Continuity of care, potentially inappropriate medication, and health care outcomes among the elderly: evidence from a longitudinal analysis in Taiwan.

Background: Better continuity of care (COC) is associated with improved health care outcomes, such as decreased hospitalization and emergency department visit. However, little is known about the effect of COC on potentially inappropriate medication.
Objectives: This study aimed to investigate the association between COC and the likelihood of receiving inappropriate medication, and to examine the existence of a mediating effect of inappropriate medication on the relationship between COC and health care outcomes and expenses.
Methods: A longitudinal analysis was conducted using claim data from 2004 to 2009 under universal health insurance in Taiwan. Participants aged 65 years and older were categorized into 3 equal tertiles by the distribution of COC scores. This study used a propensity score matching approach to assign subjects to 1 of 3 COC groups to increase the comparability among groups. Generalized estimating equations were used to examine the association between COC, potentially inappropriate medication, and health care outcomes and expenses.
Results: The results revealed that patients with the best COC were less likely to receive drugs that should be avoided [odd ratios (OR), 0.44; 95% confidence interval (CI), 0.43-0.45) or duplicated medication (OR, 0.22; 95% CI, 0.22-0.23) than those with the worst COC. The findings also indicated that potentially inappropriate medication was a partial mediator in the association between COC and health care outcomes and expenses.
Conclusion: Better COC is associated with fewer negative health care outcomes and lower expenses, partially through the reduction of potentially inappropriate medication. Improving COC deserves more attention in future health care reforms.