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Introduction

Narcolepsy can be a debilitating sleep disorder caused by the dysregulation of neurophysiological pathways that control the stability of sleep and wake states in patients.1 Although narcolepsy is an uncommon condition and has an estimated worldwide prevalence of 26 to 50 per 100 000 individuals,2 narcolepsy is associated with economic burdens due to high health care resource use, substantial functional limitations, and reduced employment and work productivity for a number of patients.3,4 Studies also show that patients with narcolepsy have a higher medical and psychiatric comorbidity burden and a trend toward greater mortality relative to the general population.5-8

Onset of narcolepsy generally occurs during the patient’s second decade9,10 and a delay between symptom onset and diagnosis is commonly reported; the delay in diagnosis can take only a few years or can last ≥ 10 years,11-14 but the chronicity of narcolepsy mandates that patients receive life-long treatment regardless of the age of onset. Narcolepsy tends to be clinically defined by the symptom tetrad of excessive daytime sleepiness (EDS), cataplexy, hypnagogic or hypnopompic hallucinations, and sleep paralysis15; recent recognition that polysomnography (PSG) can characterize the symptom of disturbed nocturnal sleep often reported by patients suggests that narcolepsy actually comprises a symptom pentad.16 However, patients typically do not show all 5 symptoms. Investigators recently validated short rapid eye movement sleep latency (≤ 15 minutes) on nocturnal PSG as a biomarker with a high specificity of 99.2% (95% CI, 98.5–100.0) and a sensitivity of 50.6% (95% CI, 46.3–54.9) for narcolepsy diagnosis.17

Several lines of research support an autoimmune explanation for narcolepsy, such as associating the condition with seasonal streptococcus infections, H1N1 influenza and vaccination,18 and the identification of a specific genotype of the human leukocyte antigen, HLA-DQB1*06.19 This genotype may underlie the observed loss of hypocretin (orexin)-producing neurons associated with narcolepsy.20 Consequently, using hypocretin as a biological marker to confirm the diagnosis of narcolepsy was incorporated into the Diagnostic and Statistical Manual (fifth edition), which recommends hypocretin assessment in cerebrospinal fluid as a confirmatory diagnostic test when narcolepsy is suspected.21 However, hypocretin levels in cerebrospinal fluid are not typically used to diagnose narcolepsy because hypocretin testing is not widely available for clinical use.

Although research has increased the overall knowledge of narcolepsy, no published studies have characterized awareness and perceptions of this condition in the general population or among physicians. Therefore, our study surveyed individuals drawn from the general population and a representative sample of physicians, including sleep specialists, to quantitatively evaluate their understanding and perceptions of narcolepsy. Such characterization may identify gaps or misconceptions that can be targeted to improve diagnosis and overall care of narcolepsy patients.

Methods

The Awareness and Knowledge of Narcolepsy (AWAKEN) study was conducted in the United States by Harris Interactive and consisted of 2 online surveys: 1 in the general population and the other among physicians (Article Appendix). Harris Interactive was commissioned to undertake these surveys by Jazz Pharmaceuticals, with input from the Narcolepsy Network, Wake Up Narcolepsy, and the National Sleep Foundation.

The sample for the general population survey was drawn from the Harris Poll Online Panel and consisted of 1000 qualified respondents aged ≥ 18 years who responded to 1 of the 12 813 invitations that were sent to individuals. The online panel consists of several million members globally who consented to be contacted for public opinion surveys and who were recruited from multiple, vetted sources including social media, websites, and telephone recruitment of targeted populations.

For inclusion in the physician sample, physicians had to be in practice between 2 and 30 years, spend ≥ 75% of their professional time in direct patient care, and have no affiliation with any pharmaceutical, biotechnology, or medical device company other than for clinical trials. The sample consisted of 300 primary care physicians (PCPs; general practice, family practice, and internal medicine) who treat ≥ 50 patients per month for any condition (609 physicians responded to 3500 sent invitations), and 100 sleep medicine specialists (neurologists, psychiatrists, pulmonologists, and PCPs), which resulted from 622 physicians responding to 1905 invitations. Sleep specialists were identified based on a definition using the above criteria plus self-reported data about the number of patients treated for sleep disorders each month; physicians were required to treat ≥ 30 patients for sleep disorders per month to qualify. Additionally, PCPs were required to be board certified in sleep medicine to qualify as sleep specialists.

The surveys were expected to take 15 to 20 minutes to complete and were conducted between May 11 and 23, 2012 via an online survey instrument hosted by Harris Interactive. E-mails sent to participants included a URL link to the survey website and a password that protected participant anonymity and ensured that the participant could take the survey only once. Questions in both surveys were designed to capture information on the participant’s knowledge and perceptions of narcolepsy, including its symptoms and its impact. The physician survey had additional questions relating to diagnosis.

The general population data were weighted to 2011 US Census parameters22 for education, age by gender, race/ethnicity, region, and household income to bring them in line with the population of US residents aged ≥ 18 years. The weighting algorithm also included a propensity score that adjusted for attitudinal and behavioral differences between subjects who are online versus those who are not, subjects who join online panels versus those who do not, and subjects who responded to this survey versus those who did not.

Physician data were weighted to American Medical Association Physician Masterfile23 parameters for gender by years in practice, region, and specialty to help them fit the profiles of PCPs, neurologists, psychiatrists, and pulmonologists in the United States. Other qualifications such as years in practice, number of patients seen per month, and the number of patients with sleep disorders seen per month (for sleep specialists) were considered.

Descriptive analysis was performed using 2-tailed t tests with a significance of P < 0.05.

Results
Survey Populations

Characteristics of the 2 survey populations are shown in Table 1. General population respondents were mainly white (70%), were approximately evenly distributed by gender, and had a mean age of 46.3 years. Physician respondents were predominantly male in both the PCP (56%) and sleep specialist subpopulations (67%), and the mean age was similar for both PCPs and sleep specialists (~48 years). Primary care physicians were almost exclusively and evenly distributed between family practice (47%) and internal medicine (50%). Sleep specialists concentrated primarily in psychiatry (49%), neurology (20%), and pulmonology (11%). Although board certification in sleep medicine was reported by 36% of the sleep specialists, only 1% of PCPs were board certified in sleep medicine.

View: Table 1
Characteristics of the Survey Populations
Characteristic
General population US Adults (N = 1000)
Gender, %
 Female 51
 Male 49
Mean age, y 46.3
Race, %
 White 70
 Black/African American 11
 Hispanic 13
 Other 3
 Declined to answer 3
Physicians (N = 400) PCPs (n = 300) Sleep Specialists (n = 100)
Gender, %
 Male 56 67
 Female 44 33
Mean age, y 48.0 47.6
Specialty, %
 Family practice 47 9a
 General practice 3 0
 Internal medicine 50 11
 Neurology 0 20a
 Psychiatry 0 49a
 Pulmonary diseases 0 11a
Board certified in sleep medicine, % 1 36a
Patients seen and/or treated for sleep disorders per month per physician, mean ± SD (range) 50.5 ± 39.6 (0–333) 98.5 ± 59.9 (30–400)a

aP < 0.05 relative to PCPs.

Abbreviations: PCP, primary care physician; SD, standard deviation.

Narcolepsy Awareness and Knowledge

The majority (70%) of the general population respondents had heard of narcolepsy. However, only 7% of these individuals reported being “very” or “extremely” knowledgeable about it (Figure 1A) and ranked narcolepsy at about the same level as Parkinson’s disease. Further measures of narcolepsy knowledge in the general population discussed in the following sections of this article include all survey respondents who indicated they had heard of narcolepsy.

View: Figure 1
Perceptions of narcolepsy relative to other diseases. (A) Proportion of respondents who reported being “very” or “extremely” knowledgeable about narcolepsy. (B) Proportion of respondents who considered narcolepsy a “very” or “extremely” serious condition.

*P < 0.05 versus general population; P < 0.05 versus primary care physicians.

Although knowledge of narcolepsy was significantly higher among physicians compared with the general population, knowledge of the condition was generally low; 62% of sleep specialists and 24% of PCPs reported being “very” or “extremely” knowledgeable (Figure 1A). This level of knowledge was lower than for other sleep disorders, including sleep apnea and restless legs syndrome. Of the board-certified sleep specialists, 84% reported being “very” or “extremely” knowledgeable about narcolepsy, but only 49% of non–board-certified sleep specialists reported these levels of knowledge. Knowledge was also higher among non-psychiatrist sleep specialists; 80% reported being “very” or “extremely” knowledgeable about narcolepsy compared with 42% of psychiatric sleep specialists.

The majority of general population and physician respondents perceived narcolepsy as a “very” or “extremely” serious condition (Figure 1B), but it was perceived as among the lowest in disease severity across all respondent groups; only restless legs syndrome was considered less severe than narcolepsy by physicians, and both restless legs syndrome and sleep apnea had lower severity ratings than narcolepsy among the general population.

Impact of Narcolepsy

There was generally low recognition of the impact of narcolepsy. Fifty percent of sleep specialists, 46% of PCPs, and 32% of the general population considered narcolepsy to be a condition that is a public health concern. Similarly, the perceived economic impact of narcolepsy was low; only 52% of sleep specialists, 38% of PCPs, and 24% of the general population thought that narcolepsy conveys a significant economic burden. Relative to the general population, significantly higher proportions of physicians perceived narcolepsy to have an impact on patients as well as on family, friends, and caregivers with regard to health status, daily function, and social relationships (P < 0.05; Figure 2). Except for the recognition by physicians that narcolepsy can similarly impact social relationships among patients, family, friends, and caregivers, the impact of narcolepsy was consistently perceived as higher for patients (Figure 2).

View: Figure 2
Perceived impact of narcolepsy on patients and caregivers with regard to: (A) overall health; (B) relationships with family/friends/caregivers; (C) quality of life; and (D) ability to function/perform on a daily basis. General population bars in each panel represent survey respondents who have heard of narcolepsy.

*P < 0.05 versus family/friends/caregivers; P < 0.05 versus general population.

Among participants who said that narcolepsy has an impact on patients in any way, the risk of accidents was the most commonly identified consequence of narcolepsy across the 3 respondent populations, and sleep specialists showed significantly lower recognition (59%; P < 0.05) relative to PCPs (71%) and the general population (74%). Career and job problems were the second most recognized consequence, with similar proportions across the respondent populations (61%–63%). However, the proportion of sleep specialists who acknowledged the psychological impact (depression and anxiety) of narcolepsy (53%) was significantly higher compared with PCPs and the general population (39% and 40%, respectively; P < 0.05). Nevertheless this identification was made by approximately half of the specialists. Across the respondent groups, the economic and social outcomes of narcolepsy were poorly recognized. The belief that narcolepsy causes a financial burden to patients was expressed by 11%, 18%, and 20% of the general population, PCPs, and sleep specialists, respectively; the lack of social or community involvement by patients with narcolepsy was identified by 24% to 26% of respondents.

Diagnosis and Management

There was low awareness that narcolepsy is associated with children and young adults in all populations and awareness was lowest among PCPs. An association of narcolepsy with children (aged 5–12 years) and adolescents (aged 13–17 years) was recognized by 14% and 4% of PCPs, respectively. Similarly, low proportions of sleep specialists (12%) and the general population (12%) associated narcolepsy with children, and somewhat higher proportions of sleep specialists (24%) and the general population (20%) acknowledged that narcolepsy can be present in teenagers.

Recognition of individual narcolepsy symptoms was consistently low in the general population and most of the symptoms were not identified by PCPs; however, sleep specialists had a higher rate of symptom recognition (Figure 3). In particular, there was substantially lower awareness of the nocturnal symptoms associated with narcolepsy relative to other symptoms. Of the 5 key symptoms, EDS was most recognized by PCPs (64%) and the general population (46%); sleep specialists had higher recognition of cataplexy (82%), followed by EDS (70%). Less than half of sleep specialists (41%) identified disruptive nocturnal sleep as a narcolepsy symptom. Sixty-three percent of sleep specialists and 39% of PCPs identified both EDS and cataplexy, the two symptoms most commonly associated with narcolepsy, and recognition of both of these symptoms was higher among the non–board-certified sleep specialists (71% vs 49%). More board-certified than non–board-certified sleep specialists recognized all 5 key symptoms of narcolepsy (30% vs 18%, respectively), but the identification of individual symptoms varied for both groups of sleep specialists (Table 2). Identification of the 2 key symptoms was 69% among psychiatrists, compared with 57% of non-psychiatrists, but recognition of all 5 symptoms was low among psychiatrists (17%) and non-psychiatrists (28%).

View: Table 2
Recognition of Narcolepsy Symptoms Among Sleep Specialists Stratified by Board Certification
Narcolepsy Symptom Percentage of Physicians
Board-Certified Sleep Specialists (n = 36) Non–Board-Certified Sleep Specialists (n = 64)
All 5 symptoms 30% 18%
Excessive daytime sleepiness 54% 79%
Cataplexy 70% 90%
Sleep paralysis 56% 62%
Hypnagogic hallucinations 66% 57%
Disruptive nocturnal sleep 46% 38%
View: Figure 3
Recognition of individual narcolepsy symptoms. General population bars represent survey respondents who have heard of narcolepsy.

*P < 0.05 versus general population; P < 0.05 versus primary care physicians.

Comfort with diagnosing narcolepsy was low, even among sleep specialists (Figure 4A). Nearly one quarter of sleep specialists (22%) and 53% of PCPs reported not being comfortable diagnosing narcolepsy. Conversely, 42% of sleep specialists and 9% of PCPs felt “very” or “extremely” comfortable diagnosing the disease. When sleep specialists were stratified by certification, higher comfort with diagnosis was observed among those who were board certified (59% vs 32%; Figure 4B). However, 11% of those who were board certified still stated discomfort with making such a diagnosis (Figure 4B). Non-psychiatric sleep specialists were more comfortable making a narcolepsy diagnosis (60% reported being “very” or “extremely” comfortable), whereas only 23% of psychiatrists felt comfortable diagnosing the condition.

View: Figure 4
Comfort level of physicians for making a narcolepsy diagnosis, which includes (A) primary care physicians and sleep specialists; and (B) sleep specialists stratified by board certification.

*P < 0.05 versus sleep specialists; P < 0.05 versus primary care physicians.

Multiple visits and referrals to other physicians were both reported to be a common occurrence prior to a narcolepsy diagnosis. Sleep specialists estimated that patients had an average of 6.6 visits to physicians before receiving a confirmed diagnosis of narcolepsy. Furthermore, 80% of PCPs stated that they refer patients who present with narcolepsy symptoms to a specialist and 54% of sleep specialists also reported referring their patients to another specialist (Figure 5). Tests that may assist in diagnosis were administered or ordered by less than half of physicians (Figure 5), even among sleep specialists. In particular, sleep specialists reported using PSG (46%) or a Multiple Sleep Latency Test (MSLT; 47%) when narcolepsy was suspected.

View: Figure 5
Frequency of physician referrals and requested tests when a patient presents with narcolepsy symptoms

*P < 0.05 versus sleep specialists; P < 0.05 versus primary care physicians.

Abbreviations: ESS, Epworth Sleepiness Scale; MSLT, Multiple Sleep Latency Test; PSG, polysomnography.

When the clinical options for a patient presenting with potential symptoms of narcolepsy were stratified by physicians who were board certified, use of diagnostic tests was lower among physicians who were not board certified. Only 40% of the non–board-certified sleep specialists used PSG or MSLT, and 24% administered the Epworth Sleepiness Scale compared with the 55%, 59%, and 52% of board-certified physicians who used these tests, respectively; 62% of non–board-certified sleep specialists referred patients to a specialist, compared with 41% of board-certified specialists. Similarly, when stratified by psychiatric versus non-psychiatric sleep specialists, the psychiatrists reported a higher referral rate (74%) relative to non-psychiatrists (36%). Fewer psychiatrists than non-psychiatrists used diagnostic tests such as PSG (25% vs 65%), MSLT (25% vs 68%), and the Epworth Sleepiness Scale (17% vs 51%).

Discussion

Our survey is the first study to characterize the basic understanding and perceptions of narcolepsy in the general population and among physicians. The survey highlights that although there was an overall awareness of narcolepsy among the study populations, there was also a lack of knowledge about the condition. The lack of awareness in the general population was not entirely unexpected, given that narcolepsy is a rare and unpublicized disease. However, substantial gaps of knowledge were evident in clinician recognition of narcolepsy and its symptoms, even among physicians and board-certified sleep specialists; these gaps likely contribute to the low level of comfort that physicians also expressed in diagnosing this condition.

Fewer PCPs recognized specific key narcolepsy symptoms compared with sleep specialists, but overall symptom identification was low, even among sleep specialists; < 1 in 4 sleep specialists were familiar with all 5 symptoms comprising the narcolepsy pentad. The lack of symptom recognition among sleep specialists may have been driven by the high proportion of psychiatrists, who generally considered themselves less knowledgeable than non-psychiatric sleep specialists; however, recognition of all 5 symptoms was nevertheless only 30% among physicians board certified in sleep medicine.

Despite published studies on the socioeconomic burden of narcolepsy,3,4,2426 few survey participants acknowledged the impact of narcolepsy on patients or families or its consideration as a public health issue. The higher recognition of the psychological impact of narcolepsy among sleep specialists compared with other survey participants likely resulted from the presence of the psychiatrists in this respondent group. Interestingly, the identification of accident risk was highest in the general population; such a risk is important from the safety perspective because narcolepsy may be associated with driving and work-related accidents.27,28

With additional regard to the burden of narcolepsy, it should be noted that few survey respondents, both in the general and physician populations, recognized that narcolepsy is often associated with children and young adults. This lack of awareness may be of special concern for several reasons. In addition to affecting scholastic achievement in children,29 age of narcolepsy onset and age of diagnosis have been suggested to modulate the disease-related burden such that an earlier diagnosis improves occupational prognosis and aspects of living.26 Furthermore, lack of recognition in an early age group may potentially contribute to the delay in diagnosis that has consistently been reported for narcolepsy.11-14 Several other findings from this survey support the presence of a delayed diagnosis, including the report of multiple visits prior to diagnosis and frequent referrals of patients with narcolepsy symptoms, even among sleep specialists. In fact, referrals was the most common strategy reported even among sleep specialists, and was more frequent than testing with PSG or MSLT, both of which are recommended,30 but were performed or ordered by less than half of the sleep specialists.

Although the overall results of this survey are unique because these specific perspectives were not previously evaluated, the data are consistent with reports of a difficult path to the diagnosis of narcolepsy for patients12,14,31 and provide reasons for the complexity of this journey (ie, the low awareness of early onset, unfamiliarity with symptoms, and low comfort level for diagnosis). Importantly, the presence of comorbidities is common in patients with narcolepsy.5,6 These comorbidities may result in misdiagnosis, especially in children and adolescents32,33; comorbidities further exacerbate the difficulty of diagnosis and increase the importance of timely symptom recognition with the performance of appropriate diagnostic tests.

It is important to consider the study limitations when interpreting or generalizing the results of our survey. As with all surveys, the possibility of potential selection bias exists because individuals who agreed to participate may have characteristics and perceptions different from those who did not agree to participate. Another limitation was the relatively low proportion of board-certified sleep specialists in the sample of sleep medicine physicians compared with non–board-certified specialists. A final limitation of the study was the disproportionate representation of psychiatrists (49%) relative to other physicians within the sample of sleep specialists. Both the low proportion of board-certified sleep specialists and the high proportion of psychiatrists likely resulted from use of a definition of sleep specialists that was of our own design; treatment of > 30 patients with sleep disorders per month was the primary criterion, which is believed to be adequate for differentiating sleep specialists from those who occasionally saw patients with sleep disorders. However, an important point to consider is that in clinical practice, it is likely that not all physicians treating patients with narcolepsy are board-certified in sleep medicine or even sleep specialists. A population more representative of sleep specialists, using more traditional criteria for identification, such as board-certification in sleep medicine or membership in the American Academy of Sleep Medicine, may provide different results and perspectives.

Conclusion

The lack of knowledge about narcolepsy expressed in the general population and in physicians indicates a need for educational initiatives to raise narcolepsy awareness, especially among the specialists who must recognize and treat this disease. Appropriate programs should focus on increasing symptom recognition and providing information on the availability of diagnostic tests that can be used. Additionally, these initiatives should not only target physicians, but should include nurse practitioners, physician assistants, and other healthcare providers as well. Educational programs should also provide information to individuals who have narcolepsy or those who care for patients with narcolepsy. Dialogue between individuals and their healthcare providers regarding symptoms and their impact should be increased; both patients and healthcare providers should feel equally comfortable initiating the discussions.

Our survey aims to be a first step in further evaluation of the existing knowledge gaps in narcolepsy diagnosis and to provide the impetus for the development of educational programs which target a broad population. Increased awareness and knowledge about narcolepsy and its symptoms is integral for patients to receive earlier diagnosis, medical attention, and appropriate treatment, which can help reduce the patient and societal burden of narcolepsy.

Open-access expire date: 
Mon, 06/23/2014