Gilbert MacKenzie

Comparison of infrared coagulation and rubber band ligation for first and second degree haemorrhoids: a randomised prospective clinical trial.

One hundred and thirty seven previously untreated out-patients with first and second degree haemorrhoids were allocated at random to treatment by infrared coagulation (n=66) or rubber band ligation (n=71). Complete follow up was obtained in 122 patients (60 who had undergone infrared coagulation (group 1), and 62 rubber band ligation (group 2)) at periods from three months to one year after completion of treatment. Infrared coagulation produced a satisfactory outcome in 51 patients (85%): 34 were rendered asymptomatic and 17 improved. Rubber band ligation produced a satisfactory outcome in 57 patients (92%): 33 were rendered asymptomatic and 24 improved. Both methods were equally effective in first and second degree haemorrhoids. The incidence of side effects, particularly discomfort, during and after treatment was significantly higher in those treated by rubber band ligation (p less than 0.001). This appeared to be an appreciable deterrent to future patient compliance. The number of patients losing more than 24 hours from work was higher after rubber band ligation than after infrared coagulation. The number of treatments necessary to cure symptoms did not differ significantly between the two methods. Infrared coagulation was significantly faster than rubber band ligation (p less than 0.001). Infrared coagulation is a simple, fast, and effective outpatient method for the treatment of first and second degree haemorrhoids with fewer troublesome side effects and higher patient acceptability than rubber band ligation.

Long-term survival following cancer of the male breast in Northern Ireland. A report of 81 cases

Eighty‐one patients with cancer of the male breast were studied. The majority (79) presented with a mass in the breast and in 8 patients the tumor was found by chance. Two patients presented with serosanguinous discharge. Average duration of symptoms was 11.9 months. Thirty patients had Stage I, 25 had Stage II, 16 had Stage III, and 8 had Stage IV disease. Fifty‐three patients had simple mastectomy, nine had lumpectomy, six had radical mastectomy, and five had biopsy only. Eight had no local surgery. Overall 5‐and 10‐year survival allowing for all causes of death was 38% and 17%, respectively. Coxs (1972) proportional hazard regression model was used to assess the contribution of various factors to survival. Age at presentation, postoperative hormone therapy, postoperative radiotherapy, site of the primary tumor within the breast, and type of local surgery did not contribute to survival. Only the stage of disease contributed to survival and did so in the expected direction.

Prophylactic lidocaine in the early phase of suspected myocardial infarction

Four hundred two patients with suspected myocardial infarction seen within 6 hours of the onset of symptoms entered a double-blind randomized trial of lidocaine vs placebo. During the 1 hour after administration of the drug the incidence of ventricular fibrillation or sustained ventricular tachycardia among the 204 patients with acute myocardial infarction was low, 1.5%. Lidocaine, given in a 300 mg dose intramuscularly followed by 100 mg intravenously, did not prevent sustained ventricular tachycardia, although there was a significant reduction in the number of patients with warning arrhythmias between 15 and 45 minutes after the administration of lidocaine (p less than 0.05). The average plasma lidocaine level 10 minutes after administration for patients without a myocardial infarction was significantly higher than that for patients with an acute infarction. The mean plasma lidocaine level of patients on beta-blocking agents was no different from that in patients not on beta blocking agents. During the 1-hour study period, the incidence of central nervous system side effects was significantly greater in the lidocaine group, hypotension occurred in 11 patients, nine of whom had received lidocaine, and four patients died from asystole, three of whom had had lidocaine. We cannot advocate the administration of lidocaine prophylactically in the early hours of suspected myocardial infarction.

BODY-SURFACE MAP MODELS FOR EARLY DIAGNOSIS OF ACUTE MYOCARDIAL INFARCTION

Abstract The standard 12-lead ECG is only 50% sensitive for the detection of acute myocardial infarction (AMI). The majority of leads for optimal classification of AMI probably lie outside the area covered by the 6 precordial leads. Thus, body-surface mapping (BSM) may be more helpful, as a larger thoracic area is sampled. We recorded 64-lead anterior BSMs in 635 patients with chest pain suggestive of AMI and abnormal electrocardiograms (ECGs), and 125 controls without chest pain. Of the 635 patients, 325 had AMI according to World Health Organization (WHO) criteria (203 presenting with ST segment elevation, and 122 with nondiagnostic ECG), and 310 had an “abnormal ECG but not AMI.” QRS and ST-T isointegrals and variables describing map shape were derived. Subjects were randomly allocated to a training set (63 controls, 321 patients) and a validation set (62 controls, 314 patients). Multiple logistic regression was used in the training set to identify which variables gave best discrimination between groups. A model with these variables was then tested prospectively in the validation set. In stage 1 (all subjects), controls were compared with patients. In the training set, a model containing 21 variables classified 58/63 controls (specificity 92%) and 316/321 patients (sensitivity 98%). In the validation set, the model classified 48/62 controls (specificity 77.4%) and 302/314 patients (sensitivity 96%). In stage 2 (studying patients only), patients with AMI were compared with patients who had an abnormal ECG—not AMI. In the training set, a model containing 28 variables classified 132 165 patients (sensitivity 80%) with AMI and 134 156 patients (specificity 86%) with an abnormal ECG—not AMI. In the validation set, the model classified 123/160 patients (sensitivity 77%) with AMI and 131 154 patients (specificity 85%) with an abnormal ECG—not AMI. Combining results of both stages in a two-step algorithm gave an overall classification in the training set of controls 92%, abnormal ECG—not AMI 84%, AMI 80%, and in the validation set of controls 77%, abnormal ECG—not AMI 82%, AMI 74%. Thus, in conclusion, when compared with the 12-lead ECG, BSM models results in higher sensitivity and specificity for detection of AMI, particularly in patients presenting with chest pain and nondiagnostic ECG changes. The use of BSM models in such patients, may lead to the earlier detection of AMI and appropriate administration of fibrinolytic therapy and/or anti-platelet agents.

Regression models for covariance structures in longitudinal studies

A convenient reparametrization of the marginal covariance matrix arising in longitudinal studies is discussed. The new parameters have transparent statistical interpretations, are unconstrained and may be modelled parsimoniously in terms of polynomials of time. We exploit this framework to model the dependence of the covariance structure on baseline covariates, time and their interaction. The rationale is based on the assumption that a homogeneous covariance structure with respect to the covariate space is a testable model choice. Accordingly, we provide methods for testing this assumption by incorporating covariates along with time into the model for the covariance structure. We also present new computational algorithms which can handle unbalanced longitudinal data, thereby extending existing methods. The new model is used to analyse Kenward’s (1987) cattle data, and the findings are compared with published analyses of the same data set.

Haemoglobin during pregnancy: relationship to erythropoietin and haematinic status

Abstract: Objective: To investigate the effect of haematinic status on erythropoietin throughout pregnancy in order to assess whether haematinic supplementation is appropriate for all pregnant women or should be reserved for individuals in whom deficiency has been identified.

Frailty modelling for survival data from multi-centre clinical trials

Despite the use of standardized protocols in, multi-centre, randomized clinical trials, outcome may vary between centres. Such heterogeneity may alter the interpretation and reporting of the treatment effect. Below, we propose a general frailty modelling approach for investigating, inter alia, putative treatment-by-centre interactions in time-to-event data in multi-centre clinical trials. A correlated random effects model is used to model the baseline risk and the treatment effect across centres. It may be based on shared, individual or correlated random effects. For inference we develop the hierarchical-likelihood (or h-likelihood) approach which facilitates computation of prediction intervals for the random effects with proper precision. We illustrate our methods using disease-free time-to-event data on bladder cancer patients participating in an European Organization for Research and Treatment of Cancer trial, and a simulation study. We also demonstrate model selection using h-likelihood criteria.

Longitudinal trends in trauma mortality and survival in Stoke-on-Trent 1992—1998

OBJECTIVES To identify factors related to mortality and to test the null hypothesis of no longitudinal trend in mortality in patients admitted to the North Staffordshire Hospital (NSH) with an Injury Severity Score (ISS) greater than 15, between April 1992 and March 1998. DESIGN Longitudinal prospective study of 18 factors, including age, sex, mechanism of injury, anatomical injury scores and year of admission. Outcome, based on mortality at discharge, was analysed in two ways: alive or dead at discharge (mortality) and time to death or discharge (survival). RESULTS A decreasing trend (P < 0.01 ) in mortality with year of admission was detected on the log-odds scale. The trend could not be explained by a case-mix analysis, which allowed for the 17 other factors. Using multiple logistic regression analysis (mortality) and Cox proportional hazards analysis (survival), eight factors were identified as determinants of outcome: age, head AIS score, chest AIS score, abdominal AIS score, calendar year of admission, external injury AIS score, mechanism of the injury and primary receiving hospital. CONCLUSIONS The observed improvement in survival in severely injured patients must result from the interplay of factors not controlled in this analysis or improvements in patient care or both.

A comparison of patient characteristics and survival in two trauma centres located in different countries

INTRODUCTION The aim of the study was to compare patient characteristics and mortality in severely injured patients in two trauma centres located in different countries, allowing for differences in case-mix. It represents a direct bench-marking exercise between the trauma centres at the North Staffordshire Hospital (NSH), Stoke-on-Trent, UK and the Oregon Health Sciences University (OHSU) Hospital, Portland, Oregon, USA. METHODS Patients of all ages admitted to the two hospitals during 1995 and 1996 with an Injury Severity Score >15 were included, except for those who died in the emergency departments. Twenty-three factors were studied, including the Injury Severity Score, Glasgow Coma Score, mechanism of injury and anatomical site of injury. Outcome analysis was based on mortality at discharge. RESULTS The pattern of trauma differed significantly between Stoke and Portland. Patients from Stoke tended to be older, presented with a lower conscious level and a lower systolic blood pressure and were intubated less frequently before arriving at hospital. Mortality depended on similar factors in both centres, especially age, highest AIS score, systolic blood pressure and Glasgow Coma Score.The crude analysis of mortality showed a highly significant odds-ratio of 1.64 in Stoke compared with Portland. Single-factor adjustments were made for the above four factors, which had a similar influence on mortality in both centres. Adjusting for the first three factors individually did not alter the odds-ratio, which stayed in the range 1.53-1.59 and remained highly significant. Adjusting for the Glasgow Coma Score reduced the odds-ratio to 0.82 and rendered it non-significant. In a multi-factor logistic regression model incorporating all of the factors shown to influence mortality in either centre, the odds-ratio was 1.7 but was not significant. CONCLUSION The analysis illustrates the limitations and pitfalls of making crude outcome comparisons between centres. Highly significant differences in crude mortality were rendered non-significant by case-mix adjustments, supporting the null hypothesis that the two centres were equally effective in terms of this short-term indicator of outcome. To achieve a meaningful comparison between centres, adjustments must be made for the factors which affect mortality.

Sub-vastus approach is more effective than a medial parapatellar approach in primary total knee arthroplasty: a randomized controlled trial

In a prospective single-centre longitudinal randomized controlled trial 116 patients were allocated to the sub-vastus approach, and 115 to the medial parapatellar approach. At one week follow-up, compared to baseline, range of motion, Knee Society (KS) global, KS knee, and KS pain scores were significantly better in the sub-vastus group. At the one year follow-up, WOMAC global and pain scores, SF36 physical function and role-physical scores, and EuroQol utility and pain score were significantly better in the sub-vastus group. The ease of exposure in the sub-vastus approach was significantly worse. There was no significant difference in length of stay or analgesia intake. The sub-vastus approach to total knee arthroplasty was more effective than a medial parapatellar approach at both one week and one year post-operatively, but surgeons reported a less easy exposure in the sub-vastus group.