title: Co-Prescription of QT-Interval Prolonging Drugs: An Analysis in a Large Cohort of Geriatric Patients.
abstract: Drug-induced QT-interval prolongation is associated with occurrence of potentially fatal Torsades de Pointes arrhythmias (TdP). So far, data regarding the overall burden of QT-interval prolonging drugs (QT-drugs) in geriatric patients are limited.
  
  
  
  This study was performed to assess the individual burden of QT-interval prolonging drugs (QT-drugs) in geriatric polymedicated patients and to identify the most frequent and risky combinations of QT-drugs.
  
  
  
  In the discharge medication of geriatric patients between July 2009 and June 2013 from the Geriatrics in Bavaria-Database (GiB-DAT) (co)-prescriptions of QT-drugs were investigated. QT-drugs were classified according to a publicly available reference site (CredibleMeds®) as ALL-QT-drugs (associated with any QT-risk) or High-risk-QT-drugs (corresponding to QT-drugs with known risk of Torsades de Pointes according to CredibleMeds®) and in addition as SmPC-high-risk-QT-drugs (according to the German prescribing information (SmPC) contraindicated co-prescription with other QT-drugs).
  
  
  
  Of a cohort of 130,434 geriatric patients (mean age 81 years, 67% women), prescribed a median of 8 drugs, 76,594 patients (58.7%) received at least one ALL-QT-drug. Co-prescriptions of two or more ALL-QT-drugs were observed in 28,768 (22.1%) patients. Particularly risky co-prescriptions of High-risk-QT-drugs or SmPC-high-risk-QT-drugs with at least on further QT-drug occurred in 55.9% (N = 12,633) and 54.2% (N = 12,429) of these patients, respectively. Consideration of SmPCs (SmPC-high-risk-QT-drugs) allowed the identification of an additional 15% (N = 3,999) patients taking a risky combination that was not covered by the commonly used CredibleMeds® classification. Only 20 drug-drug combinations accounted for more than 90% of these potentially most dangerous co-prescriptions.
  
  
  
  In a geriatric study population co-prescriptions of two and more QT-drugs were common. A considerable proportion of QT-drugs with higher risk only could be detected by using more than one classification-system. Local adaption of international classifications can improve identification of patients at risk.
authors.affiliation: Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: Simone
authors.initials: S
authors.lastname: Schächtele
authors.affiliation: Geriatrics in Bavaria-Database (Geriatrie in Bayern-Datenbank, GiB-DAT), Nürnberg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Tümena
authors.affiliation: Geriatrics in Bavaria-Database (Geriatrie in Bayern-Datenbank, GiB-DAT), Nürnberg, Germany.|Geriatrics Center Erlangen, Waldkrankenhaus St. Marien gGmbH, Erlangen, Germany.
authors.forename: Karl-Günter
authors.initials: KG
authors.lastname: Gaßmann
authors.affiliation: Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: Martin F
authors.initials: MF
authors.lastname: Fromm
authors.affiliation: Institute of Experimental and Clinical Pharmacology and Toxicology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: Renke
authors.initials: R
authors.lastname: Maas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D004359:Drug Therapy, Combination / Q000009:adverse effects; D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology*; D005260:Female; D015577:Geriatric Assessment / Q000706:statistics & numerical data*; D006801:Humans; D008133:Long QT Syndrome / Q000139:chemically induced* / Q000453:epidemiology*; D008297:Male; D004364:Pharmaceutical Preparations / Q000145:classification*; D055656:Prescriptions / Q000706:statistics & numerical data*; D012306:Risk
chemical_list: D004364:Pharmaceutical Preparations