Medication adherence, utilization of healthcare services, and mortality of patients with epilepsy on opiate replacement therapy: A retrospective cohort study

Amber Askarieh; Ian Morrison; Kevin Ross; Colin McCowan; Keith Matthews; Brian Kidd; Craig A Heath

doi:10.1016/j.yebeh.2021.107829

Medication adherence, utilization of healthcare services, and mortality of patients with epilepsy on opiate replacement therapy: A retrospective cohort study

Epilepsy Behav. 2021 Apr:117:107829. doi: 10.1016/j.yebeh.2021.107829. Epub 2021 Feb 20.

Authors

Amber Askarieh¹, Ian Morrison², Kevin Ross³, Colin McCowan⁴, Keith Matthews⁵, Brian Kidd⁵, Craig A Heath⁶

Affiliations

¹ Department of Neurology, Institute of Neurological Sciences, Langlands Drive, Glasgow G51 4LB, UK. Electronic address: amber.askarieh@ggc.scot.nhs.uk.
² Department of Neurology, Ninewells Hospital, James Arrot Drive, Dundee DD2 1SG, UK.
³ Institute of Inflammation, Infection & Immunology, College of Medicine, Veterinary & Life Sciences, University of Glasgow, Sir Graeme Davies Building, 120 University Place, Glasgow G12 8TA, UK.
⁴ School of Medicine, University of St Andrews, N Haugh, St Andrew's KY16 9TF, UK.
⁵ Division of Molecular and Clinical Medicine, University of Dundee, Nethergate, Dundee DD1 4HN, UK.
⁶ Department of Neurology, Institute of Neurological Sciences, Langlands Drive, Glasgow G51 4LB, UK.

PMID: 33621811
DOI: 10.1016/j.yebeh.2021.107829

Abstract

Introduction: Substance misuse is not uncommonly recognized in people with epilepsy (PWE). Mortality is significantly greater in those with comorbid substance misuse, but it remains unclear whether epilepsy care and management contribute to this. This cohort study aimed to compare the rates of mortality in PWE receiving opiate replacement therapy (ORT) and PWE alone, as well as evaluate their medication adherence, levels of engagement with epilepsy services as currently delivered, and utilization of unscheduled hospital care.

Material and methods: A 5-year historical cohort for PWE was identified and manually validated using electronic patient records registered with NHS Tayside. Overall incidence rates for mortality and contact with emergency health care services were calculated for PWE receiving ORT and PWE alone. Engagement with outpatient epilepsy services was also noted. Adherence to antiepileptic drugs (AEDs) was expressed in terms of medication possession ratio (MPR).

Results: Of the 1297 PWE attending a tertiary care epilepsy service, 68 (5.3%) PWE were receiving ORT. The mortality rate was significantly greater in PWE on ORT in comparison to PWE only (7.4% vs 1.7 %; P < 0.05; relative risk of death: 4.34, 95% CI 1.19-15.7), as well as the incidence of emergency healthcare services contact being higher (24.5% vs 17.7%; P < 0.05; incidence rate ratio: 1.39, 95% CI: 1.12-1.71). Poor adherence to AEDs was also more common in PWE on ORT (28.4% vs 23.5%; P = 0.02), as well as failure to engage with elective outpatient services (8.4% vs 3.0%; P < 0.05; rate ratio 2.77, 95% CI: 1.86-4.1).

Conclusion: People with epilepsy on ORT are less likely to engage with elective epilepsy services as currently delivered or take AEDs as prescribed despite most of these patients having daily attendance at a community pharmacist. This may contribute to the significantly increased rates of mortality and unscheduled hospital care. Clinicians and policymakers should consider service redesign to meet the demands of this high-risk population in an attempt to reduce mortality and morbidity.

Keywords: Adherence; Antiepileptic drugs; Epilepsy; Methadone; Mortality; Opiate.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Anticonvulsants / therapeutic use
Cohort Studies
Epilepsy* / drug therapy
Humans
Medication Adherence
Opiate Substitution Treatment*
Retrospective Studies

Substances

Anticonvulsants