Sleepiness in Narcolepsy

Circadian rhythm of daytime sleepiness in pediatric narcolepsy: A pilot study

BACKGROUND AND OBJECTIVE

Excessive daytime sleepiness (EDS) has been far back reported as the most disabling symptom in the pediatric narcoleptic patients. However, there is a lack of studies to examine the circadian rhythms of EDS in pediatric narcoleptic population. Therefore, we aim to investigate the circadian rhythm of EDS in pediatric narcolepsy patients.

METHODS

We identified 50 pediatric narcoleptic patients (36 males and 14 females, mean age 13.68 ± 2.75 years). Data were collected through interviews and the relevant questionnaires (children depression inventory [CDI] and the pediatric quality of life inventory [PedsQL]).

RESULT

The frequencies of sleep attacks during different intervals of the day differed significantly, with higher frequency in the morning (p < .001). The times of sleep attacks in the morning and in the afternoon were significantly associated with the degree of impairment on class and the severity of worry about sleepiness, with spearman correlation coefficient ranging from .289 to .496 (p < .05). The total scores of PedsQL and CDI differed significantly among morning sleepiness dominant, afternoon sleepiness dominant, and evening sleepiness dominant groups (p = .042, p = .040). The severity scores of the narcoleptic patients' sleepiness had two peaks, one of which occurred at 16:00, and the other peaks occurred at about 11:00.

CONCLUSION

These results suggest that changes based on the circadian rhythm of sleepiness of the pediatric narcoleptic patients should be made in the treatment strategy. In addition, regulating the secretion of melatonin could serve as a promising treatment to relieve sleepiness in the future.

The Impact of Symptom Severity on Health-Related Quality of Life in People with Narcolepsy Type 1

OBJECTIVE

To assess the impact of symptom severity on health-related quality of life (HRQoL) in people with narcolepsy type 1 (NT1).

METHODS

A total of 174 people with NT1 were enrolled. They completed the Narcolepsy Severity Scale (NSS) and EQ-5D-3L consisting of five dimensions (EQ-5D utility values) and a visual analog scale (EQ-5D VAS). The relationship between severity of symptoms and HRQoL dimensions was evaluated by Pearson correlation analyses. Logistic regression was used to identify significant predictors of HRQoL. Nomogram was established based on results of independent predictors of factors on logistic regression analyses.

RESULTS

The mean score for NSS, EQ-5D utility values, and EQ-5D VAS were 29.8 (10.08), 0.78 (0.09), and 64.30 (19.84) in people with NT1, respectively. NSS score showed a significant correlation with self-care (r = 0.157, p < .05), usual activities (r = 0.236, p < .01), pain/discomfort (r = 0.174, p < .05), anxiety/depression (r = 0.2, p < .01), and EQ-5D utility values (r = -.261, p < .01). EDS (excessive daytime sleep), cataplexy, hallucinations, paralysis, and disrupted nocturnal sleep (DNS) were significantly associated to EQ-5D VAS (r ranged from -0.154 to -0.354, p < .05). EDS (OR = -0.297) and DNS (OR = -0.16) were predictors of HRQoL. NSS score (OR = -0.360) and treatment (OR = 0.215) were predictors of the metrics of HRQoL. The C-indices of the nomogram were 0.726.

CONCLUSION

The severity of symptoms could disrupt self-care and usual activities, and increase pain/discomfort and anxiety/depression. HRQoL might be improved by alleviating symptom severity.

Evaluation of psychometric properties of patient-reported outcome measures frequently used in narcolepsy randomized controlled trials: a systematic review

Study Objectives

To systematically determine subjective and objective outcome measures used to measure the efficacy of narcolepsy interventions in randomized controlled trials (RCTs) in adults and children and assess psychometric properties of patient-reported outcome measures (PROMs) used.

Methods

We searched bibliographical databases and clinical trial registries for narcolepsy RCTs and extracted objective and subjective outcome measures. If PROMs were used, we searched for psychometric studies conducted in a narcolepsy population using bibliographical databases and appraised using Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) guidelines.

Results

In total, 80 different outcome measures were used across 100 RCTs. Epworth Sleepiness Scale (ESS) (n = 49) and Maintenance of Wakefulness Test (n = 47) were the most frequently used outcome measures. We found 19 validation studies of 10 PROMs in narcolepsy populations. There was limited evidence for validity or responsiveness of the ESS; yet sufficient reliability (pooled ICC: 0.81–0.87). Narcolepsy Severity Scale (NSS) had sufficient reliability (pooled ICC: 0.71–0.92) and both adult and pediatric versions had sufficient discriminant validity (treated/untreated). Content validity was only evaluated in pediatric populations for ESS-CHAD and NSS-P and rated inconclusive. Quality of evidence of the psychometric studies for all scales ranged from very low to low.

Conclusions

Although recognized by regulatory bodies and widely used as primary outcome measures in trials, there is surprisingly little evidence for the validity, reliability, and responsiveness of PROMs frequently used to assess treatment efficacy in narcolepsy. The field needs to establish patient-centered minimal clinically important differences for the PROMs used in these trials.

Lipocalin-type prostaglandin D synthase levels increase in patients with narcolepsy and idiopathic hypersomnia

STUDY OBJECTIVES

Excessive daytime sleepiness (EDS) is a frequent cause for consultation and a defining symptom of narcolepsy and idiopathic hypersomnia (IH). The associated mechanisms remain unclear. Lipocalin-type prostaglandin D synthase (LPGDS) is a plausible sleep-inducing candidate. This study is to compare cerebral spinal fluid (CSF) and serum LPGDS levels in patients group with hypersomnia of central origin, including those with narcolepsy type 1 (NT1) and type 2 (NT2) and IH, to those in healthy controls (Con).

METHODS

Serum LPGDS, CSF LPGDS, and CSF hypocretin-1(Hcrt-1) levels were measured by ELISA in 122 narcolepsy patients (106 NT1 and 16 NT2), 27 IH, and 51Con.

RESULTS

LPGDS levels in CSF (p = 0.02) and serum (p < 0.001) were 22%-25% lower in control subjects than in patients with EDS complaints, including NT1, NT2, and IH. In contrast to significant differences in CSF Hcrt-1 levels, CSF L-PGDS levels and serum L-PGDS were comparable among NT1, NT2, and IH (p > 0.05), except for slightly lower serum LPGDS in IH than in NT1 (p = 0.01). Serum L-PGDS correlated modestly and negatively to sleep latency on MSLT (r = -0.227, p = 0.007) in hypersomnia subjects.

CONCLUSIONS

As a somnogen-producing enzyme, CSF/serum LPGDS may serve as a new biomarker for EDS of central origin and imply a common pathogenetic association, but would complement rather than replaces orexin markers.

Reliability and validity of the Chinese version of Narcolepsy Severity Scale in adult patients with narcolepsy type 1

OBJECTIVE

To evaluate reliability and validity of the Chinese version of Narcolepsy Severity Scale (NSS) in adult patients with narcolepsy type 1 (NT1).

METHODS

One hundred and fifty-one adult patients (≥18 years) with NT1 were recruited. All filled out the 15-item Chinese version of NSS. Item analysis included critical ratio and correlation analysis. The validity of NSS was assessed by exploratory factor analysis, discriminant validity and convergent validity. Reliability of NSS was assessed by Cronbach's α coefficient, spilt-half reliability and test-retest reliability.

RESULTS

Critical value of all 15 items ranged from 3.01 to 13.36. Each item was significantly correlated with the total score by a correlation coefficient (r) ranging from 0.219 to 0.700. Three common domains were extracted and 15 items explained 54.86% of the total variance. There was a shift in domains compared to the English version likely due to cultural differences. Cronbach's α coefficient for the total scale of 15 items was 0.821 and for three factors was 0.726, 0.748 and 0.760 respectively. The NSS had good correlation with Epworth sleepiness scale scores, Insomnia severity index scores and moderate correlation with mean the sleep latency of polysomnographic recording, and European Quality of Life-5 Dimensions Questionnaire. The Chinese version of NSS showed good spilt-half reliability and test-retest reliability.

CONCLUSION

The Chinese version of NSS shows satisfactory psychometric properties with good validity and reliability. It is applicable to evaluate the severity and consequences of symptoms in Chinese adult patients with NT1.

Determination of thresholds for minimally important difference and clinically important response on the functional outcomes of sleep questionnaire short version in adults with narcolepsy or obstructive sleep apnea

PURPOSE

This study estimated thresholds for clinically important responses and minimally important differences for two indicators of improvement for the 10-item version of the functional outcomes of sleep questionnaire (FOSQ-10).

METHODS

Participants with excessive daytime sleepiness with narcolepsy or obstructive sleep apnea received 12 weeks of solriamfetol treatment. Participants completed the FOSQ-10 and other patient-reported outcome measures, including the single-item patient global impression of change (PGI-C) assessment. Clinicians completed the single-item clinician global impression of change (CGI-C) for each participant. Data from the two studies were analyzed separately, both without regard to treatment assignment. In total, 690 participants (47% female, mean age 48 years, 77% Caucasian, 91% from North America) were enrolled. Two clinically important changes, defined as a minimally important difference and a clinically important response, were determined using distribution and anchor-based analyses. A receiver operating characteristic analysis was used to determine the optimal FOSQ-10 change threshold.

RESULTS

Spearman correlations between change in FOSQ-10 scores and PGI-C and CGI-C were - 0.57 and - 0.49 for participants with narcolepsy and - 0.42 and - 0.37 for participants with obstructive sleep apnea. Receiver operating characteristic analysis suggested minimally important difference and clinically important response estimates of 1.7 and 2.5 and 1.8 and 2.2 points in narcolepsy and obstructive sleep apnea, respectively.

CONCLUSIONS

Minimally important difference and clinically important response estimates for the FOSQ-10 for adults with excessive daytime sleepiness in narcolepsy or obstructive sleep apnea will be helpful for interpreting changes over time and defining a clinical responder. CLINICALTRIALS.

GOV IDENTIFIERS

NCT02348593 (first submitted January 15, 2015) and NCT02348606 (first submitted January 15, 2015).

Narcolepsy Quality-of-Life Instrument with 21 Questions: A Translation and Validation Study in Chinese Pediatric Narcoleptics

OBJECTIVE

This study aimed to translate and validate the narcolepsy quality-of-life instrument with 21 questions (NARQoL-21) in Chinese pediatrics with narcolepsy.

METHODS

NARQoL-21 was translated following the 10 steps of scale translation. The translated version was tested by exploratory factor analysis (EFA), confirmatory factor analysis (CFA), known-group validity, criterion validity, Cronbach's α and test-rest reliability.

RESULTS

The Chinese version of NARQoL-21 consisted of two factors: (psychosocial factors and future outlook factor), including 20 items. EFA yielded 3 domains for psychosocial factors and 1 domain for future outlook factor. The Chinese version had a negative correlation with the overall Modified Epworth Sleepiness Scale (r = -0.518, p<0.001) and meaningful difference in score between drug naïve and treated group (p<0.05). The Cronbach's α coefficient was higher than 0.7 and intraclass correlation coefficient (ICC) ranged from 0.75 to 0.905, indicating that it had good reliability.

CONCLUSION

The Chinese version of the NARQoL-21 is available and can be used to evaluate the health-related quality of life (HRQoL) of pediatric narcoleptics, despite that there is a shift in factors compared to the English version due to cultural differences. Future studies are recommended to further validate the scale in Chinese pediatrics with narcolepsy.

A 10-Year Longitudinal Observational Study Of Cataplexy In A Cohort Of Narcolepsy Type 1 Patients

PURPOSE

Narcolepsy type 1 (NT1) is thought to have a chronic persistent course. This study aimed to assess the natural course of cataplexy in patients with NT1 at 2, 6, and 10 years after stabilizing symptoms. Other secondary objectives included assessing sleep quality, body mass index (BMI), and comorbidities at recruitment and 10 years later.

PATIENTS AND METHODS

Cataplexy symptoms, the Epworth sleepiness scale (ESS), sleep quality (assessed using the Pittsburgh sleep quality index [PSQI]), BMI, and comorbid conditions were prospectively monitored in 38 patients with NT1. The study sample comprised 38 patients with narcolepsy (males=27). The mean ages at disease onset and recruitment were 17.7 ± 5.6 years and 24.3 ± 8.6 years, respectively.

RESULTS

In 42% of the cohort, the anti-cataplectic medications were stopped at the end of the study without disturbing symptoms of cataplexy. Additionally, there was an apparent significant reduction in the frequency of cataplexy over time. The mean ESS score decreased by more than 4 points from 19.4 ± 2.9 to 15 ± 4.3 (p<0.001) while on the same pharmacotherapy. The number of patients with a PSQI score of <5 (indicating good sleep quality) increased from 6 (15.8%) to 15 (39.5%) (p=0.004). The BMI increased from 30 ± 5.1 to 33.3 ± 6 kg/m² (p=0.001). No changes were documented in comorbidities.

CONCLUSION

The findings suggest that the course of NT1 is not stable. Over a 10-year period, cataplexy symptoms improved or disappeared in a large proportion of patients, and there was an improvement in daytime sleepiness and nighttime sleep quality. More prospective studies that repeatedly monitor CSF-HCRT are needed to confirm the current findings.