If it ain't broke, don't fix it. Most diagnostic tests have good sensitivity (they pick up most cases of real disease) but relatively poor specificity (they pic

If it ain't broke, don't fix it. Most diagnostic tests have good sensitivity (they pick up most cases of real disease) but relatively poor specificity (they pick up lots of false positives). Actively looking for asymptomatic disease does identify some diseases earlier and improve outcomes for those patients, but it also subjects a large number of patients to expensive, inconvenient, painful and risky tests and treatment. The benefits to the former group are matched almost exactly by the harms to the latter group, so (with very few exceptions) just waiting for symptoms to emerge gives you the same net benefits at significantly lower cost.