title: Prevalence of drug interactions in hospital healthcare.
abstract: OBJECTIVE
  To study the prevalence of drug interactions in hospital healthcare by reviewing literature.
  
  
  METHODS
  A review was carried out of studies written in Spanish and English on the prevalence of drug interactions in hospital care published in Pubmed between January 1990 and September 2008. The search strategy combined free text and MeSH terms, using the following keywords: "Drug interaction", "prevalence" and "hospital". For each article, we classified independent variables (pathology, age of population, whether patients were hospitalized or not, geographical location, etc.) and dependent variables (number of interactions per 100 patients studied, prevalence of patients with interactions, most common drug interactions, and others).
  
  
  RESULTS
  The search generated 436 articles. Finally, 47 articles were selected for the study, 3 provided results about drug interactions with real clinical consequences, 42 about potential interactions, and 2 described both. The prevalence of patients with interactions was between 15 and 45 % and the number of interactions per 100 patients was between 37 and 106, depending on the group of studies analyzed. There was a considerable increase in these rates in patients with heart diseases and elderly persons.
  
  
  CONCLUSIONS
  There is a large number of studies on the prevalence of drug interactions in hospitals but they report widely varying results. The prevalence is higher in patients with heart diseases and elderly people.
authors.affiliation: Servicio de Farmacia, Hospital Universitario Virgen del Rocío, Avda. Manuel Siurot s/n., 41013, Seville, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Espinosa-Bosch
authors.forename: Bernardo
authors.initials: B
authors.lastname: Santos-Ramos
authors.forename: María Victoria
authors.initials: MV
authors.lastname: Gil-Navarro
authors.forename: María Dolores
authors.initials: MD
authors.lastname: Santos-Rubio
authors.forename: Roberto
authors.initials: R
authors.lastname: Marín-Gil
authors.forename: Paloma
authors.initials: P
authors.lastname: Villacorta-Linaza
mesh_terms: D000367:Age Factors; D016303:Clinical Pharmacy Information Systems / Q000706:statistics & numerical data; D015897:Comorbidity; D004347:Drug Interactions; D064420:Drug-Related Side Effects and Adverse Reactions; D006801:Humans; D008508:Medication Errors / Q000706:statistics & numerical data; D010607:Pharmacy Service, Hospital / Q000706:statistics & numerical data; D019338:Polypharmacy; D012307:Risk Factors