Subjects
We contacted over the phone all epilepsy patients who attended the outpatient clinic of the department of neurology at the University Medical Centre in Utrecht (UMCU), The Netherlands between January 2007 and September 2009. After consent, they were sent questionnaires. The UMCU is a secondary and tertiary referral centre for epilepsy, with epilepsy surgery facilities and a teaching hospital. Inclusion required a diagnosis of partial epilepsy, age between 16 and 80 years, an IQ higher than 80, a normal neurological examination and the ability to complete a Dutch questionnaire. Exclusion criteria were presence of a neurological deficit, e.g. due to stroke or malignancy in the patient. The local medical ethics committee approved this study.
Questionnaires
Two questionnaires were sent to the patients. One was completed by the patient and one by their main caregiver. Patients were asked to give the caregiver questionnaire to the person on whom they at times need to rely because of their epilepsy. If there was no such person, patients were asked to state this as well.
Data on age, gender, marital status, employment, seizure frequency, seizure type and side effects of treatment were obtained from the patient. From the caregiver, data were obtained on gender, relationship to the patient, whether he or she lives with the patient, number of hours per week given to patient care and if he or she received professional help in patient care. The HRQOL questionnaires of patients and caregivers consisted of two generic, validated questionnaires: the RAND-36 [9] and the EQ5D [10]. The RAND-36 consists of 36 questions providing HRQOL scores on the eight domains mental health, social functioning, vitality, role emotional, bodily pain, general health, physical functioning and role physical (minimum 0, optimum 100). These domains are expressed in two summary scores (range 0–100), reflecting the mental (MCS) and physical component scores of HRQOL. The EQ5D consists of two items: five questions giving a utility score (minimum 0, optimum 1) and a VAS score to express QOL on a range of 0–100%.
Coping style was measured using the Utrecht Coping List (UCL) [11], providing coping style profiles. This is a validated questionnaire that measures coping style for problems and unpleasant events in daily life. Subscores describe an individual tendency to seven coping strategies: passive reaction pattern, active confronting, palliative reaction, seeking social support, avoidance, expressing emotions and reassuring thoughts. The UCL is based on the premise that coping strategies are not exclusive and may be present in various combinations [11].
Analysis
Statistical analyses were performed using SPSSv15.0 (SPSS Inc., Chicago, USA). A retrospective powercalculation was done to assess the number of participants needed to reach power of 0.80 to find a statistically significant difference in mental component score of 4 or more, which is considered a minimal important difference in epilepsy patients [12]. A minimum of 35 participants would be needed for this power level.
Summary scores on the eight RAND-36 domains, the MCS (mental component score) and physical component score, were calculated [13]. The scores of both patients and caregivers were compared to the general Dutch population scores using a two-tailed independent sample t test [9]. EQ5D utility scores were calculated (British MVH A1 guidelines). Patient and caregiver scores were compared to scores from the Dutch population using a two-tailed independent sample t test [10]. Scores on the various coping styles were calculated and compared to the general Dutch population [11]. All population scores were matched according to age and sex.
The association of scores on RAND-36 domains, MCS, physical component score and coping style of patients to those of their caregivers was investigated using Pearson’s correlation co-efficient.
The Pearson correlation coefficient was used to investigate the association between coping styles of caregivers and their RAND-36 MCS and physical component scores. The coping style having the strongest association with MCS was studied in a multivariate regression analysis.
First, the association between MCS/PCS and caregiver characteristics (age, gender, relationship to patient, co-habiting, hours of care given to patient and receiving professional help in patient care) and epilepsy characteristics of the patient [duration of epilepsy, seizure frequency, number of anti-epileptic drugs (AED) and experiencing adverse side-effects], was studied by univariate regression analysis, selecting characteristics associated with a p value less than 0.20. To study independent effects of coping style and caregiver and epilepsy characteristics on HRQOL, all selected parameters, including the coping style with the strongest association to MCS were entered in a stepwise backwards multivariate linear regression analysis, with caregivers’ MCS/PCS as the dependent variable.