Table 2 The WHO criteria help to distinguish between population-based screening and opportunistic case-finding

Condition

· The condition should be an important health problem.

· There should be a recognisable latent or early symptomatic stage.

· The natural history of the condition, including development from latent to declared disease should be adequately understood.

Test

· There should be a suitable test or examination.

· The test should be acceptable to the population.

Treatment

· There should be an accepted treatment for patients with recognised disease

Screening Program

· There should be an agreed policy on whom to treat as patients.

· Facilities for diagnosis and treatment should be available.

· The cost of case-findings (including diagnosis and treatment of patients diagnosed) should be economically balanced in relation to possible expenditure on medical care as a whole.

· Case-findings should be a continuing process and not a ‘once and for all’ project.