Bowker's Test Research Articles

Use of a Body Proportionality Index for Growth Assessment of Preterm Infants

To evaluate the utility of weight-for-length (defined as gm/cm(3), known as the "ponderal index") as a complementary measure of growth in infants in neonatal intensive care units (NICUs). This was a secondary analysis of infants (n=1214) of gestational age 26 to 29 weeks at birth, included in a registry database (1991-2003), who had growth data at birth and discharge. Weight-for-age and weight-for-length were categorized as small (<10th percentile), appropriate, or large (>90th percentile). Statistical agreement between the weight-for-age and weight-for-length measures was poor (kappa=0.02 at birth, 0.10 at discharge; Bowker test for symmetry, P< .0001). From birth to discharge, the percentage of small-for-age infants increased from 12% to 21%, the percentage of small-for-length infants decreased from 10% to 4%, the percentage of large-for-age infants remained similar (<1%), and the percentage of large-for-length infants increased from 5% to 17%. At discharge, 92% of the small-for-age infants were appropriate or large-for-length, and 19% of the appropriate-for-age infants were large-for-length. Weight-for-age and weight-for-length are complementary measures. Weight-for-length or other measures of body proportionality should be considered for inclusion in routine growth monitoring of infants in the NICU.

Contrast-enhanced T1-weighted Fluid-attenuated Inversion-recovery BLADE Magnetic Resonance Imaging of the Brain: An Alternative to Spin-echo Technique for Detection of Brain Lesions in the Unsedated Pediatric Patient?

We compared contrast-enhanced T1-weighted magnetic resonance (MR) imaging of the brain using different types of data acquisition techniques: periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER, BLADE) imaging versus standard k-space sampling (conventional spin-echo pulse sequence) in the unsedated pediatric patient with focus on artifact reduction, overall image quality, and lesion detectability. Forty-eight pediatric patients (aged 3 months to 18 years) were scanned with a clinical 1.5-T whole body MR scanner. Cross-sectional contrast-enhanced T1-weighted spin-echo sequence was compared to a T1-weighted dark-fluid fluid-attenuated inversion-recovery (FLAIR) BLADE sequence for qualitative and quantitative criteria (image artifacts, image quality, lesion detectability) by two experienced radiologists. Imaging protocols were matched for imaging parameters. Reader agreement was assessed using the exact Bowker test. BLADE images showed significantly less pulsation and motion artifacts than the standard T1-weighted spin-echo sequence scan. BLADE images showed statistically significant lower signal-to-noise ratio but higher contrast-to-noise ratios with superior gray-white matter contrast. All lesions were demonstrated on FLAIR BLADE imaging, and one false-positive lesion was visible in spin-echo sequence images. BLADE MR imaging at 1.5 T is applicable for central nervous system imaging of the unsedated pediatric patient, reduces motion and pulsation artifacts, and minimizes the need for sedation or general anesthesia without loss of relevant diagnostic information.

Comparison of transcranial radiograph and magnetic resonance imaging in the evaluation of mandibular condyle position

Several image modalities have been used to assess the condylar position in the glenoid fossa. However, despite the development of more advanced techniques for imaging the temporomandibular joint (TMJ), the transcranial projection remains widely used in dentistry. The purpose of this study was to compare the condylar position in transcranial radiography (TRANS) with MRI. 70 matched pairs of TMJs (35 patients) who had undergone TRANS and MRI were evaluated. The TRANS scans were compared with the lateral, central and medial MRI scans, and the condylar position was assessed in the closed and open mouth position according to subjective and objective methods. The sensitivity, specificity and accuracy values were calculated for each group and Bowker's test was used to analyse the data. There was no statistical significance between TRANS and MRI (P > 0.05). However, even though there were similar mean values between them, the comparison with the lateral image showed higher values, which might be due to TRANS representing the lateral one-third of the condyle. It can be concluded that TRANS seems to be an acceptable method and its applicability as an adjunctive method in the condylar position should not be rejected.

Developmental stages of permanent canines, premolars, and 2nd molars in 244 Danish children

Objective. The purpose of this study was to establish reference values for maturity of permanent canines, premolars, and permanent 2nd molars in Danish children, and to focus on differences between the right and left sides, males and females, and the maxilla and mandible. Material and Methods. Panoramic radiographs from 106 males (8–14 years) and 137 females (7 years 2 months to 13 years 8 months) were analyzed, along with the maturity of the canines, premolars, and 2nd molars in each radiograph. Each tooth was categorized according to Haavikko's crown and root morphology. Inter-observer reliability was performed. For statistical analysis, Bowker's test was used for symmetry evaluation and comparison of maturity in the maxilla and mandible. The association between stage and age was presented by cumulative distributions. The Wilcoxon rank sum test was used for evaluating differences between genders. Results. Differences in maturity between the left and right sides were non-significant. A significant difference in dental maturity was observed between males and females, except for the maxillary 2nd premolar. Females matured earlier than males. The mandibular canines matured significantly earlier than the maxillary canines in females. No significant differences between the jaws were observed in the maturation of the premolars and 2nd molars. Conclusion. These reference values for dental maturity can be useful in orthodontic treatment planning and as a reference for odontological forensic age determination.

Avaliação do impacto da correção cirúrgica de distopias genitais sobre a função sexual feminina

PURPOSE: to identify the impact of pelvic reconstructive surgery on female sexual function, as well as the changes in vaginal anatomy, and to detect possible correlations between them. METHODS: a prospective, descriptive study, including 43 sexually active women with genital dystopy, undergoing surgery for pelvic organ prolapse, conducted between October 2004 and September 2006. The women completed the same multiple-choice questionnaire regarding sexual function, and analogic scales to quantify the degree of desire, arousal and satisfaction, and were clinically assessed using the pelvic organ prolapse quantification (POP-Q) staging system, before the surgery and three and six months after it. Statistical analysis was performed through the Bowker test for symmetry, Wilcoxon test, Student t test, c2 and analysis of variance (ANOVA) as appropriate, with statistical significance set at 5% (p<0.05). RESULTS: all 43 women completed the follow-up at three and six months after the surgery, but two of them lost their partners after the surgery. Quality of sexual life improved significantly (p=0.03). Symptoms such as dyspareunia (25.6% before versus 17.1% after surgery), discomfort (27.9 versus 0%), embarrassment (20.9% versus 0%) and fear (2.3% versus 0%) significantly improved (p<0.001). Analogical scales scores regarding desire (5 versus 7, p=0.001), arousal (6 versus 8, p<0.001) and satisfaction with sexual life (5 versus 7, p<0.001) also improved. There was a statistically significant improvement (p<0.001) of the POP-Q stages after the surgery. However, there was no statistically significant correlation between changes in vaginal dimensions and changes in sexual function. CONCLUSIONS: after pelvic reconstructive surgery, there was a significant improvement in the quality of sexual life and of the POP-Q stages. However, there was no correlation between them.

The Stability of Dryness Symptoms After Refitting With Silicone Hydrogel Contact Lenses Over 3 Years

To assess the stability of dryness symptoms after refitting patients wearing low-Dk/t hydrogel contact lenses with high-Dk/t silicone hydrogel contact lenses and to determine whether early dryness symptoms were predictive of discontinuation in the 3-year study. Two hundred seventy-eight hydrogel lens wearers were refitted with lotrafilcon A silicone hydrogel contact lenses for continuous wear of up to 30 nights. Self-administered questionnaires at baseline, 1 week, and 3 years captured the frequency and intensity of dryness symptoms during the day and at the end of the day. One-week and 3-year responses were compared to baseline by a Bowker test of symmetry and median change in response with Wilcoxon signed rank test. Frequency of during-the-day and end-of-day dryness decreased from baseline to 1 week and 3 years (during the day, frequency > or = "sometimes" 57.1% vs. 33.1% after 1 week and 58.5% vs. 28.8% after 3 years; end of day, 61.1% vs. 41.0% after 1 week and 64.0% vs. 35.9% after 3 years [P<0.0001 for all comparisons]). After refitting, the proportion of subjects with dryness symptoms was stable. After 1 week, the presence of frequency of at least "sometimes" and severity of at least "moderate" during-the-day and end-of-day dryness were significantly associated with study discontinuation (during-the-day frequency [P=0.007] and severity [P=0.017]; end-of-day frequency [P=0.002] and severity [P=0.003]). Dryness symptoms improved after 1 week of refitting with lotrafilcon A and remained stable through 3 years. The presence of dryness after 1 week was associated with discontinuation from contact lens wear. Refitting with silicone hydrogel lenses reduced the frequency and severity of dryness symptoms seen with hydrogel lens wear for many subjects.

Midadult Women's Attitudes About Receiving the Prophylactic Human Papillomavirus Vaccine

To determine midadult (age, > or =25 years) women's attitudes about receiving the prophylactic human papillomavirus (HPV) vaccine. Four hundred seventy-two women 25 years or older completed a 46-question survey, read an educational sheet about HPV and HPV vaccines, and then completed a 23-item survey. Frequency data were reported, and interventional effects measured by Bowker test of symmetry. After educational intervention, 50% of mid-adult women wanted to receive the vaccine, and 34.3% were undecided. A desire to be healthy (48.9%), prevent cervical cancer (42.8%), and fear of cervical cancer (35.8%) were the most common reasons for wanting the vaccine. The main reasons for not wanting the vaccine included being in a monogamous relationship (29.5%), not being at risk for acquiring HPV (15.0%), and practicing safe sex (10.8%). Midadult women have a high level of acceptance for the HPV vaccine. Our findings help support future implementation of the vaccine in this catch-up population of receptive women.

Bowker's test for symmetry and modifications within the algebraic framework

Categorical data occur in a wide range of statistical applications. If the data are observed in matched pairs, it is often of interest to examine the differences between the responses. The focus is on tests of axial symmetry in two-way tables. A commonly used procedure is the Bowker test which is a generalization of the McNemar test. The test decision is based on a chi-squared approximation which might not be adequate, for example if the table is sparse. Therefore, modifications of the test statistic have been discussed. A test of symmetry based on Bowker's test and Markov Chain Monte Carlo methods is proposed. A simulation study is carried out to determine and compare the performances of the simulation test, the Bowker test and two modifications.

A prospective study of the diagnostic potential of the knee tunnel view radiograph in assessing anterior knee pain

The aim of this comparative study was to examine the potential advantage of the tunnel view radiograph over a series of weight bearing antero-posterior (AP), lateral and skyline radiographs. The study population consisted of 240 subjects with knee pain aged 19 to 93 years. A total of 309 knees had a weight bearing AP in extension, lateral, skyline and tunnel view radiographs. Each radiograph was reported with respect to features related to osteoarthritis, modified from the Ahlback system. Each feature was assessed using the tunnel radiograph alone and then the AP, lateral and skyline views in combination without, and blind to, the information from the tunnel view. On the basis of Bowker's test, the tunnel view was more likely to pick up abnormal intercondylar notch and tibial spine osteophytes but not loose bodies. We conclude that the tunnel view is a valuable addition in the routine assessment of the knee joint in osteoarthritis but not for the diagnosis of loose bodies alone.

Phase-inversion tissue harmonic imaging compared to fundamental B-mode ultrasound in the evaluation of the pathology of large and small bowel

Our purpose was to compare phase-inversion harmonic imaging (PIHI) with conventional B-mode ultrasound (US) regarding image quality in the evaluation of bowel pathology. Forty-one patients prospectively underwent intestinal ultrasound scans with US and PIHI in randomly chosen order. Crucial technical parameters were standardized. Bowel morphology as well as perienteric pathology and complications were documented. In 24 cases, the ultrasound results were compared to those of other imaging modalities. Three radiologists evaluated (1) overall image quality, (2) lesion conspicuity and diagnostic confidence, and (3) detection of free fluid on hardcopy films. The ratings for image quality were compared using the two-sample paired t test for means and Bowker's test for symmetry (p=0.05). Compared to US, PIHI provided significantly better overall image quality, lesion conspicuity and diagnostic confidence, as well as better detection of free fluid (p< 0.05). Bowel wall pathology, detected by both modalities, showed good correlation to additional imaging modalities. In 12 patients (29.3%), a gain of crucial diagnostic information was observed with PIHI when compared to US. PIHI significantly enhances sonography of the intestine by offering better overall image quality, better visualization of bowel pathology and associated changes. Additionally, PIHI adds crucial diagnostic information in several patients.

Interobserver Agreement for Colposcopy Quality Control Using Digitized Colposcopic Images During the ALTS Trial

To estimate interobserver agreement among colposcopy quality control reviewers viewing digitized cervical images during the Atypical Squamous Cells of Undetermined Significance/Low-Grade Squamous Intraepithelial Lesion Triage Study (ALTS). Three colposcopy quality control reviewers independently examined modem-transferred digitized colposcopic images from subjects examined at four clinical centers. Reviewers indicated colposcopic impression, Reid colposcopic index scores, lesion size, and the technical quality of the image. Rates of agreement were evaluated using the kappa statistic and McNemar and Bowker tests of symmetry. Regarding colposcopic impressions, the average weighted kappa for pairs of initial reviewers was 0.36 (95% confidence interval, 0.33-0.39). kappa scores with respect to Reid colposcopic index, cervical image quality, and lesion size ranged from 0.23 to 0.28, 0.18 to 0.27, and 0.33 to 0.42, respectively. Fair rates of agreement and poor to fair kappa scores among ALTS colposcopy quality control reviewers were noted for colposcopic impression, Reid colposcopic index scores, image quality, and lesion size. Great latitude exists in the interpretation of digitized cervical images. Poor image quality partially may explain these suboptimal results.

Assessing disability in older adults: the effects of asking questions with and without health attribution

To determine the effects of using questions with and without health attribution on scores derived from a self-report disability instrument. We administered the disability component of the Late Life Function and Disability Instrument to 75 community-dwelling older adults. Then, we administered the same 16 questions with attribution to specific health conditions. We used a series of analytic methods including weighted Kappa coefficient, Bowker's Test of Symmetry and Rasch analysis to assess the effects of attribution formats. A higher prevalence of disability was reported in the non-health attributed compared with the health attributed questions (t = 5.76; p < 0.001, 95% CI 3.8-7.8). Item analyses indicated that participants were significantly more likely to report disability on the non-health attributed version on 4 of the 16 questions. For community-dwelling older adults, the use of a non-health attribution format may be preferable in instruments designed to assess prevalence of disability from contributing factors other than just health.

The Acceptability of the Female and Male Condom: A Randomized Crossover Trial

CONTEXTAlthough studies have assessed the acceptability of male and female condoms, comparative trial data are lacking.METHODSA sample of 108 women in stable relationships recruited from an urban, reproductive health clinic were randomly assigned to use 10 male or female condoms, followed by use of 10 of the other type. A nurse provided instruction in correct method use. Demographic information was collected in a baseline questionnaire; acceptability data were collected in follow‐up and exit questionnaires and coital logs. Nonparametric and chi‐square statistics were used to analyze measures of the methods’relative acceptability. Bowker's test of symmetry was adapted to test the null hypothesis of no difference in acceptability between condom types.RESULTSParticipants used 678 female and 700 male condoms. Although neither method scored high on user satisfaction measures, the 63 women completing the study protocol preferred the male condom to the female condom for ease of application or insertion, ease of removal, general fit, feel of the condom during intercourse and ease of penetration. Participants reported that their partner also favored the male condom, although women generally appeared to like this method more than their partner did. In a direct comparison between the methods at the end of the study, women generally judged male condoms superior on specified preference criteria.CONCLUSIONSAcross a range of criteria, the female condom was less acceptable than the male condom to most women and their partners. Although both types had low acceptability, they are needed and valid methods of pregnancy and disease prevention. That neither rated high on user satisfaction measures underscores the need for more barrier methods that women and men can use.

Intraindividual comparison of epithelial defects during laser in situ keratomileusis using standard and zero-compression Hansatome microkeratome heads

Purpose: To determine the difference between the standard and a modified (zero-compression) Hansatome ® microkeratome head (Bausch & Lomb) in the incidence of epithelial defects. Setting: Department of Ophthalmology, Johann Wolfgang Goethe-University, Frankfurt am Main, Germany. Methods: Ninety-three patients (186 eyes) with a mean age of 39.1 years ± 9.5 (SD) having laser in situ keratomileusis (LASIK) in both eyes were enrolled in a prospective randomized study using intraindividual comparison. In 1 eye, the flaps were created with the Hansatome microkeratome using the standard Hansatome head and in the other eye, the flaps were created with a microkeratome head with a modified design (zero-compression head). Intraoperative evaluation of epithelial defects was done using a standardized protocol. Statistical evaluation was performed with McNemar and Bowker tests. Results: Epithelial defects occurred in 21 eyes (22.6%) in which the standard head was used and in 2 eyes (2.1%) in which the zero-compression head was used. In the former group, 15 (16.1%) of the epithelial defects were larger than 1.5 mm 2; the remaining 6 (6.4%) were smaller than 1.5 mm 2. In the latter group, both epithelial defects were smaller than 1.5 mm 2; both patients also had an epithelial defect in the eye in which the standard Hansatome head was used. The difference between the 2 Hansatome heads in the incidence ( P<.001, McNemar) and size ( P<.001, Bowker) of the epithelial defects was statistically significant. Conclusions: The Hansatome microkeratome with a zero-compression head significantly reduced the occurrence of intraoperative epithelial defects. The change in the construction of the Hansatome head is a useful improvement in LASIK technology.

Chronaxie and Accommodation Index in the Diagnosis of Muscle Denervation

To determine the sensitivity of the combined measurement of chronaxie and the accommodation index in the qualitative diagnosis of muscle denervation with needle electromyography and to compare quantitative diagnoses. Ninety-three neurogenic muscles diagnosed by needle electromyography were consecutively included for measurement of chronaxie and the accommodation index in this prospective study. The sensitivity of qualitative diagnosis was assessed for all muscles, separately for the acute and subacute-chronic denervation phase and for the complete and partial denervation. The combined measurement of chronaxie and the accommodation index showed a 90% sensitivity to needle electromyography for qualitative diagnosis of muscle denervation for all muscles. A 100% sensitivity was found for the acute denervation phase and for complete denervation. The subacute-chronic denervation phase revealed a 86% sensitivity, and partial denervation had a 88% sensitivity. The kappa coefficients did not show satisfactory agreement in quantitative diagnosis, and Bowker's test revealed a statistically significant underestimation of muscle denervation for measurement of chronaxie. The combined measurement of chronaxie and the accommodation index can be recommended for the screening of neurogenic lesions in the acute denervation phase.

SYMMETRY IN SQUARE CONTINGENCY TABLES: TESTS OF HYPOTHESES AND CONFIDENCE INTERVAL CONSTRUCTION

Bowker's test, a generalization of McNemar's test, performs well under the hypothesis of symmetry, but the estimator of variance used in the test is biased when the table is asymmetric and this calls into question the test's performance in non-null situations. We seek an alternative to Bowker's test in search of methods for simultaneous inference that are valid when the hypothesis of symmetry is false. We apply multivariate normal theory to develop chi-square tests and simultaneous confidence intervals for inferences concerning symmetry in k × k contingency tables. We propose a modified Wald statistic as a competitor to Bowker's test. We also proffer quadratic estimators of confidence intervals. In large samples, the recommended test statistic rejects the null hypothesis at the stated level of significance when the null hypothesis is true and always rejects with greater power than Bowker's test. The proffered interval estimators provide good simultaneous coverage of the pairwise differences between the population proportions at the stated confidence level.

Contrast-enhanced 3D FISP MR angiography of the aortic arch ostia: preliminary results.

The goal of this work was to evaluate three-dimensional (3D) contrast-enhanced MR angiography (MRA) for the detection of ostial stenoses of the aortic arch. Sixteen patients with suspected carotid atherosclerotic disease prospectively underwent digital subtraction angiography of the aortic arch followed by contrast-enhanced MRA using a 3D fast imaging with steady-state precession (FISP) technique (TR = 5 ms, TE = 2 ms, flip angle = 30 degrees). Three neuroradiologists blindly measured stenoses on the catheter angiograms and MRA. Evaluation included the ostia of the innominate, left carotid, and left subclavian arteries. Any significant disagreement on catheter angiography was resolved by consensus. The MRA grades of each of the three observers were then compared with the consensus grades of the contrast angiogram. Forty-eight vessels were scored, of which five had significant stenoses. MRA demonstrated 100% sensitivity, 89% specificity, 52% positive predictive value, and 100% negative predictive value. The Bowker test for symmetry indicated no significant difference between conventional angiography and MRA scores (p = 0.32-0.75), and there was good agreement between the three observers (weighted kappa = 0.75-0.86). Contrast-enhanced 3D FISP MRA may be a useful imaging modality for the detection of significant stenoses at the ostia of the major aortic arch branches.

Expression of fibroblast growth factor (FGF)-8 isoforms and FGF receptors in human ovarian tumors.

FGF-8 is a mitogenic growth factor, which is widely expressed during embryonic development but only at a very low level in adult tissues. Alternative splicing of the human FGF-8 gene potentially allows coding for 4 protein isoforms (a, b, e, f), which differ in their transforming capacity. The FGF-8 isoforms preferentially activate the receptors FGFR1IIIc, FGFR2IIIc, FGFR3IIIc and FGFR4. FGF-8 is over-expressed in human breast and prostate cancers. Expression has also been found in RT-PCR studies of human ovarian and testicular cancers. The present study was undertaken to examine which FGF-8 isoforms are expressed in ovarian cancer and whether FGF-8 receptors are also expressed. Specimens from 5 normal human ovaries and 51 ovarian tumors (1 benign tumor, 8 borderline malignancies, 42 malignant tumors of different histopathological types) were studied by RT-PCR and immunohistochemistry. FGF-8 isoform b was expressed in all ovarian tumors and in all 7 ovarian-cancer cell lines studied. Isoform a was co-expressed in 9 malignant ovarian tumors. FGF-8 mRNA was not detected by RT-PCR of 3 normal ovary samples. Immunohistochemical staining localized FGF-8 protein to cancer cells. In general, the increased intensity of FGF-8 staining was associated with loss of differentiation within the tumors (Bowker's test, p = 0.37). FGF-8 staining of surface epithelium observed on 2 normal ovaries was very faint. RT-PCR showed that FGFR1IIIc, FGFR2IIIc and FGFR4 were the FGF-8 receptors expressed in normal ovaries and in ovarian tumors. FGF-8 receptor immunoreactivity was preferentially found in normal ovary surface epithelium and tumor cells but also in some stromal cells. Collectively, our results show that ovarian cancers of a wide variety of histological types expressing receptors for FGF-8 have acquired the capacity of expressing FGF-8. This suggests that FGF-8 has an important role in ovarian tumorigenesis.

Standard and Nonstandard Log-Linear Symmetry Models for Measuring Change in Categorical Variables

Abstract This article exemplifies how to recast well-known statistical tests in terms of more general statistical models. The example used is the Bowker test, a popular test for assessing axial symmetry in square cross-tabulations. Researchers use this test to assess patterns of change in categorical variables across two occasions. This article reviews how the Bowker test can be equivalently expressed in terms of log-linear models with side constraints that specify (1) those pairs of cells that are supposed to be symmetrical with regard to the main diagonal and (2) that the main diagonal cells remain untouched when estimating expected cell frequencies. This article proposes expressing the model of axial symmetry through vectors in the design matrix. In addition, this article recasts quasi-symmetry models in terms of nonstandard log-linear models. One benefit from this new formulation is that estimation of parameters and expected cell frequencies can be performed without unfolding the cross-tabulation. The article also introduces multiple group models. In addition, it is shown how shift patterns can be made part of models. Benefits from recasting well-known tests in terms of more general statistical models include that parameters can be interpreted and that tests can be parts of more elaborate research designs.

Efficacy and safety of ramipril in long-term treatment of congestive heart failure

The long-term efficacy and safety of ramipril, a long-acting angiotensin-converting enzyme inhibitor, were evaluated in 126 patients with moderate-to-severe congestive heart failure (New York Heart Association [NYHA] functional classes II to IV at baseline) in an open, multicenter trial lasting 96 weeks. An improvement in functional class, peripheral edema, and pulmonary congestion was evident after 2 weeks. At 12 weeks, improvement had reached a plateau, which was maintained throughout the 92 weeks of treatment; 89.3% of patients showed an improvement in NYHA class from baseline to endpoint. The improvements in peripheral edema and pulmonary congestion were statistically significant for change from baseline to endpoint ( P < 0.001, P < 0.0001, respectively; Bowker's symmetry test). Secondary variables of congestive heart failure, such as orthopnea and nocturnal dyspnea, also improved substantially. There were no significant changes in laboratory variables. Ramipril is an effective and well-tolerated therapy for the long-term treatment of patients with moderate-to-severe congestive heart failure.