Steve Gallivan

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.

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.

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.

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 I 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.

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 surgeons 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.

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

Abstract 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 models 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.

Providing feedback to hospital doctors about prescribing errors; a pilot study

Objective To assess the feasibility and acceptability of obtaining data on prescribing error rates in routine practice, and presenting feedback on such errors to medical staff. Setting One clinical directorate of a London teaching trust. Methods Ward pharmacists recorded all prescribing errors identified in newly written medication orders on one day each fortnight between February and May 2005. We examined prescribing errors reported on the trust’s medication incident database for the same period. Main outcome measures Prescribing errors identified and recorded by ward pharmacists, prescribing errors reported as incident reports; prescribing error rates per clinical specialty; lead consultants’ views on receiving feedback on errors for their specialty. Results During eight data collection days, 4,995 new medication orders were examined. Of these, 462 (9.2%; 95% confidence interval 8.5 –10.1%) contained at least one prescribing error. There were 474 errors in total. Pharmacists indicated that they would have reported 19 (4%) of the prescribing errors as medication incidents. Eight prescribing errors were reported for the entire four-month study period on non-data collection days. Feedback was presented to lead clinicians of 10 clinical specialties. This included graphical summaries showing how the specialty compared with others, and a list of errors identified. This information was well-received by clinicians. Conclusion Prescribing errors identified by ward pharmacists can be systematically fed back at the level of the clinical specialty; this is acceptable to the consultants involved. Incident report data is subject to gross under-reporting. Routinely providing feedback for each consultant team or for individual prescribers will require more focussed data collection.

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. Int. J. Cancer 72:210–216, 1997.

Analytical methods for calculating the capacity required to operate an effective booked admissions policy for elective inpatient services.

In the UK, hospitals are being encouraged to introduce booked admissions policies for elective inpatient services whereby patients are given a date for hospital admission months in advance rather than being put on a waiting list and then informed of their admission date at short notice. We address the question of what level of capacity is required to operate such a system if cancellations of booked elective patients are to be kept to a low level. Methods are presented for quantifying the day to day variation in bed demand due to emergency admissions, patient initiated cancellations and variable lengths of stay amongst patients.

Comparison of detailed and succinct cohort modelling approaches in a multi-regional evaluation of cervical cancer vaccination

Mathematical models have been used extensively in the evaluation of chronic diseases and in exploring the health economics of vaccination. In this study, we examine the value of having two different cohort models based on similar assumptions, one comprehensive and one simplified, which can be used to evaluate the impact of cervical cancer vaccination. To compare models, we ran cost-effectiveness analyses in four geographical regions (Italy, the UK, Taiwan and Canada). We show that the models produce comparable results and therefore can be used independently. However, as they require different complexities of data inputs, they are more suited to different circumstances depending on the level of data inputs available or the complexity of the research question asked.