WHAT IS SCREENING?
There are three forms of prevention aimed at improving a nation’s health:
1 Primary prevention refers to the modification of risk factors (such as smoking,
diet, alcohol intake) before illness onset. The recently developed health promotion
campaigns are a form of primary prevention.
2 Secondary prevention refers to interventions aimed at detecting illness at an
asymptomatic stage of development so that its progression can be halted or retarded.
Screening is a form of secondary prevention.
3 Tertiary prevention refers to the rehabilitation of patients or treatment interventions
once an illness has manifested itself.Screening programmes (secondary prevention) take the form of health checks, such as
measuring weight, blood pressure, height (particularly in children), urine, carrying
out cervical smears and mammograms and offering genetic tests for illnesses such as
Huntington’s disease, some forms of breast cancer and cystic fibrosis. Until recently, two
broad types of screening were defined: opportunistic screening, which involves using the
time when a patient is involved with the medical services to measure aspects of their
health. For example, when seeing a patient for a sore throat the GP may decide to also
check their blood pressure, and population screening, which involves setting up services
specifically aimed at identifying problems. For example, current programmes involve
cervical screening and breast screening. Recently a new form of screening has emerged
in the form of self screening. For example, people are encouraged to practise breast and
testicular self-examination and it is now possible to buy over-the-counter kits to measure
blood pressure, cholesterol and blood sugar levels.
The aim of all screening programmes is to detect a problem at the asymptomatic
stage. This results in two outcomes. First, screening can discover a risk of the disease.
This is called primary screening. For example, cervical screening may detect precancer-
ous cells which place the individual at risk of cervical cancer, genetic screening for cystic
fibrosis would give the person an estimate of risk of producing children with cystic
fibrosis and cholesterol screening could place an individual at high risk of developing
coronary heart disease. Second, screening can detect the illness itself. This is called
secondary screening. For example, a mammogram may discover breast cancer, genetic
testing may discover the gene for Huntington’s disease and blood pressure assessment
may discover hypertension.THE HISTORY OF THE SCREENING ETHOS
Early screening programmes
Screening has increasingly become an important facet of biomedicine throughout the
twentieth century. The drive to detect an illness at an asymptomatic stage of its develop-
ment (secondary prevention) can be seen throughout both secondary and primary care
across the Western world. In 1900, Gould introduced the regular health examination in212 HEALTH PSYCHOLOGY