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PubMed1995

Interobserver variability of sonographically determined second-trimester nuchal skinfold thickness measurements.

Twenty physicians experienced in fetal sonographic evaluation obtained fetal nuchal skinfold thickness measurements in each of five pregnant women between 16 and 18 weeks' gestation. A random effects analysis of variance model was used to explore the sources of variation in the set of measurements, to determine the interobserver variability of sonographically measured second-trimester nuchal skinfold thickness. It was possible to obtain 96 measurements. Four measurements (all in the same patient) were deemed unobtainable due to fetal position. All recorded measurements were between 1.7 and 4.5 mm. The means (and ranges) for the five patients were 2.7 (1.7-3.6), 2.9 (2.0-4.5), 2.7 (2.0-4.0), 3.3 (2.2-4.0), and 2.7 (1.8-4.0) mm. The standard deviation for interobserver variability, caused by the combined effect of physician and machine imprecision, was 0.56 mm and the overall coefficient of variation was 19.8%. Interpatient differences were statistically significant (p = 0.004). Interphysician differences were not (p = 0.11). We conclude that experienced physician sonographers using high-resolution ultrasound equipment are able to obtain second-trimester nuchal skinfold thickness measurements within 1.1 mm of the estimated true value with 95% probability.

Analysis of Variance↗
PubMed2002

The association between hepatitis C infection and survival after orthotopic liver transplantation.

BACKGROUND & AIMS: The effect of hepatitis C viral (HCV) infection on patient and allograft survival after orthotopic liver transplantation is controversial. Hepatitis C recurrence after transplant is inevitable, but studies to date have not found a survival difference between recipients with and without HCV. METHODS: Using data from the United Network for Organ Sharing, we performed a retrospective cohort study of 11,036 patients who underwent 11,791 liver transplants between 1992 and 1998. The hazard rates of patient and allograft survival for patients who were HCV-positive as compared with patients who were HCV-negative were assessed by proportional-hazards analysis, with adjustment for potential confounding variables, including donor, recipient, and transplant center characteristics. RESULTS: Liver transplantation in HCV-positive recipients was associated with an increased rate of death (hazard ratio, 1.23; 95% confidence interval [CI], 1.12-1.35) and allograft failure (hazard ratio, 1.30; 95% CI, 1.21-1.39), as compared with transplantation in HCV-negative recipients. This reduction in survival persisted after adjusting for potential confounders. There was an interaction between HCV and sex (P < 0.001) with the effect of HCV on survival being most pronounced in female recipients (patient survival hazard ratio, 1.56; 95% CI, 1.35-1.81; allograft survival hazard ratio, 1.51; 95% CI, 1.34-1.70). CONCLUSIONS: HCV infection significantly impairs patient and allograft survival after liver transplantation.

Adult↗
PubMed2001

The effects of acupressure on the incidence of postoperative nausea and vomiting in postsurgical patients.

Postoperative nausea and vomiting (PONV) is one of the most common postoperative complications. Aside from pharmacological interventions, other complementary healing modalities have been introduced to assist patients in decreasing PONV and improving postoperative outcomes. This study examined acupressure as a potentially holistic and safe complement to the more traditional approach of using drugs to prevent and/or relieve nausea and vomiting in the postoperative patient. Acupressure involves constant pressure (without puncture of the skin) on the Nei Guan acupuncture points through the use of a British product called Sea-Bands (Sea Band UK Ltd, Leics, England). These bands are made of elasticated fabric, with a small round plastic button inside. A quasi-experimental research design was used to examine the effects of unilateral and bilateral application of acupressure on 157 patients who are prone to PONV: postgynecological, postplastic, and posturological surgery patients. The incidence of PONV was determined through retrospective chart reviews. The hypothesis was that there would be a difference in the incidence of PONV between 5 groups: group 1 (Sea-Bands with acupressure on both wrists), group 2 (Sea-Bands with acupressure on one wrist), group 3 (wristband without acupressure on both wrists), group 4 (wristband without acupressure on one wrist), and group 5 (no wristband). This hypothesis was examined by using a one-way analysis of variance (ANOVA); it was not supported. Neither unilateral nor bilateral application of acupressure significantly affected the incidence of nausea and vomiting. These findings must be viewed with caution, however, because power analysis showed low effect sizes and an inadequate sample size. Further research is recommended with a larger sample size. This study has made perianesthesia nurses more aware of other complementary modalities to assist patients with nausea and vomiting.

Acupressure↗
PubMed2000

Redressing the power and effect of significance. A new approach to an old problem: teaching statistics to nursing students.

Many barriers to learning are present when teaching research methods. Developing, within students of nursing, the skills of reading and interpreting research reports is vital if the profession is to contribute to the general aim of achieving a sound basis for all health care interventions. This paper overviews the current move toward evidence based practice, the challenges that are present when teaching research to nursing students and offers an approach to teaching quantitative research that will help students of nursing to understand the key concepts that form the basis of inferential statistics. In this work we argue that the traditional emphasis on probability and statistical significance needs to be redressed and that effect size and power should form the basis of teaching students the concepts involved in inferential statistics. We argue that introducing students to the key concepts in statistical decision making in a particular order, effect size then power and lastly statistical significance, will lead to a better understanding of Type I and Type II errors. After all, the purpose of hypothesis testing is to detect a treatment or intervention effect. Power is dependent upon the size of the treatment effect, thus it must be introduced after effect size. Students, we argue, must be able to understand the concept of effect size. We consider this to be a foundational concept that will help to develop a firmer grasp of the decision making processes involved in hypothesis testing. Such an approach will form a more logical approach to teaching this subject and will allow for the use of real world examples to form the basis of learning.

Bias↗
PubMed2004

[Estimating effect sizes in clinical trials].

Even though reporting of effect sizes is recommended in methodological guidelines such as the CONSORT Statement (Consolidated Standard of Reporting Trials), these quantities are still rarely included in reports on studies in rehabilitation medicine. The aim of this paper is to emphasize the relevance of reporting effect sizes and to illustrate different methods for their calculation. The implications of using different methods for calculating effect sizes are also discussed.

Clinical Trials as Topic↗
PubMed1999

[Short assessment of subjective quality of life. Application and results of a short form of the Berliner Lebensqualitätprofil (BELP-KF)].

The concurrent validity between the Berliner Lebensqualitätsprofil (BELP) and a new developed short form (BELP-KF) was tested in a sample of schizophrenia outpatients (N = 36) and turned out to be very high. The restriction to subjective quality of life questions did not lead to a greater halo-effect in the sense of an increasing similarity of single item values. Correlations with psychopathological symptoms were almost identical for both interview-versions. The same is true concerning the factorial structure of the satisfaction items which was nearly congruent. Two optional items on satisfaction with sexual life and with psychopharmacological treatment, which had been included into the short interview version, were attributable to an underlying general satisfaction dimension. Among 14 variables satisfaction with psychopharmacological treatment had the second highest factor-loading on the resulting general satisfaction factor.

Antipsychotic Agents↗
PubMed2001

Immunologic features of chromosome 22q11.2 deletion syndrome (DiGeorge syndrome/velocardiofacial syndrome).

OBJECTIVES: To characterize immunologic function and clinical characteristics in patients with chromosome 22q11.2 deletion syndrome and determine whether there was significant change over time. METHODS: This study characterized the laboratory and clinical features of the immunodeficiency in a cohort of 195 patients with chromosome 22q11.2 deletion syndrome and used cross-sectional and analysis of variance to compare the findings in different age groups with control patients. Changes over time were also characterized by a model effect method in a subset of patients who were studied serially. RESULTS: Diminished T cell counts in the peripheral blood are common in patients with chromosome 22q11.2 deletion syndrome. The pattern of changes seen with aging in normal control patients was also seen in patients with chromosome 22q11.2 deletion syndrome, although the decline in T cells was blunted. Autoimmune disease was seen in most age groups, although the types of disorders varied according to age. Infections were also common in older patients, though they were seldom life threatening. CONCLUSIONS: Slow declines in T cell populations are seen in chromosome 22q11.2 deletion syndrome. Clinical manifestations of immunodeficiency, such as recurrent infection and autoimmune disease, were common in this population but had little relationship to specific immunologic laboratory features.

Antibody Formation↗
PubMedDate not supplied

Associations of London, England, daily mortality with particulate matter, sulfur dioxide, and acidic aerosol pollution.

During the extreme pollution episodes of 1952 and 1962 in London, England, excesses in daily mortality were clearly evident. In this study, we examined daily British Smoke, sulfur dioxide, acid aerosols, and weather variables for their short-term associations with daily mortality in the more typical (nonepisodic) winters of 1965-1972. Consideration of the acid aerosol data was of special interest because this chemical component has been suspected as a causal agent in past episodes. Temporal lag structures between the variables were examined after removal of long-term components from each series in order to obtain "rational" cross-correlations. Significant associations between same-day and lagged pollution variables and mortality were found. Alternative regression models with pollution and weather variables were also developed. The coefficients obtained were applied to the 1962 pollution episode to examine the continuity of the estimated slopes. The pollution-predicted deaths fit the observed deaths well, which supports the applicability of such deviation-derived coefficients to the absolute scale. These models were also employed to estimate mean excess daily deaths attributed hypothetically to air pollution. On average, mean effect ranged from 2-7% of all deaths during the nonepisodic winters in Greater London, but the 95% confidence intervals of these estimates overlapped for all model specifications examined. This estimated pollutant mixture "effect" cannot be attributed to a particular pollutant because of a lack of quantitative information on the relative downward biases caused by both analytical errors and errors in the spatial representativeness of each respective pollution index.

Acids↗
PubMedDate not supplied

Simple visual reaction time in organolead manufacturing workers: influence of the interstimulus interval.

The authors conducted this investigation to study the effects of interstimulus interval duration for a given simple visual reaction time trial on the relationship between lead exposure and reaction time. Organolead manufacturing workers (n=222) and nonexposed referents (n=62) were administered a neurobehavioral test battery that included simple visual reaction time. Simple visual reaction time was measured over 44 trials; interstimulus intervals ranged from 1 to 10 s in a randomly generated sequence that was identical for all study subjects. Mean reaction times for both lead-exposed and nonexposed subjects were longest for interstimulus intervals of 1 and 2 s. Mean reaction times in response to moderate (4-6 s) and long (7-10 s) interstimulus intervals were mainly associated with lead exposure; this association led the authors to suggest that interstimulus interval duration modifies the relationship between lead exposure and simple visual reaction time performance. In simple visual reaction time protocols, stronger associations between reaction time and lead exposure may be found if the analysis trials are separated with interstimulus intervals of less than 3 s duration.

Age Factors↗
PubMed1997

Field studies of comfort and discomfort in sitting.

A previous study defined sitting comfort and discomfort as independent entities associated with different factors: discomfort is related to biomechanics and fatigue factors, and comfort to a sense of well-being and aesthetics. In this study a checklist for evaluation of chair comfort and discomfort was analysed in two field studies. In the first study two groups of subjects, ten secretaries and ten managers, evaluated two groups of ten chairs. Subjects assessed each chair three times during a workday using three different types of scales. The results of a factor analysis reconfirmed the factor structure of comfort and discomfort. Analysis of variance demonstrated that discomfort was related to fatigue accumulated during the workday, but it was not related to chair design. There was no significant Chair x Time period interaction, which implies that the rank order of preference among a set of chairs was established during the first assessment and did not change during the day. In a second field study 37 secretaries used three different formats of a Chair Evaluation Checklist with 14 items. The results of a factor analysis again confirmed the factor structure of comfort and discomfort. Analyses of variance demonstrated that subjects can evaluate comfort and discomfort simultaneously without any halo-effect. The results have methodological implications for measurement of comfort and discomfort. The findings for comfort, as defined, carry an important message that aesthetic design matters. This could provide a unifying focus for ergonomists and designers.

Analysis of Variance↗
PubMed2002

Examining contrast effects in performance appraisals: using appropriate controls and assessing accuracy.

In research on contrast effects in performance appraisals, control conditions or measures of accuracy have rarely been used. In the present study, the authors included appropriate controls and used expert ratings to develop "true scores" for assessing accuracy. The study is an examination of the influence of 3 variables on performance ratings: (a) the sequence of viewing and rating performance, (b) the delay between viewing and rating performance, and (c) whether the target of the performance rating was the same person as the anchor. Experimental conditions did not have the expected differential effects on target ratings, but target ratings in all the experimental conditions showed contrast effects when compared with ratings in relevant control conditions. The target ratings in experimental conditions were accurate, however, as assessed by comparisons with true scores, thus raising questions about the relationship between contrast effects and accuracy.

Analysis of Variance↗
PubMed1997

The availability heuristic: effects of fame and gender on the estimated frequency of male and female names.

In two experiments, Canadian undergraduates heard a list of 13 male names and 13 female names; then they estimated how many male and female names there seemed to be. In Experiment 1, the list consisted of 26 famous names or 26 nonfamous names. Both male and female participants gave similar estimates for the number of male and female names, contradicting hypotheses of a bias toward males or toward one's own gender. In Experiment 2, where the list contained names of famous men and nonfamous women or names of famous women and nonfamous men, participants gave higher estimates for the gender that was famous (effect size d = 0.78). This result confirmed Tversky and Kahneman's (1973) fame availability effect and showed it to be moderate to large in size.

Adult↗
PubMed1999

A critical analysis of randomised clinical trials on neck pain and treatment efficacy. A review of the literature.

The efficacy of physiotherapy or chiropractic treatment for patients with neck pain was analysed by reviewing 27 randomised clinical trials published 196-1995. Three different methods were employed: systematic analyses of; methodological quality; comparison of effect size; analysis of inclusion criteria, intervention and outcome according to The Disablement Process model. The quality of most of the studies was low; only one-third scored 50 or more of a possible 100 points. Positive outcomes were noted for 18 of the investigations, and the methodological quality was high in studies using electromagnetic therapy, manipulation, or active physiotherapy. High methodological quality was also noted in studies with traction and acupuncture, however, the interventions had either no effect or a negative effect on outcome. Pooling data and calculation of effect size showed that treatments used in the studies were effective for pain, range of motion, and activities of daily living. Inclusion criteria, intervention, and outcome were based on impairment in most of the analysed investigations. Broader outcome assessments probably would have revealed relationships between treatment effect and impairment, functional limitation and disability.

Activities of Daily Living↗
PubMed2004

Quality of life in glaucoma patients: regression analysis and correlation with possible modifiers.

PURPOSE: To verify the quality of life in a Brazilian glaucoma population and the influence of possible modifiers (e.g., visual acuity, visual field impairment). METHODS: Forty-five consecutive patients from CEROF - Federal University of Goias, Brazil were included prospectively in the study. The quality of life was assessed using the Portuguese version of the VFQ. Possible modifiers were evaluated, initially separately with the Spearman's Correlation and then together in a regression model. RESULTS: The mean age was 59.6 +/- 12.4 years. The mean quality of life score was 79 +/- 15 (range 45-100). Age (r = -0.402, p = 0.006), visual acuity in the better eye (r = -0.497, p = 0.001) and in the worse eye (r = -0.608, p < 0.001), Hodapp-Parrish-Anderson visual field grading scale in the better (r = -0.353, p = 0.01) and worse eye (r = -0.387, p = 0.009), visual field Mean Deviation (MD) in the better (r = 0.355, p = 0.01) and worse eye (r = 0.320, p = 0.04) and ability to perform a visual field test in both eyes (r = -0.397, p = 0.007) were significantly correlated with the quality of life scores. However, only age (younger, better quality of life, p = 0.008) and visual acuity in the better eye (direct relation, p = 0.04) were significant in the regression model (r = 0.633, r(2) = 0.401). CONCLUSIONS: The VFQ may be a useful tool to assess the quality of life in glaucoma patients. The preliminary results indicate that age and visual acuity in the better eye are the main factors related to the quality of life in these patients.

Age Factors↗