Further evidence for the reliability and validity of the Fatigue and Daytime Sleepiness Scale.
BACKGROUND
Myotonic dystrophy type 1 (DM1) is an inherited neuromuscular disease causing, among other symptoms, fatigue and excessive daytime sleepiness, which are frequently undifferentiated by patients and/or clinicians. The Fatigue and Daytime Sleepiness Scale (FDSS) has been devised to measure these two overlapping symptoms as a single clinical entity.


OBJECTIVE
To further examine the reliability and the construct validity of the FDSS in patients with DM1.


METHODS
The scale was administered to 48 DM1 patients on two occasions at a 2week-interval. Intra-rater reliability and internal consistency were established by calculating the intraclass correlation coefficient (ICC) and Cronbach's alpha, respectively. Construct validity was assessed by using the known-group method. More precisely, the mean FDSS score of patients with and without subjective complaints of fatigue and/or sleepiness was compared.


RESULTS
The FDSS showed good intra-rater reliability (ICC=0.83) and acceptable internal consistency (Cronbach's alpha =0.6). Also, the FDSS was able to distinguish between patients who had fatigue and sleepiness complaints from those who did not (mean FDSS score of 10.6 vs 8.0, p=0.01), suggesting good construct validity.


CONCLUSIONS
Overall, the present study supports the continued use of the FDSS as a reliable and valid instrument to measure fatigue and daytime sleepiness in patients with DM1 for either clinical or research purposes.
Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux du Saguenay-Lac-St-Jean, Hôpital de Jonquière, Saguenay, Québec, Canada; Centre de recherche Charles-Le-Moyne, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada.
Benjamin
B
Gallais
Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux du Saguenay-Lac-St-Jean, Hôpital de Jonquière, Saguenay, Québec, Canada; Centre de recherche Charles-Le-Moyne, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Québec, Canada.
Cynthia
C
Gagnon
Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux du Saguenay-Lac-St-Jean, Hôpital de Jonquière, Saguenay, Québec, Canada; Département des sciences de la santé, Université du Québec à Chicoutimi, Saguenay, Québec, Canada.
Geneviève
G
Forgues
Groupe de recherche interdisciplinaire sur les maladies neuromusculaires (GRIMN), Centre intégré universitaire de santé et de services sociaux du Saguenay-Lac-St-Jean, Hôpital de Jonquière, Saguenay, Québec, Canada.
Isabelle
I
Côté
ÉCOBES - Recherche et transfert, Cégep de Jonquière, Saguenay, Québec, Canada; Département des sciences de la santé, Université du Québec à Chicoutimi, Saguenay, Québec, Canada. Electronic address: luclaberge@cegepjonquiere.ca.
Luc
L
Laberge
D000328:Adult; D006970:Disorders of Excessive Somnolence / Q000175:diagnosis* / Q000209:etiology*; D005221:Fatigue / Q000175:diagnosis* / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009223:Myotonic Dystrophy / Q000150:complications*; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D055815:Young Adult
Daytime sleepiness; Fatigue; Myotonic dystrophy; Outcome assessment; Reliability; Validity