Introduction: Since sleep is found to be a fundamental part in experiencing quality of life and health it is of importance that nurses and other health care personnel strive to improve sleep and prevent sleep disturbances. Insomnia, which is the most common form of sleep disturbances, has also been found to be related with cardiac disorders. Elderly people are especially vulnerable for poor sleep; prevention of sleep disturbances should be of regard when caring for older persons. The Minimal Insomnia Symptom Scale (MISS) is a three item screening instrument previously found to be psychometrically sound and capable of identifying insomnia in the general population (20-64 years). However, its measurement properties have not been studied in an elderly population. Our aim was to test the measurement properties of the MISS among people aged 65+ in Sweden.
Methods and materials: Data from a cross-sectional survey of 548 elderly individuals were analyzed in terms of assumptions of summation of items, reliability and optimal cut-off score by means of ROC-curve analysis and compared with self-reported insomnia criteria. The items of MISS describes the major features of insomnia, i.e. difficulties initiating sleep, waking at night and not feeling refreshed by sleep. A total score ranging between 0 and 12 is calculated, where higher scores indicate more severe insomnia.
Results: Reliability was found to be 0.81. ROC analysis where MISS was compared with self-reported insomnia criteria (i. e. day-time sleepiness, not feeling refreshed by sleep, experiencing sleep difficulties). Optimal cut-off score was identified as more or equal to 7, and sensitivity 93%, specificity 84%.
Conclusions: Data support the measurement properties of MISS as an insomnia screening instrument among elderly persons and its brevity as well as the easy scoring system makes it appealing in clinical practice.