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How rare are adverse drug effects? Assessing the frequency of harm effects of drug treatments for the management of sciatica in primary care

Date and Location




Monday 23 September 2013 - 10:30 - 12:00


Presenting author and contact person

Presenting author

Daniela Junqueira

Contact person

Daniela Junqueira
Abstract text
Background: Adverse drug reactions (ADRs) are among leading causes of death in many countries and yet are often regarded as rare events. This misconception is usually a consequence of optimistic interpretations regarding their frequency. Moreover, even mild ADRs may be responsible for poor treatment adherence, the use of additional medication to control existing ADRs, can result in new ADRs and self-medication behaviours. Objectives: We aimed to investigate and classify the frequency of ADRs of drugs suggested to manage sciatica in accordance to standard categories by the World Health Organization - Uppsala Monitoring Centre (WHO-UMC) system. Methods: We assessed trials that detailed ADRs in a systematic review investigating the efficacy of drugs administered in primary care for the management of sciatica. The frequency of ADRs was classified according to WHO-UMC categories: very common when frequency >10%, common when >1% and <10%, uncommon when >0.1% and <1%, rare when >0.01% and <0.1%. ADRs were grouped according to MedDRA terminology and we present data on a subset of ADRs usually labelled of mild or moderate severity. Results: Nine studies provided data on the frequency of 34 unique ADRs. Frequencies of ADRs ranged from 7.1 to 71.4% (constipation), 1.1 to 22.2% (nausea), 0.6 to 13.3% (dyspepsia), 0.9 to 35.7% (dry mouth), 0.9 to 14.3% (headache), 0.9 to 25% (drowsiness), 4.7 to 20% (epigastric pain), and 0.6 to 7.1% (dizziness). Conclusions: In accordance to WHO-UMC system, ADRs associated to drugs administered to manage sciatica are common or very common effects. Therefore, the assumption that ADRs are rare events in the management of sciatica is underestimated. Reporting often influence our judgment regarding adverse outcomes with the intervention appearing more favourable than it should and systematic reviews need to improve methods to address safety parameters with more precision and accuracy. Reference: Pinto, RZ. et al. BMJ 2012;344:e497