Introduction
Functional neurological disorder (FND) represents genuine and involuntary neurological symptoms and signs that have characteristic clinical features and represent a problem of voluntary control and perception despite the normal basic structure of the nervous system.1 Manifestations of FND are varied, such as decreased or increased movement, loss of sensation, difficulties in speech, abnormal gait or posture, cognitive symptoms and seizure-like episodes (functional seizures (FS)).1 FND can have a significant impact on the sufferer’s quality of life.2 Patients often present with comorbid psychiatric conditions, with both depression and anxiety occurring in up to 40% of patients with FND.3 4
The FND of movement and sensation has a prevalence of roughly 50 per 100 000 population and an incidence of 4–12 per 100 000 population per year. FS contributes a further 1.5–4.9 per 100 000 population per year, with a prevalence of 2–33 per 100 000 population.5 Patients with FND make up 9% of neurology admissions6 and 16% of neurology clinic referrals.7 Delayed diagnoses of FND lead to worse outcomes for patients,3 as well as preventable costs, such as missed work, general practitioner (GP) and specialist appointments, and investigations. Diagnostic uncertainty in the midst of ongoing symptoms can lead to intangible costs, such as decreased quality of life (QOL). These costs carry a burden on patients, clinicians, healthcare systems and the economy.
The costs of FND (and other medical conditions) can be separated into direct and indirect costs. Direct costs represent resources used for healthcare (eg, the cost of investigations and time spent on assessments by a doctor), as well as out-of-pocket costs to the patient. Indirect costs represent productivity losses arising from morbidity-related sickness absence (eg, loss of employment and cost of childcare while hospitalised). Direct and indirect costs together constitute the economic burden of FND, which can be estimated by measuring the monetary valuation of healthcare utilisation and lost productivity in patient samples.
The literature concerning the economic cost of FND is sparse, and any conclusions that may be drawn from it are limited by the heterogeneity of the studies that focus on the topic. Studies vary in the costs included in their analysis, with many focusing only on hospital costs.8 However, Stephen et al’s comprehensive study highlights that people with FND accrue similar costs to those with refractory epilepsy and demyelinating disorders. The cost of FND alone was estimated to be $1.2 billion annually in the USA in 2017,9 and these costs appear to depend on the patient’s satisfaction with the explanation of their diagnosis.10 In Denmark, Jennum et al showed a nearly tenfold increase in combined direct and indirect costs in FS patients compared with healthy controls.11
Studies that assessed indirect costs reported these costs as being higher than the direct medical costs resulting from the disorder.8 It has been found that patients with FND are more likely not to be working for health reasons and to be receiving disability-related state financial benefits than patients with other neurological disorders.12 No study has yet assessed whether symptom severity and/or duration impact the economic cost of FND.
In this study, we set out to evaluate the direct and indirect costs associated with FND through a retrospective questionnaire-based assessment of people referred to a tertiary FND specialist assessment clinic.