Changes in medication preceding out-of-hospital cardiac arrest where resuscitation was attempted

To describe recent changes in medication preceding out-of-hospital cardiac arrest (OHCA) where resuscitation was attempted.

OHCA victims were identified by the Swedish Cardiac Arrest Register and linked by means of their unique 10-digit personal identification numbers to the Prescribed Drug Register. We identified new claimed prescriptions during a 6-month period before the OHCA compared with those claimed in the period 12 to 18 months before. The 7-digit Anatomical Therapeutical Chemical codes of individual drugs were used. The study period was November 2007-January 2011.

OHCA victims with drugs were (1) older than those who did not claim any drugs in any period (70 ± 16 years vs. 54 ± 22 years, P < 0.001), (2) more often women (34% vs. 20%, P < 0.001), and (3) had more often a presumed cardiac etiology (67% vs. 54%, P < 0.001). The OHCA victims were less likely to have ventricular tachycardia/ventricular fibrillation as the first recorded rhythm (26% vs. 33%, P < 0.001) or to survive 1 month (9% vs. 17%, P < 0.0001). New prescriptions were claimed by 5122 (71%) of 7243 OHCA victims. The most frequently claimed new drugs were paracetamol (acetaminophen) 10.3%, furosemide 7.8%, and omeprazole 7.6%. Of drugs known or supposed to cause QT prolongation, ciprofloxacin was the most frequent (3.4%) altogether; 16% had a new claimed prescription of a drug included in the "qtdrugs.org" lists.

Most OHCA victims had new drugs prescribed within 6 months before the event but most often intended for diseases other than cardiac. No claims can be made as to the causality.