Health-related quality of life in narcolepsy

Health-related quality of life in narcolepsy

EMMA DAN IEL S , MART IN A . K ING , IAN E . SM ITH and

JOHN M . SHNEERSONRespiratory Support and Sleep Centre, Papworth Hospital, Cambridge, UK

Accepted in revised form 30 October 2000; received 1 March 2000

INTRODUCTION

Narcolepsy is a sleep disorder characterised by two main

symptoms; excessive daytime sleepiness with sleep attacks, and

cataplexy (sudden loss of muscle tone brought on by emotion).

Onset is usually in the second or third decades of life, although

around 6% of narcoleptics have symptoms before they are

10-years-old (Broughton and Broughton 1994). Narcolepsy

can a�ect performance at school, obtaining and maintaining

employment, formation of relationships, family life and

participation in social activities.

There is no cure for narcolepsy, but the severity of daytime

sleepiness can be reduced by stimulant medication, and

antidepressants are used to suppress cataplexy. It can be

di�cult to ®nd the optimum dose of stimulant medication with

which sleepiness is improved without the induction of side-

e�ects.

There have been previous reports of the psychosocial e�ects

of narcolepsy from a small number of authors (Broughton and

Ghanem 1976; Broughton et al. 1981; Kales et al. 1982;

Broughton et al. 1983; Broughton et al. 1984; Rogers 1984;

Alaia 1992; Broughton 1992a, b), but few concerning subject-

ive reports of how narcoleptics perceive their own health status

in terms of functional and emotional status and general well-

being (Ferrans et al. 1992; Beusterien et al. 1999). Broughton

et al. (1981) compared the life e�ects of narcolepsy in three

di�erent countries, but there has been no large United

Kingdom (UK) study and many published reports are more

than 15-years-old.

The aim of this study is to describe the health status and

psychosocial aspects of those with narcolepsy in the UK,

compared to normative data, and to assess the relationship of

drug treatment for the symptoms of narcolepsy.Correspondence: Miss Emma Daniels, Respiratory Support and Sleep

Centre, Papworth Hospital, Papworth Everard, Cambridge, CB3 8RE,

UK. Tel.: 01480 830541 (ext. 4170); Fax: 01480 830620; e-mail:

[email protected]

J. Sleep Res. (2001) 10, 75±81

SUMMARY Narcolepsy is a chronic sleep disorder characterised by symptoms of excessive daytime

sleepiness and cataplexy. The aim of this study was to describe the health-related

quality of life of people with narcolepsy residing in the UK. The study comprised a

postal survey of 500 members of the UK narcolepsy patient association, which included

amongst other questions the UK Short Form 36 (SF-36), the Beck Depression

Inventory (BDI), and the Ullanlinna Narcolepsy Scale (UNS). A total of 305

questionnaires were included in the ®nal analysis. The results showed that the subjects

had signi®cantly lower median scores on all eight domains of the SF-36 than normative

data, and scored particularly poorly for the domains of role physical, energy/vitality,

and social functioning. The BDI indicated that 56.9% of subjects had some degree of

depression. In addition, many individuals described limitations on their education,

home, work and social life caused by their symptoms. There was little di�erence

between the groups receiving di�erent types of medication. This study is the largest of

its type in the UK, although the limitations of using a sample from a patient association

have been recognised. The results are consistent with studies of narcolepsy in other

countries in demonstrating the extensive impact of this disorder on health-related

quality of life.

KEYWORDS amphetamines, excessive daytime sleepiness, narcolepsy, psychosocial

e�ects, quality of life, Short Form 36

Ó 2001 European Sleep Research Society 75

METHODS

Subjects

A questionnaire was sent to 500 members of the United

Kingdom Association of Narcolepsy (UKAN). These were

randomly selected by the UKAN membership secretary from

the UKAN con®dential database. The total membership of

UKAN was unknown at the time of the study.

Instruments

The questionnaire was divided into three sections. The ®rst

section comprised: questions regarding subjects' age and sex;

their diagnosis and treatment of narcolepsy; other concurrent

conditions; the Ullanlinna narcolepsy scale (UNS) (Hublin

et al. 1994a); and psychosocial aspects of narcolepsy. The

second section comprised the UK Short Form 36 health survey

questionnaire (SF-36) (Brazier et al. 1992; Garratt et al. 1993)

and the third section comprised the Beck depression inventory

(BDI) (Beck et al. 1961).

Ullanlinna narcolepsy scale

The UNS is an epidemiological tool designed to diagnose

narcolepsy (Hublin et al. 1994a). It comprises 11 questions

about sleepiness and cataplexy, each of which has ®ve possible

answers. Each answer is allocated a score between 0 and 4,

giving a total possible score of 0±44. A higher score indicates

more severe and frequent symptoms. The authors suggest that

a score greater than or equal to 14 indicates a diagnosis of

narcolepsy.

Psychosocial aspects

The questions regarding the psychosocial aspects of narcolepsy

were designed speci®cally for this study. They enquired

whether having narcolepsy had caused avoidance of, or

problems with, di�erent aspects of life such as school, work,

relationships, home and recreation. In addition to answering

speci®c questions, subjects were invited to add further com-

ments about particular problems they had experienced due to

narcolepsy.

Short form 36

The health status of the subjects was assessed using the SF-36

(Garratt et al. 1993), a widely used and validated question-

naire (Brazier et al. 1992; Jenkinson et al. 1993), which

quanti®es subjective reports of health in terms of functional

status, emotional status and general well being. The SF-36

comprises 36 questions divided into the following eight

domains representing di�erent aspects of health status:

1 Physical functioning, which is the subject's ability to walk up

stairs, carry groceries and so forth.

2 Role limitations due to physical problems, i.e. whether

physical health has caused problems with everyday life.

3 Role limitations due to emotional problems, i.e. whether

emotional health has caused problems with everyday life.

4 Social functioning, which is how emotional or physical

health has a�ected normal social activities.

5 Mental health, which is a re¯ection of mood.

6 Energy/vitality.

7 Bodily pain.

8 General health perceptions.

Thus the dimensions e�ectively cover functional status, well-

being and overall evaluation of health (Brazier et al. 1992).

A lower score indicates poorer health status.

Beck depression inventory

The prevalence and severity of depression was measured by the

BDI (Beck et al. 1961). This comprises 21 questions each with

four possible answers which are allocated a higher score the

more severe the symptom. The total possible score range is

0±63. The higher the total score, the more severely depressed

the subject is.

Data handling and statistical analysis

All questionnaires were checked for completeness of the age

and sex categories, and for the medication that was being

taken for narcolepsy. Subjects who had not speci®ed their age

or gender, or who were under 18 years of age, were removed

from the dataset. Subjects taking moda®nil were also excluded

from the dataset as they formed too small a group for separate

analysis.

The SF-36 was scored according to the instructions outlined

in the UK SF-36 analysis and interpretation manual (Jenkin-

son et al. 1996). The UNS was scored according to the method

outlined in the paper by Hublin et al. (1994a). The BDI was

scored in the conventional way and the scores divided into the

following severity categories as suggested by normative data

(Bowling 1991): normal (no depression) 0±9; mild depression

10±15; mild-moderate depression 16±19; moderate-severe

depression 20±29; severe depression > 29.

The SPSS computer package was used for statistical

analysis. The relationships between the UNS score and each

of the eight SF-36 domain scores, and the UNS score with the

BDI were tested using the Kendall Correlation Coe�cients.

Each subject was allocated the mean normative score for each

SF-36 dimension according to their age and sex. These values

were taken from Jenkinson et al. (1996) for those under the age

of 65 years and from data used in the paper by Sharples et al.

(2000) for those aged 65 years and over. There is no UK

published data that covers the whole age range required for

this study. The two studies cited above are similar in that they

both used general practitioner lists to randomly select people

from the general population. They di�er in terms of the area of

the UK that the people were selected from, and how the survey

was administered (postal vs. face-to-face interview). There has

been no analysis to show if and how these di�erences may

a�ect the results. A Wilcoxon Matched-Pairs Signed Ranks

76 E. Daniels et al.

Ó 2001 European Sleep Research Society, J. Sleep Res., 10, 75±81

Test was used to compare the UKAN SF-36 data with the

normative data, as none of the UKAN SF-36 scale scores

followed a normal distribution.

The subjects were divided into four groups according to the

combination of medication they were taking for narcolepsy

(Table 1). Cross-tabulation using a chi-square test was used to

ensure there were no di�erences in sex distribution between the

four groups. Kruskal±Wallis one-way analysis of variance was

used to test for di�erences in age distribution, SF-36 domain

scores and BDI scores. The Mann±Whitney U-test was used

where appropriate to assess whether any one particular

medication group had signi®cantly di�erent SF-36 or BDI

scores to the other groups.

RESULTS

A total of 313 questionnaires were returned anonymously to

the Sleep Centre, Papworth Hospital (return rate � 62.6%).

One subject was excluded for not specifying their gender, three

were excluded for being under the age of 18 years, and four

were excluded for taking moda®nil. Thus the total number of

subjects included in the analysis was 305.

Of the 305 subjects, 60.7% were female. The age range was

18 years to 89 years, with a median of 56 years. Almost half

(48.9%) were diagnosed with narcolepsy by a neurologist,

28.5% were diagnosed by hospital consultants with di�erent

specialities and 18.4% by their general practitioner. The

earliest diagnosis of narcolepsy recorded in the UKAN

population was in 1927. An increasing number of people

received a diagnosis over each decade and 32.1% of the

population were diagnosed from 1990 to the time of the survey

in 1997. Only 26.6% reported that they had regular appoint-

ments with a consultant or general practitioner to review their

narcolepsy. The UNS scores of the UKAN population ranged

from 4 to 43 with a median of 22. Two hundred and seventy

people had a UNS score greater or equal to 14, which has been

suggested to indicate a diagnosis of narcolepsy (Hublin et al.

1994a).

Psychosocial aspects

The percentages of the UKAN population who answered

positively to each of the psychosocial questions are listed in

Table 2. Additional comments included being unable to bath

when alone in the house because of the risk of falling asleep

and problems using electrical and gas appliances. Subjects also

reported being punished at school by teachers who thought

they were lazy.

Beck depression inventory

The BDI scores of the UKAN population ranged from 0 (no

depression) to 48 (severe depression) with a median score of

11, which falls into the mild depression category. The BDI

indicated that 56.9% of the UKAN population were depressed

(BDI ³ 10) with moderate or severe depression (BDI ³ 20) in

15.1% of responders. There was no correlation between the

UNS score and the BDI.

SF-36

The SF-36 scores showed great variability in all dimensions.

There was no correlation between the UNS score and any of

the SF-36 scale scores. The UKAN group had signi®cantly

Table 1 Narcolepsy medication

Group number Medication type Number in sample

1 Stimulant and anticataplexy 61

2 Stimulant only 148

3 Anti-cataplexy only 22

4 Neither stimulant or anticataplexy 74

Table 2 Psychosocial impact of narcolepsy:

percentage of positive replies to questions that

inquired whether having narcolepsy had cau-

sed avoidance, or problems with di�erent

aspects of life

Category Problem

Percentage of

positive replies

Di�culty with school due Di�culty concentrating in class 57.7

to symptoms Frequent days o� school 9.5

Achieving less than capable of 55.4

Di�culty making friends 17.0

Being bullied or teased 19.0

Di�culty with work Unable to use quali®cations gained 28.2

due to symptoms Lost or left a job 36.7

Di�culty with relationships Limited opportunity to meet potential partners 27.2

due to symptoms Caused a relationship to end 18.7

Di�culty in the home Cooking 38.7

due to symptoms Ironing 27.9

Bathing children 13.4

Supervising children 31.5

Di�culty with leisure Taking holidays 37.4

activities due to Visiting the cinema/theatre 76.7

symptoms Visiting the pub or night-clubs 39.0

Attending sports events 25.9

Playing sports 39.7

Quality of life in narcolepsy 77


lower SF-36 scores on all scales than age and sex matched

normative data (Fig. 1). The scale that showed the greatest

di�erence between medians was role limitation due to physical

problems, followed by (in descending order): energy/vitality,

social functioning, role limitation due to emotional problems,

general health perceptions, mental health, physical functioning

and bodily pain.

Medication subgroups

There was no signi®cant di�erence in the sex distribution or

age distribution between the four medication groups. The only

SF-36 domains in which a signi®cant di�erence was seen

between medication groups 1±4 (Table 1), were physical

function (P � 0.003) and social function (P � 0.048). Those

who took both stimulant and anticataplexy medication (group

1) had signi®cantly lower scores, indicating poorer health

status than the rest of the sample population for both of these

scales. Group 1 also had the lowest median score for the other

six scales but the di�erences were not signi®cant.

There was a signi®cant di�erence in the BDI scores between

the four medication groups (P � 0.02) with the mean rank for

group 1 being higher than the mean ranks for the other three

groups. A comparison of the BDI scores for group 1 with the

other three groups combined together showed that the scores

of group 1 were signi®cantly higher, indicating more severe

depression than the rest of the UKAN population

(P � 0.0002).

DISCUSSION

The results of this study show that members of UKAN have a

poorer health status, as measured by all eight scales of the SF-

36, than the general UK population. It has also shown that

narcolepsy has a detrimental e�ect on the psychosocial aspects

of life and that over half of the sample are depressed to some

extent. These results are consistent with studies regarding

people with narcolepsy living in other countries (Roth and

Nevsimalova 1975; Broughton and Ghanem 1976; Broughton

et al. 1981; Broughton et al. 1983; Broughton et al. 1984;

Ferrans et al. 1992; Broughton 1992b; Merritt et al. 1992;

Yang and Clerk 1998), except for one study which showed

even greater e�ects (Alaia 1992).

The greatest e�ect of narcolepsy in this study, as re¯ected by

the SF-36, is on role limitation due to physical problems (role

physical). Physical health limited the subjects by restricting the

type of, and the amount of time spent on, work or other

Figure 1. Median SF-36 scores of UKAN sample and age-sex matched normative data.



activities. They had not accomplished as much as they had

hoped and/or had di�culties performing work or other

activities. Narcoleptics commonly avoid situations which

could be embarrassing or harmful if they were to fall asleep

inappropriately or have cataplexy.

The biggest reported impact of narcolepsy was on leisure

activities such as visiting the cinema or theatre (76.7%),

playing sports (39.7%) and taking holidays (37.4%).

Narcolepsy also a�ected schooling, with over 50% having

di�culty concentrating in class and feeling that they had

achieved less than they were capable. Presumably in the

majority of these cases, narcolepsy had remained untreated at

this important time as only 8% of the sample had received a

diagnosis by 16 years of age with a further 14.5% being

diagnosed by the age of 21 years. The earliest age of diagnosis

was 10 years (n � 3). Almost 20% of the sample were bullied,

teased or had di�culty making friends. After leaving school,

27% have been unable to use the quali®cations they did gain

and 36.7% have lost or left a job because of narcolepsy. It has

been reported that many narcoleptics perceive that their job

performance has deteriorated due to memory and concentra-

tion problems, which they attribute to narcolepsy (Broughton

and Ghanem 1976,; Broughton et al. 1981; Alaia 1992).

The subjects reported di�culty in performing everyday tasks

such as cooking (38.7%), ironing (27.9%), or supervising

children (31.5%). Other studies have shown that narcoleptics

have more accidents when driving (Alaia 1992), at home, at

work, and attributable to smoking than the general population

(Broughton et al. 1981; Broughton et al. 1984; Broughton

1992a, b; Cohen et al. 1992).

It has been suggested that the accumulation of all these

e�ects of narcolepsy can cause deterioration in emotional

health (Broughton and Ghanem 1976; Kales et al. 1982; Alaia

1992). It has also been proposed that depression may be

endogenous to narcolepsy (Roth and Nevsimalova 1975;

Broughton et al. 1981), as abnormalities in rapid eye move-

ment (REM) sleep, such as reduced REM sleep latency, are

common to depression and narcolepsy (Broughton et al.

1981). In the current study, 56.9% of participants were

depressed to some extent, as re¯ected by the BDI scores, and

as a group the narcolepsy sample had signi®cantly poorer

scores on the SF-36 domain role limitation due to emotional

health, than a sample from the UK general population. The

prevalence of depression in this sample is similar to that found

in other studies (Broughton and Ghanem 1976; Broughton

et al. 1981; Broughton et al. 1983; Broughton et al. 1984;

Mosko et al. 1989; Merritt et al. 1992).

The energy/vitality scale was the second most a�ected aspect

of health status in the UKAN sample compared to normative

data. People with narcolepsy have excessive daytime sleepi-

ness, with unwelcome sleep attacks rather than feelings of

physical tiredness, although they may have di�culty distin-

guishing between the meanings of the two when faced with a

questionnaire with no accompanying explanation. Sleepiness

may have been better measured in our group by the Epworth

Sleepiness Score (ESS) (Johns 1991). There is only a moder-

ately close correlation between the ESS and the SF-36 energy/

vitality scale (Briones et al. 1996).

A similar pattern of impairment of health status has been

shown using the SF-36 in a North American population of

narcoleptics who were not taking any stimulant medication

(Beusterien et al. 1999). Themajority of our subjectswere taking

stimulant and/or anticataplexy medication. However, whatever

the medication combination being taken, health status was not

returned to normal. In our study, those who were taking both

stimulant and anti-cataplexy treatment had signi®cantly lower

scores for two of the eight SF-36 domains, and signi®cantly

higher scores for the BDI than the other three medication

groups. The results show that the treatments being used are not

su�ciently e�ective to restore health status to normal. Mosko

et al. (1989) reported that depression associatedwith narcolepsy

did not improve with stimulant medication and Merrit et al.

(1992) reported a greater prevalence of depression in narcolepsy

than in the general population, which was independent of

pharmacological treatment. It has also been found that some

narcoleptics choose to put up with some of their symptoms

because the drug-induced side-e�ects are worse (Alaia 1992).

Only a quarter of the UKAN population reported having

regular follow-up appointments with their general practitioner

or consultant to review their narcolepsy symptoms, and

presumably the medication of the others is not being checked

regularly to see if it is optimal. Almost a quarter of

respondents were taking no medication at all, and nearly

three-quarters were not taking speci®c anti-cataplexy medica-

tion, although two-thirds of these may be obtaining some relief

from cataplexy from their stimulant medication. These results

suggest that the drug management of most people with

narcolepsy is inadequate.

The new non-amphetamine wake-promoting drug moda®nil

has been shown to produce higher scores than a placebo for

the role physical, energy/vitality, social function and role

emotional on the SF-36 in narcoleptics. But even with this and

careful patient management, the majority of scores did not

return to normal (Beusterien et al. 1999). The number of

subjects in our survey taking moda®nil was too small to enable

any statistical comparisons to be made with this study.

Even though our study shows that narcolepsy has a

detrimental e�ect on health status, it did not ®nd any

correlation between the severity of the two main symptoms,

as re¯ected by the UNS, and the BDI or SF-36 scale scores.

One possible reason is that worsening narcolepsy symptoms do

not progressively impair health status. Some other authors

have shown that depression is not related to the severity of

symptoms in narcolepsy (Alaia 1992), although other research

has shown the opposite.

It is possible that the UNS does not truly re¯ect the severity

of narcolepsy. Using speci®c scoring criteria duplicated in the

current study, the UNS was reported to be 98.8% speci®c and

100% sensitive in determining the narcoleptic syndrome

(Hublin et al. 1994a). However, in a subsequent survey of

the Finnish Twin Cohort, 75 people met the UNS scoring

criteria for narcolepsy; but after further examination, a



diagnosis of narcolepsy was only veri®ed in three people, i.e.

4% of the original 75 (Hublin et al. 1994b). This suggests that

the UNS is not as reliable for diagnosing narcolepsy or

determining its severity as was ®rst claimed.

Since the survey used in the current study was designed and

completed, two more questionnaires have been developed and

validated in a bid to diagnose narcolepsy without laboratory

investigations or clinical interview by a sleep disorder specialist

(Parkes et al. 1998; Anic-Labat et al. 1999). These could be

considered for use in addition to, or as an alternative to theUNS.

The sample used for the current study was taken from

members of UKAN, an association for people with narco-

lepsy. It may not be representative of the total UK narcolepsy

population, and some members may not have a de®nite

diagnosis of narcolepsy. It could be that only those with

particularly severe symptoms of narcolepsy join a support

group, but equally the support of the association may improve

their health status. The questionnaire was returned by 62.6%

of those to whom it was sent, who may not be representative of

the original 500. The majority of people who took part in the

survey were female, when no di�erence in sex ratio was

expected. These factors should be taken into account in the

interpretation of the results, but it is unlikely that any other

methodology could provide information about such a large

sample of those with narcolepsy living in the UK where there

are few sleep centres carrying out full diagnostic procedures.

Despite its limitations, the current study has the advantage

of being based on a larger UK narcolepsy population than any

other health-related quality of life study. It is apparent that the

symptoms of narcolepsy a�ect many aspects of working, home

and social life. Although patients receive treatment for their

symptoms, mainly with conventional amphetamine and/or

anticataplexy medication, their health-related quality of life

remains much poorer than that of the general UK population.

ACKNOWLEDGEMENTS

We would like to thank both the administration of the

Narcolepsy Association UK (UKAN) 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 and advice.

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