Guidelines on statistical methods.
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Research Design↗
Biomedical subjects
S J Day
Publications and source records attributed to S J Day.
Use of Beighton score to compare joint mobility between groups.
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Female↗
Factors associated with joint mobility in an adolescent population.
Fixed torque devices were used to measure joint mobility at three sites in 364 adolescents including 39 families with at least two siblings. Increasing age and being male were associated with reduced laxity, and a strong effect of family was observed in the 39 sibling sets studies. The population included 47 Asians whose mobility was similar to that of the non-Asians, though the female/male difference was apparently greater in the former group. None of the above conclusions apply to index finger hyperextension, and it is apparent that genetic and constitutional factors only affect mobility at some sites. Such observations could lead to a review of current scoring systems for clinical hypermobility.
Adolescent↗
Motor responses of the oesophagus to intraluminal distension in normal subjects and patients with oesophageal clearance disorders.
Oesophageal motor responses to intraluminal distension were studied manometrically in 16 healthy volunteers and in nine patients with disordered swallowing, who had prolonged oesophageal clearance without structural abnormality. In the normal subjects distension was associated with an increased number of secondary contractions above the balloon, decrease of all contractile activity below the balloon and was accompanied by an aborally propulsive force which occurred independently of the perception of discomfort. Cholinergic blockade abolished the proximal distension induced contractile response, but did not affect primary peristalsis. Despite normal sensory thresholds, proximal excitatory responses to distension were absent in six and distal inhibition was absent in seven patients. These results show that the normal human oesophagus responds to distension with a proximal enhancement of propulsive motor activity, mediated through a cholinergic pathway. This may be defective in some patients with disordered oesophageal transit. Investigation of the motor responses to intraluminal distension may thus be a useful adjunct to standard manometry for studying patients with suspected oesophageal clearance dysfunction and might allow identification of disordered enteric nervous control.
Adult↗
Motor responses of the small intestine to intraluminal distension in normal volunteers and a patient with visceral neuropathy.
The motor responses of the small intestine to intraluminal distension were studied proximal and distal to an inflatable balloon in 13 normal volunteers. During fasting, distension rapidly induced a persistent localised inhibition of distal contractile activity with a small proximal increase. Proximally, phase III activity was unaffected during distension but its propagation across and appearance below the balloon was inhibited. Upon deflating the balloon a normal motor pattern rapidly returned. Similar changes were observed during distension in the fed state. The changes in the motor pattern resemble those of the intrinsically mediated 'peristaltic reflex', studied in animals, and suggest that in man the response to balloon distension may also be mediated through an intrinsic mechanism. A patient with a visceral neuropathy, studied in a similar manner, had no inhibition of distal motor activity during distension, suggesting a functional defect of the enteric nerves. Further observations of the motor responses to distension in similar patients seem indicated to determine the usefulness of this technique for evaluating enteric nervous system function when an abnormality is suspected.
Adult↗
Effect of aspirin on pruritus.
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Aspirin↗
Differential diagnosis of motoneurone disease from other neurological conditions.
Analysis of 422 patients with clinical diagnoses of motoneurone disease (MND), multiple sclerosis, cervical spondylosis with myelopathy, or stroke, from two referral centres, suggested a simple four-step algorithm for diagnosing MND. The algorithm provided a 98% sensitivity (true positive diagnosis) and 86% specificity, and therefore gives a baseline for diagnostic criteria suitable for use in clinical research of MND.
Algorithms↗
Controlled trial of small bipolar probe in bleeding peptic ulcers.
204 of 460 patients with upper gastrointestinal bleeding admitted to a busy district hospital were found to be bleeding from peptic ulcers or to have signs of recent haemorrhage at endoscopy within 24 h of admission. To determine if the small bipolar probe could stop bleeding or rebleeding, patients were allocated to electrocoagulation (101) or not (103); other aspects of treatment were identical. Groups were stratified by ulcer site to give similar numbers in each. To allow for differences in sex, age, initial haemoglobin, presence of other diseases, and shock, data were analysed by logistic regression. Fewer patients in the treated group (17) continued to bleed or rebled compared with controls (34). Rebleeding and mortality rates in the treated group were higher early in the trial, suggesting the need for experience in application of the probe. Further improvements in technology and technique may result in significant reductions in mortality.
Clinical Trials as Topic↗
Transferrin receptor expression in non-malignant and malignant human breast tissue.
The expression of transferrin receptor by normal, pregnant and benign hyperplastic breast lesions and by breast carcinomas has been investigated immunohistochemically using two monoclonal antibodies directed against the receptor. Unlike a previous immunohistological study in which staining was confined to malignant breast, transferrin receptor has been detected in pregnant breast and in benign lesions as well as in all carcinomas examined. The latter showed variable reactivity but with staining of most cells in 70 per cent of cases. Although the expression of transferrin receptor in non-malignant conditions may be related to cell proliferation, as has been suggested from studies of activated cells, the extent of reactivity of carcinomas has shown no correlation with tumour characteristics such as differentiation and local tumour spread. It is therefore suggested that the immunologically active transferrin receptor of breast carcinomas may have significance other than that relating to proliferation. The finding that with some carcinomas differences in staining occurred between the two antibodies is a further illustration of the complexities of the nature of transferrin receptor.
Adenofibroma↗
The expression of fucosylated type 2 blood group chains in human breast and their significance.
Monoclonal antibodies directed against O(H) blood group antigen and 3-fucosyl-N-acetyllactosamine have been used to investigate the incidence and significance of these type 2 blood group chains in non-malignant and malignant human breast tissue. The findings have been compared with those obtained with the fucose-binding lectins, Ulex europeus I and Lotus tetragonolobus. The expression of O(H) antigen in non-malignant breast is heterogeneous and shows no relationship to blood group status. Its expression in carcinomas shows no relationship to prognostic parameters such as differentiation and node status, whereas loss of Ulex europeus I binding is related to metastasis. The presence of 3-fucosyl-N-acetyllactosamine is limited in non-malignant breast, apart from pregnancy, but in carcinomas shows a relationship to differentiation, a feature not seen with fucose-binding lectins. It is apparent that to obtain the maximum amount of information about the modifications occurring in fuco-substances that appear to be of significance in breast malignancy, it is important to use monospecific probes as well as reagents with broader specificities, such as lectins.
ABO Blood-Group System↗
The utilization of [3H] sugars by non-malignant and malignant human breast.
The utilization of [3H] sugars and leucine by non-malignant and malignant human breast has been assessed using an organ culture technique with subsequent tissue autoradiography. The uptake of sugars by normal and hyperplastic breast was generally constant, with some differences observed in the utilization of galactose by acini of normal and hyperplastic tissues. After 24 h incubation localization was predominantly at the luminal cell periphery. The utilization of sugars by carcinomas was much more variable. Differences were observed between adjacent cells and cell groups of the same tumour. The uptake of individual sugars within a carcinoma was also varied being either similar to, or greater or lesser than normal breast. Variation between carcinomas was also present. No correlation between type and differentiation was noted in this respect, but there was between localization of sugars and differentiation. Better differentiated areas in tumours showed patterns similar to non-malignant breast whilst localization in poorly differentiated cell groups was cytoplasmic. The uptake of leucine was more constant and proved to be a useful indicator of viability. While this approach cannot give information with regard to differences in glycoprotein structure between non-malignant and malignant breast, it has been of value in determining the heterogeneity of tumour cells with regard to the enzymes involved in glycosylation. As such it would be of use in assessing the uniformity of response to agents modifying glycosylation.
Breast↗
Expression of the antigen detected by the monoclonal antibody Ca 19.9 in human breast tissues.
The incidence and significance of the expression of the antigen defined by the monoclonal antibody Ca 19.9 (Sialyl Lea) has been assessed in human breast tissue. Frozen and formalin-fixed, paraffin embedded specimens of normal, hyperplastic, pregnant breast and carcinomas were examined using an immunoperoxidase technique. Ductal and acinar epithelium of normal and hyperplastic tissues showed variable reactivity in frozen sections but there was a reduction in staining in comparable samples after fixation and processing, such that in many instances only focal ductal epithelium reacted. A distinctive feature in the pregnant breast was the absence of staining in acini showing differentiated secretory activity, despite a reaction in adjacent nonsecretory acini and ducts. The overall incidence of detection of the Ca 19.9 antigen in breast carcinomas was 62%, but in half of these only a small number of cells stained. A significant relationship between expression of Sialyl Lea and poor differentiation of carcinomas was identified, but there was no correlation with local lymph node status. In contrast to the non-malignant tissue fixation and processing had little effect on the reactivity of carcinomas. It is suggested that this difference may be quantitative in nature, with malignant breast showing much greater expression, or be related to organisation of the antigen. The observations concerning carcinomas and pregnant breast indicate that the synthesis of the Ca 19.9 antigen is related to the state of differentiation and functional activity of human breast.
Antibodies, Monoclonal↗
Do wet suits affect swimming speed?
A randomised cross-over trial was conducted to see if wet suits increase swimming speed--a question which has been fiercely debated in the fat-growing endurance sport of Triathlon. Sixteen swimmers volunteered to undertake two 30 minute swims, one with and one without a wet suit. With wet suits the subjects swam an average of 24.9 lengths of a 66 m pool. Without wet suits they swam 23.2 lengths. A 95% confidence interval for the difference is from 0.8 to 2.6 lengths (p less than 0.001). This result suggests that regulations about the use of wet suits must be agreed internationally to ensure equal competition whilst promoting the health and safety aspects of sport.
Adult↗
Internal pilot studies for estimating sample size.
We develop the idea of using data from the first 'few' patients entered in a clinical trial to estimate the final trial size needed to have specified power for rejecting H0 in favour of H1 if a real difference exists. When comparing means derived from Normally distributed data, there is no important effect on test size, power or expected trial size, provided that a minimum of about 20 degrees of freedom are used to estimate residual variance. Relative advantages and disadvantages of using larger internal pilot studies are presented. These revolve around crude expectations of the final study size, recruitment rate, duration of follow-up and practical constraints on the ability to prevent the circulation of unblinded randomization codes to investigators and those involved in editing and checking data.
Clinical Trials as Topic↗
Statistics notes: blinding in clinical trials and other studies.
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Clinical Trials as Topic↗
Use of confidence intervals and sample size calculations in health economic studies.
OBJECTIVE: To discuss the calculation and application of confidence intervals in pharmacoeconomic studies. DATA SYNTHESIS: The increasing frequency with which pharmacoeconomic evaluations are made within clinical trials makes it possible to obtain information on the outputs and costs of an intervention in each patient of a sample under study. This allows the same statistical principles commonly used in clinical trials to be applied to cost or cost-effectiveness data. The methodology described in this article would allow expression of cost-effectiveness ratios in the form of confidence intervals. The calculation of the cost-effectiveness ratio by means of a confidence interval may have important practical consequences, both in decision-making on the choice of 1 intervention versus another and in calculating the size of the sample necessary to identify statistically significant differences, from both clinical and economic points of view. CONCLUSIONS: The complementary use of confidence intervals and sensitivity analysis makes it possible to measure uncertainty related and unrelated to variability in sample data, allowing the decision to adopt 1 technology or another to be based on the most objective information available. Although several ethical and methodologic concerns remain to be addressed, this methodology may contribute to improving the more rational and efficient use of drugs.
Confidence Intervals↗