Factors Associated with Underreporting of Adverse Drug Reactions by Health Care Professionals: A Systematic Review Update

INTRODUCTION: Underreporting is a major limitation of the voluntary reporting system of adverse drug reactions (ADRs). A 2009 systematic review showed the knowledge and attitudes of health professionals were strongly related with underreporting of ADRs. OBJECTIVE: Our aim was to update our previous systematic review to determine factors (sociodemographic, knowledge and attitudes) associated with the underreporting of ADRs by healthcare professionals. METHODS: We searched the MEDLINE and EMBASE databases for studies published between 2007 and 2021 that met the following inclusion criteria: (1) published in English, French, Portuguese or Spanish; (2) involving health professionals; and (3) the goal was to evaluate factors associated with underreporting of ADRs through spontaneous reporting. RESULTS: Overall, 65 papers were included. While health professional sociodemographic characteristics did not influence underreporting, knowledge and attitudes continue to show a significant effect: (1) ignorance (only serious ADRs need to be reported) in 86.2%; (2) lethargy (procrastination, lack of interest, and other excuses) in 84.6%; (3) complacency (the belief that only well tolerated drugs are allowed on the market) in 46.2%; (4) diffidence (fear of appearing ridiculous for reporting merely suspected ADRs) in 44.6%; and (5) insecurity (it is nearly impossible to determine whether or not a drug is responsible for a specific adverse reaction) in 33.8%, and the absence of feedback in 9.2%. In this review, the non-obligation to reporting and confidentiality emerge as new reasons for underreporting. CONCLUSIONS: Attitudes regarding the reporting of adverse reactions continue to be the main determinants of underreporting. Even though these are potentially modifiable factors through educational interventions, minimal changes have been observed since 2009. CLINICAL TRIALS REGISTRATION: PROSPERO registration number CRD42021227944. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40264-023-01302-7.