Cluster randomised trials in the medical literature: two bibliometric surveys

Background: Several reviews of published cluster randomised trials have reported that about half did not take clustering into account in the analysis, which was thus incorrect and potentially misleading. In this paper I ask whether cluster randomised trials are increasing in both number and quality of reporting. Methods: Computer search for papers on cluster randomised trials since 1980, hand search of trial reports published in selected volumes of the British Medical Journal over 20 years. Results: There has been a large increase in the numbers of methodological papers and of trial reports using the term 'cluster random' in recent years, with about equal numbers of each type of paper. The British Medical Journal contained more such reports than any other journal. In this journal there was a corresponding increase over time in the number of trials where subjects were randomised in clusters. In 2003 all reports showed awareness of the need to allow for clustering in the analysis. In 1993 and before clustering was ignored in most such trials. Conclusion: Cluster trials are becoming more frequent and reporting is of higher quality. Perhaps statistician pressure works

Resource use data by patient report or hospital records: Do they agree?

Background: Economic evaluations alongside clinical trials are becoming increasingly common. Cost data are often collected through the use of postal questionnaires; however, the accuracy of this method is uncertain. We compared postal questionnaires with hospital records for collecting data on physiotherapy service use. Methods: As part of a randomised trial of orthopaedic medicine compared with orthopaedic surgery we collected physiotherapy use data on a group of patients from retrospective postal questionnaires and from hospital records. Results: 315 patients were referred for physiotherapy. Hospital data on attendances was available for 30% (n = 96), compared with 48% (n = 150) of patients completing questionnaire data (95% Cl for difference = 10% to 24%); 19% (n = 59) had data available from both sources. The two methods produced an intraclass correlation coefficient of 0.54 (95% Cl 0.31 to 0.70). However, the two methods produced significantly different estimates of resource use with patient self report recalling a mean of 1.3 extra visits (95% Cl 0.4 to 2.2) compared with hospital records. Conclusions: Using questionnaires in this study produced data on a greater number of patients compared with examination of hospital records. However, the two data sources did differ in the quantity of physiotherapy used and this should be taken into account in any analysi

Measuring diet in primary school children aged 8-11 years: validation of the Child and Diet Evaluation Tool (CADET) with an emphasis on fruit and vegetable intake.

Background/Objectives:The Child And Diet Evaluation Tool (CADET) is a 24-h food diary that measures the nutrition intake of children aged 3-7 years, with a focus on fruit and vegetable consumption. Until now CADET has not been used to measure nutrient intake of children aged 8-11 years. To ensure that newly assigned portion sizes for this older age group were valid, participants were asked to complete the CADET diary (the school and home food diary) concurrently with a 1-day weighed record. Subjects/Methods:A total of 67 children with a mean age of 9.3 years (s.d.: ± 1.4, 51% girls) participated in the study. Total fruit and vegetable intake in grams and other nutrients were extracted to compare the mean intakes from the CADET diary and Weighed record using t-tests and Pearson's r correlations. Bland-Altman analysis was also conducted to assess the agreement between the two methods. Results: Correlations comparing the CADET diary to the weighed record were high for fruit, vegetables and combined fruit and vegetables (r=0.7). The results from the Bland-Altman plots revealed a mean difference of 54 g (95% confidence interval: -88, 152) for combined fruit and vegetables intake. CADET is the only tool recommended by the National Obesity Observatory that has been validated in a UK population and provides nutrient level data on children's diets. Conclusions:The results from this study conclude that CADET can provide high-quality nutrient data suitable for evaluating intervention studies now for children aged 3-11 years with a focus on fruit and vegetable intake

A priori postulated and real power in cluster randomized trials: mind the gap

BACKGROUND: Cluster randomization design is increasingly used for the evaluation of health-care, screening or educational interventions. The intraclass correlation coefficient (ICC) defines the clustering effect and be specified during planning. The aim of this work is to study the influence of the ICC on power in cluster randomized trials. METHODS: Power contour graphs were drawn to illustrate the loss in power induced by an underestimation of the ICC when planning trials. We also derived the maximum achievable power given a specified ICC. RESULTS: The magnitude of the ICC can have a major impact on power, and with low numbers of clusters, 80% power may not be achievable. CONCLUSION: Underestimating the ICC during planning cluster randomized trials can lead to a seriously underpowered trial. Publication of a priori postulated and a posteriori estimated ICCs is necessary for a more objective reading: negative trial results may be the consequence of a loss of power due to a mis-specification of the ICC

A re-appraisal of the reliability of the 20 m multi-stage shuttle run test

This is the author's PDF version of an article published in European journal of applied physiology in 2007. The original publication is available at www.springerlink.co

Monitoring of lung edema by microwave reflectometry during lung ischemia-reperfusion injury in vivo

It is still unclear whether lung edema can be monitored by microwave reflectometry and whether the measured changes in lung dry matter content (DMC) are accompanied by changes in PaO(2) and in pro-to anti-inflammatory cytokine expression (IFN-gamma and IL-10). Right rat lung hili were cross-clamped at 37 degrees C for 0, 60, 90 or 120 min ischemia followed by 120 min reperfusion. After 90 min (DMC: 15.9 +/- 1.4%; PaO(2): 76.7 +/- 18 mm Hg) and 120 min ischemia (DMC: 12.8 +/- 0.6%; PaO(2): 43 +/- 7 mm Hg), a significant decrease in DMC and PaO(2) throughout reperfusion compared to 0 min ischemia (DMC: 19.5 +/- 1.11%; PaO(2): 247 +/- 33 mm Hg; p < 0.05) was observed. DMC and PaO(2) decreased after 60 min ischemia but recovered during reperfusion (DMC: 18.5 +/- 2.4%; PaO(2) : 173 +/- 30 mm Hg). DMC values reflected changes on the physiological and molecular level. In conclusion, lung edema monitoring by microwave reflectometry might become a tool for the thoracic surgeon. Copyright (c) 2006 S. Karger AG, Basel

The reliability and validity of three non-radiological measures of thoracic kyphosis and their relations to the standing radiological Cobb angle

UnlabelledHyperkyphosis is implicated in a mounting list of negative outcomes, including higher mortality. Hyperkyphosis research is hindered due to difficulties inherent in its measurement. By showing that three clinical measures of kyphosis are suitable for use in large scale, longitudinal, hyperkyphosis studies, we will facilitate much needed research in this field.IntroductionThe objective of this study is to describe the reliability of three non-radiological kyphosis measures (Debrunner kyphosis angle, flexicurve kyphosis index, and flexicurve kyphosis angle) and their validity compared to the Cobb angle and to approximate a Cobb angle from non-radiological kyphosis measures.MethodsWe analyzed data from 113 participants aged ≥ 60 years with kyphosis angle ≥ 40°. Cobb angle was measured on a standing lateral thoracolumbar radiograph using bounds at T4 and T12. Non-radiological measures of kyphosis were made three times by a single rater and a 4th time by a blinded second rater.ResultsIntra- and inter-rater reliabilities for non-radiological assessments were high (intra-class correlations of 0.96 to 0.98) and did not differ from each other. Pearson correlations, estimating validity, ranged from 0.62 to 0.69 and did not differ. The Debrunner angle was close to the Cobb angle, with scaling factor of 1.067 and an offset of 5°. The Flexicurve kyphosis angle had to be scaled by 1.53 to obtain the equivalent Cobb angle. The scaling factor for the Flexicurve kyphosis index to Cobb angle was 315, with an offset of 5°. Compared to the measured Cobb angle, Cobb angles predicted using the non-radiological measures had similar magnitude errors (standard deviations of the differences ranging between 10.24 and 11.26).ConclusionsEach non-radiological measurement had similar reliability and validity. Low cost, ease of use, and robustness to variations in spine contour argue for the Flexicurve in longitudinal kyphosis assessments. The approximate conversion factors provided will permit translation of non-radiological measures to Cobb angles

Assessment of a self-reported Drinks Diary for the estimation of drinks intake by care home residents: Fluid Intake Study in the Elderly (FISE)

Objectives: We evaluated the accuracy of a newly developed self-completed Drinks Diary in care home residents and compared it with direct observation and fluid intake charts. Design: Observational study. Setting: Residential care homes in Norfolk, UK. Participants: 22 elderly people (18 women, mean age 86.6 years SD 8.6, 12 with MMSE scores <27). Measurements: Participants recorded their own drinks intake over 24 hours using the Drinks Diary while care staff used the homes’ usual fluid intake chart to record drinks intake. These records were compared with drinks intake assessed by researcher direct observation (reference method), during waking hours (6am to 10pm), while drinks taken from 10pm to 6am were self-reported and checked with staff. Results: Drinks intake assessed by the Drinks Diary was highly correlated with researcher direct observation (Pearson correlation coefficient r=0.93, p<0.001, mean difference -163ml/day) while few staff-completed fluid charts were returned and correlation was low (r=0.122, p=0.818, mean difference 702ml/day). The Drinks Diary classified 19 of 22 participants correctly as drinking enough or not using both the European Food Safety Authority and US recommendations. Conclusion: The Drinks Diary estimate of drinks intake was comparable with direct observation and more accurate (and reliably completed) than staff records. The Drinks Diary can provide a reliable estimate of drinks intake in elderly care home residents physically and cognitively able to complete it. It may be useful for researchers, care staff and practitioners needing to monitor drinks intake of elderly people, to help them avoid dehydration

Tumor volume in subcutaneous mouse xenografts measured by microCT is more accurate and reproducible than determined by 18F-FDG-microPET or external caliper

<p>Abstract</p> <p>Background</p> <p>In animal studies tumor size is used to assess responses to anticancer therapy. Current standard for volumetric measurement of xenografted tumors is by external caliper, a method often affected by error. The aim of the present study was to evaluate if microCT gives more accurate and reproducible measures of tumor size in mice compared with caliper measurements. Furthermore, we evaluated the accuracy of tumor volume determined from ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) PET.</p> <p>Methods</p> <p>Subcutaneously implanted human breast adenocarcinoma cells in NMRI nude mice served as tumor model. Tumor volume (n = 20) was determined <it>in vivo </it>by external caliper, microCT and ¹⁸F-FDG-PET and subsequently reference volume was determined <it>ex vivo</it>. Intra-observer reproducibility of the microCT and caliper methods were determined by acquiring 10 repeated volume measurements. Volumes of a group of tumors (n = 10) were determined independently by two observers to assess inter-observer variation.</p> <p>Results</p> <p>Tumor volume measured by microCT, PET and caliper all correlated with reference volume. No significant bias of microCT measurements compared with the reference was found, whereas both PET and caliper had systematic bias compared to reference volume. Coefficients of variation for intra-observer variation were 7% and 14% for microCT and caliper measurements, respectively. Regression coefficients between observers were 0.97 for microCT and 0.91 for caliper measurements.</p> <p>Conclusion</p> <p>MicroCT was more accurate than both caliper and ¹⁸F-FDG-PET for <it>in vivo </it>volumetric measurements of subcutaneous tumors in mice.¹⁸F-FDG-PET was considered unsuitable for determination of tumor size. External caliper were inaccurate and encumbered with a significant and size dependent bias. MicroCT was also the most reproducible of the methods.</p

A Method of Drusen Measurement Based on the Geometry of Fundus Reflectance

BACKGROUND: The hallmarks of age-related macular degeneration, the leading cause of blindness in the developed world, are the subretinal deposits known as drusen. Drusen identification and measurement play a key role in clinical studies of this disease. Current manual methods of drusen measurement are laborious and subjective. Our purpose was to expedite clinical research with an accurate, reliable digital method. METHODS: An interactive semi-automated procedure was developed to level the macular background reflectance for the purpose of morphometric analysis of drusen. 12 color fundus photographs of patients with age-related macular degeneration and drusen were analyzed. After digitizing the photographs, the underlying background pattern in the green channel was leveled by an algorithm based on the elliptically concentric geometry of the reflectance in the normal macula: the gray scale values of all structures within defined elliptical boundaries were raised sequentially until a uniform background was obtained. Segmentation of drusen and area measurements in the central and middle subfields (1000 μm and 3000 μm diameters) were performed by uniform thresholds. Two observers using this interactive semi-automated software measured each image digitally. The mean digital measurements were compared to independent stereo fundus gradings by two expert graders (stereo Grader 1 estimated the drusen percentage in each of the 24 regions as falling into one of four standard broad ranges; stereo Grader 2 estimated drusen percentages in 1% to 5% intervals). RESULTS: The mean digital area measurements had a median standard deviation of 1.9%. The mean digital area measurements agreed with stereo Grader 1 in 22/24 cases. The 95% limits of agreement between the mean digital area measurements and the more precise stereo gradings of Grader 2 were -6.4 % to +6.8 % in the central subfield and -6.0 % to +4.5 % in the middle subfield. The mean absolute differences between the digital and stereo gradings 2 were 2.8 +/- 3.4% in the central subfield and 2.2 +/- 2.7% in the middle subfield. CONCLUSIONS: Semi-automated, supervised drusen measurements may be done reproducibly and accurately with adaptations of commercial software. This technique for macular image analysis has potential for use in clinical research