Quality of label information on qt-interval prolongation of medicinal products registered in the EU

Background: The summary of product characteristics (SPC) is the most important (indirect) source of information for healthcare providers (HCP) to gain information on QT prolonging properties of drugs. However, we have noticed that information regarding QT prolongation varies between different products, which may hamper the uptake of the information. Objective: To systematically assess the number of products reporting an impact on QT interval in the SPC, and the variation in nature of the observed QT prolonging effect described and recommendations given to the HCP. Methods: The SPCs of products centrally approved in Europe between 1.1.2006 and 1.5.2012 were screened. Of those mentioning 'QT', we examined in which sections of the SPC 'QT prolongation' was mentioned. The nature of the message on QT prolongation and the advice on cautionary measures related to QT prolongation was examined as well as the relation between both. Results: Of the 172 screened products, 44 products contained information on QT in the SPC. QT related issues were most commonly reported in section 4.4 (special warnings and precautions, 66 %) and section 4.8 (undesirable effects, 57 %). In almost half of the products, the main message was that either the drug prolongs the QT interval (18 %), or potentially prolongs the QT interval (20 %). The SPC contained a negative message (the drug does not prolong the QT interval) in 23 % and no clear positive or negative message on QT prolongation in 39 % of the SPCs. Sixty-two percent of the SPCs gave the advice to act with caution in patients with QT related risk factors (n = 25), and 16 % explained the association of QT prolongation with ventricular arrhythmias (n = 27). The advice on monitoring of patients was given in 34 % of the SPCs (n = 15). Products that were more likely to have QT-prolonging properties according to the SPC provided more information on QT prolongation in the SPC. Conclusion: We observed that products, that were more likely to have QT prolonging properties according to the SPC, provided more information on QT prolongation in the SPC. We advise the development of a more extensive guideline concerning reporting on QT prolonging in SPCs, in order to guide prescribers more clearly.