The 'Bench Rite' Orthosis Decreases Cervical Muscle Activation During the Bench Press

BACKGROUND

There is little data available that examines the activation of the cervical paraspinal muscles that occurs during the bench press. It is intuitive that activation of these muscles may lead to increased loads across the cervical spine and may increase the risk of injury to the intervertebral disks of the cervical spine.

HYPOTHESIS

The hypothesis of this study is that by supporting the cervical spine with the "Bench Rite" cervical spine orthosis, there will be less muscular activation of the cervical paraspinal muscles as determined by electromyography when performing the bench press.

STUDY DESIGN

Comparative electromyographic study - Level of evidence III (case-control study).

METHODS

Fifteen healthy subjects performed two sets (with and without the cervical orthosis) of five repetitions of a 60 percent maximum repetition on the bench press for each muscle group tested (pectoralis major, deltoid, C5 paraspinal, trapezius). Electromyography was used to determine the maximum isometric contraction and concentric contraction of each muscle with and without the cervical orthosis. The concentric contraction of each muscle group was reported as a percentage of maximum voluntary isometric contraction.

RESULTS

The use of the "Bench Rite" cervical spine orthosis resulted in a statistically significant decrease in muscle activation in the C5 paraspinal (37 percent; p=0.0001) and deltoid muscles (9.8 percent; p=0.001) and a significant increase in trapezius muscle activation (9.3 percent; p=0.03). No differences were found in muscle activation of the pectoralis major with or without the use of the cervical spine orthosis (0.8 percent; p=0.90).

CONCLUSIONS

Weightlifters may consider utilizing the "Bench Rite" cervical orthosis while performing the bench press to decrease cervical paraspinal muscle activation without impacting the muscle activation of the pectoralis major.

Risk factors outperform intracranial large artery stenosis predicting unfavorable outcomes in patients with stroke

Background

This study examined how intracranial large artery stenosis (ILAS), symptomatic and asymptomatic ILAS, and risk factors affect unfavorable outcome events after medical treatment in routine clinical practice.

Methods

This was a 24-month prospective observational study of consecutively recruited stroke patients. All participants underwent magnetic resonance angiography, and their clinical characteristics were assessed. Outcome events were vascular outcome, recurrent stroke, and death. Cox regression analyses were performed to identify potential factors associated with an unfavorable outcome, which included demographic and clinical characteristics, the risk factors, and stenosis status.

Results

The analysis included 686 patients; among them, 371 were assessed as ILAS negative, 231 as symptomatic ILAS, and 84 as asymptomatic ILAS. Body mass index (p < .05), hypertension (p = .01), and old infarction (p = .047) were factors relating to vascular outcomes. Hypertension was the only factor for recurrent stroke (p = .035). Poor glomerular filtration rate (< 30 mL/min/1.73 m²) (p = .011) and baseline National Institutes of Health Stroke Scale scores (p < .001) were significant predictors of death.

Conclusions

This study extended previous results from clinical trials to a community-based cohort study by concurrently looking at the presence/absence of stenosis and a symptomatic/asymptomatic stenotic artery. Substantiated risk factors rather than the stenosis status were predominant determinants of adverse outcome. Although the degree of stenosis is often an indicator for treatment, we suggest risk factors, such as hypertension and renal dysfunction, should be monitored and intensively treated.

Network Analysis of Y-STR in Six Ethnic Populations in Guangxi and Its Forensic Significances

Abstract

Objective To explore the distribution of genetic structure of Y-SNP and Y-STR genetic markers in different ethnic groups and its application in forensic science. Methods SNaPshot minisequencing was used to detect the polymorphisms of 12 Y-SNP loci in 439 males from 6 ethnic groups, including Guangxi Han, Guangxi Jing, Guangxi Miao, Guangxi Yao, Guangxi Zhuang and Guangxi Dong. DNATyperTM Y26 kit was used to multiplex-amplify 26 Y-STR loci. The PCR products were analyzed by 3130xl genetic analyzer. The network analysis of Y-STR haplotype under the same Y-SNP haplogroup was analyzed by Network 5.0 software. Results Six haplogroups defined by 12 Y-SNP loci were detected in 6 ethnic groups, and 362 haplotypes were detected in 26 Y-STR loci. The haplotype diversity was 0.996 6. In the C haplogroup, the samples from Guangxi Yao, Guangxi Zhuang and Guangxi Dong were clustered on different branches; in the O1 haplogroup, those from Guangxi Zhuang, Guangxi Miao and Guangxi Jing were relatively independent and clustered separately; in the O2 haplogroup, some samples from Guangxi Miao and Guangxi Yao were gathered in a cluster. Conclusion Based on the Y-STR network analysis of samples with identical haplogroup of Y-SNP, some ethnic groups can be preliminarily distinguished, which could be used to infer male suspects' ethnic group through detecting their genetic markers left in the crime scene.

Delayed diagnosis of tuberculosis: risk factors and effect on mortality among older adults in Hong Kong

OBJECTIVE

To assess the risk factors and effects of delayed diagnosis on tuberculosis (TB) mortality in Hong Kong.

METHODS

All consecutive patients with TB notified in 2010 were tracked through their clinical records for treatment outcome until 2012. All TB cases notified or confirmed after death were identified for a mortality survey on the timing and causes of death.

RESULTS

Of 5092 TB cases notified, 1061 (20.9%) died within 2 years of notification; 211 (4.1%) patients died before notification, 683 (13.4%) died within the first year, and 167 (3.3%) died within the second year after notification. Among the 211 cases with TB notified after death, only 30 were certified to have died from TB. However, 52 (24.6%) died from unspecified pneumonia/sepsis possibly related to pulmonary TB. If these cases are counted, the total TB-related deaths increases from 191 to 243. In 82 (33.7%) of these, TB was notified after death. Over 60% of cases in which TB diagnosed after death involved patients aged ≥80 years and a similar proportion had an advance care directive against resuscitation or investigation. Independent factors for TB notified after death included female sex, living in an old age home, drug abuse, malignancy other than lung cancer, sputum TB smear negative, sputum TB culture positive, and chest X-ray not done.

CONCLUSIONS

High mortality was observed among patients with TB aged ≥80 years. Increased vigilance is warranted to avoid delayed diagnosis and reduce the transmission risk, especially among elderly patients with co-morbidities living in old age homes.

Optimising the utility of pleural fluid adenosine deaminase for the diagnosis of adult tuberculous pleural effusion in Hong Kong

INTRODUCTION

Pleural fluid adenosine deaminase level can be applied to rapidly detect tuberculous pleural effusion. We aimed to establish a local diagnostic cut-off value for pleural fluid adenosine deaminase to identify patients with tuberculous pleural effusion, and optimise its utility.

METHODS

We retrospectively reviewed the medical records of consecutive adults with pleural fluid adenosine deaminase level measured by the Diazyme commercial kit (Diazyme Laboratories, San Diego [CA], United States) during 1 January to 31 December 2011 in a cluster of public hospitals in Hong Kong. We considered its level alongside early (within 2 weeks) findings in pleural fluid and pleural biopsy, with and without applying Light's criteria in multiple scenarios. For each scenario, we used the receiver operating characteristic curve to identify a diagnostic cut-off value for pleural fluid adenosine deaminase, and estimated its positive and negative predictive values.

RESULTS

A total of 860 medical records were reviewed. Pleural effusion was caused by congestive heart failure, chronic renal failure, or hypoalbuminaemia caused by liver or kidney diseases in 246 (28.6%) patients, malignancy in 198 (23.0%), non-tuberculous infection in 168 (19.5%), tuberculous pleural effusion in 157 (18.3%), and miscellaneous causes in 91 (10.6%). All those with tuberculous pleural effusion had a pleural fluid adenosine deaminase level of ≤100 U/L. When analysis was restricted to 689 patients with pleural fluid adenosine deaminase level of ≤100 U/L and early negative findings for malignancy and non-tuberculous infection in pleural fluid, the positive predictive value was significantly increased and the negative predictive value non-significantly reduced. Using this approach, neither additionally restricting analysis to exudates by Light's criteria nor adding closed pleural biopsy would further enhance predictive values. As such, the diagnostic cut-off value for pleural fluid adenosine deaminase is 26.5 U/L, with a sensitivity of 87.3%, specificity of 93.2%, positive predictive value of 79.2%, negative predictive value of 96.1%, and accuracy of 91.9%. Sex, age, and co-morbidity did not significantly affect prediction of tuberculous pleural effusion using the cut-off value.

CONCLUSION

We have established a diagnostic cut-off level for pleural fluid adenosine deaminase in the diagnosis of tuberculous pleural effusion by restricting analysis to a level of ≤100 U/L, and considering early pleural fluid findings for malignancy and non-tuberculous infection, but not Light's criteria.

Epidemiology of Enterobius vermicularis infection among elementary school children in Hualien, Taiwan from 2007 to 2012

Enterobius vermicularis is the most common human intestinal parasite, and its control among school children is an important public health issue. The objective of this study was to document the present situation of E. vermicularis infection in school children in Hualien. The administrative divisions in Hualien county include 13 districts (3 in a mountainous area, 10 in a rural/urban area). Between 2007 and 2012, a total of 41,191 children in 13 districts in Hualien were examined using consecutive 2-day adhesive cellophane paper perianal swabs. Our results showed Enterobius egg-positive infection rates of 5.79% (452/7,089) in 2007, 6.25% (457/7,312) in 2008, 5.37% (385/7,173) in 2009, 4.98% (330/6,804) in 2010, 4.91% (301/6,133) in 2011, and 4.68% (279/5,960) in 2012. Compared to the previously reported national average in Taiwan (range, 1.53-2.23%), the prevalence of E. vermicularis in Hualien is relatively high. The infection rates were 7.55-29.10% in mountainous areas and 0.50- 12.43% in rural/urban areas. All first and fourth grade students in elementary schools in Hualien were selected as study participants. The average infection rate of the first grade students (6.71%) was higher than that of the fourth grade students (4.23%). These results indicate that enterobiasis remains an important parasitic disease among school children in Hualien, especially those in mountainous areas.

Test equality in binary data for a 4 × 4 crossover trial under a Latin-square design

When there are four or more treatments under comparison, the use of a crossover design with a complete set of treatment-receipt sequences in binary data is of limited use because of too many treatment-receipt sequences. Thus, we may consider use of a 4 × 4 Latin square to reduce the number of treatment-receipt sequences when comparing three experimental treatments with a control treatment. Under a distribution-free random effects logistic regression model, we develop simple procedures for testing non-equality between any of the three experimental treatments and the control treatment in a crossover trial with dichotomous responses. We further derive interval estimators in closed forms for the relative effect between treatments. To evaluate the performance of these test procedures and interval estimators, we employ Monte Carlo simulation. We use the data taken from a crossover trial using a 4 × 4 Latin-square design for studying four-treatments to illustrate the use of test procedures and interval estimators developed here. Copyright © 2016 John Wiley & Sons, Ltd.

Clinical management of adults and children with multidrug-resistant and extensively drug-resistant tuberculosis

BACKGROUND

Globally there is a burgeoning epidemic of drug monoresistant tuberculosis (TB), multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB). Almost 20% of all TB strains worldwide are resistant to at least one major TB drug, including isoniazid. In several parts of the world there is an increasing incidence of MDR-TB, and alarmingly, almost a third of MDR-TB cases globally are resistant to either a fluoroquinolone or aminoglycoside. This trend cannot be ignored because drug-resistant TB is associated with greater morbidity compared to drug-susceptible TB, accounts for almost 25% of global TB mortality, is extremely costly to treat, consumes substantial portions of budgets allocated to national TB programmes in TB-endemic countries and is a major threat to healthcare workers, who are already in short supply in resource-poor settings. Even more worrying is the growing epidemic of resistance beyond XDR-TB, including resistance to newer drugs such as bedaquiline and delamanid, as well as the increasing prevalence of programmatically incurable TB in countries like South Africa, Russia, India and China. These developments threaten to reverse the gains already made against TB.

SOURCES

Articles related to MDR-TB and XDR-TB found on PubMed in all languages up to September 2016, published reviews, and files of the authors.

AIM AND CONTENT

To review the clinical management of adults and children with MDR- and XDR-TB with a particular emphasis on the utility of newer and repurposed drugs such as linezolid, bedaquiline and delamanid, as well as management of MDR- and XDR-TB in special situations such as in HIV-infected persons and in children.

IMPLICATIONS

This review informs on the prevention, diagnosis, and clinical management of MDR-TB and XDR-TB.

Exact tests in binary data under an incomplete block crossover design

To improve the power of a parallel groups design and reduce the time length of a crossover trial, we may consider an incomplete block crossover design. Under a distribution-free random effects logistic regression model, we derive an exact test and a Mantel-Haenszel Type of summary test procedure for testing non-equality in binary data when comparing three treatments. We employ Monte Carlo simulation to evaluate the performance of these test procedures. We find that both test procedures developed here can perform well in a variety of situations. We use the data taken as a part of the crossover trial comparing the low and high doses of an analgesic with a placebo for the relief of pain in primary dysmenorrhea to illustrate the use of the proposed test procedures.

Exploiting broad-area surface emitting lasers to manifest the path-length distributions of finite-potential quantum billiards

Broad-area vertical-cavity surface-emitting lasers (VCSELs) with different cavity sizes are experimentally exploited to manifest the influence of the finite confinement strength on the path-length distribution of quantum billiards. The subthreshold emission spectra of VCSELs are measured to obtain the path-length distributions by using the Fourier transform. It is verified that the number of the resonant peaks in the path-length distribution decreases with decreasing the confinement strength. Theoretical analyses for finite-potential quantum billiards are numerically performed to confirm that the mesoscopic phenomena of quantum billiards with finite confinement strength can be analogously revealed by using broad-area VCSELs.

Immigrants and tuberculosis in Hong Kong

OBJECTIVE

To examine the impact of immigrant populations on the epidemiology of tuberculosis in Hong Kong.

DESIGN

Longitudinal cohort study.

SETTING

Hong Kong.

PARTICIPANTS

Socio-demographic and disease characteristics of all tuberculosis notifications in 2006 were captured from the statutory tuberculosis registry and central tuberculosis reference laboratory. Using 2006 By-census population data, indirect sex- and age-standardised incidence ratios by place of birth were calculated. Treatment outcome at 12 months was ascertained from government tuberculosis programme record forms, and tuberculosis relapse was tracked through the notification registry and death registry up to 30 June 2013.

RESULTS

Moderately higher sex- and age-standardised incidence ratios were observed among various immigrant groups: 1.06 (Mainland China), 2.02 (India, Pakistan, Bangladesh), 1.59 (Philippines, Thailand, Indonesia, Nepal), and 3.11 (Vietnam). Recent Mainland migrants had a lower sex- and age-standardised incidence ratio (0.51 vs 1.09) than those who immigrated 7 years ago or earlier. Age younger than 65 years, birth in the Mainland or the above Asian countries, and previous treatment were independently associated with resistance to isoniazid and/or rifampicin. Older age, birth in the above Asian countries, non-permanent residents, previous history of treatment, and resistance to isoniazid and/or rifampicin were independently associated with poor treatment outcome (other than cure/treatment completion) at 1 year. Birth outside Hong Kong was an independent predictor of relapse following successful completion of treatment (adjusted hazard ratio=1.76; 95% confidence interval, 1.07-2.89; P=0.025).

CONCLUSION

Immigrants carry with them a higher tuberculosis incidence and/or drug resistance rate from their place of origin. The higher drug resistance rate, poorer treatment outcome, and excess relapse risk raise concern over secondary transmission of drug-resistant tuberculosis within the local community.

Sample size determination for testing nonequality under a three-treatment two-period incomplete block crossover trial

To reduce the lengthy duration of a crossover trial for comparing three treatments, the incomplete block design has been often considered. A sample size calculation procedure for testing nonequality between either of the two experimental treatments and a placebo under such a design is developed. To evaluate the performance of the proposed sample size calculation procedure, Monte Carlo simulation is employed. The accuracy of the sample size calculation procedure developed here is demonstrated in a variety of situations. As compared with the parallel groups design, a substantial proportional reduction in the total minimum required sample size in use of the incomplete block crossover design is found. A crossover trial comparing two different doses of formoterol with a placebo on the forced expiratory volume is applied to illustrate the use of the sample size calculation procedure.

Testing equality and interval estimation of the generalized odds ratio in ordinal data under a three-period crossover design

The crossover design can be of use to save the number of patients or improve power of a parallel groups design in studying treatments to noncurable chronic diseases. We propose using the generalized odds ratio for paired sample data to measure the relative effects in ordinal data between treatments and between periods. We show that one can apply the commonly used asymptotic and exact test procedures for stratified analysis in epidemiology to test non-equality of treatments in ordinal data, as well as obtain asymptotic and exact interval estimators for the generalized odds ratio under a three-period crossover design. We further show that one can apply procedures for testing the homogeneity of the odds ratio under stratified sampling to examine whether there are treatment-by-period interactions. We use the data taken from a three-period crossover trial studying the effects of low and high doses of an analgesic versus a placebo for the relief of pain in primary dysmenorrhea to illustrate the use of these test procedures and estimators proposed here.

Test equality between two binary screening tests with a confirmatory procedure restricted on screen positives

In studies of screening accuracy, we may commonly encounter the data in which a confirmatory procedure is administered to only those subjects with screen positives for ethical concerns. We focus our discussion on simultaneously testing equality of sensitivity and specificity between two binary screening tests when only subjects with screen positives receive the confirmatory procedure. We develop four asymptotic test procedures and one exact test procedure. We derive sample size calculation formula for a desired power of detecting a difference at a given nominal [Formula: see text]-level. We employ Monte Carlo simulation to evaluate the performance of these test procedures and the accuracy of the sample size calculation formula developed here in a variety of situations. Finally, we use the data obtained from a study of the prostate-specific-antigen test and digital rectal examination test on 949 Black men to illustrate the practical use of these test procedures and the sample size calculation formula.

Notes on testing equality and interval estimation in Poisson frequency data under a three-treatment three-period crossover trial

When the frequency of event occurrences follows a Poisson distribution, we develop procedures for testing equality of treatments and interval estimators for the ratio of mean frequencies between treatments under a three-treatment three-period crossover design. Using Monte Carlo simulations, we evaluate the performance of these test procedures and interval estimators in various situations. We note that all test procedures developed here can perform well with respect to Type I error even when the number of patients per group is moderate. We further note that the two weighted-least-squares (WLS) test procedures derived here are generally preferable to the other two commonly used test procedures in the contingency table analysis. We also demonstrate that both interval estimators based on the WLS method and interval estimators based on Mantel-Haenszel (MH) approach can perform well, and are essentially of equal precision with respect to the average length. We use a double-blind randomized three-treatment three-period crossover trial comparing salbutamol and salmeterol with a placebo with respect to the number of exacerbations of asthma to illustrate the use of these test procedures and estimators.

Notes on testing noninferiority in ordinal data under the parallel groups design

When testing the noninferiority of an experimental treatment to a standard (or control) treatment in a randomized clinical trial (RCT), we may come across the outcomes of patient response on an ordinal scale. We focus our discussion on testing noninferiority in ordinal data for an RCT under the parallel groups design. We develop simple test procedures based on the generalized odds ratio (GOR). We note that these test procedures not only can account for the information on the order of ordinal responses without assuming any specific parametric structural model, but also can be independent of any arbitrarily subjective scoring system. We further develop sample size determination based on the test procedure using the GOR. We apply Monte Carlo simulation to evaluate the performance of these test procedures and the accuracy of sample size calculation formula proposed here in a variety of situations. Finally, we employ the data taken from a trial comparing once-daily gatifloxican with three-times-daily co-amoxiclav in the treatment of community-acquired pneumonia to illustrate the use of these test procedures and sample size calculation formula.

The effect of excision of the posterior arch of C1 on C1/C2 fusion using transarticular screws

Transarticular screw fixation with autograft is an established procedure for the surgical treatment of atlantoaxial instability. Removal of the posterior arch of C1 may affect the rate of fusion. This study assessed the rate of atlantoaxial fusion using transarticular screws with or without removal of the posterior arch of C1. We reviewed 30 consecutive patients who underwent atlantoaxial fusion with a minimum follow-up of two years. In 25 patients (group A) the posterior arch of C1 was not excised (group A) and in five it was (group B). Fusion was assessed on static and dynamic radiographs. In selected patients CT imaging was also used to assess fusion and the position of the screws. There were 15 men and 15 women with a mean age of 51.2 years (23 to 77) and a mean follow-up of 7.7 years (2 to 11.6). Stable union with a solid fusion or a stable fibrous union was achieved in 29 patients (97%). In Group A, 20 patients (80%) achieved a solid fusion, four (16%) a stable fibrous union and one (4%) a nonunion. In Group B, stable union was achieved in all patients, three having a solid fusion and two a stable fibrous union. There was no statistically significant difference between the status of fusion in the two groups. Complications were noted in 12 patients (40%); these were mainly related to the screws, and included malpositioning and breakage. The presence of an intact or removed posterior arch of C1 did not affect the rate of fusion in patients with atlantoaxial instability undergoing C1/C2 fusion using transarticular screws and autograft.

Optimal allocation of sample sizes to multicenter clinical trials

In this article, we discuss an approach for optimal sample size allocation in designing multicenter clinical trials. The method we studied was adapted from a stratified sampling survey design. The sample size allocated to centers is a function of the center's treatment cost, the standard deviation of the endpoint, and the availability of patients. We illustrate our approach using two hypothetical scenarios derived from our experiences in designing and conducting multicenter clinical trials. Simulation results are also presented.

Five interval estimators of the risk difference under stratified randomized clinical trials with noncompliance and repeated measurements

We often employ stratified analysis to control the confounding effect due to centers in a multicenter trial or the confounding effect due to trials in a meta-analysis. On the basis of a general risk additive model, we focus discussion on interval estimation of the risk difference (RD) in repeated binary measurements under a stratified randomized clinical trial (RCT) in the presence of noncompliance. We develop five asymptotic interval estimators for the RD in closed form. These include the interval estimator using the weighted least-squares (WLS) estimator, the WLS interval estimator with tanh (-1)(x) transformation, the Mantel-Haenszel (MH) type interval estimator, the MH interval estimator with tanh (-1)(x) transformation, and the interval estimator using the idea of Fieller's theorem and a randomization-based variance. We employ Monte Carlo simulation to study and compare the finite-sample performance of these interval estimators in a variety of situations. We include an example studying the use of macrophage colony-stimulating factor to reduce the risk of febrile neutropenia events in acute myeloid leukaemia patients published elsewhere to illustrate the use of these estimators.

Testing and estimation of proportion (or risk) ratio under the matched-pair design with multiple binary endpoints

The proportion ratio (PR) of responses between an experimental treatment and a control treatment is one of the most commonly used indices to measure the relative treatment effect in a randomized clinical trial. We develop asymptotic and permutation-based procedures for testing equality of treatment effects as well as derive confidence intervals of PRs for multivariate binary matched-pair data under a mixed-effects exponential risk model. To evaluate and compare the performance of these test procedures and interval estimators, we employ Monte Carlo simulation. When the number of matched pairs is large, we find that all test procedures presented here can perform well with respect to Type I error. When the number of matched pairs is small, the permutation-based test procedures developed in this paper is of use. Furthermore, using test procedures (or interval estimators) based on a weighted linear average estimator of treatment effects can improve power (or gain precision) when the treatment effects on all response variables of interest are known to fall in the same direction. Finally, we apply the data taken from a crossover clinical trial that monitored several adverse events of an antidepressive drug to illustrate the practical use of test procedures and interval estimators considered here.

Notes on interval estimation of the generalized odds ratio under stratified random sampling

It is not rare to encounter the patient response on the ordinal scale in a randomized clinical trial (RCT). Under the assumption that the generalized odds ratio (GOR) is homogeneous across strata, we consider four asymptotic interval estimators for the GOR under stratified random sampling. These include the interval estimator using the weighted-least-squares (WLS) approach with the logarithmic transformation (WLSL), the interval estimator using the Mantel-Haenszel (MH) type of estimator with the logarithmic transformation (MHL), the interval estimator using Fieller's theorem with the MH weights (FTMH) and the interval estimator using Fieller's theorem with the WLS weights (FTWLS). We employ Monte Carlo simulation to evaluate the performance of these interval estimators by calculating the coverage probability and the average length. To study the bias of these interval estimators, we also calculate and compare the noncoverage probabilities in the two tails of the resulting confidence intervals. We find that WLSL and MHL can generally perform well, while FTMH and FTWLS can lose either precision or accuracy. We further find that MHL is likely the least biased. Finally, we use the data taken from a study of smoking status and breathing test among workers in certain industrial plants in Houston, Texas, during 1974 to 1975 to illustrate the use of these interval estimators.

Hypothesis testing and estimation in ordinal data under a simple crossover design

Since each patient serves as his/her own control, the crossover design can be of use to improve power as compared with the parallel-groups design in studying noncurative treatments to certain chronic diseases. Although the research studies on the crossover design have been quite intensive, the discussions on analyzing ordinal data under such a design are truly limited. We propose using the generalized odds ratio (GOR) for paired sample data to measure the relative effect on patient responses for both treatment and period in ordinal data under a simple crossover trial. Assuming the treatment and period effects are multiplicative, we note that one can easily derive the maximum likelihood estimator (LE) in closed forms for the GOR of treatment and period effects. We develop asymptotic and exact procedures for testing treatment and period effects. We further derive asymptotic and exact interval estimators for the GOR of treatment and period effects. We use the data taken from a crossover trial to assess the clarity of leaflet instructions between two devices among asthma patients to illustrate the use of these test procedures and estimators developed here.

Notes on testing noninferiority in multivariate binary data under the matched-pair design

Since therapeutic efficacy is often measured by multiple endpoints, it will be of use if one can incorporate the information on various variables of response into procedures for testing noninferiority to improve power of a univariate test procedure for each individual variable. On the basis of the proposed mixed effects logistic regression model for multivariate binary data under the matched-pairs design, we develop procedures for testing noninferiority with respect to the odds ratio in multivariate binary data under the matched-pair design. We discuss use of Bonferroni's and Scheffe's methods to control the inflation in Type I error due to multiple tests. We further employ Monte Carlo simulation to evaluate and compare the performance of these test procedures. Finally, we use the data taken from a crossover clinical trial that monitored several adverse events of an antidepressive drug to illustrate the use of test procedures derived here.

Obstructive lung disease does not increase lung cancer mortality among female never-smokers in Hong Kong

SETTING

High lung cancer mortality is observed among female never-smokers in Hong Kong.

OBJECTIVE

To examine the relationship between obstructive lung disease (chronic obstructive pulmonary disease and/or asthma) and lung cancer mortality by sex and smoking status.

DESIGN

A cohort of elderly clients (aged ≥65 years) in a health maintenance programme were followed prospectively through linkage with the territory-wide death registry for causes of death, using identity card number as the unique identifier.

RESULTS

After 516,055 person-years of follow-up, respectively 1297, 872 and 1908 deaths were caused by lung cancer, other tobacco-related malignancies and non-tobacco-related malignancies. In the overall analysis, obstructive lung disease was independently associated with mortality due to lung cancer (aHR 1.86, P < 0.001) after adjustment for potential confounders. However, no association was detected among female never-smokers (HR 0.97, P = 0.909), in sharp contrast with female ever-smokers, male never-smokers and male ever-smokers (HR 1.98, 2.34 and 2.09, respectively, P from 0.047 to <0.001). Consistent results were observed after exclusion of all deaths in the initial 3 years.

CONCLUSION

Obstructive lung disease exerted differential effects on lung cancer mortality across different sex and smoking subgroups in this Asian population, with a conspicuous absence of effect among female never-smokers.

Analysis of Poisson frequency data under a simple crossover trial

When the frequency of occurrence for an event of interest follows a Poisson distribution, we develop asymptotic and exact procedures for testing non-equality, non-inferiority and equivalence, as well as asymptotic and exact interval estimators for the ratio of mean frequencies between two treatments under a simple crossover design. Using Monte Carlo simulations, we evaluate the performance of these test procedures and interval estimators in a variety of situations. We note that all asymptotic test procedures developed here can generally perform well with respect to Type I error and can be preferable to the exact test procedure with respect to power if the number of patients per group is moderate or large. We further find that in these cases the asymptotic interval estimator with the logarithmic transformation can be more precise than the exact interval estimator without sacrificing the accuracy with respect to the coverage probability. However, the exact test procedure and exact interval estimator can be of use when the number of patients per group is small. We use a double-blind randomized crossover trial comparing salmeterol with a placebo in exacerbations of asthma to illustrate the practical use of these estimators.

Notes on interval estimation of the gamma correlation under stratified random sampling

We have developed four asymptotic interval estimators in closed forms for the gamma correlation under stratified random sampling, including the confidence interval based on the most commonly used weighted-least-squares (WLS) approach (CIWLS), the confidence interval calculated from the Mantel-Haenszel (MH) type estimator with the Fisher-type transformation (CIMHT), the confidence interval using the fundamental idea of Fieller's Theorem (CIFT) and the confidence interval derived from a monotonic function of the WLS estimator of Agresti's α with the logarithmic transformation (MWLSLR). To evaluate the finite-sample performance of these four interval estimators and note the possible loss of accuracy in application of both Wald's confidence interval and MWLSLR using pooled data without accounting for stratification, we employ Monte Carlo simulation. We use the data taken from a general social survey studying the association between the income level and job satisfaction with strata formed by genders in black Americans published elsewhere to illustrate the practical use of these interval estimators.

A semi-parametric approach to the frequency of occurrence under a simple crossover trial

To analyze the frequency of occurrence for an event of interest in a crossover design, we propose a semi-parametric approach. We develop two point estimators and four interval estimators in closed forms for the treatment effect under a random effects multiplicative risk model. Using Monte Carlo simulations, we evaluate these estimators and compare the four interval estimators with the classical interval estimator suggested elsewhere in a variety of situations. We note that the point estimator using the ratio of two arithmetic averages of mean frequencies under a multiplicative risk model can be comparable to the point estimator using the ratio of two geometric averages of mean frequencies. We note that as long as the number of patients per group is large, all the four interval estimators developed here can perform well. We also note that the classical interval estimator derived under the commonly assumed Poisson distribution for the frequency data can be conservative and lose precision if the Poisson distribution assumption is violated. We use a double-blind randomized crossover trial comparing salmeterol with a placebo in exacerbations of asthma to illustrate the practical use of these estimators.

Exact sample-size determination in testing non-inferiority under a simple crossover trial

For testing the non-inferiority (or equivalence) of an experimental treatment to a standard treatment, the odds ratio (OR) of patient response rates has been recommended to measure the relative treatment efficacy. On the basis of an exact test procedure proposed elsewhere for a simple crossover design, we develop an exact sample-size calculation procedure with respect to the OR of patient response rates for a desired power of detecting non-inferiority at a given nominal type I error. We note that the sample size calculated for a desired power based on an asymptotic test procedure can be much smaller than that based on the exact test procedure under a given situation. We further discuss the advantage and disadvantage of sample-size calculation using the exact test and the asymptotic test procedures. We employ an example by studying two inhalation devices for asthmatics to illustrate the use of sample-size calculation procedure developed here.

Interval estimation of the proportion ratio in repeated binary measurements under a stratified randomized clinical trial with noncompliance

The proportion ratio (PR) of a positive response between an experimental treatment and a standard treatment (or placebo) is often used to measure the relative treatment efficacy in a randomized clinical trial (RCT). For ethical reasons, it is almost inevitable to encounter some patients not complying with their assigned treatment. Furthermore, when there are confounders in a RCT or meta-analysis, we commonly employ stratified analysis to control the confounding effects on interval estimation of the PR. On the basis of a general risk multiplicative model, we focus our discussion on interval estimation of the PR in repeated binary data under a stratified RCT with noncompliance. We develop seven asymptotic closed-form interval estimators for the PR. We apply Monte Carlo simulation to study the finite-sample performance of these interval estimators in a variety of situations. We note that the two interval estimators with the logarithmic transformation based on the commonly used weighted least squares (WLS) approach can be liberal, while the three interval estimators with the Mantel-Haenszel (MH) weight derived from various methods can consistently perform well. We also note that the two estimators with the estimated optimal weight defined in the context using Fieller's Theorem and a randomization-based approach may not necessarily produce a confidence interval preferable to the MH-type interval estimators for the PR with respect to accuracy and precision.

The relaxation effect and mechanism of action of higenamine in the rat corpus cavernosum

Higenamine mediates cardiotonic, vascular relaxation and bronchodilator effects. The relaxation effects and the mechanism of action of higenamine on the rat corpus cavernosum (CC) were assessed to investigate the effect of higenamine on penile erection. Strips of CC and aorta were used in organ baths for isometric tension studies. Tension was measured with isometric force transducers, and muscle relaxation was expressed as the percent decrease in precontraction induced by phenylephrine (PE). The relaxation reactions were investigated in an endothelial-denuded group and groups pretreated with N(G)-nitro-L-arginine methyl ester (NO synthesis inhibitor), propranolol (β-receptor blocker), indomethacin (COX inhibitor), glibenclamide (K(+)(ATP) channel inhibitor), 4-aminopyridine (membrane potential-dependent potassium channel inhibitor) and methylene blue (guanylyl cyclase inhibitor) for 30 min. Intracavernous pressure (ICP) was assessed in rats after the intravenous administration of higenamine, and changes in guanosine 3',5'-cyclic monophosphate and adenosine 3',5'-cyclic monophosphate (cAMP) concentrations were measured on the basis of the higenamine concentration. Also, the combined reaction of higenamine and the phosphodiesterase type-5 (PDE-5) inhibitors was assessed. Higenamine induced relaxation of the CC and the aortic strips precontracted with PE in a dose-dependent manner. The CC was significantly more relaxed than the aortic rings in response to the same higenamine concentration (P<0.05). The CC relaxation reaction was suppressed by the β-receptor blocker propranolol. The cAMP concentration increased gradually with increased higenamine concentration (P<0.05). The ICP also increased with increased higenamine concentration in vivo (P<0.05). In the group pretreated with 10(-7) M higenamine, the relaxation reaction of CC induced by the PDE-5 inhibitor increased significantly, compared with CC exposed to the PDE-5 inhibitor but not pretreated with higenamine (P<0.05). In conclusion, higenamine induced relaxation of the rat CC in a dose-dependent manner. The effect may be mediated through β-adrenoceptors. The results suggest that higenamine may be valuable as a new lead compound for treating erectile dysfunction.

Sample size determination for testing equality in a cluster randomized trial with noncompliance

For administrative convenience or cost efficiency, we may often employ a cluster randomized trial (CRT), in which randomized units are clusters of patients rather than individual patients. Furthermore, because of ethical reasons or patient's decision, it is not uncommon to encounter data in which there are patients not complying with their assigned treatments. Thus, the development of a sample size calculation procedure for a CRT with noncompliance is important and useful in practice. Under the exclusion restriction model, we have developed an asymptotic test procedure using a tanh(-1)(x) transformation for testing equality between two treatments among compliers for a CRT with noncompliance. We have further derived a sample size formula accounting for both noncompliance and the intraclass correlation for a desired power 1 - β at a nominal α level. We have employed Monte Carlo simulation to evaluate the finite-sample performance of the proposed test procedure with respect to type I error and the accuracy of the derived sample size calculation formula with respect to power in a variety of situations. Finally, we use the data taken from a CRT studying vitamin A supplementation to reduce mortality among preschool children to illustrate the use of sample size calculation proposed here.

Test non-inferiority and sample size determination based on the odds ratio under a cluster randomized trial with noncompliance

Because the odds ratio (OR) possesses certain desirable statistical properties, the OR has been recommended elsewhere to measure the relative treatment effect in establishing non-inferiority. For cost efficiency, we may often employ a cluster randomized trial (CRT), in which randomized units are clusters of patients. Furthermore, it is not uncommon to encounter data in which there are patients not complying with their assigned treatment. Under the Dirichlet multinomial model, we have developed a test statistic for assessing non-inferiority based on the OR between two treatments under a CRT with noncompliance. We have further derived a sample size formula accounting for both noncompliance and the intraclass correlation for a desired power 1 - β of detecting non-inferiority with respect to the OR at a nominal α level. Using Monte Carlo simulation, we have evaluated the performance of the proposed test statistic and sample size formula. Finally, we use the CRT studying the effect of vitamin A supplementation on mortality among preschool children to illustrate the use of the sample size formula given here.

Test non-inferiority (and equivalence) based on the odds ratio under a simple crossover trial

For testing the non-inferiority (or equivalence) of a generic drug to a standard drug, the odds ratio (OR) of patient response rates has been recommended to measure the relative treatment efficacy. On the basis of a random effects logistic regression model, we develop asymptotic test procedures for testing non-inferiority and equivalence with respect to the OR of patient response rates under a simple crossover design. We further derive exact test procedures, which are especially useful for the situations in which the number of patients in a crossover trial is small. We address sample size calculation for testing non-inferiority and equivalence based on the asymptotic test procedures proposed here. We also discuss estimation of the OR of patient response rates for both the treatment and period effects. Finally, we include two examples, one comparing two solution aerosols in treating asthma, and the other one studying two inhalation devices for asthmatics, to illustrate the use of the proposed test procedures and estimators.

PPARdelta inhibits IL-1beta-stimulated proliferation and migration of vascular smooth muscle cells via up-regulation of IL-1Ra

Activation of peroxisome proliferator-activated receptor (PPAR) delta by GW501516, a specific PPARdelta ligand, significantly inhibited interleukin (IL)-1beta-induced proliferation and migration of vascular smooth muscle cells (VSMCs). This effect of GW501516 was dependent on transforming growth factor-beta, and was mediated through the up-regulation of IL-1 receptor antagonist. The inhibitory effect of GW501516 on VSMC proliferation was associated with cell cycle arrest at the G1 to S phase transition, which was accompanied by the induction of p21 and p53 along with decreased cyclin-dependent kinase 4 expression. Inhibition of cell migration by GW501516 was associated with the down-regulation of matrix metalloproteinase (MMP)-2 and MMP-9 in IL-1beta-treated VSMCs. Inhibition of extracellular signal-regulated kinase significantly reduced the GW501516-mediated inhibition of IL-1beta-stimulated VSMC proliferation. These results suggest that PPARdelta plays an important role in the pathophysiology of diseases associated with the proliferation and migration of VSMCs.

Surface X-ray speckles: coherent surface diffraction from Au(001)

We present coherent speckled x-ray diffraction patterns obtained from a monolayer of surface atoms. We measured both the specular anti-Bragg reflection and the off-specular hexagonal reconstruction peak for the Au(001) surface reconstruction. We observed fluctuations of the speckle patterns even when the integrated intensity appears static. By autocorrelating the speckle patterns, we were able to identify two qualitatively different surface dynamic behaviors of the hex reconstruction depending on the sample temperature.

Newer fluoroquinolones for treating respiratory infection: do they mask tuberculosis?

Possible masking of tuberculosis (TB) in treatment of community-acquired respiratory infection by newer fluoroquinolones has not been examined in randomised controlled trials. We undertook a randomised, open-label controlled trial involving adults with community-acquired pneumonia or infective exacerbation of bronchiectasis encountered in government chest clinics in Hong Kong. 427 participants were assigned by random permutated blocks of 20 to receive either amoxicillin clavulanate (n = 212) or moxifloxacin (n = 215). Participants were followed for 1 yr for active pulmonary TB. Excluding three participants with positive baseline culture, 13 developed active pulmonary TB: 10 (4.8%) out of 210 were given amoxicillin clavulanate, and three (1.4%) out of 214 were given moxifloxacin. The difference was significant by both proportion and time-to-event analysis. Post hoc analysis showed a significant decrease in the proportion with active pulmonary TB from 4.8% to 2.4% and 0% among participants given amoxicillin clavulanate (n = 210), moxifloxacin for predominantly 5 days (n = 127) and 10 days (n = 87), respectively. The log rank test for trend also showed a significant difference between the three subgroups. Regression models reaffirmed the linear effect; the adjusted odds ratio (95% confidence interval) of active pulmonary TB after moxifloxacin exposure up to predominantly 10 days was 0.3 (0.1-0.9). Newer fluoroquinolones appear to mask active pulmonary TB.