Guidelines for the initial biopsy diagnosis of suspected chronic idiopathic inflammatory bowel disease. The British Society of Gastroenterology Initiative

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How does functional disability in early rheumatoid arthritis (RA) affect patients and their lives? Results of 5 years of follow-up in 732 patients from the Early RA Study (ERAS)

OBJECTIVES

To assess the impact of rheumatoid arthritis (RA) on function and how this affects major aspects of patients' lives.

METHODS

The inception cohort of RA patients was recruited from rheumatology out-patient departments in nine National Health Service (NHS) hospital trusts in England. All consecutive patients with RA of less than 2 yr duration, prior to any second-line (disease-modifying) drug treatment were recruited and followed-up for 5 yr. Standard clinical, laboratory and radiological assessments, and all hospital-based interventions were recorded prospectively at presentation and yearly. The outcome measures were clinical remission and extra-articular features, functional ability [functional grades I-IV and Health Assessment Questionnaire (HAQ)], use of aids, appliances and home adaptations, orthopaedic interventions, and loss of paid work.

RESULTS

A total of 732 patients completed 5 yr of follow-up, of whom 84% received second-line drugs. Sixty-nine (9.4%) had marked functional loss at presentation, compared with normal function in 243 (33%), and by 5 yr these numbers had increased in each group, respectively, to 113 (16%) and 296 (40%). Home adaptations and/or wheelchair use by 5 yr were seen in 74 (10%). Work disability was seen in 27% of those in paid employment at onset. One hundred and seventeen (17%) patients underwent orthopaedic surgery for RA, 55 (8%) for major joint replacements. Marked functional loss at 5 yr was more likely in women [odds ratio (OR) 1.63, 95% confidence interval (CI) 1.04-2.5], patients older than 60 yr (OR 1.94, 95% CI 1.3-2.9), and with HAQ > 1.0 at presentation (OR 4.4, 95% CI 2.8-7.0).

CONCLUSIONS

Clinical profiles of RA patients treated with conventional drug therapy over 5 yr showed that a small proportion of patients (around 16%) do badly functionally and in terms of life events, whereas around 40% do relatively well. The details and exact figures of cumulative disability are likely to be useful to clinicians, health professionals and patients. The rate of progression and outcome in these patients can be compared against future therapies with any disease-modifying claims.

Monitoring the results of cardiac surgery by variable life-adjusted display

BACKGROUND

Conventional assessment of the outcome of cardiac surgery usually takes the form of retrospective mortality figures and, at best, indicates an average performance over time. Summary tables conceal good and bad runs, and without risk adjustment they are difficult to interpret. We developed a refinement of the cumulative sum method that weights death and survival by each patient's risk status and provides a display of surgical performance over time.

METHODS

The variable life-adjusted (VLAD) plot shows the difference between expected and actual cumulative mortality. VLAD shows whether a surgeon's performance is above or below what might be expected. This mortality-scoring system accumulates penalties for each death and rewards for every survivor, based on the inherent risk of perioperative death of each case concerned.

FINDINGS

We illustrate the results of three performance reviews, displayed as VLADs. The first shows the results of an individual surgeon for 547 consecutive cardiac-surgical cases. The overall mortality was 36% less than that predicted by the Parsonnet scoring system. The second displays the results for 5000 consecutive patients who underwent cardiopulmonary bypass between 1992 and 1996, divided into six contemporaneous series. The predicted mortality was 9% compared with 6% actual mortality. The third is a plot for a trainee surgeon and clearly shows how a period of poor performance was identified and then substantially improved, which would not have been revealed by conventional tables of summary statistics.

INTERPRETATION

VLAD provides a graphical display of risk-adjusted survival figures for individual surgeons or units over time and could be modified to monitor performance over a range of treatments and outcomes.

Comparison of the prevalence of reversible airways obstruction in rural and urban Zimbabwean children

The prevalence of reversible airways obstruction has been assessed in children in three areas in Zimbabwe--northern Harare (high socioeconomic class urban children), southern Harare (low socio-economic class urban children), and Wedza Communal Land (rural children from peasant families). Peak expiratory flow (PEF) was measured before and after six minutes' free running in 2055 Zimbabwean primary school children aged 7-9 years. Height and weight were measured and nutritional state expressed as a percentage of the 50th centile for age (Tanner-Whitehouse standards). Reversible airways obstruction was deemed to be present when peak expiratory flow was below the 2.5th centile for height before exercise and rose by more than 15% after inhalation of salbutamol and when it fell by 15% or more after exercise and rose again after salbutamol. The prevalence of reversible airways obstruction was 5.8% (95% confidence interval 4.1-7.5%) in northern Harare (n = 726); 3.1% (1.8-4.5%) in southern Harare (n = 642), and 0.1% (0.0-0.4%) in Wedza (n = 687). In northern Harare, the only study area in which white children were found, the prevalence of reversible airways obstruction was similar in white (5.3%, 10/188) and black (5.9%, 32/538) children. Indicators of nutritional state also showed no significant differences between white and black children in northern Harare but were lower in southern Harare and lower still in Wedza. Urban living and higher material standards of living appear to be associated with a higher prevalence of reversible airways obstruction in children in Zimbabwe.

Identification of systems failures in successful paediatric cardiac surgery

Patient safety will benefit from an approach to human error that examines systemic causes, rather than blames individuals. This study describes a direct observation methodology, based on a threat and error model, prospectively to identify types and sources of systems failures in paediatric cardiac surgery. Of substantive interest were the range, frequency and types of failures that could be identified and whether minor failures could accumulate to form more serious events, as has been the case in other industries. Check lists, notes and video recordings were employed to observe 24 successful operations. A total of 366 failures were recorded. Coordination and communication problems, equipment problems, a relaxed safety culture, patient-related problems and perfusion-related problems were most frequent, with a smaller number of skill, knowledge and decision-making failures. Longer and more risky operations were likely to generate a greater number of minor failures than shorter and lower risk operations, and in seven higher-risk cases frequently occurring minor failures accumulated to threaten the safety of the patient. Non-technical errors were more prevalent than technical errors and task threats were the most prevalent systemic source of error. Adverse events in surgery are likely to be associated with a number of recurring and prospectively identifiable errors. These may be co-incident and cumulative human errors predisposed by threats embedded in the system, rather than due to individual incompetence or negligence. Prospectively identifying and reducing these recurrent failures would lead to improved surgical standards and enhanced patient safety.

Use of the short form 36 (SF36) for health status measurement in rheumatoid arthritis

The patient-administered Health Assessment Questionnaire (HAQ) is widely used in rheumatology studies. Another health quality assessment technique commonly used for other non-rheumatological conditions is the 'Short Form 36' (SF36). This has questions designed to assess eight aspects of health ranging from physical limitations to general perceptions of vitality and mental well-being. This study presents information on the health status of 137 patients with rheumatoid arthritis (RA) assessed by both the SF36 and HAQ. Summary statistics are given for the elements of the SF36 according to age, gender, disease measures of RA and the presence of co-morbidity. There were significant associations between the physical functioning score of the SF36 and the HAQ score. with other measures of disease activity and severity, and with co-morbidity, although there was considerable inter-patient variability. These findings suggest that future applications of health status questionnaires are possible.

Cardiac ECMO for biventricular hearts after paediatric open heart surgery

OBJECTIVE

To delineate predictors of hospital survival in a large series of children with biventricular physiology supported with extracorporeal membrane oxygenation (ECMO) after open heart surgery.

RESULTS

81 children were placed on ECMO after open heart surgery. 58% (47 of 81) were transferred directly from cardiopulmonary bypass to ECMO. Hospital survival was 49% (40 of 81) but there were seven late deaths among these survivors (18%). Factors that improved the odds of survival were initiation of ECMO in theatre (64% survival (30 of 47)) rather than the cardiac intensive care unit (29% survival (10 of 34)) and initiation of ECMO for reactive pulmonary hypertension. Important adverse factors for hospital survival were serious mechanical ECMO circuit problems, renal support, residual lesions, and duration of ECMO.

CONCLUSIONS

Hospital survival of children with biventricular physiology who require cardiac ECMO is similar to that found in series that include univentricular hearts, suggesting that successful cardiac ECMO is critically dependent on the identification of hearts with reversible ventricular dysfunction. In our experience of postoperative cardiac ECMO, the higher survival of patients cannulated in the operating room than in the cardiac intensive care unit is due to early effective support preventing prolonged hypoperfusion and the avoidance of a catastrophic cardiac arrest.

Women's involvement with the decision preceding their caesarean section and their degree of satisfaction

OBJECTIVE

To assess the extent to which women contribute to the decision for caesarean section and their satisfaction with the decision and procedure.

DESIGN

Observational study of women undergoing caesarean section who were interviewed using a standard proforma.

SETTING

University College Hospital, London.

PARTICIPANTS

One hundred and two consecutive women undergoing caesarean section.

RESULTS

The women's perceived reason for the caesarean section agreed with the doctors' reason in 91 cases (89.2%). Only 2/29 women having elective sections stated they had no contribution, compared with 22/73 women having emergency sections (P = 0.018, two-tailed Fisher's exact test). Twenty out of 29 women (69%) having elective procedures and 37/73 women (51%) having emergency sections recorded medium or more contribution. All women except one were 50% or more satisfied with the decision. Women's satisfaction with the operation was high in the immediate post-operative period and remained so over the following six weeks. Forty-three women (49%) said they would prefer an elective section in the next pregnancy given the choice.

CONCLUSIONS

Women undergoing caesarean section were well informed and took a considerable part in the decision-making process. This suggests that women's wishes may be playing a role in increasing caesarean section rates. High levels of satisfaction with both the decision and the procedure itself indicate that caesarean section is an acceptable method of delivery, particularly when an elective procedure.

Mortality rates after surgery for congenital heart defects in children and surgeons' performance

BACKGROUND

A public inquiry into surgery for paediatric congenital heart defects in Bristol, UK, underscored the need for reliable data on overall mortality rates, which would allow assessment of individual surgeons' performance. We aimed to gather and report such data for 1 year to provide information for clinicians, researchers, policy makers, and the general public.

METHODS

We collected data on all operations (1378) for congenital heart defects done by 11 surgeons in five departments in the UK between April 1, 1997, and March 31, 1998. These operations represented about 36% of all operations done in the UK during that time. Clearly defined criteria were agreed to classify operations into subgroups.

FINDINGS

The overall mortality rate for all operations was 4.0% (95% CI 3.0-5.2). No deaths occurred for 67 arterial-switch operations. Mortality rates for coarctation, ventricular septal defect, atrioventricular septal defect, Fallot, and truncus arteriosus operations were 1.1%, 0.6%, 3.6%, 2.3%, and 28.6%, respectively. Although overall mortality rates between surgeons varied (1.6-6.9%), no surgeon's were higher than the 95% CI. The numbers of operations done by individual surgeons were small, which led to wide confidence intervals and made the detection of differences in performance difficult.

INTERPRETATION

The participating departments seemed to reach high standards of care for children with congenital heart defects, although more data would be needed to assess performance of individual surgeons. The development of quality standards will be difficult because of the complexity of defects, the different types of operations, and few patients in each subgroup. Collection of larger sets of data for more patients and centres are needed.

Prediction of perinatal morbidity at term in small fetuses: comparison of fetal growth and Doppler ultrasound

OBJECTIVE

To compare fetal growth assessed by ultrasound (change in standard deviation score of abdominal circumference and estimated fetal weight) during the third trimester with predelivery ultrasound measurements of fetal size and Doppler measurements from the umbilical and fetal arteries in order to predict suboptimal perinatal outcome in small babies at term.

DESIGN

Prospective observational study.

SETTING

Day assessment unit in a university hospital.

SUBJECTS

One hundred and four consecutive women with a clinical suspicion of a small fetus during the third trimester confirmed by ultrasound (abdominal circumference below the 10th centile) and ultimately delivered at term.

MAIN OUTCOME MEASURES

Acidaemia at birth, fetal distress requiring emergency caesarean section in labour, admission to the neonatal intensive care unit.

RESULTS

Ninety-four babies (90%) weighed less than the 10th centile and the incidence of suboptimal perinatal outcome was 27%. The largest areas under the receiver operating characteristic curves for suboptimal perinatal outcome were obtained with the change in standard deviation score of abdominal circumference and estimated fetal weight, and the ratios of aortic/middle cerebral and renal/middle cerebral pulsatility index. Although low, the odds ratios of the change in estimated fetal weight standard deviation score and the Doppler ratios were significantly different from zero.

CONCLUSION

Ultrasound assessment of fetal growth and predelivery fetal Doppler pulsatility index ratios were superior to predelivery estimates of fetal size and umbilical artery pulsatility index in predicting suboptimal perinatal outcome in small fetuses delivering at term, although the clinical value of such a prediction may be limited.

Estimating the long-term impact of a prophylactic human papillomavirus 16/18 vaccine on the burden of cervical cancer in the UK

To predict the public health impact on cervical disease by introducing human papillomavirus (HPV) vaccination in the United Kingdom, we developed a mathematical model that can be used to reflect the impact of vaccination in different countries with existing screening programmes. Its use is discussed in the context of the United Kingdom. The model was calibrated with published data. The impact of vaccination on cervical cancer and deaths, precancerous lesions and screening outcomes were estimated for a vaccinated cohort of 12-year-old girls, among which it is estimated that there would be a reduction of 66% in the prevalence of high-grade precancerous lesions and a 76% reduction in cervical cancer deaths. Estimates for various other measures of the population effects of vaccination are also presented. We concluded that it is feasible to forecast the potential effects of HPV vaccination in the context of an existing national screening programme. Results suggest a sizable reduction in the incidence of cervical cancer and related deaths. Areas for future research include investigation of the beneficial effects of HPV vaccination on infection transmission and epidemic dynamics, as well as HPV-related neoplasms in other sites.

Is hydrotherapy cost-effective? A randomised controlled trial of combined hydrotherapy programmes compared with physiotherapy land techniques in children with juvenile idiopathic arthritis

OBJECTIVES

To compare the effects of combined hydrotherapy and land-based physiotherapy (combined) with land-based physiotherapy only (land) on cost, health-related quality of life (HRQoL) and outcome of disease in children with juvenile idiopathic arthritis (JIA). Also to determine the cost-effectiveness of combined hydrotherapy and land-based physiotherapy in JIA.

DESIGN

A multicentre randomised controlled, partially blinded trial was designed with 100 patients in a control arm receiving land-based physiotherapy only (land group) and 100 patients in an intervention arm receiving a combination of hydrotherapy and land-based physiotherapy (combined group).

SETTING

Three tertiary centres in the UK.

PARTICIPANTS

Patients aged 4-19 years diagnosed more than 3 months with idiopathic arthritides, onset before their 16th birthday, stable on medication with at least one active joint.

INTERVENTIONS

Patients in the combined and land groups received 16 1-hour treatment sessions over 2 weeks followed by local physiotherapy attendances for 2 months.

MAIN OUTCOME MEASURES

Disease improvement defined as a decrease of > or =30% in any three of six core set variables without there being a 30% increase in more than one of the remaining three variables was used as the primary outcome measure and assessed at 2 months following completion of intervention. Health services resource use (in- and outpatient care, GP visits, drugs, interventions, and investigations) and productivity costs (parents' time away from paid work) were collected at 6 months follow-up. HRQoL was measured at baseline and 2 and 6 months following intervention using the EQ-5D, and quality-adjusted life-years (QALYs) were calculated. Secondary outcome measures at 2 and 6 months included cardiovascular fitness, pain, isometric muscle strength and patient satisfaction.

RESULTS

Seventy-eight patients were recruited into the trial and received treatment. Two months after intervention 47% patients in the combined group and 61% patients in the land group had improved disease with 11 and 5% with worsened disease, respectively. The analysis showed no significant differences in mean costs and QALYs between the two groups. The combined group had slightly lower mean costs (-6.91 pounds Sterling) and lower mean QALYs (-0.0478, 95% confidence interval -0.11294 to 0.0163 based on 1000 bootstrap replications). All secondary measures demonstrated a mean improvement in both groups, with the combined group showing greater improvements in physical aspects of HRQoL and cardiovascular fitness.

CONCLUSIONS

JIA is a disease in which a cure is not available. This research demonstrates a beneficial effect from both combined hydrotherapy and land-based physiotherapy treatment and land-based physiotherapy treatment alone in JIA without any exacerbation of disease, indicating that treatments are safe. The caveat to the results of the cost-effectiveness and clinical efficacy analysis is that the restricted sample size could have prevented a true difference being detected between the groups. Nevertheless, there appears to be no evidence to justify the costs of building pools or initiating new services specifically for use in this disease. However, this conclusion may not apply to patients with unremitting active disease who could not be entered into the trial because of specified exclusion criteria. For this group, hydrotherapy or combined treatment may still be the only physiotherapy option. Further research is suggested into: the investigation and development of appropriate and sensitive outcome measures for use in future hydrotherapy and physiotherapy trials of JIA; preliminary studies of methodologies in complex interventions such as physiotherapy and hydrotherapy to improve recruitment and ensure protocol is acceptable to patients and carers; hydrotherapy in the most common paediatric user group, children with neurological dysfunction, ensuring appropriate outcome measures are available and methodologies previously tried; patient satisfaction and compliance in land-based physiotherapy and hydrotherapy and European studies of hydrotherapy in rare disorders such as JIA.

Are elderly people living alone an at risk group?

OBJECTIVE

To test the hypothesis that elderly people living alone are an at risk group with a high level of morbidity that makes high demands on health and social services.

DESIGN

Secondary analysis of data from a community survey of 239 people aged 75 and over, identified from general practitioners' age-sex registers.

SETTING

Nine practices in the London boroughs of Brent and Islington.

MAIN OUTCOME MEASURES

Scores on the mini-mental state examination; stated satisfaction with life; assessment of mobility; numbers of diagnoses of major physical problems; numbers of prescribed drugs taken; urinary incontinence; alcohol consumption; contacts with general practitioners and hospital outpatient and inpatient services; contact with community health and social services.

RESULTS

There were significantly more women among those living alone (93/120 (78%) v 63/119 (53%); p < 0.0005) and the median age of elderly people living alone was higher (81 v 80; p < 0.04). Those living alone and those living with others showed no significant differences in measures of cognitive impairment, numbers of major physical diagnoses, impaired mobility, or use of general practitioner or hospital services. Stated satisfaction with life was somewhat higher in those living alone. Elderly people living alone were significantly more likely to have contact with chiropody, home help, and meals on wheels services and less likely to have someone they could contact in an emergency or at night. Living alone increased the likelihood of contact with one or more community health professionals (district nurses, health visitors, or chiropodists) considered as a group and also increased the likelihood of contact with social services as a whole. There was a tendency for more of those living alone than those living with others to have home visits from their general practitioners, but there were no significant differences in contact with hospital services between the two groups.

CONCLUSIONS

Elderly people living alone do not have an excess of morbidity compared with those living with others and do not seem to be an at risk group requiring specifically targeted assessments. More help is needed to provide elderly people living alone with a point of contact in case of emergency.

Can papilloma virus testing be used to improve cervical cancer screening?

This report investigates different options for using human papillomavirus (HPV) testing in cervical cancer prevention. These options are evaluated by a stochastic model of the progression of pre-malignancy and its relationship to HPV infection. Three screening policies are compared: 2 based on cytological screening, with or without HPV testing, and 1 in which HPV testing is the primary screening method. A policy of HPV testing for women with mildly abnormal smears would have little effect on the overall incidence of invasive cancer when compared with a policy of repeat cytology, provided follow-up is efficient. Moreover, the potential value of HPV testing as a primary screening method is strongly dependent on the proportion of neoplasias that are HPV-negative. Important factors in assessing the future role of HPV testing would be cost-effectiveness and benefits from improved compliance.

An investigation of fetal growth using serial ultrasound data

Serial ultrasonic measurements were performed in 67 Caucasian fetuses from 20 weeks' gestation until term to derive reference standards for abdominal circumference (AC) and estimated fetal weight (EFW). The variances of both AC and EFW increased with gestational age. Four mathematical models (linear, quadratic, Gompertz and Rossavik) were fitted to the log(10)(AC) and log(10)(EFW) data from each fetus using least squares regression analysis. The standard deviations of the residual error were greatest for the linear model. The linear model also overestimated the final log(10)(AC) while the linear, Gompertz and Rossavik models all overestimated the final log(10)(EFW) when these data were omitted from the fitting process. The individual quadratic constants were, therefore, used to produce 67 individual growth curves. Values of log(10)(AC) and log(10)(EFW) for each fetus at exact gestational ages between 20 and 40 weeks were derived by interpolation; the mean and standard deviation values were then used to derive centile ranges for abdominal circumference and estimated fetal weight. These standards should prove useful in the assessment of fetal growth.

Likely variations in perioperative mortality associated with cardiac surgery: when does high mortality reflect bad practice?

OBJECTIVE

Several methods exist for estimating the risk of perioperative mortality based on preoperative risk factors; graphical methods such as the variable life adjusted display (VLAD) can be used to examine how an individual surgeon's performance for a series of operations fares against what would be expected, given the case mix. This study aimed to devise a method for assessing the natural variation in outcome in order to assist with making judgements about individual performance, in particular whether seemingly poor performance could have occurred by chance.

METHOD

The risk scoring system has been derived and validated locally for cardiac surgery. A method is described for calculating the probability that an observed number of deaths occurs within a sequence of operations if perioperative mortality is regarded as a chance event with an expected value derived from the risk score. To illustrate this method, nested prediction intervals are superimposed onto VLAD plots for a series of 393 isolated coronary artery bypass and isolated valve operations performed by a single surgeon.

RESULTS

Using the locally derived risk score, the VLAD plot for the individual surgeon shows a net life gain of about 6 over the predicted number of survivors, which is observed to be within the 90% prediction interval. If the Parsonnet scoring system is used instead of the locally derived risk score, the net life gain is considerably overestimated.

CONCLUSIONS

The nested prediction intervals are straightforward to generate and can be integrated into a visually informative display. As an indication of the inherent variability in outcome, they have a valuable role in the monitoring of surgical performance.

Alcohol consumption by elderly people: a general practice survey

A random sample of 241 patients from General Practice registers in London were interviewed to assess alcohol consumption, cognitive impairment, depression and other factors. Fifty-one per cent of men and 22% of women reported use of alcohol in the previous 3 months. No significant association was found between reported drinking status and age, score on a depression scale, falls in the previous 3 months, attendance at outpatient clinics or inpatient care in the previous year. In the men abstainers were significantly more likely to show cognitive impairment than were drinkers. Amongst those respondents who admitted to drinking within the previous 3 months, total stated weekly alcohol consumption was not associated with age, cognitive impairment and scores on the depression scale, and there was no association with falls, or with outpatient or inpatient care. Only three men (3.6%) and five women (3.2%) admitted consuming more than 21 and 14 units of alcohol per week, respectively.

Withdrawing low risk women from cervical screening programmes: mathematical modelling study

OBJECTIVE

To evaluate the impact of policies for removing women before the recommended age of 64 from screening programmes for cervical cancer in the United Kingdom.

DESIGN

A mathematical model of the clinical course of precancerous lesions which accounts for the influence of infection with the human papillomavirus, the effects of screening on the progression of disease, and the accuracy of the testing procedures. Two policies are compared: one in which women are withdrawn from the programme if their current smear is negative and they have a recent history of regular, negative results and one in which women are withdrawn if their current smear test is negative and a simultaneous test is negative for exposure to high risk types of human papillomavirus.

SETTING

United Kingdom cervical screening programme.

MAIN OUTCOME MEASURES

The incidence of invasive cervical cancer and the use of resources.

RESULTS

Early withdrawal of selected women from the programme is predicted to give rise to resource savings of up to 25% for smear tests and 18% for colposcopies when withdrawal occurs from age 50, the youngest age considered in the study. An increase in the incidence of invasive cervical cancer, by up to 2 cases/100 000 women each year is predicted. Testing for human papillomavirus infection to determine which women should be withdrawn from the programme makes little difference to outcome.

CONCLUSIONS

This model systematically analyses the consequences of screening options using available data and the clinical course of precancerous lesions. If further audit studies confirm the model's forecasts, a policy of early withdrawal might be considered. This would be likely to release substantial resources which could be channelled into other aspects of health care or may be more effectively used within the cervical screening programme to counteract the possible increase in cancer incidence that early withdrawal might bring.

Assessment of mortality rates for congenital heart defects and surgeons' performance

BACKGROUND

In the absence of reliable national data, we have collected results of all operations for congenital heart defects from five departments to assess mortality rates and compare them among surgeons and departments.

METHODS

Data relating to all operations (2,718) carried out at the five centers during a period from April 1, 1997 through March 31, 1999. Clearly defined criteria were agreed for the classification of patients into various subgroups.

RESULTS

The overall hospital mortality was 4.4% (95% confidence intervals 3.7%-5.3%). Mortality for open-operations was 12.6% in neonates, 5.1% in infants, and 3.5% in children. Mortality rates were 1.1% for coarctation, 0.4% ventricular septal defect, 4.1% atrioventricular septal defect, 2.9% Fallot, 0.9% switch, and 15.6% truncus arteriosus. Although individual surgeons' mortality rates ranged from 1.8% to 7.5%, none of the 12 surgeons' data were above 95% confidence intervals. For individual surgeons, the change in mortality rates between the 2 years ranged between -3.3% and +3.8%.

CONCLUSIONS

With 2 years' data available, estimates of mortality rates are more precise as reflected by tighter confidence intervals. There were relatively small data sets for individual hospitals and surgeons, which made statistical evaluation difficult. For setting standards, data from more departments for a longer period will be required. Statistical methods alone cannot be used as a sole arbiter of what is considered acceptable performance.

A mathematical model of the development of drug resistance to cancer chemotherapy

A mathematical model incorporating descriptions of tumour growth kinetics and the effects of cytotoxic chemotherapy on established tumours, is presented. It is shown how models of this kind may be used to investigate the potential of hypothetical chemotherapy strategies, and to identify general principles for successful treatment. The model is intended to be an aid to clinicians designing new chemotherapy programmes for diseases in which progress has been disappointing.

Which patients will not benefit from further intensive care after cardiac surgery?

In intensive care units, a predictive model that identified patients who are certain to die would spare suffering and free resources for more productive work. In a prospective study to determine factors which might predict the outcome of a protracted stay in intensive care units, information was collected for 162 patients who remained in intensive care longer than 48 hours after cardiac surgery. Of these patients, 21% presented as emergencies, 35% as urgent cases, and 44% as elective cases. They were drawn from 2256 adult patients operated upon during a 12-month period in three UK centres. 115 patients (71%) who were in intensive care for more than 48 hours survived to be discharged. The median duration of stay was 6 days (range 3-90 days) and the median duration of hospital stay was 21 days (7-111 days). An existing algorithm developed and calibrated to predict outcome for general patients in intensive care was applied to forecast outcomes. Contrary to expectations, the algorithm performed well for patients after cardiac surgery. In identifying deaths in intensive care and before hospital discharge, the specificities for death at various intervals after admission were all 97% or more. There is little scope for improving the algorithm's ability to forecast longer term outcome. Furthermore, if it were to be introduced to aid decisions about withdrawal of treatment, the potential saving in intensive care bed-days would be small--less than 3% overall.

Cytological screening and management of abnormalities in prevention of cervical cancer: an overview with stochastic modelling

AIMS

To develop a mathematical model of the histological changes of precancer and the development of invasive cancer and how these are related to cytological findings. To use this to investigate the effects on incidence of cervical cancer, number of smear tests and colposcopies, of different schedules for cervical screening, and the clinical management policies for dyskaryosis.

METHODS

A stochastic model was developed relating the available data on tissue progression to the cytological findings. Two strategies, A and B, were compared: under A, women with any abnormal smear receive immediate colposcopy and treatment; under B, women with mild or borderline dyskaryosis have repeated smears at six monthly intervals with colposcopy only for persistent abnormalities.

RESULTS

The model predicted an incidence of invasive cervical cancer in an unscreened population of women aged over 18 years of 5.9 per 10,000 per year. With 70% coverage and three yearly screening under strategy A, the incidence fell to 2.00 and under B to 2.10. The number of smears required was similar but A required two to three times as many colposcopies as B. Raising the coverage to 90% reduced the incidence to around 1 per 10,000 per year but changing the screening interval, the specificity or sensitivity of cytology had much less effect.

CONCLUSION

The model has been tested under a wide range of possible variations in natural history, specificity and sensitivity of cytology. For low grade smear abnormalities, open colposcopic referral is predicted to reduce invasive cancer only slightly more than repeat cytology, at the expense of much additional colposcopy. Improving cytological coverage is suggested as more effective in reducing invasive cancer than increased use of colposcopy or more frequent screening.

Evaluating cervical cancer screening programmes for developing countries

This study evaluates cervical screening programmes for regions of the world where resources are scarce and little screening currently takes place. It investigates infrequent screening and programmes in which as many women as possible are screened just once in their lifetime. It also compares the effectiveness of cytology and human papillomavirus (HPV) testing for primary screening. Different programmes are evaluated by a stochastic model of the progression of pre-cancer, its relationship to papillomavirus infection and the diagnostic accuracy of alternative screening methods. These are compared in terms of the impact on the incidence of invasive cancer and resource use. Important factors that determine the suitability of different screening programmes are the available resources and the expected population coverage. Blanket screening for women aged 30-59 years, with the aim of covering all just once in their lifetime, could reduce the incidence of invasive cancer by up to 30%. A 10-year programme would require about 50% more routine screening tests to bring about the same reduction in incidence and a 5-year programme about 2.5-3 times as many. With either approach it would be more effective for resource use to concentrate on screening women aged 30-59 than a wider age group. Whether HPV testing would be more effective as a primary screening method than cytology depends on the underlying prevalence of HPV infection, the accuracy of cytology, the cost and the suitability of the testing procedure under field conditions.

Early identification of divergent performance in congenital cardiac surgery

OBJECTIVES

Heterogeneous caseload and poorly quantified risk stratification make it difficult to monitor outcomes in congenital cardiac surgery. Reliance on formal statistical hypothesis testing may lead to substantial delays before a pattern of poor outcome can be established. Here, we report alternative methods for alerting surgeons to potential problems at an earlier stage.

METHODS

Graphical methods developed for monitoring adult cardiac surgery have been adapted for use in congenital cardiac surgery. To illustrate their potential, we have retrospectively examined mortality data for a single surgeon involving 315 cases. Partial risk adjustment has been carried out according to patient's age and the open/closed categorization of the surgical procedure. Additional information has been derived by ranking procedures in order of their complexity and displaying the proportion of the surgeon's cases in each complexity stratum.

RESULTS

The display of a surgeon's mortality data adjusted for age and open/closed category provides an easily understood chart of performance and allows one to identify periods when performance appears divergent, relative to the surgeon's own overall standards. Cases carried out during such periods can then be scrutinized by alternative methods. One such method is to examine caseload complexity during the periods of apparent divergent performance compared with other periods.

CONCLUSIONS

These methods, while in no way representing formal statistical tests, provide a means that can alert surgeons to potential problems and help to identify sequences of cases that might benefit from further scrutiny.

Ultrasonic fetal weight estimation: analysis of inter- and intra-observer variability

Standard ultrasound measurements were performed by two observers in 40 third-trimester fetuses. Observers were blinded to the results of the measurements. Estimated fetal weight (EFW) was calculated using two published formulae. The intra-observer standard deviation for EFW, assessed using one-way analysis of variance, was < 75 g for both observers. The 95% prediction intervals for inter-observer comparisons of EFW, calculated using the limits of agreement method, were -187.3 g to 139.8 g, and -159.9 g to 124.3 g, using the two formulae. The results suggest that measurements of EFW are reproducible. The prediction interval is comparable to the weekly fetal weight increment in normal fetuses.