Assessment of Underutilisation of Medication Two studies assessed under-use of medication using the Assessment of Underutilisation of Medication (AUM) index.25 30 Gallagher et al25 reported a greater reduction in the proportion of intervention group patients with prescribing omissions postintervention (by the AUM index) compared with the control group (absolute risk reduction 21.2%, 95% CI 13.3% to 29.1%). Schmader et al30 reported a reduction in the number of conditions with omitted drugs postintervention in the intervention group relative to the control group; the difference in change in AUM score was −0.3 (p