TY - JOUR T1 - Commentary JF - British Journal of General Practice JO - Br J Gen Pract SP - 130 LP - 130 DO - 10.3399/bjgp08X277122 VL - 58 IS - 547 AU - Paul Hodgkin Y1 - 2008/02/01 UR - http://bjgp.org/content/58/547/130.abstract N2 - The theological justification of general practice usually stresses personal continuing care and tri-partite diagnosis. In reality the main scientific basis for having generalists practising in the community is because gatekeeping is an effective way to increase the prevalence of serious disease in the population of patients whom hospital doctors see. Since a high prevalence of disease in a population ensures that the positive predictive value of signs and symptoms is increased, having effective gatekeepers turns out to make the diagnostic task of hospital doctors easier. And by the same token enables GPs to be much better at diagnosing normalcy — ‘I don't know what's wrong with you but it isn't serious’ is predicated on the fact that an absent sign or symptom has a high negative predictive value in low prevalence populations. Gatekeeping might have … ER -