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

Article type
Authors
Junqueira DRG1, Ferreira ML2, Pinto RZ2, Cândido RCF3, Ferreira PH4
1Centro de Estudos do Medicamento, Universidade Federal de Minas Gerais, Brazil; Faculty of Health Science, The University of Sydney, Australia
2George Institute for Global Health, University of Sydney, Australia
3Centro de Estudos do Medicamento, Universidade Federal de Minas Gerais, Brazil
4Discipline of Physiotherapy, Faculty of Health Sciences, University of Sydney, Australia
Abstract
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.