Clinical meaning
Health screening programs systematically test asymptomatic individuals to identify disease in its early, treatable stages before symptoms develop. Effective screening programs must meet the Wilson-Jungner criteria: the condition must be an important health problem, there must be an accepted treatment, facilities for diagnosis and treatment must be available, there must be a recognizable latent or early stage, a suitable and acceptable test must exist, the natural history of the condition must be understood, there must be an agreed-upon policy on treatment, the cost of screening must be economically balanced, and screening should be a continuous process. Screening differs from diagnostic testing: screening tests asymptomatic populations to identify those who MAY have a disease (requires confirmation), while diagnostic testing evaluates symptomatic individuals or those with positive screening results to establish a definitive diagnosis. Screening test accuracy is measured by sensitivity (ability to correctly identify those WITH the disease — true positive rate) and specificity (ability to correctly identify those WITHOUT the disease — true negative rate). The practical nurse plays a key role in facilitating screening programs by educating patients on the importance of screening, assisting with specimen collection, scheduling follow-up, and reporting results.