There has always been some questions in my mind about the common tests for fatigue and sleepiness with myotonic dystrophy. A new study from the Netherlands confirms this. They have developed a new modified scale that works much better for myotonic dystrophy patients.
Introduction: Fatigue and excessive daytime
sleepiness are frequent complaints in myotonic dystrophy type
1 (DM1) that often overlap. We aimed to construct a combined
fatigue and daytime sleepiness rating scale for DM1 using the
Rasch measurement model.Methods: Questionnaires, including
the Epworth Sleepiness Scale, Fatigue Severity Scale, and
Daytime Sleepiness Scale, were completed by 354 patients.
Data were subjected to Rasch analyses and tested for required
measurement issues such as appropriate response categories,
absence of item bias, local independence, and unidimensional-
Results: The initial 22 items did not meet Rasch model
expectations. After rescoring and removing misfitting items, the
final 12-item scale showed good model fit and unidimensional-
ity. High internal consistency (person separation index ¼
0.80)and validity were demonstrated
Conclusions: The Rasch-builtFatigue and Daytime Sleepiness Scale, developed specifically for DM1 patients, provides interval measures on a single contin-
uum. Its use is suggested for future clinical trials and therapeutic follow-up.