Background & Aims: Efforts to reduce costs in health care may raise co
ncerns about underuse of medical procedures, This study prospectively
assessed underuse of upper gastrointestinal endoscopy in a cohort of p
atients in whom we have recently published data on overuse of endoscop
y. Methods: Underuse was identified by formal necessity criteria for e
ndoscopy, obtained by an explicit panel process. Outpatients were cons
ecutively included in two clinical settings. Setting A consisted of 20
primary care physicians and 7215 patient visits that occurred within
1 month. Setting B consisted of 920 visits that occurred during 3 week
s at an outpatient clinic. Results: During these 8135 visits, 611 pati
ents complained of upper digestive symptoms; 63 of them underwent endo
scopy. Underuse was identified in 72 patients (11.8%), The two clinica
l situations mainly responsible for underuse of endoscopy were uninves
tigated peptic symptoms resistant to treatment and dysphagia. At first
follow-up, 29 of the patients with initial underuse still fulfilled c
riteria of necessity (underuse rate, 4.7%). One-year follow-up showed
underuse of endoscopy in 5 patients. Conclusions:This prospective evid
ence shows that underuse of a medical procedure exists. The estimated
overuse and underuse of endoscopy in this cohort were approximately eq
ual (5%). improving quality of care will require reductions of both ov
eruse and underuse of medical procedures.