Wilcoxon Signed Rank Sum Test Research Articles

Predictors of hyperacute clinical worsening in ischemic stroke patients receiving thrombolytic therapy.

Although long-term outcome determinants in acute ischemic stroke (AIS) patients have been defined, less is known about those predicting hyperacute worsening after thrombolytic therapy (TT). We investigated predictors of short-term clinical worsening (National Institutes of Health Stroke Scale [NIHSS] change > or =4 within 24 hours of admission). We studied 201 AIS patients who received TT within 6 hours of symptom onset. We determined baseline demographics, comorbidities, NIHSS at baseline and at 24 hours after TT, head computed tomography scan before and within 24 hours after TT, and angiographic recanalization in patients treated with intra-arterial (IA) thrombolysis. Significance of relationships was evaluated by t test or Wilcoxon signed rank sum test. Logistic regression model (LRM) was fitted to determine independence of significant variables. Of 201 patients, 13% worsened, 39% improved, and 48% remained unchanged 24 hours after TT. Most patients (72%) received IA thrombolysis. Patients who deteriorated, compared with those who improved, were more likely to have complicating intracranial hemorrhage (ICH; P<0.001), absent recanalization (P=0.026), and higher blood glucose (BG; P=0.049). Hyperglycemia (>150 mg/dL) was greater in patients who worsened even in presence of recanalization (P=0.004, odds ratio [OR] 6.47). LRM showed that adjusted OR for increased risk of bad outcome and mortality for an increase of BG by 50 mg/dL is 1.56 and 1.38, respectively. Hyperglycemia and ICH are independent predictors of hyperacute worsening in AIS patients receiving TT. Although recanalization is the purpose of IA thrombolysis, its impact on clinical improvement may not be apparent without strict BG control.

Statistical Evaluation of Rehabilitation to the Disabled Elderly based Takizawa-Program

Elderly cases offered Takizawa-Program as one of the rehabilitation techniques were evaluated statistically. Initially we clarified the characteristics of the total FIM (Functional Independent Measure) score and the relation between the number of improved items and of worsened ones. Furthermore, we investigated the multidimensional relevance of 18 FIM items to explain the characteristics of improvement or aggravation clear, and obtained four factors by factor analysis and classified into six groups by cluster analysis, and then extracted some specific cases. Finally, we statistically verified the effect about the 18 FIM evaluation items using the t-test, a sign test and the Wilcoxon signed rank sum test, and several items in the FIM were turned out to be significantly effective.

Contrast-enhanced MR angiography vs intra-arterial digital subtraction angiography for carotid imaging: activity-based cost analysis.

The aim of this study was to compare the costs of performing contrast-enhanced MR angiography (CE MRA) with intra-arterial digital subtraction angiography (DSA) for the evaluation of carotid atherosclerotic disease. Activity-based cost analysis was used to identify the costs of performing each procedure. The variable direct costs of performing CE MRA and DSA were determined in 20 patients by using detailed time and motion studies. All personnel directly involved in the cases were tracked to the nearest minute and all consumable items used were recorded. Moreover, procedure times were prospectively recorded for an additional 80 patients who underwent both DSA and CE MRA. The variable direct costs of bed usage in the angiography day-case unit, all direct fixed costs as well as indirect costs were assessed from hospital and departmental accounting records. Total costs for each procedure were calculated and compared using Wilcoxon signed-rank sum test. Mean aggregate costs were Euro 721 for DSA and Euro 306 for CE MRA, resulting in potential savings of Euro 415 per patient (p<0.0001). On average, a DSA procedure thus cost approximately 2.4 (95% confidence intervals: 2.2-2.6) times more than CE MRA to our medical institution. Sensitivity analyses confirmed the robustness of our conclusions across wide ranges of plausible values for various parameters. Assuming equal diagnostic performance, institutions may have substantial cost savings if CE MRA is used instead of DSA for carotid imaging.

Effect of continuing or finishing high-level sports on airway inflammation, bronchial hyperresponsiveness, and asthma: A 5-year prospective follow-up study of 42 highly trained swimmers

Abstract Background: Mild eosinophilic airway inflammation and bronchial hyperresponsiveness-ie, mild asthma-have been shown to affect a high proportion of endurance athletes. The persistence of airway inflammation, bronchial hyperresponsiveness, and asthma in this population is not known, however, inasmuch as follow-up studies of athletes' asthma have not been performed. Objective: The purpose of this study was to investigate effect of finishing high-level sports on airway inflammation, bronchial hyperresponsiveness, and asthma. Methods: Forty-two elite competitive swimmers, most of them from the Finnish national team (37/42; 88%), were followed for 5 years in a prospective manner. All of the swimmers completed questionnaires and underwent resting spirometry, histamine challenge testing, and skin prick tests at baseline and at follow-up. Twenty-nine swimmers (69%) also gave induced sputum samples on both occasions. Sixteen (38%) of the swimmers had continued their competitive careers during follow-up (active swimmers), but 26 (62%) had stopped competing more than 3 months before the follow-up examination (past swimmers). Results: Bronchial responsiveness was increased in 7 (44%) of the 16 active swimmers at baseline and in 8 (50%) of the 16 active swimmers at follow-up; it was increased in 8 (31%) of the 26 past swimmers at baseline and in 3 (12%) of the 26 past swimmers at follow-up (McNemar test, P = .025). The difference in the change in bronchial hyperresponsiveness between the study groups was significant (likelihood ratio test, P = .023). Current asthma (defined as bronchial hyperresponsiveness and exercise-induced bronchial symptoms monthly) was observed in 5 (31%) of the active swimmers at baseline and in 7 (44%) of the active swimmers at follow-up; of the past swimmers, it occurred in 6 (23%) at baseline and in 1 (4%) at follow-up (McNemar test, P = .025). The difference in the change in current asthma between the study groups was significant (likelihood ratio test, P = .0040). The sputum differential cell counts of eosinophils and lymphocytes increased significantly during the follow-up period in the active swimmers (Wilcoxon signed rank sum test; P = .033 and P = .0029, respectively); in the past swimmers, the sputum differential cell counts of eosinophils tended to decrease during the follow-up period ( P = .17), whereas the differential cell counts of lymphocytes did not change significantly. The changes in the sputum differential cell counts of eosinophils between the study groups differed significantly (Mann-Whitney U test, P = .019). Conclusion: In swimmers who had stopped high-level training, bronchial hyperresponsiveness and asthma attenuated or even disappeared. Mild eosinophilic airway inflammation was aggravated among highly trained swimmers who remained active during the 5-year follow-up. Our results suggest that athletes' asthma is partly reversible and that it may develop during and subside after an active sports career. (J Allergy Clin Immunol 2002;109:962-8.)

Effect of continuing or finishing high-level sports on airway inflammation, bronchial hyperresponsiveness, and asthma: a 5-year prospective follow-up study of 42 highly trained swimmers.

Mild eosinophilic airway inflammation and bronchial hyperresponsiveness-ie, mild asthma-have been shown to affect a high proportion of endurance athletes. The persistence of airway inflammation, bronchial hyperresponsiveness, and asthma in this population is not known, however, inasmuch as follow-up studies of athletes' asthma have not been performed. The purpose of this study was to investigate effect of finishing high-level sports on airway inflammation, bronchial hyperresponsiveness, and asthma. Forty-two elite competitive swimmers, most of them from the Finnish national team (37/42; 88%), were followed for 5 years in a prospective manner. All of the swimmers completed questionnaires and underwent resting spirometry, histamine challenge testing, and skin prick tests at baseline and at follow-up. Twenty-nine swimmers (69%) also gave induced sputum samples on both occasions. Sixteen (38%) of the swimmers had continued their competitive careers during follow-up (active swimmers), but 26 (62%) had stopped competing more than 3 months before the follow-up examination (past swimmers). Bronchial responsiveness was increased in 7 (44%) of the 16 active swimmers at baseline and in 8 (50%) of the 16 active swimmers at follow-up; it was increased in 8 (31%) of the 26 past swimmers at baseline and in 3 (12%) of the 26 past swimmers at follow-up (McNemar test, P =.025). The difference in the change in bronchial hyperresponsiveness between the study groups was significant (likelihood ratio test, P =.023). Current asthma (defined as bronchial hyperresponsiveness and exercise-induced bronchial symptoms monthly) was observed in 5 (31%) of the active swimmers at baseline and in 7 (44%) of the active swimmers at follow-up; of the past swimmers, it occurred in 6 (23%) at baseline and in 1 (4%) at follow-up (McNemar test, P =.025). The difference in the change in current asthma between the study groups was significant (likelihood ratio test, P =.0040). The sputum differential cell counts of eosinophils and lymphocytes increased significantly during the follow-up period in the active swimmers (Wilcoxon signed rank sum test; P =.033 and P =.0029, respectively); in the past swimmers, the sputum differential cell counts of eosinophils tended to decrease during the follow-up period (P =.17), whereas the differential cell counts of lymphocytes did not change significantly. The changes in the sputum differential cell counts of eosinophils between the study groups differed significantly (Mann-Whitney U test, P =.019). In swimmers who had stopped high-level training, bronchial hyperresponsiveness and asthma attenuated or even disappeared. Mild eosinophilic airway inflammation was aggravated among highly trained swimmers who remained active during the 5-year follow-up. Our results suggest that athletes' asthma is partly reversible and that it may develop during and subside after an active sports career.

A Cephalometric Study of Facial Growth in van der Woude Syndrome

To test the hypothesis that maxillary growth and lower lip form in patients with van der Woude syndrome (VDW) is different from patients with non-syndromic cleft lip and palate. Retrospective, case-control study at a tertiary cleft center, Chang Gung Memorial Hospital, Taipei, Taiwan. Records of 53 patients with VDW, who presented for treatment during the years 1968 through 1998 were obtained. Twenty-three of 53 patients had received at least one lateral cephalogram during the course of their treatment. Of these 23, in 17 it was possible to find non-syndromic case controls with identical cleft type, sex, and method of cleft palate repair, with year of birth matching within 1 year of the corresponding VDW patient. For these 17 pairs of VDW and non-syndromic cleft controls, cephalogram acquisition dates were checked to see how well the corresponding pairs matched. A total of 43 pairs of cephalograms were deemed to be acceptably matched because the ages at acquisition differed by less than 15% of the VDW patient's age. Thirteen measurements were derived from the 11 standard lateral cephalometric landmarks recorded on each cephalogram. The data were classified into five groups according to age at time of cephalogram, and sets of paired non-syndromic cleft and VDW measurements were tested for differences using a Wilcoxon signed rank sum test in two ways, first including all cleft types and then including only those patients with complete bilateral cleft lip and palate. A longitudinal growth analysis considering the movement of the skeletal A and B points was performed on the patients with complete bilateral cleft lip and palate. For the osseous measurements, anteroposterior maxillary length as described by the anterior nasal spine (ANS)-posterior maxillary point distance was statistically significantly shorter in the VDW patients of age 13 years and older, by 5.3 mm. Maxillary height, as described by the nasion-ANS distance was shorter in the VDW patients, closely approaching statistical significance in the age range 7 through 11 years. The lip soft tissue measurements showed significantly greater protrusion over several age ranges in the VDW patients. The longitudinal growth analysis showed a significantly more inferior vertical position of the B point in the controls. This study demonstrates a few statistically significant differences in maxillary growth and lip conformation between VDW and matching controls. Small sample sizes for each age group hamper the ability to fully interpret or generalize the pattern of these differences.

A study of anthropometric measures before and after external septoplasty in children: a preliminary study.

To test the hypothesis that surgery on the growing nasal septum does not adversely affect nasal and midfacial dimensions. Paired study. Tertiary care center. Children treated consecutively during a 4-year period; all had significant nasal obstruction and cosmetic disfigurement secondary to skeletal septal deformities. Nasal septal surgery (using an external approach), in which the quadrilateral cartilage was removed, remodeled, and reinserted as a free graft. Anthropometric linear measurements and indexes of the face and nose preoperatively and postoperatively; nasal dorsum length, nasal height, nasal dorsum index, nasal tip protrusion, columellar length, facial height, face width, upper face height, facial index, nose-upper face height index, and columellar length-nasal tip protrusion index. Continuous measurements were transformed into ordered categories with reference to normative data. Data were analyzed using Wilcoxon signed rank sum test (alpha level of.05) and by applying the Bonferroni adjustment for multiple testing. Twenty-six children were studied (12 females and 14 males); age at surgery ranged from 4.5 to 15.5 years (mean age, 9.5 years); average age at postoperative measurement, 12.5 years; mean follow-up, 3.1 years. Only nasal dorsum length (P =.007) and nasal tip protrusion (P =.04) were decreased by a statistically significant level before the Bonferroni adjustment. The change was not considered clinically significant. Thus, relative to age-appropriate norms, the dimensions of the nose and midface and their proportionality did not change after surgery. Appropriate nasal septal surgery involving excision and subsequent reinsertion of a remodeled segment of the quadrilateral cartilage has no deleterious effects on development of the nose and midface. We question the absolute dogma that nasal surgery in children must always be avoided.

The Clinical Characteristics of Initial Drug Resistance in MDR-TB Patients

Background : Multidrug-resistant tuberculosis(MDR-TB) in patients is mainly caused by acquired drug resistance. However, a small proportion of MDR-TB is caused by initial drug resistance(IDR), which may be somewhat different from acquired drug resistance. This study analyzed the clinical characteristics of IDR in MDR -TB patients to use the results as basic data in managing the disease. Methods : A retrospective study of 30 IDR cases in MDR-TB patients from Jan. 1995 to Dec. 1998 was performed. In order to analyze the clinical characteristics, the age, sex, family history, duration of negative conversion, number of resistant drugs, treatment regimens, duration of treatment, extent of disease and cavitary lesion on the chest X-ray was examined. In order to analyze the level of improvement, the extent of the disease and cavitary lesion on the chest X-ray, tested by Wilcoxon signed rank sum test, and the disease free interval rate of 1-year and 4-year was examined using the Kaplan-Meier method. Results : The mean age of the patients was 46.6 years and the sex ratio 1:1. Six(20%) patients had a family history. The mean negative conversion of the sputum AFB stain was 2.6 months. The number of resistant drugs was 7.6 and the number of used drugs 3.6. Twenty-three(67%) patients were treated for less than 12months and 28(93%) patients were treated with first-line drugs. The extent of the disease and the cavitary lesion on the chest X-ray improved after treatment(p

Postanal repair for faecal incontinence: long-term follow-up.

To determine the long-term outcome of postanal repair, and to assess whether the preoperative and physiological tests had any bearing on this outcome. Review included an opportunity for assessment with anal manometry and anal ultrasound. Review of all patients (n = 22) over a 10 year period from 1986 to 1996. Comparison was of pre-operative symptoms to symptoms at review. Correlation of outcome with pre-operative manometry and the results of manometry and ultrasound at review (n = 6) was determined. Assessment was possible in 19 of the 22 patients. Follow-up ranged from 2 to 10 years (median, 8 years). Two had stomas created at 6 and 9 months and are considered failures. Seven patients considered the operation a success, in four it improved their symptoms and in six it was considered a failure. Comparison of pre- and postoperative symptoms scores found a statistically significant improvement (P = 0.0093; two-tailed Wilcoxon signed rank sum test). The outcome was not influenced by the results of pre-operative anal manometry. Anal ultrasound found five sphincter defects in six patients. Such defects did not preclude improvement from postanal repair. Although the results showed improvement or success in only 11 (58%) of the patients this was felt to be important given that these patients may have few alternatives other than complicated procedures or a stoma. Postanal repair has a place in the management of faecal incontinence.

Psychological outcomes amongst cleft patients and their families

Our aims were to determine the psychological status of a sample of cleft lip and palate patients and their parents using standardised interviews and to assess subjects' satisfaction with cleft treatment. In all, 242 interviews of 112 patients and 130 parents were carried out in nine base hospitals used for cleft treatment. 73%s% ( n=38) of 15- and 20-year-old subjects felt their self-confidence had been very much affected as a result of their cleft. 60% of all 112 interviewed patients were teased about speech or cleft related features. A significant minority of 15-year-old subjects (23%, n=7) felt excluded from treatment planning decisions. Despite high levels of overall satisfaction with cleft care, 60% ( n=78) of parents and 37% ( n=41) of interviewed patients made suggestions for improvements. No agreement between parent/child pairs for their satisfaction with clinical outcome of cleft related features was found using the weighted kappa statistic to determine the level of agreement. Differences between parents' and their child's satisfaction ratings for cleft related features were not statistically significant except for the ratings for ‘lip’ ( P<0.005) and ‘teeth’ ( P<0.05) for 15-year-old subjects (Wilcoxon signed rank sum test). Patients' views on planned treatment should therefore be independently sought from their parents' views, as no agreement was found within the groups for perceived satisfaction with clinical outcome. This study demonstrates the importance of identifying ‘psychological outcome’ as well as ‘clinical outcome’ in order to improve rehabilitation for cleft lip and palate patients. Seven families were referred for counselling for cleft-associated emotional problems as a result of this survey.

Advantages of permutation (randomization) tests in clinical and experimental pharmacology and physiology.

1. The statistical procedures that are used most commonly in clinical and experimental pharmacology and physiology are designed to test for differences between two means. 2. The classical procedures for detecting such differences are those in which, under the population model of inference, the test statistic is referred to the t- or F-distributions. The validity of statistical inferences from these tests depends on a number of assumptions. Foremost among these is that the experimental groups have been constructed by taking random samples from defined populations. The statistical inferences then apply to the sampled populations. 3. In biomedical research this sampling process is seldom followed. Instead, samples are usually acquired by non-random selection, and are then divided by randomization into experimental groups. This being the case, it is theoretically invalid to use the classical t- or F-tests to analyse the experimental results. 4. The validity of inferences from the classical tests also depends on other assumptions, such as that the sampled populations are normal in form and of equal variance. It is difficult to be certain that these assumptions are fulfilled when group sizes are small, as they usually are in pharmacology and physiology. Breach of them, especially if the groups are unequal in size, can lead to serious statistical errors. 5. Exact permutation tests are designed to make statistical inferences under the randomization model. These conclusions apply only to the results of experiments actually performed. By permuting the statistic of interest, such as the difference between arithmetic means, geometric means, medians, mid-ranges or mean-ranks of randomized groups of observations, the probability is calculated that the observed difference or a more extreme one could have occurred by chance. This inferential process is consistent with the way most biomedical experiments are designed and conducted. 6. Exact permutation tests, or sampled permutation tests based on Monte Carlo random sampling of all possible permutations, can now be performed on personal computers. They are commended to biomedical investigators as being superior to the classical tests for analysing their experimental results when the central tendencies of two independent groups, or of two sets of measurements on the same group, are compared. 7. When there is doubt that the assumptions for t-tests are satisfied, investigators sometimes use non-parametric rank-order procedures such as the Wilcoxon-Mann-Whitney rank-sum test for independent groups or the Wilcoxon signed rank-sum test for paired observations.(ABSTRACT TRUNCATED AT 400 WORDS)

The effect of using a pre-brushing mouthwash (PlaxR) on removal of tooth stain in vivo and in vitro

The aim of this study was to determine whether the use of a pre-brushing mouthwash Plax reduced extrinsic tooth-staining in vivo and in vitro. Firstly, in a double-blind placebo controlled cross-over study, 20 subjects with tooth staining used Plax or a placebo for 14-day periods separated by a 1-month wash-out period. The area of stain was assessed before and after each mouthwash had been used from clinical photographs. Secondly, extracted 3rd molar teeth were stained with tea and chlorhexidine. After exposure to either Plax or placebo, the teeth were brushed in a standardized manner. The area and intensity of stain were assessed before and after rinsing and brushing. Results of the study in vivo showed that the mean % stained area for any of the surfaces studied changed very little throughout the study. No statistically significant changes were detected (Student t-test, p > 0.05). Results of the study in vitro showed that the mean area of stain fell by 19% after exposure to Plax and by 17% after exposure to placebo. No statistically significant changes were detected (Student t-test, p > 0.05). There were also no significant changes in intensity (Wilcoxon signed rank sum test p > 0.1).

Collagen synthesis in intact skin is suppressed during wound healing.

Simultaneous monitoring of total collagen synthesis as well as synthesis in intact skin and in the wound to verify the higher priority of wound healing after surgery. Synthesis of acute phase proteins is stimulated by surgical trauma. At the same time, production of albumin is inhibited and there is a net catabolism of skeletal muscle proteins. Similarly, the authors have found a transient inhibition of total collagen synthesis after surgery. The authors hypothesized a lower priority in synthesis of structural and peripheral collagen for the benefit of wound healing. The concentrations of the carboxyterminal propeptide of type I procollagen (PICP) and the aminoterminal propeptide of type III procollagen (PIIINP) were measured in suction blister fluid of intact skin and in wound fluid in ten surgical patients. PICP and PIIINP concentrations in serum were also measured. Specific radioimmunoassays were used. In peripheral skin, the median preoperative concentrations of PICP and PIIINP were 228 and 140 micrograms/L, respectively. On postoperative days 1, 2, 4 and 7, the median concentration of PICP was 145 (p = 0.01, Wilcoxon signed rank sum test), 102 (0.02), 159 (0.03), and 152 (0.06) micrograms/L, respectively. The postoperative medians of PIIINP were 68 (p = 0.17), 76 (0.04), 66 (0.06), and 56 (0.03) micrograms/L, respectively. At the same time, collagen synthesis in the wound increased dramatically from the second day on. After an initial decrease, propeptide concentrations in serum gradually increased from the fourth day on. Collagen synthesis is regulated for the benefit of the wound during the acute phase response.

Biologic effects after a single dose of poly(I):poly(C12U) in healthy volunteers

Poly(I):poly(C12U) (mismatched double-stranded RNA; atvogen), an interferon inducer, is active against human immunodeficiency virus in vitro. To determine the extent and duration of the biologic effects of poly(I):poly(C12U), we administered a single dose of the drug to healthy volunteers in a randomized, double-blind, placebo-controlled 2-week crossover study. We analyzed blood for alpha and gamma interferons, neopterin, 2',5'-oligoadenylate synthetase, lymphocyte surface markers, lymphocyte proliferation after exposure to soluble antigens and mitogens, and natural killer cell activity. Minimal biologic effects were observed after administration of a single 200-mg dose to four volunteers; therefore, the dose was increased to 600 mg in 10 subjects. Only neopterin levels and symptoms were greater after administration of 600 mg of poly(I):poly(C12U) than after administration of placebo (Wilcoxon signed rank sum test, P = 0.06). A definite response in 2',5'-oligoadenylate synthetase activity, however, was seen in a few subjects. Neither alpha nor gamma interferon was detectable in serum after poly(I):poly(C12U) dosing. The neopterin changes after administration of poly(I):poly(C12U) were similar at both poly(I):poly(C12U) dose levels, with an early decrease at 6 h, a peak at 1 day, and a gradual decrease toward the baseline over the following 3 days. A mild flu-like syndrome occurred in one-half of the subjects following administration of poly(I):poly(C12U) and in only one subject following administration of placebo. This syndrome resolved within 16 h after poly(I):poly(C12U) dosing. We conclude that poly(I):poly(C12U) does not induce measurable levels of interferon and causes only minimal biologic or toxic effects among those parameters measured after administration of a single dose in the 200- to 600-mg dose range in health volunteers.