Chapter Ten. The major causes of ill health
Key points
• Disease and national health strategy
• Approaches to disease prevention
– Immunization
– Screening
• Tackling the major causes of ill health
– Cardiovascular disease
– Cancers
– Accidents
– Mental illness
– HIV/AIDS
OVERVIEW
Over the last century, there has been a big shift in the burden of disease – from the infectious diseases of the nineteenth and early twentieth centuries to chronic diseases in the twentieth century and now. Chronic diseases such as coronary heart disease (CHD) and cancer are also strongly related to lifestyle factors such as smoking, poor diet, physical inactivity and alcohol consumption. Changes over time in the burden of disease have shifted the emphasis of public health from health protection measures to tackle infectious diseases towards health promotion policy targeting individual behaviour and lifestyle risk factors, as well as the wider determinants of health, such as poverty and education. Health protection is nevertheless still an important strategy in the context of new, emerging and resurgent infectious diseases (such as HIV, Ebola virus, vCJD, avian and swine flu, and tuberculosis). New diagnostic technologies, including those based on genetics, could also play a role in improving population health. This chapter reviews two key strategies in disease prevention – immunization and screening – and goes on to discuss approaches to some of the major causes of ill health in the twenty-first century – CHD, cancers, accidents, mental illness and HIV.
Introduction
Most international health strategies seek to secure improvements in health by increasing life expectancy and reducing premature death (adding years to life) and increasing the quality of life and minimizing illness (adding life to years). In England, this is achieved by focusing on key health areas that are
• a major cause of premature death or avoidable ill health
• responsive to effective intervention
• amenable to measurement and monitoring.
Saving Lives: Our Healthier Nation (DH 1999a) identified cancers, coronary heart disease (CHD) and stroke, accidents and undetermined injury and mental health as the priority areas. The Public Health Agency of Canada [http://www.phac-aspc.gc.ca] also includes chronic respiratory diseases, diabetes and musculoskeletal diseases. The focus of many strategies is on the prevention of specific diseases rather than the promotion of health in the community as a whole or improvements in the health of specific groups. There are many priority issues, and listing them should not imply that their relationship to behaviours such as smoking is not recognized. Other national strategies focus on risk factors that cause ill health such as smoking, alcohol and diet (e.g. Scottish Office 1998).
The two most common causes of death in the UK are CHD and cancers. Tackling these major causes of ill health is often driven by a medical model which focuses on early diagnosis and treatment of disease or its precursors such as hypertension or diabetes. The National Service Framework for Diabetes (DH 2001a), for example, focuses on the identification of people with diabetes; clinical care; managing diabetic emergencies; the care of people with diabetes in hospital; diabetes and pregnancy; and the detection and management of long-term complications.
However, prevention of diseases requires addressing the risk factors that are common to many diseases:
• reducing smoking prevalence
• improving diet and nutrition
• increasing physical activity
• reducing overweight and obesity.
Chapter 11 discusses how these lifestyle changes are being addressed through health promotion interventions.
The most common way of assessing health improvement is through a reduction in mortality and morbidity. Practitioners may thus find it hard to move outside of this disease-focused framework and think about how they can tackle the major causes of health within a salutogenic approach. For example, the objective for the priority area of mental health is expressed as the promotion of health, but the setting of targets for achievement led to its expression as disease-focused: ‘To reduce the death rate from suicide and undetermined injury by at least a fifth by 2010’ (DH 1999a).
Disease prevention is only one strand of public health practice. The key purposes of public health identified in the standards for specialist public health practice are
• to improve health and well-being in the population
• to prevent disease and minimize its consequences
• to prolong valued life
• to reduce inequalities in health.
One of the key areas of competence is the surveillance and assessment of the population’s health and well-being. This chapter explores two different approaches to disease prevention: screening and immunization.
Approaches to disease prevention
The central question in disease prevention is whether to adopt
• the population approach in which the aim is to lower the average level of risk in the population or
• the high-risk approach in which people at particular risk are identified and offered advice and treatment.
Because most conditions follow a roughly normal distribution in the population as a whole, there are many more people with a risk factor or condition in the main body of the population. The prevention paradox (Rose 1993) suggests that many people need to take protective action in order to prevent illness in a few. There would therefore be more improvement in population health if everyone reduced their risk (e.g. their cholesterol level) than if the few in the high-risk category reduced their cholesterol level to the mean.
This supports the whole population approach rather than a targeted approach, which might initially appear the more logical choice. Rose (1993) suggests that many interventions that aim to improve health have relatively small influences on the health of most people and therefore the purported benefits of population programmes are over-stressed to encourage people to take action. This section examines the concept of screening – the process of actively seeking to identify precursors to disease in those who are presumed to be healthy – as a means of preventing disease. Screening has been a recognized and accepted part of general health care but in recent years the cost-effectiveness, efficacy and acceptability of such mass programmes have been questioned.
Infectious diseases account for one-third of all deaths worldwide. Diarrhoea, measles, tuberculosis (TB) and malaria alone account for nearly 10 million and 18% of all deaths in low-income countries (WHO 2008). Getting Ahead of the Curve, the UK strategy for combating infectious diseases (and other forms of health protection) (DH 2002a), describes new threats to health:
• the re-emergence of diseases once thought to be conquered (e.g. TB, polio)
• the emergence of new diseases (e.g. most notably HIV, but 2003 saw the emergence of SARS, an outbreak in China that rapidly spread to other countries, and 2009 saw a worldwide swine flu pandemic)
• terrorism.
There are many reasons why infectious diseases have again become a major public health problem, prompting the UK government to set up a Health Protection Agency in 2003 to review new and emerging infectious diseases and strengthen surveillance systems. One factor is the indiscriminate use of antibiotics to treat illnesses and to promote growth in animals which has led to increased microbial resistance. Other factors in the spread of such diseases include population movement, poverty and poor social conditions.
The spread of TB
TB is an example of a disease where worsening social conditions enable the spread of infection. The WHO declared TB a global emergency in 1993, and in 1998 it estimated that one-third of the world’s population is infected with mycobacterium tuberculosis. The UK saw a steady decline in TB notifications from 50,000 cases annually in the 1940s to about 5000 cases in the 1980s as a consequence of the introduction of BCG immunization and anti-tubercular therapies. Yet TB cases have risen by 73% in London since 1987 and the incidence in some London boroughs exceeds 50 per 100,000, the majority of these cases being in people born in countries where the disease is endemic. The spread of HIV infection and the emergence of multi-drug resistance are contributing to the worsening impact of the disease worldwide.
Immunization has been one of the major strategies to tackle infectious diseases. In Angola, for example, 10 million children were vaccinated against polio in 3 days in 2003. Yet in the same year the UK saw the emergence of serious public concerns over the safety of the measles, mumps and rubella (MMR) vaccination programme (since recognized as unfounded) that saw immunization rates in London drop to 55%. This section examines the dilemmas for practitioners posed by immunization and the challenges of assessing and communicating risk to the public.
Screening
The National Screening Committee defines screening as:
a public health service in which members of a defined population, who do not necessarily perceive they are at risk of, or are already affected by a disease or its complications, are asked a question or offered a test, to identify those individuals who are more likely to be helped than harmed by further tests or treatment to reduce the risk of a disease or its complications.
There are several different types of screening in use:
• mass screening of whole population groups, for example breast and cervical screening of women
• selective screening of high-risk groups, for example the proposed testing of new arrivals for TB and HIV
• anonymous screening used to detect trends in public health, for example diabetic patients in general practice
• opportunistic screening when the opportunity is taken at a general consultation to ask about health-related behaviour
• health screening not linked to a particular disease, but looking at lifestyles in general, for example well woman clinics
• genetic screening investigating inheritable factors in order to assist parenting decisions, for example sickle cell screening
• routine screening in infancy and childhood.
There are particular ethical issues associated with screening and it is not unambiguously a good thing. It may move someone from presuming themselves to be healthy to a state of having an identified disease or condition, with the attendant anxiety and potentially invasive treatment for the patient. Its benefits, therefore, in terms of earlier diagnosis necessitating less radical treatment and reduced morbidity and mortality, must outweigh the disadvantages or costs.
The National Screening Committee has set out a framework for screening that elaborates on the guidelines and principles laid out by the World Health Organization in 1968 (Wilson Jungner 1968):
• The disease should be common and serious.
• The disease should have a recognized latent stage during which early symptoms can be detected.
• There should be a simple, safe, precise and validated screening test.
• The test should be acceptable to the population.
• There should be an effective treatment or intervention for patients identified through early detection, with evidence of early treatment leading to better outcomes than late treatment.
• The screening programme should be effective in reducing mortality or morbidity.
• The benefit from the screening programme should outweigh the physical and psychological harm (caused by the test, diagnostic procedures and treatment).
• The opportunity cost of the screening programme (including testing, diagnosis, treatment, administration, training and quality assurance) should be economically balanced in relation to expenditure on medical care as a whole (i.e. value for money).
Screening programmes may mean that less attention is given to understanding and tackling the causes of the disease. A range of risk factors have been identified as associated with breast cancer including body weight, limited breastfeeding and alcohol consumption.
Screening for prostate cancer
Prostate cancer is the second leading cause of cancer deaths in men in the UK. Each year 34,000 cases are diagnosed and there are over 10,000 deaths. Yet screening for prostate cancer is controversial. By the age of 80, approximately 50% of men will have some form of prostate cancer but more men will die with the disease than of it. Screening for prostate cancer involves the examination of asymptomatic men by blood test for prostate-specific antigen (PSA). Raised levels of PSA are not a very reliable indicator of cancer. This may be followed by a digital rectal examination to detect enlargement or change in the prostate gland. Those who have the disease may be offered prostatectomy or radiotherapy and those with advanced disease may have hormone manipulation therapy to slow or shrink the tumour. These interventions carry risks of increased pain and varying levels of incontinence or impotence. An increased level of testing may lead to a dilemma of whether to treat any cancer aggressively or to adopt a more conservative approach of ‘wait and see’. Screening for prostate cancer does not therefore currently satisfy the basic criteria for screening – that testing will improve the prognosis of those with the disease, improve quality of life and that there is an effective treatment available.
Two large international trials into prostate cancer have contradictory conclusions:
The European Randomized Study of Screening for Prostate Cancer (ERSPC) studied 182,000 men aged between 50 and 74 and found that screening could cut deaths by 20% whilst the Prostate, Lung, Colorectal, and Ovarian (PLCO) cancer screening trial reported no benefit.
In 2001, the UK launched an ‘informed choice’ approach that included new information leaflets and DIPEx (database of individual patient experience). Yet critics argue that the provision of written information to ensure that patients can make informed choices is not sufficient. The information must be understood and framed in such a way that does not suggest there is a right or wrong choice.
Donovan et al (2001) cite several studies that show that decision aids such as videos result in higher levels of knowledge but have varying effects on the decisions themselves. They claim that at least 20 minutes are needed to provide accurate and understandable information. They also raise the problem of communicating risk to the public, arguing that ‘strong statements’ are needed to explain the uncertainties of the benefits of early detection and treatment of localized prostate cancer.
Screening is a popular service and there is a constant demand for more screening from patients, pressure groups, the media and clinicians. In the UK, there are only three national cancer screening programmes for breast cancer, cervical cancer, and for bowel cancer using faecal occult blood testing. Yet it is only worthwhile when there is an effective intervention or treatment that is more effective if delivered early on in the development of a disease condition. The national screening programmes for breast and cervical cancer highlight several issues about successful screening programmes in relation to the key principles outlined above. The first of these is whether there is evidence that it reduces mortality. Breast cancer is the largest cause of death in women aged under 65 and accounts for around 12,000 deaths each year (ONS 2009). A number of trials were established to assess the effectiveness of a breast screening programme. The Forrest report in 1986 concluded that there was a case for mammography screening for women aged 50–64 and in 2008 for women aged 47–73. The programme started in 1988, centrally funded and with national quality assurance mechanisms. However, the contribution of screening programmes to any reduction in mortality is constantly questioned. The age-standardized death rate from breast cancer has fallen dramatically from around 42 per 100,000 in 1990 to 27 per 100,000 in 2007. Some studies attribute this to the screening programme but as national coverage was not achieved until 1993 it is likely that the fall is due to improved treatment. An updated Cochrane review (Gøtzsche and Nielsen 2009) concluded there was little evidence from large randomized trials to support mammography programmes.
Screening is not a cost-free activity. There is a delicate balance between detecting all with the disease while protecting those without the disease from false alarms and unnecessary invasive procedures (see Table 10.1).
| Benefits | Disadvantages |
|---|---|
| Improved prognosis for some detected individuals | Over-treatment of insignificant or minor abnormalities, for example lumpectomy |
| Less radical treatment | Expensive |
| Reassurance for those with negative results | False reassurance for those with false-negative results Anxiety or unnecessary treatment for those with false-positive results Problems arising from the screening test itself |
The UK leaflet has the authoritative title ‘Breast screening: the facts’, which suggests the information can be trusted. An analysis of information given to women in six countries showed that the important harms of screening (over-diagnosis and over-treatment of healthy women) were not mentioned (Gøtzsche et al 2009).
A key principle of screening is that the costs of testing, diagnosis and treatment should be balanced in relation to expenditure on care as a whole. The breast cancer screening programme was estimated to cost £8638 per life saved when it was set up (Clarke and Fraser 1991). Professor Michael Baum, a key figure in the setting up of the breast screening programme, has called for it to be scrapped, arguing that far more attention should be given to more effective treatment for those showing symptoms (Baum 1999).
Particular emphasis is placed on achieving high uptake rates of screening. For example, general practices receive an incentive payment for cervical smears achieved for more than 80% of their eligible female population. Emphasis has been placed in the breast screening programme on systems that reduce the length of time that a woman has to wait for further tests or treatment (all urgent GP referrals should be seen within 14 days).
Another principle of screening is that the test should be socially and ethically acceptable and benefits should outweigh any physical or psychological harm that might arise from testing.
Chlamydia is a common but asymptomatic sexually transmitted infection (STI). Opportunistic screening for those less than 25 years of age is offered in the UK. Studies show (Pavlin et al 2006) the following barriers to uptake:
• ignorance and inaccurate information
• stigma arising from its association as an STI
• fear and anxiety about infertility
• anxiety about partner notification
• discomfort with sample collection.
What health promotion interventions might improve the wide-scale adoption of cervical screening?
• Targeting those never screened through careful checking of patient records and the Prior Notification List.
• Invitation telephone calls and counselling.
• Improving acceptability of the procedure through better health education information.
• More sensitivity to social and cultural factors.
• Opportunistic screening.
• Patient rewards and incentives.
• Letter from a celebrity.
It is apparent that achieving good coverage of a national screening programme depends on understanding the psychological factors that may influence attendance and ensuring the accessibility and acceptability of the programme itself. Certain groups – working-class women, lesbians and ethnic minorities – are much less likely to attend for either mammography or a smear test.
Immunization
Immunization has been a key strategy in the decline of infectious diseases over the last 100 years and one objective of the Alma Ata declaration (WHO 1978) was to immunize the populations of the world against the majority of infectious diseases. Vaccination works by introducing a small amount of the organism to stimulate the body’s immune system to produce antibodies against that disease, resulting in immunity. The aim is to protect the individual against serious disease and to protect the community as a whole (herd immunity) – when members of a community who are not immune to a disease are still protected from it provided sufficient numbers of people in that community are immune. Achieving a high degree of herd immunity (e.g. for measles, 90% of the population needs to be immunized, see http://www.immunisation.nhs.uk) means that unprotected individuals are less likely to encounter the disease, and therefore both immunized and unimmunized individuals are protected.
The success of vaccination programmes against a disease such as smallpox (declared eradicated by WHO) has meant that the introduction of other vaccinations such as influenza or meningitis has been less questioned. However, vaccines have been blamed for adverse health effects. For example, the whooping cough vaccine was linked to brain damage and in the late 1990s a major controversy arose in the UK over the MMR vaccine and a supposed link to autism and Crohn’s disease. Public confidence in vaccine safety dropped and MMR uptake fell to 55% in some parts of London (see www.hpa.org.uk).
This concern led to the highlighting of major ethical concerns about immunization programmes. In June 2003 a High Court judge ruled that two girls aged 4 and 10 should be given the MMR vaccination according to their father’s wishes and overruling their mother’s objections. The judge’s decision was not a move to compulsory vaccination but was made in the interest of the children, to which the separated parents could not agree.
Refusing polio vaccination is illegal in Belgium. Vaccination is a condition of school entry in the USA. In this way, individual freedom is curtailed to safeguard population health and all are exposed to the same risks and contribute to the herd immunity. Of course, the counter-argument is that if there are reasonable grounds for doubt about vaccine safety, individuals should have the right to make their own competent and informed judgement. The challenge for practitioners is how they can enable parents to make informed decisions. The linking of doctors’ payments to the number of children immunized may lead to a lack of trust by parents that any advice offered is disinterested.
There are many reasons in addition to current concerns about vaccine safety that explain why individuals may not be vaccinated and these are common to a range of diseases:
• low levels of knowledge about the disease, for example 17% of men who have sex with men do not know that hepatitis means inflammation of the liver and 25% do not know of the existence of a vaccine (Hickson et al 1999)
• low levels of perceived susceptibility
• lack of information about the vaccination process
• lack of understanding how general population risks apply to the individual.
Vaccination against the human papillomavirus (HPV) associated with cervical cancer and genital warts started in the UK in 2008. The vaccine is prophylactic and therefore given in pre-adolescence to girls aged 12 or 13 years. Initial studies of reaction to the programme reveal the main concern of young women to be the vaccination process itself. Those who refused to have their daughters vaccinated were mostly active refusers on the grounds of safety and efficacy (Stretch et al 2008).
Different approaches have been taken to facilitate vaccination uptake including:
• social marketing campaigns promoting vaccination
• health care environments that enable disclosure and full discussion of risk assessment
• use of peer educators.
Practitioners may find it challenging to negotiate the tension between meeting imposed targets and addressing clients’ worries which may have been fuelled by negative media coverage. Arguments about the need to achieve a certain level of herd immunity are unlikely to persuade individual parents.
The prevention of CHD and stroke
• CVD is responsible for almost 17 million deaths each year worldwide, and is a major cause of mortality. Nearly 80% of CVD diseases mortality occurs in developing countries.
• Heart and circulatory disease is the UK’s biggest killer, causing 39% of deaths in the UK.
• The death rate from CHD continues to fall significantly (for people less than 65 years, they have fallen by 45% in the last decade) but not as fast as in some countries (it fell by 49% in Denmark and 45% in Norway and Austria). Among developed countries only Finland and Ireland have higher death rates from CHD than the UK.
• There are over one million prescriptions of cholesterol-lowering drugs – statins – dispensed in England every month and these now cost the NHS more than any other class of drug with over £440 million spent in 2001 (an increase of £113 million since 2000).
• Around 40% of men and women have raised blood pressure. The Interheart study estimated that 22% of heart attacks in Western Europe were due to a history of high blood pressure.
• Mortality from CHD is around 60% higher in smokers. Exposure to second-hand smoke increases the risk of CHD by around 25%.
• Thirty per cent of CHD and 20% of stroke is estimated to be due to low fruit and vegetable consumption.
• Work stress, lack of social support depression and hostile personality are consistently associated with CHD.
• Sixty-three per cent of heart attacks in Western Europe are estimated to be due to abdominal obesity (a high waist to hip ratio).
Cardiovascular diseases, including CHD or ischaemic heart disease and cerebrovascular disease (stroke) and its precursors hypertension (high blood pressure) and angina, are common in the general population. CVD is the second most commonly reported longstanding illness in the UK (after musculoskeletal conditions) (ONS 2008). Registrations from the Quality and Outcomes Framework (QoF) of general practice suggests there are over 1.1 million men living with angina and around 970,000 who have had a heart attack. In 2006, nearly 28% of the UK population reported a cardiovascular condition.
CHD is the most common cause of premature death in the UK. It is often thought of as a disease of affluence – the result of a diet high in fat, excessive alcohol and executive stress. In fact, CHD, like most other diseases, is most common in deprived communities; death rates from CHD among unskilled men are three times higher than among professional men, due partly to higher smoking rates (Acheson 1998).
The National Service Framework (NSF) (DH 2000a) identifies three levels of prevention:
• reducing heart disease in the population as a whole, through reduction in the prevalence of risk factors
• prevention of CHD in high-risk patients in primary care
• secondary prevention to reduce the risk of subsequent cardiac problems in patients admitted to hospital with CHD.
Whilst there is recognition of the broader determinants of CHD, most interventions are underpinned by an individual behaviour change model of health promotion. There is an implicit assumption that it is lifestyle changes that will bring about a reduction in CHD, and the NSF CHD (DH 2000a) focuses specifically on smoking, physical activity and diet as modifiable risk factors.
As we have seen earlier, primary prevention can be developed in two ways: by using a whole population approach or through selective targeting of individuals deemed to be at higher risk. Large-scale studies in the mid-1990s looked at the effectiveness of routine screening and lifestyle advice in primary care consultations by practice nurses (British Family Heart Study, Wood et al (1994) and OXCHECK study) and concluded that such preventive checks were of little benefit. The NSF CHD requires that all practices have a systematic approach of identifying those at high risk using an appropriate protocol that would include smoking status, physical activity, body mass index, blood pressure, serum cholesterol and diabetes/plasma glucose. Those with high risk according to such indicators would then be offered tailored advice on how to reduce their risks.
In 2008, the government launched the NHS Health Check, a scheme described as ‘predict and prevent’, to screen everyone aged between 40 and 74 for vascular risk every 5 years.
