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PubMed2003

Influence of seat foam and geometrical properties on BioRID P3 kinematic response to rear impacts.

As the primary interface with the human body during rear impact, the automotive seat holds great promise for mitigation of Whiplash Associated Disorders (WAD). Recent research has chronicled the potential influence of both seat geometrical and constitutive properties on occupant dynamics and injury potential. Geometrical elements such as reduced head to head restraint, rearward offset, and increased head restraint height have shown strong correlation with reductions in occupant kinematics. The stiffness and energy absorption of both the seating foam and the seat infrastructure are also influential on occupant motion; however, the trends in injury mitigation are not as clear as for the geometrical properties. It is of interest to determine whether, for a given seat frame and infrastructure, the properties of the seating foam alone can be tailored to mitigate WAD potential. Rear impact testing was conducted using three model year 2000 automotive seats (Chevrolet Camaro, Chevrolet S-10 pickup, and Pontiac Grand Prix), using the BioRID P3 anthropometric rear impact dummy. Each seat was distinct in construction and geometry. Each seat back was tested with various foams (i.e., standard, viscoelastic, low or high density). Seat geometries and infrastructures were constant so that the influence of the seating foams on occupant dynamics could be isolated. Three tests were conducted on each foam combination for a given seat (total of 102 tests), with a nominal impact severity of Delta V = 11 km/h (nominal duration of 100 msec). The seats were compared across a host of occupant kinematic variables most likely to be associated with WAD causation. No significant differences (p < 0.05) were found between seat back foams for tests within any given seat. However, seat comparisons yielded several significant differences (p < 0.05). The Camaro seat was found to result in several significantly different occupant kinematic variables when compared to the other seats. No significant differences were found between the Grand Prix and S-10 seats. Seat geometrical characteristics obtained from the Head Restraint Measuring Device (HRMD) showed good correlation with several occupant variables. It appears that for these seats and foams the head-to-head restraint horizontal and vertical distances are overwhelmingly more influential on occupant kinematics and WAD potential than the local foam properties within a given seat.

Accidents, Traffic↗
PubMed1999

Pilot trial for the assessment of relative bioavailability in generic drug product development: statistical power.

In developing generic drug products, pilot trials are used for identifying successful test formulations to enter pivotal trials. In this study, we derive the power function based on the log-normal distribution and evaluate the effects of potential influential factors-the true test-reference ratio, intrasubject variability, and sample sizes-on the statistical power of a pilot trial to identify successful test formulations, defined as the probability that the test-reference ratio estimate from a pilot trial falls within a predetermined acceptance range when the true ratio is acceptable. Of these influential factors, the test-reference ratio exhibits the largest impact on the statistical power of a pilot trial, followed by intrasubject variability, sample sizes of pivotal trials, and sample sizes of pilot trials. The sample sizes that are used in pilot trials (8-12 subjects) may be sufficient for test products with low intrasubject variability and true ratio close to 1 and may fall short otherwise.

Biological Availability↗
PubMed2005

Infrared ear thermometers--parameters influencing their reading and accuracy.

Infrared ear thermometers (IRETs) are extensively used for measuring the temperature of a human body. For accurate measurements with IRETs they have to be calibrated regularly with an appropriate and traceable calibration system. Such systems are neither widely available nor are there many competent (accredited) laboratories which can provide traceability for IRETs. This paper describes some important influential parameters in the calibration and use of IRETs, which were observed during the extensive research on IRETs and have not been reported in the literature yet. IRET readings, and consequently also their most important metrological characteristics, accuracy and uncertainty of measurement, depend on these influential parameters. According to our findings, we would like to warn users of medical radiation thermometers, not only IRETs but also forehead thermometers and infrared temperature scanning systems, that they should be extremely careful in selection, maintenance and use of medical radiation thermometers. Measurement accuracy, as it is required by several technical standards, is hard to achieve with the majority of currently available medical radiation thermometers.

Artifacts↗
PubMed2006

Relaxing the rule of ten events per variable in logistic and Cox regression.

The rule of thumb that logistic and Cox models should be used with a minimum of 10 outcome events per predictor variable (EPV), based on two simulation studies, may be too conservative. The authors conducted a large simulation study of other influences on confidence interval coverage, type I error, relative bias, and other model performance measures. They found a range of circumstances in which coverage and bias were within acceptable levels despite less than 10 EPV, as well as other factors that were as influential as or more influential than EPV. They conclude that this rule can be relaxed, in particular for sensitivity analyses undertaken to demonstrate adequate control of confounding.

Bias↗
PubMed2006

Age at disability milestones in multiple sclerosis.

Many efforts have been devoted to the description of the prognosis of multiple sclerosis and its possible influential factors in terms of time to reach disability milestones. By contrast, the age at which patients with multiple sclerosis reach these milestones has not yet stirred much interest. We have tested the hypothesis whether the prognosis of multiple sclerosis depends on the current age of patients and the initial course of the disease. We have assessed disease onset and course, and assignment of scores of irreversible disability in 1844 patients with multiple sclerosis. We have used three scores on the Kurtzke Disability Status Scale as benchmarks of disability accumulation: DSS 4 (limited walking but without aid), DSS 6 (walking with unilateral aid) and DSS 7 (wheelchair-bound). We used Kaplan-Meier analyses to estimate the age of the patients at assignment of disability milestones. The possible influence of the initial course of multiple sclerosis and of other clinical variables early assessable in the disease on these outcome measures was also studied, using the Kaplan-Meier curves for univariate analyses and Cox models for multivariate analyses. For the 1844 patients, median ages at time of assignment of irreversible disability were 44.3 years (95% CI 43.3-45.2) for a score of DSS 4, 54.7 years (95% CI 53.5-55.8) for DSS 6 and 63.1 years (95% CI 61.0-65.1) for DSS 7. These results were essentially similar whether the initial course of multiple sclerosis was exacerbating-remitting or progressive, and whatever the initial symptomatology. Females reached disability milestones at an older age than males. The most influential clinical factor was age at clinical onset of multiple sclerosis: the younger the onset, the younger the age at assignment of disability milestones. Therefore, prognosis in multiple sclerosis appears, at least to some extent, as age-dependent and not substantially affected by the initial course, be it exacerbating-remitting or progressive. Aside acute focal recurrent inflammation and diffuse chronic neurodegeneration, accelerated ageing-related mechanisms may operate in the central nervous system of multiple sclerosis patients.

Adult↗
PubMed2002

Factors affecting the initiation of breastfeeding: implications for breastfeeding promotion.

Breastfeeding rates in the United Kingdom (UK) are one of the lowest in the developed world and certainly the lowest in Europe. There have been numerous studies of breastfeeding in the UK, most of which have adopted a quantitative approach, and they have largely focused on obstetric or socio-demographic factors in the decision to breastfeed. Whilst these studies have an important role to play, this paper draws on a study that adopts a qualitative methodology to explore women's personal experiences and perceptions of breastfeeding. A qualitative study of 19 primagravidae was undertaken and completed in 1998. Participants were recruited to the study via 12 antenatal clinics in the West Midlands, England, UK. Their ages ranged from 16 to 30 years and the majority described themselves as 'white'. The majority of participants were in paid employment in a variety of occupations. The study was prospective in design. Participants were interviewed three times either during pregnancy or after childbirth: the first stage was between 6 and 14 weeks of pregnancy; the second stage was between 34 and 39 weeks; and the third stage was between 6 and 14 weeks after childbirth. The data indicate that there are several factors affecting breastfeeding initiation. First, infant feeding decisions seem to be made prior to, or irrespective of, contact with health professionals. Secondly, the data suggest that health promotion campaigns in the UK have been influential in their ability to educate women about the benefits of breastfeeding. However, this did not dissuade participants from formula feeding once their decision was made. The desire for paternal involvement also seemed to be another influential factor; fathers were either seen as able to alleviate the daily grind of early motherhood, or there was a desire for 'shared parenting'. Finally, some of the formula feeding women expressed a strong desire to re-establish their identities as separate individuals and as 'non-mothers'.

Adolescent↗
PubMed2001

Gender and race differences in the predictors of daily health practices among older adults.

Preventive health behaviors are crucial for older adults' well-being. This study examined the factors that influence the practice of positive daily health behaviors over time in a sample of older adults (N = 1266) and investigated whether explanatory factors differ by health behavior, gender or race. Physical activity, weight maintenance, smoking, alcohol consumption and sleep patterns were examined as dependent variables. Independent variables included demographic characteristics, baseline health behavior, health status variables, psychological factors and social network characteristics. Results indicate that age and health status are important predictors of preventive health behaviors. However, the factors that predict preventive health behaviors vary by behavior, gender and race. The independent variables included in this study were most successful in explaining cigarette smoking and weight maintenance, and least successful in explaining amount of sleep. In addition, results suggest that social network variables are particularly influential for women's health behaviors, while health status is more influential among men. Greater education predicts better health behaviors among whites, while formal social integration seems particularly important for the health behaviors of older black women. These results indicate that examining older adults' health behaviors by race and gender leads to a fuller understanding of these behaviors.

Aged↗
PubMed1991

Possibilities of consensus: toward democratic moral discourse.

The concept of consensus is often appealed to in discussions of biomedical ethics and applied ethics, and it plays an important role in many influential ethical theories. Consensus is an especially influential notion among theorists who reject ethical realism and who frame ethics as a practice of discourse rather than a body of objective knowledge. It is also a practically important notion when moral decision making is subject to bureaucratic organization and oversight, as is increasingly becoming the case in medicine. Two models of consensus are examined and criticized: pluralistic consensus and overlapping consensus. As an alternative to these models, the paper argues that consensus refers to the dialogic aspects of a broader normative conception of democratic moral agency. When the preconditions for that dialogic democratic practice are met, consensus has a justificatory role in ethics; when they are not, consensus, as distinct from mere agreement, does not emerge and can have no moral authority.

Bioethical Issues↗
PubMed2006

Thrombocytopaenia in lupus as a marker of adverse outcome--seeking Ariadne's thread.

OBJECTIVE: To assess the role of thrombocytopaenia as an independent predictor of outcome in patients with systemic lupus erythematosus (SLE). METHODS: This was a single-centre, retrospective, matched case-control study (1:2). Fifty consecutive Greek SLE patients were selected at random who had developed thrombocytopaenia during the disease course (cases) were compared with 100 SLE patients with no history of thrombocytopaenia, and matched for age, sex and disease duration (controls). Overall damage was assessed at the end of follow-up, using Systemic Lupus International Collaborating Clinics index. Total number of irreversible organ-damage events for both groups were recorded. Rates for specific outcomes and incidence-rate ratios (IRRs) for damage were estimated. Multivariate analysis estimating influential clinical and immunological factors for outcome, including thrombocytopaenia, was performed. RESULTS: After 583 person-years of follow-up for cases and 1155 for controls, we found that thrombocytopaenic individuals have a higher risk for damage (IRR 1.96, 1.52-2.53) compared with their matched controls and this effect persists throughout the course of their disease. They also have a predilection to certain types of damage involving heart and kidneys. Among other significant factors associated with damage in multivariate analysis (disease activity, serositis, anti-cardiolipin antibodies, central nervous system involvement), thrombocytopaenia appears as the most influential. CONCLUSION: Thrombocytopaenia is a quantitive and qualitative marker of impending damage in SLE patients.

Adolescent↗
PubMed1996

Transesophageal echocardiography in myocardial revascularization: II. Influence on intraoperative decision making.

This study was conducted to determine how transesophageal echocardiography (TEE) guides intraoperative decision making during myocardial revascularization. Although its usefulness in influencing clinical decision making during cardiac valvular surgery is well documented, the clinical utility of TEE in patients undergoing myocardial revascularization is less clear. We studied the performance of five community-based, full-time cardiac anesthesiologists during 75 surgical procedures. All patients were monitored with radial artery and pulmonary artery catheters as well as biplane TEE. Immediately after each clinical intervention, the anesthesiologist was asked to determine how real-time TEE influenced the therapy, which single monitor was most influential, and why each therapy was initiated. Of the 584 interventions, TEE was the single most important guiding factor in 98 instances (17%). Interventions involving fluid administration contributed to 277 of 584 (47%) of the total clinical decisions. TEE was the most important monitor influencing fluid administration in 82 of 277 instances (30%), versus the pulmonary artery catheter in 20 of 277 instances (7%). TEE was the single most important monitor in guiding other therapies as follows: antiischemic therapy, 8 of 38 = 21%; vasopressor or inotrope administration, 4 of 115 = 3%; vasodilator therapy, 1 of 38 = 3%; antiarrhythmic medications, 0 of 16 = 0%; and depth of anesthesia, 1 of 72 = 1%. In 2 of 75 patients (3%), critical surgical interventions were made solely on the basis of TEE. Also, TEE was found to act in concert with other monitors in 254 of 584 interventions (43%). TEE is often influential in guiding decision making in myocardial revascularization when incorporated as a routine monitor in the intraoperative setting. Information from TEE has been most commonly used to guide the management of fluid administration and institution of antiischemic therapy. In a small subset of patients, TEE appears to be useful in guiding critical surgical interventions.

Adult↗
PubMed2000

Value of point-of-care blood testing in emergent trauma management.

BACKGROUND: No prospective study demonstrates the value of point-of-care laboratory testing (POCT) in the management of major trauma. METHODS: In a prospective, noninterventional, study of 200 major trauma patients, we evaluated the influence of a blood POCT profile (hemoglobin, Na+, K+, Cl-, blood urea nitrogen, glucose, pH, PCO2, PO2, HCO3-, base deficit, and lactate) on emergent diagnostic and therapeutic interventions. Physicians responded to a standardized set of questions on their diagnostic and therapeutic plans before and after the availability of POCT results. Management plan changes were deemed emergently appropriate, if they were influenced by the POCT results and, within the ensuing 30 minutes, the change in management was likely to reduce morbidity or conserve resources. RESULTS: For emergently appropriate plan changes, Na+, Cl-, K+, and blood urea nitrogen were never influential, whereas in each of 6.0% of cases (95% confidence interval [CI], 3.5%-10.2%) at least one of the remaining POCT parameters was influential. An emergently appropriate change was based on hemoglobin in 3.5% of cases (95% CI, 1.0%-6.1%), blood gas parameters in 3.0% of cases (95% CI, 0.64%-5.7%), lactate in 2.5% of cases (95% CI, 1.1%-5.7%), and glucose in 0.5% of cases (95% CI, 0.1%-2.8%). All of these cases involved blunt injury. CONCLUSION: Na+, Cl-, K+, and blood urea nitrogen levels do not influence the initial management of major trauma patients. In patients with severe blunt injury, hemoglobin, glucose, blood gas, and lactate measurements occasionally result in morbidity-reducing or resource-conserving management changes.

Adolescent↗
PubMed1993

Socioeconomic influence on small area hospital utilization.

Health care policy makers, concerned with the rising cost of health care, have focused on the observed variation in the use of hospitals as a potential area in which to lower health care costs, i.e., if hospital utilization can be decreased, health care costs may also decline. However, it is crucial that the reasons for the observed variation in the current practice be understood or attempts to reduce costs may lead to policies that harm groups of patients and the providers and institutions currently delivering care. Using hospital discharge data from 59 hospital market communities in the lower peninsula of Michigan in 1984-86, the authors examined possible associations between socioeconomic characteristics and the observed small area variation in hospital discharge rates. First, a series of Poisson regressions was used for each of five covariates and 112 modified diagnosis-related groups (DRGs). Then, multiple regressions were examined, utilizing the five socioeconomic characteristics, after excluding statistically influential communities. The results indicate that community characteristics, including education, poverty, and unemployment, have a statistically significant association with the observed small area hospital discharge rate for many DRGs. Moreover, the direction of the effect is consistent across multiple disease categories. In multiple regressions, the five selected socioeconomic variables explained 48% of the variance for medical admissions and 19% for surgical admissions. For most DRGs, high educational levels were associated with lower hospitalization rates. The authors also identified statistically influential communities whose hospital utilization profile was different from that of most communities in Michigan.

Diagnosis-Related Groups↗
PubMed2001

Strategies for maintaining a handstand in the anterior-posterior direction.

PURPOSE: The purpose of this analysis was to determine the contributions made by wrist, shoulder, and hip joint torques in maintaining a handstand. METHODS: Handstand balances (N = 6) executed on a force plate and recorded with two genlocked video cameras were subjected to inverse dynamics analysis to determine anterior-posterior joint torques at the wrists, shoulders, and hips. Multiple regression analyses were conducted to investigate which of the joint torques were influential in accounting for anterior-posterior whole-body mass center (CM) movement. RESULTS: Results demonstrated that, in general, all calculated joint torques contributed to CM movement. In a number of trials, wrist torque played a dominant role in accounting for CM variance. Ostensibly, superior handstand balances are characterized by important contributions from wrist torques and shoulder torques with little influence from hip torques. In contrast, hip torques were found to be increasingly influential in less successful balances. CONCLUSIONS: It is concluded that multiple joints are utilized in maintaining a handstand balance in the anterior-posterior direction, and there appears to be two joint involvement strategies, which supports similar findings from postural research on normal upright stance.

Adolescent↗
PubMed2006

The impact of comorbidities on the change in short-form 36 and oswestry scores following lumbar spine surgery.

STUDY DESIGN: This is an observational study of 3482 patients undergoing lumbar spine surgery from the National Spine Network. OBJECTIVES: To explore the influence of medical and psychosocial comorbidities on the change in Short-form 36 (SF-36) general health survey and condition-specific Oswestry Disability Index (ODI) scores in patients undergoing lumbar spine surgery. SUMMARY OF BACKGROUND DATA: It remains unclear as to which type of health instrument is more appropriate for monitoring improvement in patients who undergo lumbar spine surgery. Most clinicians would suspect that comorbidities (medical and psychosocial) play a significant role in the outcome of spine patients. Yet, it has been difficult to quantify specifically the impact of comorbidities on the responsiveness of traditional health status instruments for spine patients. METHODS: Analysis of variance was performed to assess the difference in the change in survey scores across comorbidity groups for the population of National Spine Network patients who had undergone lumbar spine surgical intervention and completed 3-month and 1-year follow-up surveys. Multiple linear regressions were used to identify the most influential individual comorbidities on the change scores. RESULTS: Comorbidities had a significant impact on the change in scores at 3 months and 1 year. The average change in bodily pain, physical function, physical component summary scores of the SF-36, as well as ODI scores decreased in response to surgery as the number of comorbidities increased. Psychosocial comorbidities such as an active compensation case, self-rated poor health, and smoking exerted large effects on the change in survey scores after surgery (P < 0.003). Medical disorders such as headaches, depression, and nervous system disorders were also highly influential (P < 0.05). CONCLUSIONS: The negative impact of medical and psychosocial comorbidities on the change in SF-36 general health survey and condition-specific ODI scores, despite spine surgery, highlights the need for researchers and clinicians to consider these comorbidities when using these, and perhaps all, health survey instruments and interpreting these scores after surgery. Contrary to current assumptions regarding condition-specific health surveys, medical and psychosocial comorbidities similarly affect the generic SF-36 and condition-specific ODI. Further studiesare needed to determine if spine surgery outcomes can be improved by specifically addressing potentially modifiable comorbidities, which negatively impact survey scores, or whether comorbidity burden should play a role in the selection process for surgical intervention. Failure to incorporate consideration of medical and psychosocial comorbidities into preoperative discussions can be a failure to allow our patients (and ourselves) to have realistic expectations and, consequently, the best possible outcome from their treatment choice.

Aged↗
PubMed2006

The role of cardiovascular disease in the identification and management of depression by primary care physicians.

OBJECTIVE: The objective of this study was to describe the influence of cardiovascular disease (CVD) on identification and management of depression by primary care physicians. METHOD: Three hundred fifty-five adults with and without significant depressive symptoms who were screened in primary care offices and invited to participate completed a baseline in-home assessment. CVD was assessed by self-report and psychologic status was assessed with commonly used, validated standard questionnaires. At the index visit, doctors' ratings of depression and reports of active management were obtained on 340 of the 355 patients who completed in-home interviews. RESULTS: Older adults who reported heart failure were more likely to be identified as depressed than were older adults who did not report heart failure (unadjusted odds ratio [OR]: 2.34; 95% confidence interval [CI]: 1.13-4.85; Wald chi(2) = 5.20, df = 1, p = 0.023). In multivariate models that controlled for potentially influential characteristics such as age, marital status, education, ethnicity, functional status, level of depression, cognitive impairment, attitudes about depression, use of medical care, and number of medications, the findings remained statistically significant. Among older adults identified as depressed, older adults with heart failure were significantly less likely to be actively managed for depression than were older adults without heart failure (unadjusted OR: 0.33; 95% CI: 0.14-0.76; Wald chi(2) = 6.73, df = 1, p = 0.009). After controlling for potentially influential covariates, these findings remained substantially unchanged. CONCLUSIONS: CVD, in particular heart failure, may influence the identification and management of depression among older patients by primary care physicians. The findings underlie the importance of developing interventions that integrate the management of depression and CVD in primary care settings.

Aged↗
PubMed2002

Parenting stress and parents' willingness to accept treatment in relation to behavioral problems of children with attention-deficit hyperactive disorder.

The purpose of this research was to explore parenting stress and parents' willingness to accept treatment in relation to the behavioral problems of children with Attention-Deficit Hyperactive Disorder (ADHD). A total of 100 subjects, either fathers or mothers of children with ADHD, were recruited by convenience sampling from southern Taiwan. The results of this research were: (1) the standardized score for parents' perception of the behavioral problems of their ADHD children was 67.09. (2) The standardized score for parents perception of parenting stress was 62.00. (3) The parents who were most willing to accept treatment were those in the parent training group. (4) The behavioral problems of ADHD children were significantly related to parenting stress (p .001). (5) ADHD children's behavioral problems and parental self-awareness of psychological and emotional problems were the two variables most influential on parenting stress, and recognition of the pathological cause was the most influential factor in willingness to accept treatment. Through this research we also found that the parents hoped that a parent training group would be established. Therefore, nursing personnel can try to develop parent training groups in order to relieve parents' parenting stress.

Adult↗
PubMed2007

An interagency network perspective on HIV prevention.

OBJECTIVE: The objective of this study was to describe the network structures of agencies and individuals engaged in HIV prevention in a North Carolina county. STUDY DESIGN: The authors conducted a cross-sectional study of interconnected agencies and individuals identified through snowball sampling. Participants were interviewed face to face with a structured questionnaire about interactions with others in the network. Network characteristics such as density and centralization were computed with UCINET software. RESULTS: The network of 11 agencies had an information exchange density of 14%. Exchanges of clients and funds were even more rare. The network of 17 individuals influential in HIV prevention was better connected with a density of 42%. CONCLUSIONS: The HIV prevention agencies in the county were not functioning as a network and thus were not benefiting the community to their full potential. Any connectedness between the agencies may be attributable to the better connections between influential individuals, several of whom worked for the agencies in the agency network.

Community Networks↗
PubMed2005

Physical landscapes in biological membranes: physico-chemical terrains for spatio-temporal control of biomolecular interactions and behaviour.

The evolving complexities of biological membranes are discussed from the point of view of potential roles of the physical constitution of the membrane. These include features of the surface and dipole potentials and membrane 'rafts'. These properties are outlined; they emphasize that protein-lipid and specific lipid environments are influential parameters in how biomolecular interactions may take place with and within membranes. Several fluorescence detection technologies directed towards measurement of these properties are also outlined that permit high-resolution experimental determination of intermolecular interactions with membranes by measuring small changes of these potentials. These point to the possibility that the membrane dipole potential in particular is enormously influential in determining the behaviour of receptor and signalling systems within membrane rafts, and offers the means of a novel mechanism for biological control.

Cell Membrane↗