A total of 85 patients were recruited. Among them, 49 patients answered the QOLIE-31-P. Forty-eight patients were included in the final sample for the analysis of the QoL, while one subject was excluded due to excessive amounts of missing data. The lack of answers of the QOLIE-31-P questionnaire was produced because it is considerably longer than the other assessment tools and more restrictive because patients are not allowed to answer it in case of seizure in the last 4 h (or generalized clonic seizure in the last 24 h). Description of the diverse main demographic and clinical variables included in the study is shown in Table 1. The overall distribution of AED with the most frequent and the older generation treatments can be found in Supplementary Tables 1 and 2.
Table 1 Characteristics of the patients with epilepsy Analysis of GAD-7, NDDI-E, ESS, and clinical variables
The previous diagnosis of anxiety was significantly associated with the GAD-7 categorical (OR = 14.5 [2.1, 295.5], p = 0.020) and numerical scores (OR = 1.21 [1.09, 1.36], p < 0.001). The diagnosis of depression was significantly associated with the NDDI-E categorical (OR = 6.3 [1.2, 48.0], p = 0.043) and numerical scores (OR = 1.24 [1.08, 1.42], p = 0.002). The number of patients with diagnosis of anxiety and depression according to the GAD-7 and NDDI-E scores, respectively, is shown in Table 2, together with the description of the distribution of GAD-7 and NDDI-E scores.
Table 2 Scale scores of anxiety (GAD-7), depression (NDDI-E), somnolence (ESS), and quality of life (QOLIE-31-P) of the patients with epilepsy Regarding the relationship between the diagnosis of anxiety and depression and the types of epilepsy, no significant associations were found with either generalized epilepsy (10/85 = 11.8%) or tonic–clonic seizures (9/85 = 10.6%). The diagnosis of depression presented statistically significant association with focal epilepsy (47/85 = 55.3%; OR = 4.5 [1.3, 20.7], p = 0.029), particularly with focal impaired awareness seizures (13/85 = 15.3%; OR = 5.3 [1.5, 19.5], p = 0.011). The diagnosis of anxiety was significantly related to temporal lobe epilepsy (10/85 = 11.8%; OR = 4.3 [1.0, 18.1], p = 0.044). No statistically significant association was found between the types of epilepsy and seizure frequency.
Concerning the analysis of specific AED, the previous diagnosis of depression was significantly associated with the use of lacosamide (17/85 = 20%; OR = 4.6 [1.4, 15.4], p = 0.012). No significant associations were found with either between the previous diagnosis of anxiety and lacosamide or between the two most used drugs in our sample, which were lamotrigine (22/85 = 25.9%) and levetiracetam (27/85 = 31.8%), and anxiety or depression.
There was no statistically significant association between diagnosis of SAHS and ESS categorical (p = 0.993) and numerical scores (p = 0.658). The number of sleeping hours (p = 0.563 for categorical ESS, p = 0.288 for numerical ESS), sleep disturbance (p = 0.634 for categorical ESS, p = 0.937 for numerical ESS), waking up during the night (p = 0.501 for categorical ESS, p = 0.733 for numerical ESS), and problems to fall asleep (p = 0.539 for categorical ESS, p = 0.859 for numerical ESS) were not significantly associated with ESS. The distribution of the ESS scores and the number of patients with sleepiness according to the corresponding scores are shown in Table 2.
Univariate analysis of QOLIE-31-P
A statistically significant negative association was found between NDDI-E and the QOLIE-31-P total score and the QOLIE-31-P score from every subscale. The same results were found with GAD-7, except for the medication effects subscale. No significant associations were identified with the ESS.
QOLIE-31-P total and energy scores were significantly associated (negative association) with sleep disturbance, waking up during the night, and problems falling asleep. QOLIE-31-P mood and overall QoL scores were significantly associated (negative association) with sleep disturbance and problems to fall asleep. QOLIE-31-P daily activity score was significantly associated (negative association) with problems to fall asleep. Lower QOLIE-31-P seizure worry scores (higher worry) were significantly associated with waking up during the night.
Statistically significant lower scores (worse situation) were identified for female sex in QOLIE-31-P total, mood, daily activities, seizure worry, and overall QoL. Statistically significant positive relationship was observed between age and QOLIE-31-P medication effect score (better or higher scores with higher age). Drug-resistant epilepsy and the number of AED presented statistically significant lower QOLIE-31-P total, mood, cognition (only drug-resistant epilepsy), and medication effect scores (worse scores for every case). Regarding the diverse types of epilepsy, temporal lobe epilepsy was associated with lower QOLIE-31-P total and seizure worry scores (worse scores for both scales).
With respect to the assessment of the QOLIE-31-P scores and the presence of at least one epileptic seizure per month, lower overall QoL subscale scores were associated with the presence of monthly epileptic seizures (β = − 11.1, p = 0.049). No significant associations were found for the remaining subscales or the final QOLIE-31-P score.
Results from the univariate models are shown in Fig. 1 and Supplementary Tables 3–10. The description of the distribution of each QOLIE-31-P score is shown in Table 2.
Multivariate analysis of QOLIE-31-P
The final model included GAD-7 score, NDDI-E score, the number of sleeping hours, problems to fall asleep, drug-resistant epilepsy, and sex as covariates. Four of these variables showed statistically significant negative association after correction for multiple comparisons. These variables were the GAD-7 numerical score (β = − 1.21, adjusted p = 0.006), the NDDI-E numerical score (β = − 1.42, adjusted p = 0.006), drug-resistant epilepsy (β = − 8.08, adjusted p = 0.045), and female sex (β = − 7.83, adjusted p = 0.034). The interpretation of the GAD-7 and NDDI-E results is that, for each additional point, the QOLIE-31-P total score is 1.21 and 1.42 points lower (worse QoL), respectively. The interpretation of the other two coefficients is that patients with drug-resistant epilepsy and women present 8.08 and 7.83 less QOLIE-31-P points than patients with less than two AED and men. The complete results are shown in Table 3.
Table 3 QOLIE-31-P total score model adjusted for multiple covariates With respect to the QOLIE-31-P subscale scores, GAD-7 was significantly associated with lower or worse energy (β = − 1.96, adjusted p = 0.006), mood (β = − 3.27, adjusted p < 0.001), daily activities (β = − 1.93, adjusted p = 0.020), and seizure worry (β = − 2.54, adjusted p < 0.001) scores. NDDI-E showed a statistically significant association with lower energy (β = − 1.97, adjusted p = 0.025), daily activities (β = − 2.61, adjusted p = 0.018), medication effects (β = − 1.79, adjusted p = 0.038), and overall QoL (β = − 1.89, adjusted p < 0.001) scores, which reflect worse situation in relation to higher levels of depression in each scale. Sleep disturbance was significantly associated with lower energy (β = − 14.77, adjusted p = 0.025) and mood (β = − 12.40, adjusted p = 0.027) scores. Lower QOLIE-31-P scores (worse QoL) were also found in the following associations: seizure frequency and mood score (β = − 2.46, adjusted p = 0.023), drug-resistant epilepsy and medication effects score (β = − 16.93, adjusted p = 0.038), problems to fall asleep and overall QoL score (β = − 11.64, adjusted p = 0.022), female sex and seizure worry (β = − 21.29, adjusted p = 0.005), and overall QoL (β = − 8.52, adjusted p = 0.049) scores. In contrast, statistically significant associations with higher scores (better QoL) were found between age and medication effects score (β = 0.61, adjusted p = 0.024) and between duration of epilepsy history and energy score (β = 0.41, adjusted p = 0.041). Generalized epilepsy was associated with lower daily activity score (β = − 20.31, adjusted p = 0.041), while focal epilepsy was related to higher energy score (β = 13.23, adjusted p = 0.028). The use of lacosamide was associated with higher energy score (β = 16.62, adjusted p = 0.036). Regarding the QOLIE-31-P cognition score, no model with multiple covariates presented significant results.
The significance for the QOLIE-31-P total and the subscale scores are shown in Fig. 1. The results from the models adjusted for multiple covariates, except the QOLIE-31-P total and cognition scores, are shown in Supplementary Tables 11–16.