screeningtests

ScreeningTests

Screening tests are evaluations conducted in asymptomatic individuals or populations to identify those who may have a disease or be at increased risk, enabling earlier diagnostic workup or preventive action. A screening test is not conclusive; positive results require confirmatory testing and follow-up, while negative results do not guarantee absence of disease.

Screening tests span multiple modalities, including imaging, laboratory assays, and genetic testing. Common examples include mammography for breast cancer, low-dose CT for lung cancer in high‑risk smokers, stool-based tests and colonoscopy for colorectal cancer, Pap smears and HPV testing for cervical cancer, newborn metabolic and genetic screens, and lipid or blood pressure assessments for cardiovascular risk. Genetic screening may assess risk for inherited conditions, with interpretation often influenced by penetrance and family history.

Guidelines for screening consider disease prevalence, test sensitivity and specificity, potential benefits, harms from false positives or overdiagnosis, cost-effectiveness, and resource availability. Programs may target specific age groups or risk populations and specify recommended intervals and follow-up pathways. Informed consent and privacy considerations are important in genetic or disclosing risk information.

Performance metrics include sensitivity (ability to detect disease), specificity (ability to exclude disease), positive and negative predictive values, and likelihood ratios. Limitations include false positives leading to unnecessary procedures, false negatives giving false reassurance, and the possibility of overdiagnosis or incidental findings.