Incidence of pediatric narcolepsy diagnosis and management: evidence from claims data

Abstract

Study Objectives:

The purpose of this study was to characterize the incidence of pediatric narcolepsy diagnosis, subsequent care, and potential sociodemographic disparities in a large US claims database.

Methods:

Merative MarketScan insurance claims (n = 12,394,902) were used to identify youth (6–17 years of age) newly diagnosed with narcolepsy (International Classification of Diseases, 10th revision codes). Narcolepsy diagnosis and care 1 year postdiagnosis included polysomnography with Multiple Sleep Latency Test, pharmacological care, and clinical visits. Potential disparities were examined by insurance coverage and child race and ethnicity (Medicaid-insured only).

Results:

The incidence of narcolepsy diagnosis was 10:100,000, primarily type 2 (69.9%). Most diagnoses occurred in adolescents with no sex differences, but higher rates in Black vs White youth with Medicaid. Two thirds had a prior sleep disorder diagnosis and 21–36% had other co-occurring diagnoses. Only half (46.6%) had polysomnography with Multiple Sleep Latency Test (± 1 year postdiagnosis). Specialty care (18.9% pulmonary, 26.9% neurology) and behavioral health visits were rare (34.4%), although half were prescribed stimulant medications (51.0%). Medicaid-insured were 86% less likely than commercially insured youth to have any clinical care and 33% less likely to have polysomnography with Multiple Sleep Latency Test.

Conclusions:

Narcolepsy diagnoses occurred in 0.01% of youth, primarily during adolescence, and at higher rates for Black vs White children with Medicaid. Only half overall had evidence of a diagnostically required polysomnography with Multiple Sleep Latency Test, underscoring potential misdiagnosis. Many patients had co-occurring conditions, but specialty and behavioral health care were limited. Results suggest misdiagnosis, underdiagnosis, and limited narcolepsy treatment, as well as possible disparities. Results highlight the need to identify determinants of evidence-based pediatric narcolepsy diagnosis and management.

Citation:

Tang SH, Min J, Zhang X, et al. Incidence of pediatric narcolepsy diagnosis and management: evidence from claims data. J Clin Sleep Med. 2024;20(7):1141–1151.

BRIEF SUMMARY

Current Knowledge/Study Rationale: Little is known about the incidence of pediatric narcolepsy, extent of co-occurring conditions, and whether there are gaps in the extent of rigorous evaluation and care for this condition. Insurance claims data can offer insights into the incidence, management, and potential disparities in narcolepsy care.

Study Impact: Many pediatric patients with a narcolepsy diagnosis did not have evidence-based diagnostic procedures, and the majority had co-occurring sleep and other conditions. In addition, evidence of specialty care and behavioral health visits were rare, especially in Medicaid-insured vs commercially insured patients. Collectively, findings point to a high likelihood of underdiagnosis, misdiagnosis, and limited care, underscoring the need for increased access to multidisciplinary, comprehensive sleep services.

INTRODUCTION

Narcolepsy is a chronic disorder of central hypersomnolence with significant adverse impacts on psychosocial and physical health functioning.^1,2 Narcolepsy is characterized by excessive daytime sleepiness, as well as common symptoms of hypnagogic hallucinations and sleep paralysis, with 2 subtypes: type 1 (with cataplexy) and type 2 (without cataplexy).³ Much of the research on narcolepsy to date has focused on adults because pediatric narcolepsy is especially rare, with a global average prevalence between 20 and 50 per 100,000.⁴ Although narcolepsy disease onset often occurs in childhood or early adolescence, the incidence of new diagnoses is unknown,³ and there is an estimated 15-year age gap between symptom onset and diagnosis.⁵ Missed diagnosis during childhood could be due to gaps in clinicians’ knowledge about narcolepsy, misidentification of excessive sleepiness in a group known for insufficient sleep, and in distinguishing narcolepsy symptoms from symptoms of other neurological, endocrinologic, and psychiatric disorders in children.⁶ Delayed diagnosis could also be a result of children and families having difficulty articulating narcolepsy symptoms and/or recognizing what is considered “excessive” daytime sleepiness.⁷ Limited access to pediatric sleep laboratories could also delay confirmation of a suspected diagnosis. The American Academy of Sleep Medicine diagnostic criteria for narcolepsy types 1 and 2 (Table 1) both include evaluation of mean sleep latency and number of sleep-onset rapid eye movement sleep periods on a Multiple Sleep Latency Test (MSLT), ideally with a preceding polysomnography.³

Table 1.

Narcolepsy diagnostic criteria according to the International Classification of Sleep Disorders, third edition, text revision.³

Narcolepsy: Patient experiences excessive daytime sleepiness—daily bouts of uncontrollable drowsiness or an overpowering urge to sleep—happening for ≥ 3 months. The symptoms are not attributed to chronic lack of sleep, circadian disruptions, mental disorders, OSA, medication or substance use side effects/withdrawal symptoms.
Narcolepsy Type 1:	Narcolepsy Type 2:
Required symptoms: Excessive daytime sleepiness Cataplexy	Required symptoms: Excessive daytime sleepiness No cataplexy
Required diagnostic test findings: At least 1 of the following: Either: Mean sleep latency ≤ 8 minutes and ≥ 2 SOREMPs as determined by MSLT. A SOREMP in the first 15 minutes of sleep, as observed during the nocturnal polysomnogram. CSF hypocretin-1 ≤ 110 pg/ml or < 1/3 of the mean levels observed in healthy participants using the same assay.	Required diagnostic test findings: Mean sleep latency ≤ 8 minutes and ≥ 2 SOREMPs as determined by MSLT. (Note: A SOREMP in the first 15 minutes of sleep on the previous nocturnal PSG may replace 1 of the SOREMPs on the MSLT). CSF hypocretin-1 > 110 pg/ml or > 1/3 of the mean levels observed in healthy participants using the same assay.

Presence of these diagnostic criteria is not reflected in MarketScan database. Diagnostic criteria from International Classification of Sleep Disorders, third edition, text revision are copyright of the American Academy of Sleep Medicine and used here with permission. CSF = cerebrospinal fluid, MSLT = Multiple Sleep Latency Test, SOREMP = sleep onset rapid eye movement sleep periods, OSA = obstructive sleep apnea.

Few studies have examined pediatric narcolepsy diagnostic and treatment patterns on a large scale, which could help guide targeted efforts to enhance clinicians’ and families’ awareness, early identification, and evidence-based narcolepsy care. One longitudinal study using 2010–2015 US insurance claims data from privately insured patients found higher rates of co-occurring health conditions and health care use compared to controls in a cohort of 1,427 pediatric patients with narcolepsy.⁸ However, diagnostic incidence and treatment patterns were not examined. Another longitudinal study using adult and pediatric claims data from Japan found increases in narcolepsy incidence and prevalence from 2010–2019, as well as increased stimulant medication use. However, data on nonpharmacological care in pediatrics, such as visits with relevant specialty care (eg, neurology, pulmonary) and behavioral health providers, were not examined.⁹ Identifying gaps in pediatric narcolepsy care is especially important given the consequences of missed and/or delayed diagnosis and the potential benefits of early identification.^5–7 For example, misdiagnosis can lead to exposure to unnecessary medications and reduced psychosocial functioning and quality of life.⁵ Some narcolepsy symptoms may be inappropriately perceived by others, especially teachers, leading to children with undetected narcolepsy being labeled as “lazy” or “unmotivated.”⁵

Although there is no cure for narcolepsy, evidence-based management of common narcolepsy symptoms, including excessive daytime sleepiness, fragmented nighttime sleep,¹⁰ and cataplexy, consists of a combination of medication and behavioral treatments. National¹¹ and international¹² guidelines indicate that sodium oxybate, modafinil, and other stimulant medications can effectively treat excessive daytime sleepiness and other narcolepsy symptoms. Behavioral approaches include adherence to a strict sleep–wake schedule, diet changes, healthy sleep habits, exercise to promote daytime wakefulness, and scheduled naps.^6,11 However, the extent to which pediatric patients diagnosed with narcolepsy receive these evidence-based treatments as part of outpatient care is unknown. Further underscoring the need for evidence-based narcolepsy symptom management,^7,13 research on children diagnosed with narcolepsy indicates that treatment should target the breadth of symptoms that adversely affect well-being (eg, social–emotional, academic, and physical health).² In a recent qualitative study, adolescents with narcolepsy expressed frustration about symptom management and particularly symptom-related social challenges that were not adequately addressed as part of their narcolepsy care.¹³

In addition to knowledge gaps regarding pediatric narcolepsy diagnosis and evidence-based care, little is known about whether the racial, ethnic, and socioeconomic disparities seen in sleep health and common sleep disorders (eg, insomnia, obstructive sleep apnea) are observed in pediatric narcolepsy. Adult and pediatric research demonstrates that racially and ethnically minoritized individuals and/or those of lower-socioeconomic-status backgrounds are more likely to experience some sleep disorders, such as obstructive sleep apnea, and less likely to obtain treatment.^14–17 Research with adults shows that the age of onset and the nature of narcolepsy symptoms may vary by race and ethnicity. For instance, Chinese adults with narcolepsy experienced an earlier onset of symptoms (∼10 years of age)¹⁸ than predominantly White adults with narcolepsy in France and Quebec (∼24 years of age).¹⁹ One study found that Black/African American adults with narcolepsy exhibited more excessive daytime sleepiness scores and lower cerebrospinal fluid hypocretin levels in the absence of cataplexy compared with adults of White, Asian, and Hispanic/Latinx backgrounds with narcolepsy.²⁰ Overall, there is a paucity of epidemiological data on narcolepsy in racially and ethnically minoritized individuals, and most narcolepsy diagnosis and treatment research has been conducted primarily with White individuals.¹⁴ Because racism and discrimination are root causes of sleep health disparities, and health disparities more broadly,^16,21 there may be similar inequities in pediatric narcolepsy care, which could in turn have implications for interventions to promote equitable identification and management of this condition.

The purpose of this study was to characterize the incidence of pediatric narcolepsy diagnosis, associated sociodemographic factors and co-occurring conditions, and subsequent care using a large-scale sample of Medicaid and commercial insurance claims in the United States. This study overcomes the limitations of prior claims-based narcolepsy research^8,9 by examining both publicly and privately insured patients and by evaluating pharmacological and other methods of narcolepsy care, such as visits with relevant specialties, behavioral health, and primary care clinicians. Our first study aim was to examine the incidence of narcolepsy diagnosis among children and adolescents across sociodemographic factors, co-occurring conditions, and health care settings. Our second aim was to examine any diagnostic evaluation in the 1 year prior up to, at the time of, and in the 1-year period following diagnosis and clinical care 1 year postdiagnosis. Our third aim was to explore potential sociodemographic disparities in narcolepsy incidence, evaluation, and receipt of care in the 1 year following diagnosis. Sociodemographic disparities were examined according to insurance type, with Medicaid as a proxy for lower socioeconomic status,^22,23 and, within the Medicaid-insured subsample with available race and ethnicity data, disparities by race and ethnicity. We hypothesized that children with commercial insurance would have a higher incidence of new narcolepsy diagnoses and more frequent treatment than those with Medicaid insurance, based on prior research showing delayed diagnosis and management of pediatric obstructive sleep apnea among children with public insurance.^22,23 Comparisons of narcolepsy diagnosis and care by patient race and ethnicity in the Medicaid subsample were exploratory.

METHODS

Data

We used data from the 2016–2018 Merative MarketScan research insurance claims database (Merative, Ann Arbor, Michigan) and International Classification of Diseases, 10th revision (ICD-10) diagnostic codes to identify a cohort of children aged 6–17 years with a diagnosis of narcolepsy type 1 (G47.4, G47.411), type 2 (G47.41, G47.419), or narcolepsy in conditions classified elsewhere (G47.42, G47.421, G47.429) given during the 2017 calendar year (January 1–December 31). To reflect the incidence rather than the prevalence of narcolepsy diagnosis, patients were included in this cohort if narcolepsy was their first sleep disorder diagnosis in 2017 and they did not have a prior diagnosis of narcolepsy in the 1 year before their 2017 diagnosis. Children with a 2017 narcolepsy diagnosis that also had any other ICD-10 sleep disorder diagnosis in the 1 year prior to their 2017 narcolepsy diagnosis were included in the cohort (see Table S1 ^{(98.7KB, pdf)} in the supplemental material for listing of sleep disorder diagnoses). This research was deemed exempt by the Institutional Review Board of Children’s Hospital of Philadelphia.

As shown in Figure 1, there were 12,394,902 enrolled patients in the 2017 MarketScan database. Those with a narcolepsy diagnosis prior to 2017 were excluded based on the cohort definition (n = 506). An additional 378 patients with a narcolepsy diagnosis in 2017 were excluded because they did not have continuous enrollment during the 1 year prior to and 1 year after narcolepsy diagnosis and/or did not have drug benefits, as these benefits were necessary to track narcolepsy management via medication prescriptions. We also excluded 20 patients aged 0–5 years from the cohort, given concerns about diagnostic validity and exceedingly low prevalence of narcolepsy in very young children.³ A final sample of 700 patients aged 6–17 years were included in the narcolepsy study cohort (Table 2). In the Medicaid subsample, 60 patients were excluded from analyses exploring racial and ethnic differences due to having no race and ethnicity data (n = 35) or due to very small sample sizes that precluded comparisons by race and ethnicity (Hispanic/Latinx, n = 16; Other, n = 9).

Figure 1. Definition of study cohort, analytic sample, and narcolepsy management.

CNS = central nervous system, MSLT = Multiple Sleep Latency Test, PSG = polysomnography, SNRIs = serotonin and norepinephrine reuptake inhibitors, SSNRIs = selective serotonin and norepinephrine reuptake inhibitors, SSRIs = selective serotonin reuptake inhibitors.

Table 2.

Patient characteristics at the time of first narcolepsy diagnosis in 2017 by insurance provider.

	All (n = 700)	Commercial (n = 368)	Medicaid (n = 332)	P d
Age group, n (%)
6–11 years	167 (23.9%)	53 (14.4%)	114 (34.3%)	<.001
12–17 years	533 (76.1%)	315 (85.6%)	218 (65.7%)
Age, years, mean (SD)	13.6 (3.1)	14.4 (2.7)	12.7 (3.1)	<.001
Sex, n (%)
Male	320 (45.7%)	158 (42.9%)	162 (48.8%)	.12
Female	380 (54.3%)	210 (57.1%)	170 (51.2%)
Race and ethnicity, n (%)a
Hispanic/Latinx	—	—	15 (4.5%)	—
Non-Hispanic/Latinx Black	—	—	156 (47.0%)
Non-Hispanic/Latinx White	—	—	117 (35.2%)
Other	—	—	9 (2.7%)
Missing (Medicaid only)	—	—	35 (10.5%)
≥ 1 sleep disorder dx 1 year before/at time of narcolepsy dx, n (%)	434 (62.0%)	232 (63.0%)	202 (60.8%)	.54
Co-occurring conditions 1 year before or at time of narcolepsy dx, n (%)
Complex chronic conditions	150 (21.4%)	81 (22.0%)	69 (20.8%)	.69
Neurodevelopmental conditions	187 (26.7%)	82 (22.3%)	105 (31.6%)	.005
Behavioral health conditions	250 (35.7%)	140 (38.0%)	110 (33.1%)	.17
Region, n (%)b
Northeast	—	55 (14.6%)	—	—
North Central	—	104 (27.5%)	—
South	—	181 (47.9%)	—
West	—	36 (9.5%)	—
Unknown (commercial only)	—	2 (0.5%)	—
Narcolepsy diagnosis, n (%)				.02
Type 1 with cataplexy	177 (25.3%)	107 (29.1%)	70 (21.1%)
Type 2 without cataplexy	489 (69.9%)	241 (65.5%)	248 (74.7%)
In conditions classified elsewhere	34 (4.9%)	20 (5.4%)	14 (4.2%)
Evaluation in 1 year prior to 2017 dx, n (%)
PSG with MSLT	58 (8.3%)	31 (8.4%)	27 (8.1%)	.88
PSG (no MSLT)	59 (8.4%)	31 (8.4%)	28 (8.4%)	.99
MSLT (no PSG)	4 (0.6%)	1 (0.3%)	3 (0.9%)	.35
Visit with narcolepsy dx in 2017, n (%)c				<.001
At PSG + MSLT visit	125 (17.9%)	71 (19.3%)	54 (16.3%)
At PSG visit (no MSLT)	23 (3.3%)	5 (1.4%)	18 (5.4%)
At MSLT visit (no PSG)	8 (1.1%)	5 (1.4%)	3 (0.9%)
Pulmonary visit	56 (8.0%)	45 (12.2%)	11 (3.3%)
Neurology visit	87 (12.4%)	49 (13.3%)	38 (11.4%)
Behavioral health visit	10 (1.4%)	9 (2.4%)	1 (0.3%)
Primary care visit	136 (19.4%)	76 (20.7%)	60 (18.1%)
Other outpatient specialty or nonspecialty care visit	241 (34.4%)	102 (27.7%)	139 (41.9%)
Other inpatient/hospital visit	13 (1.9%)	6 (1.6%)	7 (2.1%)
Provider or visit type unknown	1 (0.1%)	—	1 (0.3%)

^aRace and ethnicity are sociopolitical constructs and do not reflect genetic or biological differences. Race and ethnicity data were available for Medicaid-insured children only. ^bUS region was available for commercially insured children only. ^cVisit with narcolepsy diagnosis was defined by the order of categories listed above, because these categories were not mutually exclusive. For example, 16 patients in the PSG + MSLT visit category had a primary care visit on the same day. ^dChi-squared tests, Fisher’s exact test, and t test. dx = diagnosis, MSLT = Multiple Sleep Latency Test, PSG = polysomnography.

Variables

Sociodemographic variables

Sociodemographic variables included child’s age, sex, and insurance provider. Race and ethnicity data were only available for Medicaid-insured children. These data were self-reported by patients/families and grouped into the following categories by Merative: Non-Hispanic/Latinx White (hereafter, “White”), non-Hispanic/Latinx Black/African American (hereafter, “Black”), Hispanic/Latinx, and Other. Data on patients’ regional location in the United States were available for commercially insured children only.

Co-occurring conditions

We included co-occurring conditions identified via ICD-10 codes because these could affect the diagnosis and management diagnosed with narcolepsy. Complex chronic conditions (CCCs),²⁴ which include cardiovascular, neuromuscular, congenital or genetic, technology dependence, gastrointestinal, hematology or immunology, malignancy, metabolic, renal, respiratory, neonatal, and transplant-related conditions, were indexed during the 1 year prior to and/or at the time of narcolepsy diagnosis. We also indexed whether children were diagnosed with any neurodevelopmental disorders (ND; eg, autism, pervasive developmental disorders) or behavioral health conditions (BH; eg, attention deficit/hyperactivity disorder, major depressive disorder, generalized anxiety disorder) in the 1 year prior to and/or at the time of narcolepsy diagnosis, given well-documented linkages between ND and/or BH concerns and elevated sleep problems.^25,26 Table S2 ^{(98.7KB, pdf)} shows diagnostic groupings and ICD-10 codes for ND and BH diagnoses. We created 6 separate indexes to reflect the presence of CCCs, ND, and BH diagnoses in the 1 year prior to or at the same time as narcolepsy diagnosis as well as in the 1 year prior to or at the time of the first sleep disorder diagnosis in 2017.

Narcolepsy diagnosis and care

Narcolepsy diagnostic evaluation and management methods were selected based on guidelines for evidence-based evaluation and treatment.^6,11,12 Using Current Procedural Terminology codes, we identified whether patients received a polysomnography (PSG) with an MSLT , PSG only, or MSLT only. These diagnostic methods were examined: (1) in the 1 year prior to the 2017 narcolepsy diagnosis; (2) at the same time as the 2017 narcolepsy diagnosis; and (3) in the 1 year following narcolepsy diagnosis.

Care for narcolepsy was examined in the 1 year following diagnosis and included pharmacological management as well as visits with clinical providers. Pharmacological management was defined using prescription claims for stimulants (modafinil, methylphenidate, amphetamine, lisdexamfetamine, methamphetamine, dextroamphetamine); sodium oxybate; monoamine oxidase inhibitors (selegiline); selective histamine H3-receptor inverse agonist (pitolisant), tricyclic antidepressants (clomipramine, imipramine, trimipramine maleate); selective serotonin and norepinephrine reuptake inhibitors (venlafaxine and desvenlafaxine); selective serotonin reuptake inhibitor (fluoxetine); and selective norepinephrine reuptake inhibitors (atomoxetine).

Clinical management through visits with care providers were identified using a combination of codes for the provider type and visit location in MarketScan claims data. We included claims for pediatric and adult pulmonary and neurology visits, because these specialties often manage narcolepsy. Subspecialists, including sleep clinicians, are not coded in the MarketScan databases but are considered to be subsumed within broader specialties (eg, pulmonary). We also indexed visits with primary care, which included family medicine and internal medicine, and visits with behavioral health providers, including psychologists, child and adult psychiatrists, psychiatric nurses, therapists, and mental health outpatient facility visits.

Statistical analysis

Analyses were conducted using STATA 16 (StataCorp LLC, College Station, Texas) and SAS 9.4 (SAS Institute Inc., Cary, North Carolina). Descriptive statistics were used to characterize the incidence of narcolepsy diagnosis as well as sociodemographic information and co-occurring conditions for the narcolepsy cohort. Descriptive statistics were also used to examine patterns of narcolepsy diagnostic and management methods in the 1 year following diagnosis. Chi-squared tests and logistic regression models were used to examine the potential disparities in narcolepsy incidence and management by insurance type, with adjustments for child’s age (6–11 years vs 12–17 years), sex, presence of other sleep disorder diagnoses in the 1 year prior to or at the same time of narcolepsy diagnosis, and presence of any CCCs, ND, and BH diagnoses in the 1 year prior to or at the time of the first sleep disorder diagnosis in 2017 and narcolepsy diagnosis. In analyses comparing racial and ethnic groups, White children were used as the reference group to reflect racial privilege in health care access.^27,28 As noted above, children of Latinx/Hispanic backgrounds and those labeled as “Other” were excluded given the small sample sizes. The “Other” category also lacks granular information and likely represents substantial heterogeneity in race and ethnicity, limiting interpretation.

RESULTS

Narcolepsy incidence, patient sociodemographic characteristics, and co-occurring conditions

Table 2 summarizes sociodemographic characteristics and co-occurring conditions for the 720 patients identified with a first narcolepsy diagnosis in 2017. The overall incidence of narcolepsy diagnosis for children 6–17 years of age enrolled in the 2017 MarketScan database (n = 9,045,461) was 0.01%. Of the 700 patients with a new narcolepsy diagnosis, 25.3% were diagnosed with narcolepsy type 1 (with cataplexy), 69.9% with type 2 (without cataplexy), and 4.9% with narcolepsy in conditions classified elsewhere. Most diagnoses occurred in adolescent patients (74.1%). Rates of diagnosis were similar for males and females.

Nearly two thirds (61.9%) of patients newly diagnosed with narcolepsy had another sleep disorder diagnosis in 1 year prior to or at the time of narcolepsy diagnosis. The most common sleep disorders at the time of narcolepsy diagnosis were obstructive sleep apnea, other hypersomnia, and snoring. A total of 21.4% of patients with narcolepsy had a CCC diagnosis in the 1 year before or at the time of the narcolepsy diagnosis, with the most common CCC diagnoses being neurologic and neuromuscular disorders, hematologic and immunologic disorders, and metabolic disorders. A total of 26.7% of patients had an ND diagnosis and 35.7% had a BH diagnosis in the 1 year before or at the time of narcolepsy diagnosis. The most common ND diagnoses were attention deficit/hyperactivity disorder, autism, and other pervasive developmental disorders, and the most common BH diagnoses were major depressive disorder, other anxiety disorder, and panic disorder.

Narcolepsy diagnosis

In the 1 year before the 2017 narcolepsy diagnosis, 8.3% of patients received a PSG with MSLT, 8.4% a PSG only, and 0.6% an MSLT only. Over one third (34.4%) of patients received their 2017 narcolepsy diagnosis at an outpatient specialty or nonspecialty care visit, and 19.4% received their diagnosis at a primary care visit. Very few patients were diagnosed at a visit with a pulmonary (8.0%), neurology (12.4%), or behavioral health (1.4%) provider. Only 17.9% (n = 127) of patients received their narcolepsy diagnosis using the required, gold-standard diagnostic approach, PSG with MSLT. An additional 3.3% received their diagnosis at a PSG visit without an MSLT, and 1.1% received their diagnosis at an MSLT visit without a PSG.

In the 1 year following the 2017 narcolepsy diagnosis, 23.6% of patients received a PSG with MSLT evaluation in the 1 year following diagnosis. For some patients, this was a reevaluation; 28% (n = 74) of the 264 patients who received PSG with MSLT, PSG only, or MSLT only in the 1 year following diagnosis had one of these assessment types at the time of their narcolepsy diagnosis. When examining receipt of these evaluations at any time point (ie, 1 year before, at the time of, or 1 year after the 2017 narcolepsy diagnosis), 46.6% of unique patients had a PSG with MSLT, 11.6% with PSG only, and 1.6% with MSLT only.

Narcolepsy care

Table 2 shows rates of receipt of care in the 1 year following the 2017 narcolepsy diagnosis. Overall, most of the sample (91.4%) had at least 1 type of care across the pharmacological and other clinical management methods. Management via stimulants was the most common pharmacological care type, occurring in 51% of patients, with very few (6.0% or less) patients receiving other types of medication prescriptions and no patients receiving monoamine oxidase inhibitors or selective histamine H3-receptor inverse agonists. For other care with clinical providers, 69.6% of patients had at least 1 primary care visit (mean visit frequency = 3.3, standard deviation [SD] = 4.5) in the 1 year following narcolepsy diagnosis, and 26.9% had at least 1 neurology specialty care visit (mean visit frequency = 0.8, SD = 1.9) and 18.9% had at least 1 pulmonary specialty care visit (mean visit frequency = 0.5, SD = 1.4). Behavioral health visits occurred for 34.4% of the sample, with an average frequency of 4.9 visits (SD = 12.0).

Comparisons by insurance coverage

The incidence of narcolepsy diagnosis was only slightly lower in Medicaid-insured (0.006%) vs commercially insured youth (0.007%, P = .018). As shown in Table 3, adjusted logistic regression models comparing likelihood of receipt of care by insurance coverage showed no differences in the likelihood of PSG and/or MSLT evaluation in the 1 year following narcolepsy diagnosis. However, when examining the likelihood of ever receiving a PSG with MSLT (ie, in the 1 year prior to, at the time or, or in the 1 year following narcolepsy diagnosis), Medicaid-insured youth were 33% less likely than commercially insured youth to have ever had this evidence-based diagnostic evaluation (odds ratio [OR] = 0.67; 95% confidence interval [CI], [0.47, 0.95]; P = .02).

Table 3.

Rates of narcolepsy diagnosis and care types 1 year postdiagnosis—overall and by insurance provider (n = 700).

	Percentage of Patients Receiving Care Type				Odds Ratio for Likelihood of Care Receipt in Medicaid Patients (Ref: Commercial)d
	All	Commercial (n = 368)	Medicaid (n = 332)	P c	OR	(95% CI)	P
	n (%)	n (%)	n (%)
Evaluation (postdiagnosis)a
PSG + MSLT	165 (23.6%)	92 (25.0%)	73 (22.0%)	.34	0.83	(0.57, 1.19)	.30
PSG only	47 (6.7%)	23 (6.3%)	24 (7.2%)	.60	1.12	(0.60, 2.07)	.72
MSLT only	52 (7.4%)	31 (8.4%)	21 (6.3%)	.29	0.76	(0.41, 1.42)	.39
Any history of evaluationb
PSG + MSLT	326 (46.6%)	186 (50.5%)	140 (42.2%)	.02	0.67	(0.47, 0.95)	.02
PSG only	81 (11.6%)	35 (9.5%)	46 (13.9%)	.07	1.43	(0.88, 2.34)	.15
MSLT only	11 (1.6%)	4 (1.1%)	7 (2.1%)	.27	2.35	(0.64, 8.56)	.19
Pharmacological carec
Sodium oxybate	24 (3.4%)	19 (5.2%)	5 (1.5%)	.007	—	—	—
Monoamine oxidase inhibitor	0	0	0	—	—	—	—
Selective histamine H3-receptor inverse agonists	0	0	0	—	—	—	—
SNRIs	23 (3.3%)	13 (3.5%)	10 (3.0%)	.69	—	—	—
SSNRIs	29 (4.1%)	22 (6.0%)	7 (2.1%)	.01	—	—	—
SSRIs	42 (6.0%)	32 (8.7%)	10 (3.0%)	.001	—	—	—
Stimulants	357 (51.0%)	184 (50.0%)	173 (52.1%)	.57	1.04	(0.76, 1.42)	.81
Any pharmacological care	395 (56.4%)	212 (57.6%)	183 (55.1%)	.50	0.86	(0.63, 1.18)	.35
Other care
Pulmonary specialty care	132 (18.9%)	85 (23.1%)	47 (14.2%)	.002	0.54	(0.36, 0.82)	.003
Neurology specialty care	188 (26.9%)	107 (29.1%)	81 (24.4%)	.16	0.77	(0.54, 1.09)	.14
Primary care/family medicine	487 (69.6%)	317 (86.1%)	170 (51.2%)	<.001	0.15	(0.10, 0.22)	<.001
Behavioral health	241 (34.4%)	143 (38.9%)	98 (29.5%)	.009	0.62	(0.42, 0.90)	.01
Any pharmacological or other care	640 (91.4%)	358 (97.3%)	282 (84.9%)	<.001	0.14	(0.07, 0.28)	<.001

^aOf the 264 patients who had PSG only, MSLT only, or PSG + MSLT in the 1 year following diagnosis, 74 patients (28.0%) also had 1 of these evaluation procedures at the time of their narcolepsy diagnosis. ^bWe defined any history of evaluation as PSG + MSLT, PSG only, or MSLT only at any time, meaning this could be 1 year prior to their 2017 diagnosis, at the time of diagnosis, or in the 1 year after diagnosis. ^cSample sizes were too small for most pharmacological care types to conduct logistic regression. Chi-squared tests and binomial logistic regression models after adjusting for child’s sex, age, prior sleep disorder diagnoses, and any complex chronic conditions, behavioral health, or neurodevelopmental diagnoses during 1 year prior to and at time of narcolepsy and any other prior sleep disorder diagnosis. Bold indicates significant associations for chi-squared analyses or odds ratios (P < .05). MSLT = Multiple Sleep Latency Test, PSG = polysomnography, Ref = reference, SNRIs = selective norepinephrine reuptake inhibitors, SSNRIs = selective serotonin and norepinephrine reuptake inhibitors, SSRIs = selective serotonin reuptake inhibitors.

Regarding management, stimulant prescriptions were the only type of pharmacological care with a sufficiently large sample size to conduct analyses, and there were no differences in the likelihood of this prescription by insurance coverage, or when examining the likelihood of any type of pharmacological care receipt across insurance groups. However, compared to those with commercial insurance, Medicaid-insured youth were 46% less likely to have pulmonary follow-up (OR = 0.54; 95% CI, [0.36, 0.82]; P = .003) and 85% less likely to have primary care/family medicine follow-up (OR = 0.15; 95% CI, [0.10, 0.22]; P < .001). Medicaid-insured youth were also 38% less likely than commercially insured youth to have a behavioral health visit in the 1 year following narcolepsy diagnosis (OR = 0.62; 95% CI, [0.42, 0.90]; P = .01). Consistent with this pattern, Medicaid-insured children were 86% less likely than those with commercial insurance to receive any of these pharmacological or other care types (OR = 0.14; 95% CI, [0.07, 0.28]; P < .001).

Comparisons by race and ethnicity in the Medicaid subsample

In the Medicaid subsample, incidence of narcolepsy diagnosis differed significantly in Black (0.008%) compared to White children (0.005%, P = .01). However, as shown in Table 4, there were no significant differences comparing narcolepsy care receipt in the 1 year following diagnosis for Black vs White children, except for stimulant medication prescriptions. Stimulant medication prescriptions were more prevalent in Black children with narcolepsy (59.0%) compared with their White counterparts (44.4%, P = .01).

Table 4.

Rates of 1-year narcolepsy care types in White vs Black children in the Medicaid subsample (n = 273).

	Percentage of Patients Receiving Care Type
	White (n = 117)	Black (n = 156)	P
	n (%)	n (%)
Evaluation
Post PSG+ MSLT	27 (23.1%)	31 (19.9%)	.52
Post MSLT only	8 (6.8%)	6 (3.8%)	.26
Post PSG only	8 (6.8%)	10 (6.4%)	.88
Any history of evaluation
PSG + MSLT	53 (45.3%)	61 (39.1%)	.30
PSG only	14 (12.0%)	23 (14.7%)	.50
MSLT only	1 (0.9%)	5 (3.2%)	.24
Pharmacological care*
Stimulants	52 (44.4%)	92 (59.0%)	.01
Any pharmacological care	59 (50.4%)	94 (60.3%)	.10
Other care
Pulmonary specialty care	12 (10.3%)	17 (10.9%)	.86
Neurology specialty care	27 (23.1%)	42 (26.9%)	.46
Primary care/family medicine	52 (44.4%)	79 (50.6%)	.31
Behavioral health	37 (31.6%)	41 (26.3%)	.33
Any pharmacological or other care	96 (82.1%)	133 (85.3%)	.47

Chi-squared tests and Fisher’s exact test. *The only pharmacological care types with a large enough sample to conduct analyses were stimulants and any pharmacological care types. Children less than 5 years of age and of “other” or Hispanic/Latinx backgrounds were excluded. MSLT= Multiple Sleep Latency Test, PSG = polysomnography.

DISCUSSION

We found that the incidence of narcolepsy diagnosis in a large US claims database was 0.01%, or 10.0 per 100,000 children, with the majority (69.9%) diagnosed with narcolepsy type 2 (without cataplexy). Most new diagnoses occurred in adolescents (74.1%) at equal rates for males and females. Among Medicaid-insured youth, incidence rates were higher in Black children than in White children. Only about half of patients overall received the required PSG with MSLT diagnostic evaluation either 1 year prior to, at the time or, or 1 year following their narcolepsy diagnosis, highlighting potential misdiagnosis. A significant portion of the sample received their diagnosis at a primary care visit, and nearly two thirds had another sleep disorder diagnosis. Although the vast majority had at least 1 type of pharmacological or other clinical care claim in the 1 year following diagnosis, this was largely driven by contact with a primary care clinician and/or a medication prescription. Specialty and behavioral health care claims were rare, even though 20–36% of patients with a narcolepsy diagnosis had a co-occurring medical, neurodevelopmental, or behavioral health diagnosis. We additionally observed that Medicaid-insured children were less likely to receive evidence-based diagnostic evaluation and any clinical care compared with those with commercial insurance.

The overall incidence rates were higher than those for adult and pediatric claims data from Japan, which were between 3.1 and 4.9 per 100,000 over 9 years. Differences across studies may be due to the nature of each sample, given that the claims from Japan were largely from adults, as well as regional differences in payor systems and the accessibility of providers and sleep laboratories for narcolepsy diagnosis.⁹ Similar to another claims-based study examining co-occurring conditions in youth with narcolepsy,⁸ many patients in our cohort had a co-occurring medical, behavioral, or neurodevelopmental condition. Symptoms of these co-occurring conditions may exacerbate the psychosocial impacts of pediatric narcolepsy^2,13 and/or contribute to diagnostic complexity or misdiagnosis, particularly in children and adolescents.

Unfortunately, diagnosis of narcolepsy via PSG with MSLT, which is required to meet diagnostic criteria,³ occurred in only about half of patients and rarely occurred at the time of the patient’s first insurance claim with a narcolepsy diagnosis. Thus, the incidence of new diagnoses in this article should be interpreted with caution, because there is a high likelihood of misdiagnosis, especially as we were unable to measure the completion of other tests relevant for narcolepsy diagnosis, including validated questionnaires, neuroimaging, and tests of human leukocyte antigen or cerebrospinal fluid orexin levels.¹² Most narcolepsy diagnoses were rendered by primary care, other outpatient specialty care, or other nonspecialty care providers, further suggesting that these diagnoses could have been provisional and/or inaccurate, particularly given that sleep medicine is rarely included in physician training programs.²⁹ Our findings converge with a recent Nexus Narcolepsy Registry study, which found that more than half of adults with narcolepsy reported misdiagnosis (59%) and receipt of their first narcolepsy consultation with a general practitioner (56%), rather than a specialist.³⁰ Collectively, these findings highlight the need for increased access to evidence-based pediatric narcolepsy diagnosis across insurance types, especially considering the potential effects of misdiagnosis as well as the impacts of missed and/or delayed diagnosis.⁵

Overall, more than half of patients in our study received pharmacological care. Whereas medication is an evidence-based narcolepsy treatment approach, the low rates of evidence-based diagnostic evaluation coupled with the limited specialty care engagement in this sample raise concerns about the quality of care in newly diagnosed patients with narcolepsy. Given the strong potential for misdiagnosis, some of this pharmacological care may have been unnecessary and/or harmful. Psychosocial adjustment and medication side effects in children are frequently reported challenges for patients with narcolepsy, their caregivers, and their clinical providers,^7,31 underscoring the importance of multidisciplinary care that involves medical and behavioral specialties and comprehensive treatment. Although families and patients with narcolepsy prefer multidisciplinary care,³¹ such clinics are rare, especially in pediatrics and in more rural settings,³² which could contribute to the low rates of specialty care engagement in this study.

We found possible insurance-related disparities in narcolepsy cases; Medicaid-insured children were less likely than commercially insured children to have ever had a PSG with MSLT and to have received any type of pharmacological or other care overall. More specifically, patients with Medicaid were less likely than commercially insured youth to have claims for visits with pulmonary specialty care, behavioral health, and primary care. These findings align with other research showing reduced access to specialty care among publicly insured children,^23,33 which could be due to barriers related to socioeconomic status such as transportation and childcare needs.^34,35 It is notable that receipt of pharmacological care generally did not differ across insurance types, except for a slightly higher receipt of prescriptions for selective serotonin and norepinephrine reuptake inhibitors or selective serotonin reuptake inhibitors in children with commercial insurance.

We could only preliminarily explore racial and ethnic differences in narcolepsy incidence and care, because race and ethnicity data were available for Medicaid-insured children only, and representation across racial and ethnic groups other than Black and White was sparse. Future research should include youth and families across racial and ethnic groups, including their experiences of racism and discrimination in the health care system,^21,28 to better understand potential disparities in narcolepsy diagnosis and overall quality of care. Our findings that the incidence of narcolepsy and likelihood of stimulant prescriptions were higher among Black vs White children warrant future investigation, especially given documented racial and ethnic disparities in the quality of care for Medicaid-insured children.^36,37 For instance, one study of Medicaid-insured youth found that Black children with attention deficit/hyperactivity disorder were more likely than White children to discontinue stimulant medication,³⁶ and less likely to receive behavioral health treatment. It should be noted that racial bias may also play a role in pediatric diagnosis³⁸ and needs to be investigated in the context of sleep health disparities.

Limitations

A primary study limitation is that findings may reflect misdiagnosis, because insurance claims do not indicate whether full criteria were met (Table 1), even among cases with completed PSG and MSLT procedures, and we lacked other diagnostic data (eg, orexin levels). Because PSG with MSLT are billable procedures, our findings likely accurately reflect low rates of these diagnostic tests among patients with a narcolepsy diagnosis. However, diagnostic incidence estimates in this study should be interpreted with caution, given potential misdiagnosis. Diagnostic criteria and codes may also differ between the ICD-10 and other commonly used diagnostic manuals,³ contributing to misdiagnosis, although claims cannot be submitted to insurance without ICD-10 codes applied. Additionally, our definition of a new narcolepsy diagnosis (ie, incidence) was based on youth having no narcolepsy diagnosis in the 1 year prior to their 2017 diagnosis. Thus, our sample may have included patients that were diagnosed with narcolepsy in previous years, as well as patients with current or prior idiopathic hypersomnia or other hypersomnia diagnoses. Given the high incidence of narcolepsy type 2 (without cataplexy) in this study, there is a need for future research exploring differential diagnosis and care trajectories for patients presenting with excessive sleepiness in the absence of cataplexy. Because subsequent narcolepsy management was similarly limited to 1 year, it is possible that patients could have received additional types of care, especially for patients that can pay out of pocket for care that is not covered by insurance. Despite these limitations, the low rates of specialty and behavioral health visits could suggest suboptimal care; we would expect patients with even a provisional narcolepsy diagnosis to be seen at least annually.

The content and quality of narcolepsy management, especially for follow-up visits with providers, is also unknown and may not have included evidence-based recommendations for behavioral management of narcolepsy. It is also possible that the other forms of care management included in this study reflected care of conditions other than narcolepsy. For instance, visits with a behavioral health provider could have been related to a behavioral health condition, although our analyses covaried for all co-occurring conditions. Future studies that longitudinally examine the content and quality of narcolepsy care, as well as patient perceptions about this care, are needed.

As noted above, our race and ethnicity data were limited to Medicaid-insured children’s claims only and there was poor representation across other racial and ethnic groups. Because of these limitations, analyses only compared Black and White children with Medicaid, and we could not include covariates, unlike in the analyses comparing diagnosis and care by insurance coverage. Thus, it could be that findings such as the difference in likelihood of stimulant medication in Black vs White children would vary if co-occurring conditions (eg, attention deficit/hyperactivity disorder) were included. The limited representation of Hispanic/Latinx youth in the narcolepsy cohort should be examined in future research on disparities in narcolepsy diagnosis. We also lack data on other important sociodemographic characteristics that could be linked to receipt of and disparities in health care services, such as family language preferences, income, and proximity to pediatric care.³⁹ Because our data were drawn from insurance claims among continuously enrolled children, our sample does not include uninsured youth or underinsured youth with gaps in coverage, who make up an increasing proportion of the pediatric population and experience significant disparities in access to care.⁴⁰

CONCLUSIONS

Collectively, our study findings suggest important future directions for enhancing access to and engagement in evidence-based narcolepsy diagnosis and care. Only about half of patients had evidence of receiving the diagnostically required PSG with MSLT evaluation, raising concerns of misdiagnosis, and there were few specialty care and behavioral health visits, even though many patients received pharmacological care. Although more research is needed to better understand potential disparities in both the frequency and quality of narcolepsy care, this study provides preliminary evidence of insurance-related disparities in receipt of diagnostic evaluation and care. In light of the considerable effect of pediatric narcolepsy on children’s and families’ well-being,^2,7,31 and the consequences of misdiagnosis,³⁰ our results highlight the need for increased provider training and multidisciplinary care team access to accurately, effectively, and equitably diagnose and address this chronic pediatric health condition.

DISCLOSURE STATEMENT

All authors have reviewed and approved this manuscript. Work for this study was performed at Children’s Hospital Philadelphia, Philadelphia, PA. This work was supported by a Children’s Hospital of Philadelphia PolicyLab & Clinical Futures pilot grant awarded to Dr. Williamson. The authors report no conflicts of interest.

ABBREVIATIONS

BH

behavioral health

CCC

complex chronic conditions

CI

confidence interval

ICD

International Classification of Diseases

MSLT

Multiple Sleep Latency Test

ND

neurodevelopmental disorder

OR

odds ratio

PSG

polysomnography

SD

standard deviation