Limitations
Limitations still exist and cautions should be taken when interpreting these results. Firstly, Beers Criteria contains some medications that are not currently available on Chinese market, and vice versa; racial difference attributable to enzyme system may result in a change in drug dosage limitations, or even influence the effectiveness of certain drugs. Secondly, non-prescription medications such as over-the-counter drugs or drugs independently purchased by patients from other sources could not be accounted for in the data, which might lead to an underestimation of PIM. Thirdly, the Beers criteria do not include an evaluation of potentially prescribing omissions (PPOs) where safer or more effective alternatives are recommended. PPO is also a crucial issue that should be evaluated simultaneously with PIM when investigating the present prescribing manners.