STABILITY OF CATAPLEXY OVER SEVERAL MONTHS - INFORMATION FOR THE DESIGN OF THERAPEUTIC TRIALS

Twenty-seven narcoleptic patients severely affected with cataplexy com pleted four symptom diaries over a 4-month period in order to clarify some of the controversies surrounding assessment of anticataplectic me dications. The home diary method was found to be a viable model for th e assessment of anticataplectic activity. Assessment of reliability in 1-, 2-, 3-, 4-, 5- and 10-day intervals indicated that reliability in creases with the number of days included. A 10-day design was found to be optimal. Reliability decreased, however, with each successive diar y over the 4-month period. Power analysis indicates that two groups of 30-40 subjects in a parallel design, or one group of 30-40 subjects i n a crossover design, would be sufficient to demonstrate a significant therapeutic anticataplectic effect in most cases. A ''first diary eff ect'' was observed, suggesting that a training period prior to the act ual trial might improve reliability. Whether the patient was treated o r untreated with stimulant medications did not affect severity or fluc tuation of cataplexy, suggesting that both groups of patients could be included in therapeutic trials. No time-of-day fluctuation was observ ed in the daily distribution of cataplexy attacks. Sudden increases in cataplexy were often, although not always, caused by unusual emotiona l events or sleepiness. The finding of a long-lasting ''precataplectic '' feeling or ''aura'' pointed to the need to carefully clarify the sy mptom prior to beginning a therapeutic trial.