Unplanned medication discontinuation as a potential pharmacovigilance signal: a nested young person cohort study

Angela Peichen Sun,Bradley Kirby,Marion Bennie,Corri Black,Peter John Helms,James Stuart Mclay

doi:10.1186/2050-6511-15-11

Abstract

BackgroundBecause of relatively small treatment numbers together with low adverse drug reaction (ADR) reporting rates the timely identification of ADRs affecting children and young people is problematic. The primary objective of this study was to assess the utility of unplanned medication discontinuation as a signal for possible ADRs in children and young people.MethodsUsing orlistat as an exemplar, all orlistat prescriptions issued to patients up to 18 years of age together with patient characteristics, prescription duration, co-prescribed medicines and recorded clinical (Read) codes were identified from the Primary Care Informatics Unit database between 1st Jan 2006-30th Nov 2009. Binary logistic regression was used to assess association between characteristics and discontinuation.ResultsDuring the study period, 79 patients were prescribed orlistat (81% female, median age 17 years). Unplanned medication discontinuation rates for orlistat were 52% and 77% at 1 and 3-months. Almost 20% of patients were co-prescribed an anti-depressant. One month unplanned medication discontinuation was significantly lower in the least deprived group (SIMD 1–2 compared to SIMD 9–10 OR 0.09 (95% CI0.01 – 0.83)) and those co-prescribed at least one other medication. At 3 months, discontinuation was higher in young people (≥17 yr versus, OR 3.07 (95% CI1.03 – 9.14)). Read codes were recorded for digestive, respiratory and urinary symptoms around the time of discontinuation for 24% of patients. Urinary retention was reported for 7.6% of patients.ConclusionsIdentification of unplanned medication discontinuation using large primary care datasets may be a useful tool for pharmacovigilance signal generation and detection of potential ADRs in children and young people.

Highlights

Because of relatively small treatment numbers together with low adverse drug reaction (ADR) reporting rates the timely identification of ADRs affecting children and young people is problematic
Of the 79 children and young people prescribed orlistat, only 54 (68.3%) had a Body mass index (BMI) recorded, of which 42 (53.2%) had a BMI measured within 1 year, and 28 (35.4%) within one month of orlistat initiation
We demonstrate that using Unplanned medication discontinuation (UMD) as a surrogate for possible adverse events, routinely collected primary care datasets may be used for pharmacovigilance signal generation, validation of generated signals and confirmation of potential ADRs will require appropriately designed prospective studies

Summary

Introduction

Because of relatively small treatment numbers together with low adverse drug reaction (ADR) reporting rates the timely identification of ADRs affecting children and young people is problematic. Adverse drug reactions (ADR) represent a major source of morbidity and mortality in adults, the nature and frequency of ADRs affecting children and young people remains poorly defined. Post-marketing surveillance requires the monitoring of large patient cohorts exposed to a medication to detect ADRs. Currently, pharmacovigilance systems rely primarily on spontaneous reporting of ADRs. under-reporting of ADRs is a significant issue affecting all European ADR monitoring systems. Despite extending spontaneous ADR reporting in the UK to the public, and a wider group of healthcare professionals, public reporting rates still remain low, and significantly lower for children and young people than adults [16]

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