Transversal, Multicentric Study for Early Detection of Drug Interactions in Older Hospitalized Patients Using on Line Software in Córdoba, Argentina

A drug interaction (DI) is the mutual action of two drugs in a way that they can increase their action, even to a toxic level, o reduce it to its minimum.

Adverse drug events (ADE) are an important health problem. In the book To Err Is Human: Building a Safer Health System its authors Kohn, Corrigan and Donaldson from the "Committee on Quality of Health Care in America, Institute of Medicine" (U.S.A.) expressed that 2 out of every 100 hospital admissions were due to ADE. That results in an average increase of U$D 4,700 extra for each admission or about to 2.8 million U$D annually for a 700-bed teaching hospital. In this study were only considered direct costs. No indirect costs were taken into account, like days out of work, rehabilitation, deaths, lost of quality of life, etc.

In 2003, in a cohort study done in people of Medicare elder than 65 years old, were detected 50.1 ADE / 1000 persons a year. Of that number of ADE 13.8 were considered preventable. In Switzerland 3.3 % of hospitalisations were considered due to ADE.

Among ADE, DI are a very important part of the problem. In Canada was demonstrated that certain drug associations were responsible of an increase in the number of hospital admissions. They would not have occurred if those prescriptions would have been properly controlled or never done. In Mexico 3.8 % of patients elder than 50 years old received prescriptions of drugs, which should be avoided according to their interaction. In hospital setting DI endanger even more health and people's life. In Spain was demonstrated a prevalence of clinical relevant DI of 3 % in hospitalized patients, and in Switzerland that percentage rose 11 %. This phenomenon increased in later years, in Rotterdam DI compromising lethal risk in patients elder than 70 years old, climb from 1.5 % in 1992 to 2.9 % in 2005. Drug interactions are directly proportional to: the number of administered drugs (> 2 drugs or > 4 ); the age of patients and the number of prescribing physicians.

Older persons, for its detriment in physical condition and the pathologies they suffer from, are prone to suffer DI when being prescribed with drugs or even herbal medicines. In Brazil ambulatory patients elder than 60 years old have 2.5 pathologies diagnosed and consume in average 1.3 to 2.3 drugs. During hospitalisation the number of prescribed drugs reach 9.9 to 13.6 per patient. In a survey done in six European countries the number of drugs consumed for each ambulatory patient was 7. In Argentina according to the Instituto Nacional de Estadísticas y Censos (INDEC) the number of citizens elder than 65 years old was 3,587,620 (9.89% total population). Unfortunately there is no other information about polypharmacy or prevalent pathologies in INDEC or other medical databases or national institutions web sites.