BACKGROUND:The original Medication Appropriateness Index was validated for elderly and polymedicated patients, both in hospital and outpatient contexts. However, no studies have applied this questionnaire in patients with multiple chronic conditions. The objective of this study is to assess the reliability of a modified Medication Appropriateness Index questionnaire in a population of patients with multiple chronic conditions. METHODS:We selected patients with multiple chronic conditions who were included in an integrated care project conducted at the Hospital Universitario Virgen del Rocío. To determine inter-observer reliability, each professional (internist or hospital pharmacy specialist) applied the questionnaire under the same conditions and with the same resources. To determine intra-observer reliability, each physician applied the tool at baseline and two months later. We measured inter- and intra-observer reliability using the kappa coefficient. The proportion of overall agreement was also determined. RESULTS:We obtained a weak overall kappa (k=0.38) for inter-observer reliability and moderate (k=0.52) and very good (k=0.84) values for intra-observer reliability of the internist and specialist in hospital pharmacy, respectively. The proportion of overall agreement is very high in all three situations: 96%, 98%, and 99%, respectively. CONCLUSIONS:Despite its limitations, the Medication Appropriateness Index questionnaire modified by our group can be used, as a reliable method, to assess the appropriateness of pharmacotherapy in patients with multiple chronic conditions.