Elsevier

Sleep Medicine

Volume 5, Issue 1, January 2004, Pages 37-41
Sleep Medicine

Original article
Factors associated with a delay in the diagnosis of narcolepsy

https://doi.org/10.1016/j.sleep.2003.06.002Get rights and content

Abstract

Background: There can be a long interval from the onset of symptoms before a diagnosis of narcolepsy is made. There are no multivariate analyses reported in the literature of factors that may contribute to this delay. The aims of this study were to describe the delay in diagnosis of people with narcolepsy living in the UK and to identify associated factors.

Methods: The study comprised a postal survey of 500 members of the Narcolepsy Association UK, which included questions regarding age of onset of symptoms, year of diagnosis and subject demographics. Cox's proportional hazards regression was performed.

Results: A total of 313 questionnaires were returned of which 219 had been completed sufficiently for analysis. The interval between symptom onset and diagnosis ranged from within 1 to 61 years with a median of 10.5 years. Multivariate analysis showed that the presence of cataplexy as one of the initial symptoms and a more recent year of symptom onset were the only factors associated with time to diagnosis.

Conclusions: We have confirmed that the diagnosis of narcolepsy can be delayed for many years particularly when cataplexy is absent initially. The delay in diagnosis in the UK appears to be decreasing, probably through greater doctor and patient awareness of the clinical manifestations of narcolepsy.

Introduction

Narcolepsy is classically characterised by a tetrad of symptoms; excessive daytime sleepiness (EDS), cataplexy, sleep paralysis and hypnagogic hallucinations [1], although other symptoms are now recognised [2]. Not all four symptoms are necessary for diagnosis and the majority of people with narcolepsy do not have all of them [1], [3], [4], [5], [6], [7].

The symptoms of narcolepsy usually, but not necessarily, start in the second or third decades of life [1], [3], [4], [5], [6], [8], [9], [10], [11], [12], [13] and new symptoms can develop over many years [3], [4], [5], [9], [10], [11], [13].

Delays between the first symptom and diagnosis have been reported to range from 1 to 60 years [13], with a mean delay of between 16 and 22 years [14], [15], [16]. Patients with a more recent onset of symptoms have been reported to have a shorter interval before they were diagnosed compared to those whose symptoms started further in the past [15]. A reduction in time to diagnosis has also been shown in people with more recent dates of birth [17]. Factors such as mild- or late-onset cataplexy, concomitant sleep apnoea and socio-economic factors can also contribute to a delay in diagnosis [18].

The aim of this study was to investigate the reported delay between symptom onset and diagnosis in people with narcolepsy living in the United Kingdom. Relationships were sought between the delay in diagnosis and; age at symptom onset, year of symptom onset, presence of cataplexy as an initial symptom, number of initial symptoms, gender and who made the diagnosis.

Section snippets

Subjects and questionnaire

A questionnaire was sent to 500 members of the Narcolepsy Association UK (UKAN), randomly selected by the UKAN membership secretary from their confidential database. The total membership of UKAN was unknown at the time of the study.

The questionnaire asked which of the tetrad of narcolepsy symptoms were present, the age at onset of these symptoms, year of diagnosis, who made the diagnosis, and general subject demographics including age at time of questionnaire completion. To be included in the

Subjects

A total of 313 questionnaires (63%) were returned and 219 (70%) of these were complete and were analysed. These 219 subjects had the same gender distribution as the 94 whose questionnaires had missing data (P=0.705), but were significantly younger at the time of the questionnaire (P=0.009).

The majority of subjects were female (59.4%). They were aged between 12 and 83 years (median=54 years). EDS was reported by 98.2% of subjects, cataplexy (C) by 90%, hypnagogic hallucinations (HH) by 73.1%,

Discussion

We have described the symptom evolution and the interval between symptom onset and a diagnosis of narcolepsy being made in a sample taken from the membership of the Narcolepsy Association UK, all of whom specified that their GP or a hospital consultant had diagnosed them with narcolepsy. Excessive daytime sleepiness was reported by 98% of the subjects and a high percentage of subjects reported the additional symptoms of cataplexy, sleep paralysis and hypnagogic hallucinations. The age at onset

Acknowledgments

We would like to thank both the administration of the Narcolepsy Association UK for their help in posting the survey to their members and those who completed it. We would also like to thank the Research and Development department at Papworth Hospital for their help, particularly Susan Charman for her assistance with the statistical analysis.

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