Optimizing elderly pharmacotherapy: polypharmacy vs. undertreatment. Are these two concepts related?

This study aimed to estimate the prevalence of polypharmacy and potential prescribing omissions (PPO) and their related factors in community-dwelling elderly patients and to examine any possible relationship between these two concepts. A cross-sectional study was carried out including patients 65 years of age or over living on the island of Lanzarote (Spain). Sociodemographic, clinical and functional variables were collected, together with full data on drug therapy. The percentage of patients receiving a parts per thousand yen5 medications (polypharmacy) and the percentage of patients receiving at least one PPO according to Screening Tool to Alert doctors to Right Treatment (START) criteria (underprescription) were the two primary endpoints. A total of 1844 medications were prescribed to the 407 patients included in our study. The overall prevalence of polypharmacy was 45 %. The risk factors associated with polypharmacy were comorbidity (OR 1.98, 95 % CI 1.63-2.44), limitations in activities of daily living (ADL; OR 3.0, 95 % CI 1.51-6.11), and being prescribed a drug in the Anatomical Therapeutic Chemical classification (ATC) C group (OR 7.92, 95 % CI 4.10-16.25) or in the N group (OR 3.80, 95 % CI 2.25-6.55). START criteria identified a total of 303 PPO in 170 (41.8 %) subjects. The risk of PPO increased by 60 % for every additional point in the Charlson Comorbidity Index (OR 1.60, 95 % CI 1.35-1.91). Polypharmacy also independently predicted the odds of at least one PPO according to START criteria (OR 2.19, 95 % CI 1.36-3.55). Our findings show high rates of polypharmacy and PPO, as well as a clear relationship between these two concepts.