FULL-LENGTH ORIGINAL RESEARCH

Epilepsy surgery and meaningful improvements in quality of life: Results from a randomized controlled trial *†‡Kirsten M. Fiest, *‡§Tolulope T. Sajobi, and *†‡§Samuel Wiebe Epilepsia, **(*):1–7, 2014 doi: 10.1111/epi.12625

SUMMARY

Dr. Kirsten M. Fiest is a postdoctoral fellow at the University of Calgary.

Objective: We examine improvement and worsening in quality of life (QOL) in terms of proportions achieving minimum clinically important change (MCID), and factors related to MCID, in patients with temporal lobe epilepsy randomized to medical or surgical treatment. Methods: Eighty patients with temporal lobe epilepsy randomized to surgical (n1 = 40) or medical (n2 = 40) therapy were followed for 12 months, reporting QOL at baseline, and at 6 and 12 months. Previously established thresholds for MCID across various general and epilepsy-specific QOL instruments were used to determine meaningful improvement (positive MCID) or worsening (negative MCID). Generalized linear mixed-effects models were used to compare MCID in both groups. Results: At 6 months, 56.0% of patients in the surgical group achieved positive MCID on the Quality of Life in Epilepsy (QOLIE)-89, as compared to 11.0% of those in the medical group (p < 0.001). On the QOLIE-31, 62.0% of the surgical group and 17.0% of the medical group achieved positive MCID (p < 0.001). Substantially more medically treated patients exhibited clinically significant worsening in QOL, as compared with those surgically treated. The respective medical versus surgical proportions with worsening were 36.67% versus 13.8% in QOLIE31, 20% versus 15% in Health Utility Index-III (HUI-III), and 30% versus 19% in Short Form-36 (SF-36) Mental Composite Score (MCS). The number of patients who need to undergo surgery for one additional person to have a meaningful improvement in the QOLIE-31 is two (number needed to treat = 2). The results also favored surgery using the generic HUI-III instrument, but not with the mental of physical function subscales of the SF-36. Significance: Significantly more patients in the surgical group achieved meaningful improvement in epilepsy-specific measures of QOL at 6 and 12 months compared to those in the medical group. Substantially more patients in the medical therapy group exhibited clinically significant worsening in their QOL assessed with epilepsy-specific and generic instruments. KEY WORDS: Quality of life, Randomized controlled trial, Clinically important difference, Epilepsy surgery.

Accepted March 7, 2014. *Department of Community Health Sciences and Institute for Public Health, University of Calgary, Calgary, Alberta, Canada; †Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada; ‡Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada; and §Clinical Research Unit, University of Calgary, Calgary, Alberta, Canada Statistical Analysis was completed by KM Fiest & TT Sajobi, University of Calgary, Calgary, AB, T2N 4N1. Address correspondence to Kirsten M. Fiest, Department of Community Health Sciences, 3rd Floor TRW Building, 3280 Hospital Drive NW, Calgary, AB T2N4Z6, Canada. E-mail: [email protected]

The efficacy of temporal lobe epilepsy (TLE) surgery in controlling seizures has been demonstrated in two randomized controlled trials (RCTs) of patients with chronic drugresistant epilepsy at 1 year (64% seizure-free),1 as well as in those with recent onset of drug-resistant epilepsy at 2 years (73% seizure-free).2 In these patients, the number needed to treat with surgery for one patient to become seizure-free ranges from 1.4 to 2.0. The results of these RCTs are comparable to those of nonrandomized cohort studies,3,4 and are homogeneous across geographic regions and over time.

Wiley Periodicals, Inc. © 2014 International League Against Epilepsy

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2 K. M. Fiest et al. Moreover, although the proportion of patients remaining seizure-free declines by about 10% after 5–10 years, the benefits are robust and long lasting.5 On the other hand, 30–40% of patients undergoing left-sided TLE surgery experience reliable declines in two important functions: verbal memory and naming ability.6 This underscores the importance of considering risk–benefit trade-offs in epilepsy surgery outcomes and therefore the effect on quality of life (QOL). In a longitudinal cohort that assessed QOL 5 years after epilepsy surgery, Langfitt et al.7 demonstrated that despite reliable declines in memory function after surgery, patients who became seizure-free demonstrated improvements in QOL that were of the same magnitude as those in patients who became seizure-free and had no decline in memory function. In contrast, patients who were not seizure-free had no improvement in QOL even if memory was intact. Seizure freedom, cognitive outcomes, and QOL are closely intertwined. A systematic review of QOL outcomes after epilepsy surgery found that >90% of studies reported significant improvements in various QOL domains, most often those that assessed epilepsy-specific aspects. However, every published study reports grouped data, that is, mean scores of QOL for a group. Glaringly absent is a description of which patients, and how many, experience meaningful improvements or declines in QOL. Reporting QOL at the group level conveys no information about how many individuals experience this change—group changes that do not achieve statistical significant may be erroneously discounted. Guyatt and colleagues8 demonstrated that small group mean changes can conceal clinically important treatment effects and that large mean changes can be accounted for by a small number of patients experiencing change. The minimum clinically important difference (MCID) is the amount of change in QOL that a patient considers important, measured by QOL instruments.9–12 Using MCID allows for the assessment of change in individual patients, instead of aggregate group data, and requires knowing the thresholds in specific QOL instrument scores that signify an MCID. We examine the proportion of patients participating in an RCT of surgical versus medical therapy1 who achieved positive and negative MCID, adjusting for factors known to influence QOL.

excluded if they had a progressive central nervous system disorder or brain lesions that required urgent surgery, active psychosis, psychogenic seizures, a full-scale intelligent quotient (IQ)

Epilepsy surgery and meaningful improvements in quality of life: results from a randomized controlled trial.

We examine improvement and worsening in quality of life (QOL) in terms of proportions achieving minimum clinically important change (MCID), and factor...
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