Measuring what a screening programme does

This chapter gives understanding of measuring evidence about consequences of screening programmes, at a level needed by public health practitioners interpreting evidence for setting screening policy, or for ensuring high quality programme delivery. It takes a practical approach, illustrating with real-life case histories and examples, ranging from infant neuroblastoma to abdominal aortic aneurysm screening. The issues covered are Three Main Biases (healthy screenee effect, length time effect including overdiagnosis, lead time effect); Three Main Evaluation Methods (randomised control trials, time trend analyses, case control studies, and mention of rare conditions); Test Performance (sensitivity and specificity, positive and negative predictive value, receiver operator characteristic curves); Two Additional Sources of Information (pilot or demonstration projects, modelling); Summarising Information on all Outcomes (the numbers in the flow diagram, and decision aids) and finishing with A Note on Sound Science. Careful use of terminology is emphasised, and pitfalls with use of jargon terms (true and false, positive and negative) and misleading labels (early, late, pre-symptomatic, carcinoma in situ) are explained. The issue of overdiagnosis of inconsequential conditions is explained.

What screening does

This chapter gives a deeper understanding of screening, and of the diverse consequences it brings. It illustrates the overdetection problem with reference to mammography breast screening programmes, and explains the ‘popularity paradox’ that this leads to. In the early days, the simplistic notion that screening must automatically be beneficial meant that people only asked ‘why are we not doing it?’ Later scientific challenges brought a new question, ‘How do we tell if screening succeeds in reducing risk?’ This served well as a driving force for better evaluation, but it ignored the need to assess harmful consequences. Growing experience has revealed the need to ask ‘what are all the consequences?’ Different observers see some consequences more starkly than others depending on their viewpoint. This chapter explains why it is important to consider a complete overview of an entire programme and to recognise that overdetection, overtreatment and underdetection, are inevitable features even when screening is delivered to a high quality.

How screening started

This chapter explains how health screening began, how the aims have evolved, how evidence and organisation influenced matters, and how challenges in the future will give rise to continuing change. It begins with Gould’s address in 1900 to the American Medical Association and charts events that led, almost by accident, to the institution of comprehensive annual testing of healthy adults in the USA, and to 5 day hospital-based ‘Human Dry Dock’ screening for Japanese executives. Scientific challenge then came from two randomised control trials, which failed to find benefit, but by then screening had become an important commercial activity. Using the UK cervical screening programme as a case study, the chapter explores how the optimism of the 1960s led through disillusionment, then to programme organisation and, by the 1990s, an era of realism. Evolution of the Wilson and Jungner criteria as an aid for policy making is covered. A key challenge now is to ensure best value policy, high quality systematic programme delivery and informed choice in the face of commercial forces that lead to the glossing over of screening’s complexities and far reaching consequences.

Day-to-day management of screening programmes for public health practitioners and managers

This chapter gives the reader an appreciation of main issues that public health practitioners regularly deal with in screening, and how to approach them. This needs management skills and an understanding of screening programmes. Typical problems include preventing screening from starting when there is no sound evidence base, dealing with provision of poor quality screening, implementing policy changes within existing screening programmes, dealing with legal challenges relating to screening, and coping with damage caused by commercially driven provision of screening tests where there is lack of evidence, lack of informed choice, and no provision beyond the initial test. Dealing with any of these matters can involve using the media, and the final section of the chapter gives advice about how to cope when the media spotlight turns on screening. Prostate cancer and ovarian cancer screening are both used as case studies in this chapter.

Quality-assuring screening programmes

This chapter explains why quality assurance is essential if screening is to do more good than harm. It describes some of the history and thinking that has shaped approaches to quality in industry and in healthcare, starting with an example from the American car industry and focusing on two founding fathers of quality - W Edwards Deming, and Avedis Donabedian. It outlines Donabedian’s seven components of quality, and shows how these encompass the notion of best value in healthcare so that efforts are devoted to improving health and social justice. It then goes on to explain some of the ways of measuring screening quality, setting standards and ensuring standards are met. It uses case histories and practical examples so that the reader can easily apply the lessons in their day to day work.

Implementing screening programmes

This chapter gives the reader an understanding of the essential tasks involved in setting up a good quality screening programme. Newborn hearing screening is used as a case study. There is an old saying that all you have to do to create an effective service is choose the right things to do, then do them right. Choosing the right screening involves assessing the evidence and making policy. Doing screening right means setting up a well ordered programme for screening that is of value, ensuring that the service is always of high quality, dealing effectively with problems. It also means making sure that when there is no evidence that benefits would outweigh harms, then screening is vest avoided. Different health care systems have very different ways of planning, delivering, and funding their screening programmes. The chapter focuses on matters that are essential if screening is to achieve public health improvement - irrespective of where, and in what type of health system, it is being delivered.

Making policy on screening programmes

This chapter shows how resources, values, beliefs, and commercial factors all influence screening policy, and gives clear insight into some of the ethical dilemmas involved. Case histories include celebrity selling of HPV testing, the USA ‘Mammography Wars’ incident, the Cartwright Inquiry into events at National Women’s Hospital in Auckland in the 1960s and genetic testing. The chapter strongly emphasises the value of following robust and explicit processes when making screening policy, and argues that this is best done at national level. The reasons why screening policy-making can be difficult are explored in detail, and clear lessons are drawn from the case examples. The chapter addresses the technical aspects of using evidence, and also explains the power of the cultural belief that all screening must automatically be a good thing and of commercial, professional and institutional interests, often enacted through invisible lobbying using ‘third party’ techniques. The ethical conflicts inherent within screening are described and explored.

What screening is, and is not

This chapter reviews the different ways in which the term ‘screening’ has been and is used, and defines the meaning used throughout the rest of the book. Growth of screening programmes in the twentieth century led to a range of activities which vary widely in purpose and process, from bloodspot tests in newborn babies, through to whole body scans for the wealthy worried well. This chapter explains the different kinds of testing done on healthy people, and how these differ from diagnostic tests for solving problems that patients bring to clinicians. It explains where screening fits in the pathway of disease development. It describes the basic system that makes up a screening programme as opposed to just a screening test. It explains, using infant phenylketonuria as a case history, why screening needs to be delivered as a proper programme if it is to successfully achieve risk reduction. We describe the variation in screening delivery across different countries and emphasise that this book focuses on systematic screening programmes, aimed at risk reduction for the screened individual, based on sound evidence that harm, benefit and affordability are well balanced, and delivered to pre-agreed policy and standards.