Trends in polypharmacy over 12 years and changes in its social gradients in South Korea.

Polypharmacy is associated with adverse drug reactions and represents an economic burden on the health insurance system. The objective of our study was to assess the trends in polypharmacy and its associated factors in South Korea. This cross-sectional study used a nationwide sampled database between 2002 and 2013, including outpatients of all ages who received at least 1 prescription in the same period. Polypharmacy was defined as the concomitant prescription of ≥6 distinct medications on a single prescription at least once without a given duration. The yearly prescribing trends were calculated and plotted. We conducted comparative analyses to identify the changes in social gradients of polypharmacy between the first 2 years, 2002‒2003, and the final 2 years, 2012‒2013. We repeated logistic regressions for pediatrics