The impact of polypharmacy and drug interactions among the elderly population in Western Sicily, Italy

Aim: Primary endpoint was to report polypharmacy distribution in the general population vs ≥65 years old people and to examine the frequency of drug–drug interactions (DDIs) in the Health Local Unit of Palermo, Italy, in relationship with patients’ age. Methods: Drug prescription data for the year 2014 were extracted from the database of the Local Health Unit of Palermo Province, Italy. Patients were divided into five age groups (0–13, 14–64, 65–69, 70–74, and ≥75 year old). The detection of potential DDIs in polypharmacy profiles was performed with NavFarma software (Infologic srl, Padova, Italia), with DDI classification provided by tool Micromedex Drug Reax (Truven Health Analitics, Michigan, USA). Results: We analyzed data of 1,324,641 patients, and 15,801,191 medical prescription were recorded; of these, 11,337,796 regarded chronic conditions. The drug prescriptions reached the highest values in the 65–69 and 70–74 age groups (p = 0.005 and p = 0.008 vs age 14–64 respectively). An overall amount of 6,094,373 DDIs were detected, of which 47,173 were contraindicated. Median number of DDIs was higher in 65–69 and 70–74 age groups (p = 0.008 and p = 0.012 vs age 14–64, respectively). Regarding contraindicated DDIs a significant difference was detected comparing 14–64 vs ≥65 age groups (p = 0.010 vs 65–69 group, p= 0.005 vs 70–74 group and ≥75 group). Conclusions: Polypharmacy is a phenomenon acquiring increasing dimensions also in our province. It interests particularly the older subjects, and assumes a dramatic accent when it is put in relationship with the frequency of DDIs. A proactive vigilance about potential life threatening drug interactions is mandatory.