Registers complement notification of spontaneous adverse drug reactions

A retrospective study in Spain has obtained valuable information on severe and unknown adverse drug reactions (ADRs) from the Register of Patients and Treatments (RPT), indicating the value of such registers as tools that complement spontaneous ADR notifications.

The authors identified hospital outpatient treatment (HOT) interruptions due to unacceptable toxicity from the RPT between January 2014 and December 2017. They retrieved information regarding the demographic and clinical characteristics of patients, ADRs, and drug treatments from electronic health records.

Additionally, the Spanish Pharmacovigilance System algorithm was used to examine causality and previous knowledge of ADRs. Information on HOT risk management plans (RMPs) and their classification as inverted black triangle medicines was obtained from the European Medicines Agency (EMA).

Unacceptable toxicity led to the withdrawal of HOTs in 136 (1.5 percent) registries, which corresponded to 135 (1.7 percent) patients. A total of 51 HOTs (38.6 percent of those registered) were involved in 240 ADR/HOT pairs, of which 24 (47 percent) were additional monitoring medicines and 37 (72.5 percent) were EMA RMPs.

Lenalidomide (n=30; 12.5 percent) was the most frequent medicine involved in ADR (mainly neutropaenia, thrombocytopaenia, and bicytopaenia), followed by bevacizumab (n=19; 7.9 percent; mainly venous and pulmonary thromboembolism), and sunitinib (n=13; 5.4 percent; mainly thromboembolic events, diarrhoea, and worsening of chronic renal failure).

The most frequent ADRs were cytopaenia (n=40; 17.3 percent), asthenia (n=9; 3.9 percent), and neuropathy (n=6; 2.6 percent). All ADRs were severe, of which 10 (six patients) were poorly described or unknown and nine (five patients) were reported by spontaneous notification.