

Adolescent↗
PubMed1999

Soft tissue composition of pigs measured with dual x-ray absorptiometry: comparison with chemical analyses and effects of carcass thicknesses.

Evidence of the validity and accuracy of dual x-ray absorptiometry (DXA) to measure in vivo body composition is limited. We compared DXA estimates made in prone and side positions with measurements of chemical composition of 20 pigs (10 barrows and 10 gilts) weighing 52-113 kg. DXA yielded similar estimates of body composition in prone and side positions. DXA estimates of body composition were significantly correlated with reference compositional values (r2 = 0.927-0.998). No significant differences were found for determinations of body weight, fat mass (FM), fat free mass (FFM), bone-free, and fat-free mass (BFFFM) between DXA and chemical determinations. DXA significantly underpredicted percent fat (% fat); it underestimated FM (20%, P > 0.05), and overestimated FFM and BFFFM (6 and 9%, respectively, P > 0.05). Differences between individual determinations of FM and % fat by chemical analyses and DXA were significantly correlated with mean values. No significant correlations were found between the differences for weight, FM, % fat, FFM and BFFFM and measurements of carcass breadth (19-28 cm) and width (15-25 cm). Total errors in determination of DXA body composition variables were similar with body thicknesses less than and greater than 24 cm. These findings indicate that DXA is a valid and accurate method for determination of soft tissue composition. Initial problems with DXA determinations of % fat apparently have been reconciled partially with revisions in soft tissue analytic software.

Absorptiometry, Photon↗
PubMed1999

Detection of human herpesvirus 6 by reverse transcription-PCR.

The role of human herpesvirus 6 (HHV-6) in disease beyond primary infection remains unclear. We have developed and validated a new reverse transcription-PCR (RT-PCR) assay for HHV-6 that can determine the presence of HHV-6 in clinical specimens and differentiate between latent and replicating virus. Peripheral blood mononuclear cells from 109 children were evaluated for HHV-6 by RT-PCR, DNA PCR, and viral culture. Of these samples, 106 were suitable for analysis. A total of 20 samples were positive for HHV-6 by culture and DNA PCR, of which 19 were positive by RT-PCR (sensitivity, 95%). All 28 samples from children that were negative by viral culture, but positive by DNA PCR, were negative for viral transcripts by our RT-PCR assay. One positive RT-PCR result was observed in 56 samples that were negative by tissue culture and DNA PCR. This indicates a low rate of false-positive results (1.2%) and a specificity of 98.8%. This RT-PCR assay can reliably differentiate between latent and actively replicating HHV-6 and should allow insight into the pathogenesis of this ubiquitous virus.

Base Sequence↗
PubMed1999

Police reports on domestic incidents involving intimate partners: injuries and medical help-seeking.

This study aims to expand knowledge of partner abuse injury and help-seeking through a new source of data. We reviewed police reports during corresponding periods in 1996 and 1997 (n = 476). Complainants were injured in 17.4% of all incidents; 90% of those injured were women. Hispanics were more likely to be injured than non-Hispanics (OR = 2.06; 95% CI = 1.0, 4.25). The likelihood of injury decreased with each year of increasing age (OR = 0.95; CI = 0.91, 0.99). Only 20.5% of those injured consented to medical care. Police reports provide information on partner abuse injury that supplements hospital surveillance and household surveys.

Adolescent↗