Elsevier

Epilepsy & Behavior

Volume 62, September 2016, Pages 246-250
Epilepsy & Behavior

Depression correlates with quality of life in people with epilepsy independent of the measures used

https://doi.org/10.1016/j.yebeh.2016.07.020Get rights and content

Highlights

  • Relationship between depression and QoL in PWE is robust and true effect.

  • Atypical or subsyndromic forms of depression are as relevant as DSM-based depression in terms of impact on QoL.

  • It remains unclear whether treating depression would improve QoL in PWE.

Abstract

Purpose

A number of studies have suggested that depressed mood is one of the most important predictors of quality of life (QoL) in patients with epilepsy. However, the QoL measure used in previous studies was limited to the Quality of Life in Epilepsy (QOLIE) scales. It could be questioned whether correlation of QOLIE with measures of depression is influenced by the properties of the instruments used rather than being a valid effect. By using visual analogue scales, the current study aimed to clarify whether depression and QoL are truly correlated in patients with epilepsy.

Methods

Data from a sample of 261 outpatients with epilepsy attending the Epilepsy Clinics of the Atkinson Morley Outpatient Department, St George's Hospital in London, were analyzed. Patients were screened using the European Quality-of-Life scale (EQ-5D-3L) which includes an overall visual analogue score (EQ-VAS), the Emotional Thermometer (ET7), the Beck Depression inventory—II (BDI-II), the Hospital Anxiety and Depression scale (HADS), and the Major Depression inventory (MDI).

Results

Depression was found to significantly correlate with EQ-VAS score with r coefficient ranging from 0.42 to 0.51 and r2 coefficients ranging between 0.18 and 0.26. In addition, we identified patients who were depressed according to DSM-IV criteria (MD) and those with atypical forms of depression (AD). The EQ-5D-3L scores in these subjects compared with those without depression (ND) showed a different impact of AD and MD on QoL.

Conclusions

The relationship between depression and QoL in people with epilepsy has been demonstrated to be a robust and valid effect, not a result of potential bias of the specific measures used. However, the strength of the association is influenced by the individual instrument. Atypical or subsyndromic forms of depression are as relevant as DSM-based depression in terms of impact on QoL.

Introduction

Depression is the most frequently reported psychiatric comorbidity among patients with epilepsy. The lifetime prevalence rates range between 24% in community-based studies [1] and 50% in tertiary referral centers or surgery programs [2]. Reasons for such a close link are both biological and psychosocial [3]. In fact, on the one hand, epilepsy is a chronic disorder which brings about social discriminations, burden, and limitations [4]; on the other hand, neuroimaging and neurobiological studies are emphasizing the biological contribution to this association based on neuroanatomical and neurochemical principles [5]. This is further supported by epidemiological studies suggesting a bidirectional relationship between the two disorders, namely that depression does not always follow the onset of the epilepsy but it may also precede the onset of a seizure disorder [6], [7], suggesting an underlying common neurobiological background [8].

A number of studies pointed out that depression is the most important predictor of quality of life (QoL), perhaps even more than seizures themselves [9], [10], [11], [12]. In addition, depression has been shown to be associated with poor response of epilepsy to antiepileptic drugs (AEDs) [13], as well as poor outcome after epilepsy surgery [14]. So far, the effect of depression on QoL in patients with epilepsy has been demonstrated using the same QoL scale, namely Quality of Life in Epilepsy (QOLIE, either 89 or 31). Moreover, most of the studies have used the Beck Depression inventory (BDI) as a measure for depression and, only recently, the Hospital Anxiety and Depression scale (HADS). While the evidence to date shows a strong correlation between depression scores and QoL, it remains unclear whether this is a true effect or a function of potential biases associated with the specific scales used, namely QOLIE and Beck Depression inventory (BDI) or Hospital Anxiety and Depression scale (HADS).

This study aimed to examine the association between depression and QoL in patients with epilepsy using a different independently validated QoL instrument consisting of a visual analogue scale and four different validated measures of depression including a visual analogue scale-based instrument. The potentially different impact of different forms of depression, satisfying DSM-IV criteria and atypical forms or subsyndromic forms, on QoL was also examined.

Section snippets

Methods

This study included data collected as part of a service improvement project at the Outpatient Epilepsy Clinics, Atkinson Morley Neurosciences Centre, St George's Hospital in London. Over a ten-month period, as a routine, all patients with an established diagnosis of epilepsy according to ILAE criteria were given a number of questionnaires including those for mood and QoL. Patients with severe learning disabilities, gross cognitive abnormalities, or poor English language skills were excluded

Results

Our sample included 261 patients. Clinical and demographic characteristics are shown in Table 1. The EQ-VAS scores inversely correlated with all measures of depression with coefficients ranging between r =  0.509 (p < 0.001) for BDI-II and r =  0.420 (p < 0.001) for NDDI-E (Table 2). Adjusted linear regression scores and scatter plots are shown in Fig. 1.

Utilizing the MDI, 41 patients received a DSM-IV diagnosis of major depression (MD) while 90 had a positive screening with the NDDI-E. We, therefore,

Discussion

Our results confirm that QoL correlates with depression in patients with epilepsy irrespective of the instruments used to measure either QoL or depression including the use of visual analogue measures. This suggests that the correlation of depression with QoL is a valid effect and not a function of potential biases of the individual scales used. In fact, the EQ-VAS is a visual analogue scale and, by definition, neutral in terms of specific items that might have a strong correlation with

Disclosures

Alex J Mitchell holds the copyright on the revised Emotional Thermometers tool but has made it freely available (royalty-free) for noncommercial and clinical use. The remaining authors have no conflicts of interest. We confirm that we have read the journal's position on issues involved in ethical publication and affirm that this report is consistent with those guidelines.

Cited by (0)

View full text