Factors associated with a delay in the diagnosis of narcolepsy

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.

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.

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.

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.