Search PubMed⌕ Search

Biomedical subjects

S C Stearns

Publications and source records attributed to S C Stearns.

At least 37 records · Page 2Linked to original sources
PubMed1998

Psychosocial and educational outcomes associated with home- and clinic-based pretest education and cystic fibrosis carrier testing among a population of at-risk relatives.

We report on the psychosocial and knowledge outcomes of two different approaches to cystic fibrosis (CF) gene pretest education and carrier testing offered to 288 proactively recruited first-, second-, and third-degree relatives of people with CF. One group received pretest education and gene testing in a clinical setting from a certified genetic counselor. The other group received pretest education in their homes from a specially prepared pamphlet and were asked to send in a buccal cell sample for genotyping. No statistically significant differences between groups were noted on measures of CF knowledge, anxiety, and positive or negative affect, either while waiting for their test results or within a few weeks after they had learned their results. At both measurement points, participants who had received home education and testing reported that the testing was more convenient, but that they had received less information than they would have liked, and they were more likely to report being confused by the testing, although their level of CF knowledge was comparable to that of people who had been seen by a genetic counselor. In light of the increasing interest in home-based medical testing of all kinds, this study suggests that CF carrier testing in the home warrants further consideration as one possible approach to facilitating access to testing.

Adolescent↗
PubMed1998

Volume responses to Medicare payment reductions with multiple payers: a test of the McGuire-Pauly model.

The effects of changing financial incentives on physician's practice behaviour have long been of interest to researchers and policy makers. We test a model of physician volume response within the context of multiple payers developed by Thomas McGuire and Mark Pauly. A panel data set covering discharges from about 200 hospitals in the US over 45 months is used to carry out the empirical investigation. A fixed-effect model with generalized least squares and instrumental variable specifications is used to compute empirical evidence of volume responses from eight specialties experiencing varying degrees of Medicare payment reductions following the implementation of Omnibus Budget Reconciliation Acts of 1989 and 1990. The empirical findings are compared with McGuire and Pauly's simulated predictions. We note that in examining physician responses to Medicare payment reductions in the context of a multi-payer environment, it becomes evident that only fixing one payer's reimbursement policy is at best a partial solution to cost containment. We echo observations made by other analysts that physician responses to payment changes can be quite complex. Physicians do not all respond to payment reduction in the same way.

Budgets↗
PubMed1998

Reductions in hospital use from self management training for chronic asthmatics.

The purpose of this study was to assess the impact of asthma Self Management Training on the health status and resource use of patients with chronic asthma. The study consisted of a randomized control design of chronic asthmatic patients in a tertiary care center in India. The intervention group (153 patients) received four training sessions in addition to the regular care provided to the control group (150 patients). Health status and resource use were measured at baseline and over a one year follow-up period. The intervention group had significantly better health status (measured by breathing ability), fewer productive days lost, and lower resource use (hospitalizations and emergency room visits) than the control group. Total annual costs (direct and indirect) were also lower, though physician costs were not included in the assessment. Therefore, incorporation of asthma Self Management Training as part of clinical management of asthma can result in improvements in health status and reductions in hospital use.

Adolescent↗
PubMed1997

P-element inserts in transgenic flies: a cautionary tale.

The fruitfly, Drosophila melanogaster, can be transfected with P-elements and induced to overexpress a transfected gene whose impact on lifespan can be measured. Here, it is reported that in previous experiments a transfected gene was not expressed. This suggested a new statistical analysis indicating that (1) the size of the insert, the position and the interactions of the insert with the genetic backgrounds into which the P-element are inserted have effects on lifespan similar to those attributed to overexpression; (2) these effects occur without expression of the transfected gene; and (3) effects of interactions with backgrounds and effects of positions are as large as responses to six generations of strong directional artificial selection. Reports of effects of overexpression of transfected genes on lifespan in Drosophila melanogaster may be experimental artefacts. Credible experiments on the phenotypic effects of transgenesis need proper controls for the effects of insert size and position and should estimate the magnitudes of interactions of treatment with genetic backgrounds.

Animals↗
PubMed1996

Estimating confidence intervals for cost-effectiveness ratios: an example from a randomized trial.

Cost-effectiveness ratios usually appear as point estimates without confidence intervals, since the numerator and denominator are both stochastic and one cannot estimate the variance of the estimator exactly. The recent literature, however, stresses the importance of presenting confidence intervals for cost-effectiveness ratios in the analysis of health care programmes. This paper compares the use of several methods to obtain confidence intervals for the cost-effectiveness of a randomized intervention to increase the use of Medicaid's Early and Periodic Screening, Diagnosis and Treatment (EPSDT) programme. Comparisons of the intervals show that methods that account for skewness in the distribution of the ratio estimator may be substantially preferable in practice to methods that assume the cost-effectiveness ratio estimator is normally distributed. We show that non-parametric bootstrap methods that are mathematically less complex but computationally more rigorous result in confidence intervals that are similar to the intervals from a parametric method that adjusts for skewness in the distribution of the ratio. The analyses also show that the modest sample sizes needed to detect statistically significant effects in a randomized trial may result in confidence intervals for estimates of cost-effectiveness that are much wider than the boundaries obtained from deterministic sensitivity analyses.

Analysis of Variance↗
PubMed1996

A prospective study of the impact of patient preferences on life-sustaining treatment and hospital cost.

OBJECTIVES: Ethicists advise that life-sustaining treatment decisions should be made in keeping with patient preferences. Until recently, there has been little systematic study of the impact of patient preferences on the use of various life-sustaining treatments or the consequent cost of hospital care. This prospective study was designed to answer the following questions: a) Do patient treatment preferences about the use of life-sustaining treatment influence the treatments they receive? and b) Do patient treatment preferences influence the total cost of their hospitalization? DESIGN: A prospective, cohort study. SETTING: A university teaching hospital. PATIENTS: Hospitalized patients, at least 50 yrs of age, with short life expectancy due to end-stage heart, lung, or liver disease, metastatic cancer, or lymphoma. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Patients were interviewed to determine their desire for life-sustaining treatment and other characteristics and then were followed for 6 months to determine life-sustaining treatment use and costs during hospitalization. Two hundred forty-four patients were interviewed. Fifty-eight percent of patients expressed a desire for life-sustaining treatments to prolong life for 1 wk. During 245 subsequent hospitalizations, there were 20 episodes of mechanical ventilation, 63 episodes of intensive care, and 66 cancer treatments given. Bivariate and multivariate analyses showed no significant association between patient desire to receive treatment to prolong life and either life-sustaining treatment use (p = .59) or hospital costs (p = .20). CONCLUSION: In a university teaching hospital setting, there is no systematic evidence that patient preferences determine life-sustaining treatment use or hospital costs.

Aged↗
PubMed1996

Innovative strategies using SUDAAN for analysis of health surveys with complex samples.

Large-scale health surveys provide a wealth of information for addressing problems in health sciences research. Designed for multiple purposes, these surveys frequently have large sample sizes and extensive measurements of demographic and socioeconomic characteristics, risk factors, disease outcomes and health care service use and costs. Complex features of the sampling design typically employed to select the survey sample, coupled with the vast amount of information available from the survey database, underlie issues that must be addressed during data processing and analysis. Numerous articles in the literature have focused on the debate of whether or not, and how, to control for features of the sample design during data analysis. Traditional statistical methods for simple random samples and the software that accompanies them have historically not had the capacity to account for the survey design. Recent advancements in statistical methodology for survey data analysis have greatly expanded the analytical tools available to the survey analyst. Commercial software packages that incorporate these methods offer the analyst convenient ways for applying such tools to large survey databases in an easy and efficient manner. We present an overview of analysis strategies for survey data and illustrate their application via the SUDAAN software system. Examples for analyses are provided through data from two large US health surveys, the National Health Interview Survey and the Longitudinal Study of Aging. Questions of both a cross-sectional and longitudinal nature are addressed. The examples involve logistic regression, time-to-event analysis, and repeated measures analysis.

Aged↗
PubMed1996

Risk indicators for hospitalization during the last year of life.

OBJECTIVE: High levels of hospital expenditures for older people during their last year of life are widely documented. However, evidence of the association between prospectively measured indicators and subsequent hospitalization is sparse. This article investigates the pattern of hospitalization for a sample of Medicare enrollees during their last year of life. DATA SOURCES: Data from the Longitudinal Study of Aging, a national study of persons age 70 and older, are used. Only data on decedents are used. STUDY DESIGN: We determine individual characteristics (including functional status, evidence of disease, living arrangement, and prior hospitalization) shortly before the last year of life. A distinction is made between terminal and nonterminal admissions. National estimates and regression analyses using survey weights are conducted. PRINCIPAL FINDINGS: The likelihood of any use is high regardless of age, functional status, or the presence of major diseases. Although only a few indicators are associated with having a terminal stay, a number of indicators are associated with nonterminal use. Nonterminal stays and total nights hospitalized are positively associated with prior evidence of disease, prior hospitalization, and age, although the probability of nonterminal use decreases with age for persons over 82 years old. The relationship between use and functional status depends on whether persons lived alone, were institutionalized, or had private health insurance. CONCLUSIONS: This study demonstrates that while it is difficult to predict who will be admitted to the hospital at the time of death, a number of characteristics existing before the last year of life are associated with nonterminal hospitalization and total nights hospitalized during the last year of life.

Age Factors↗
PubMed1995

Diagnosing senescence: inferring evolutionary causes from phenotypic patterns can be misleading.

Based on the predictions of two theories for the evolution of senescence, the 'antagonistic pleiotropy' and the 'mutation accumulation' theory, an age-specific increase in mortality and a decrease in fecundity are widely used criteria to diagnose senescence in natural, and laboratory populations. In this study we question the reliability of these criteria. Using a simple model we show that similar phenotypic patterns result from optimal life histories without senescence. With a tradeoff between reproduction and period survival, optimal life histories produce patterns of increasing mortality and decreasing fecundity as organisms age, even if the tradeoff does not deteriorate with age, so that we are not forced to invoke genetic effects such as antagonistic pleiotropy or accumulation of deleterious mutations to explain such patterns. Furthermore, if optimal life history theory is applied to senescent organisms, phenotypic patterns can result that are usually not associated with senescence. We conclude that the reliability of a diagnosis of senescence based on phenotypic patterns and the comprehension of the phenomenon senescence depends critically on understanding to what extent tradeoffs are determined by the effects of segregating genes.

Aging↗
PubMed1995

The effect of channeling on home care utilization and satisfaction with care.

This study examined the relationship between participation in two home and community-based long-term care case management interventions (collectively known as the Channeling demonstration), use of formal in-home care, and satisfaction with care. Maximum likelihood estimation techniques were used to analyze the National Long-Term Care Demonstration data set. It was hypothesized that participation in the two Channeling interventions would indirectly (rather than directly) enhance satisfaction by operating through the increased use of formal in-home care. However, both Channeling models were found to have favorable direct and indirect effects on patient satisfaction.

Aged↗
PubMed1995

State risk pools and mental health care use.

State risk pools provide an opportunity for persons with mental health and substance abuse (MH/SA) problems to purchase health insurance. This study uses data from eight risk pools during the period 1988-1991 to analyze the utilization and enrollment experience for persons who submit claims for MH/SA treatment. Special consideration is given to the effect of variation in inpatient benefits across risk pools. The experience of Connecticut's risk pool differs markedly from that of the other risk pools. Given that two states (Connecticut and Florida) have restricted MH/SA benefits over time, we discuss the ability of risk pools to maintain comprehensive MH/SA benefits.

Adult↗
PubMed1995

Increasing Medicaid child health screenings: the effectiveness of mailed pamphlets, phone calls, and home visits.

OBJECTIVES: A randomized controlled trial was conducted to test the effectiveness and cost effectiveness of three outreach interventions to promote well-child screening for children on Medicaid. METHODS: In rural North Carolina, a random sample of 2053 families with children due or overdue for screening was stratified according to the presence of a home phone. Families were randomly assigned to receive a mailed pamphlet and letter, a phone call, or a home visit outreach intervention, or the usual (control) method of informing at Medicaid intake. RESULTS: All interventions produced more screenings than the control method, but increases were significant only for families with phones. Among families with phones, a home visit was the most effective intervention but a phone call was the most cost-effective. However, absolute rates of effectiveness were low, and incremental costs per effect were high. CONCLUSIONS: Pamphlets, phone calls, and home visits by nurses were minimally effective for increasing well-child screenings. Alternate outreach methods are needed, especially for families without phones.

Adult↗
PubMed1994

Selection against inbred song sparrows during a natural population bottleneck.

The genetic and demographic consequences of population subdivision have received considerable attention from conservation biologists. In particular, losses of genetic variability and reduced viability and fecundity due to inbreeding (inbreeding depression) are of concern. Studies of domestic, laboratory and zoo populations have shown inbreeding depression in a variety of traits related to fitness. Consequently, inbreeding depression is widely accepted as a fact. Recently, however, the relative impact of inbreeding on the viability of natural populations has been questioned. Work on the cheetah (Acinonyx jubatus), for example, has emphasized the overwhelming importance of environmental factors on mortality in the wild. Here we report that song sparrows (Melospiza melodia) that survived a severe population bottleneck were a non-random subset of the pre-crash population with respect to inbreeding, and that natural selection favoured outbred individuals. Thus, inbreeding depression was expressed in the face of an environmental challenge. Such challenges are also likely to be faced by inbred populations of endangered species. We suggest that environmental and genetic effects on survival may interact and, as a consequence, that their effects on individuals and populations should not be considered independently.

Animals↗
PubMed1994

The effect of Channeling on in-home utilization and subsequent nursing home care: a simultaneous equation perspective.

OBJECTIVE: This study explored the relationship between participation in a home/community-based long-term care case management intervention (known as the Channeling demonstration), use of formal in-home care, and subsequent nursing home utilization. STUDY DESIGN: Structural analysis of the randomized Channeling intervention was conducted to decompose the total effects of Channeling on nursing home use into direct and indirect effects. DATA COLLECTION METHOD: Secondary data analysis of the National Long-Term Care Data Set. PRINCIPAL FINDINGS: The use of formal in-home care, which was increased by the Channeling intervention, was positively associated with nursing home utilization at 12 months. However, the negative direct effect of Channeling on nursing home use was of sufficient magnitude to offset this positive indirect effect, so that a small but significant negative total effect of Channeling on subsequent nursing home utilization was found. CONCLUSIONS: This study shows why Channeling did not have a large total impact on nursing home utilization. The analysis did not provide evidence of direct substitution of in-home care for nursing home care because the direct reductions in nursing home utilization due to other aspects of Channeling (including, but not limited to case management) were substantially offset by the indirect increases in nursing home utilization associated with additional home care use.

Aged↗
PubMed1993

The effects of enhanced expression of elongation factor EF-1 alpha on lifespan in Drosophila melanogaster. IV. A summary of three experiments.

This paper summarizes three experiments on the genetic manipulation of fitness components involved in the evolution of lifespan through the introduction of an additional copy of the gene for elongation factor EF-1 alpha into the genome of Drosophila melanogaster. The first experiment checked a prior claim that enhanced expression of elongation factor increased the lifespan of virgin male fruitflies. It used inbred stocks; three treatment and three control lines were available. The second experiment put one treatment and one control insert into different positions on the third chromosome, then measured the influence of six genetic backgrounds on treatment effects in healthier flies. The third experiment put six treatment and six control inserts into the genetic background whose lifespan was most sensitive to the effects of treatment in the second experiment, then measured the influence of insert positions on treatment effects in healthy flies. The treatment never increased the lifespan of virgin males. It increased the lifespan of mated females in inbred flies reared to eclosion at 25 degrees, reduced it in the positions experiment, and made no difference to lifespan in the backgrounds experiment. When it increased lifespan, it reduced fecundity. In inbred flies and in the positions experiment, the treatment reduced dry weight at eclosion of females. Marginal effects of gene substitutions on tradeoffs were measured directly. The results suggest that enhanced expression of elongation factor makes local changes within the bounds of tradeoffs that are given by a pre-existing physiological structure whose basic nature is not changed by the treatment.

Animals↗
PubMed1993

A retrospective analysis of the cost-effectiveness of dental sealants in a children's health center.

A retrospective patient record analysis was conducted to study the cost-effectiveness of dental sealants placed under routine, unrestricted practice condition in a fluoridated community. The 26 dentists who provided care at the clinic over the period of the study used their own clinical judgement to determine sealant placement or alternative treatment. Dental services for 275 patients at a children's dental clinic for low-income families were evaluated. All children had at least 3 years between their first and last dental visit (mean = 5.8 years). A lifetable analysis was conducted to compare the probability of survival (restoration-free tooth years) and costs incurred to first molars of children who did not receive sealants, received any sealants, or received sealants on all first molars. Among the children with sealants, comparisons were also made between sealed and unsealed teeth in children who did and did not have a first molar restoration prior to sealant placement. Costs included the costs of sealants and restorative treatments for these teeth over time. Depending on the conditions under which sealants were placed, cost-savings or improving cost-effectiveness with time were found. A strategy of identifying children with prior restorations and sealing the remaining molars showed cost-savings within 4-6 years. For other comparisons, incremental cost-effectiveness ratios became more favorable over time.

Child↗
PubMed1992

Phenotypic plasticity for life-history traits in Drosophila melanogaster. III. Effect of the environment on genetic parameters.

We estimated genetic and environmental variance components for developmental time and dry weight at eclosion in Drosophila melanogaster raised in ten different environments (all combinations of 22, 25 and 28 degrees C and 0.5, 1 and 4% yeast concentration, and 0.25% yeast at 25 degrees C). We used six homozygous lines derived from a natural population for complete diallel crosses in each environment. Additive genetic variances were consistently low for both traits (h2 around 10%). The additive genetic variance of developmental time was larger at lower yeast concentrations, but the heritability did not increase because other components were also larger. The additive genetic effects of the six parental lines changed ranks across environments, suggesting a mechanism for the maintenance of genetic variation in heterogenous environments. The variance due to non-directional dominance was small in most environments. However, there was directional dominance in the form of inbreeding depression for both traits. It was pronounced at high yeast levels and temperatures but disappeared when yeast or temperature were decreased. This meant that the heterozygous flies were more sensitive to environmental differences than homozygous flies. Because dominance effects are not heritable, this suggests that the evolution of plasticity can be constrained when dominance effects are important as a mechanism for plasticity.

Adaptation, Physiological↗