Psychometric properties of the Medical Outcomes Study Sleep measure

Abstract

Background and purpose: Sleep is an active and highly organized biological process that is an important component of life. Self-report measures of sleep provide information that can be useful for characterizing the quality of sleep in subgroups of the population. A 12-item self-report sleep measure, the Medical Outcomes Study Sleep measure, was developed and evaluated previously in a sample of 3445 individuals with chronic illness.

Patients and methods: In this study, we evaluate the psychometric properties of the MOS Sleep measure in a nationally representative sample of 1011 US adults aged 18 and older and in a sample of 173 adults with neuropathic pain participating in a clinical drug trial.

Results: The average age of the general population sample was 46; 51% were female and 81% were white. The average age of the sample of adults with neuropathic pain was 72; 53% were female and 95% were white. Internal consistency reliability estimates for the MOS Sleep scales were 0.73 or higher, with the exception of the daytime somnolence scale in the US general population, which was 0.63. At baseline of the clinical trial, the neuropathic pain patients reported significantly more sleep disturbance and daytime somnolence, as well as less quantity and adequacy of sleep than patients in the general US population. The MOS Sleep scales were found to be responsive to change in the clinical trial with statistically significant improvements observed after administration of pregabalin for sleep disturbance (standardized response mean, SRM=−0.76, P=0.0007), shortness of breath (SRM=−0.20, P=0.0302), sleep adequacy (SRM=0.57, P=0.0014), sleep quantity (SRM=0.55, P=0.0086), and sleep problems (SRM=−0.62, P=0.0036).

Conclusions. This study provides further support for the reliability and validity of the MOS Sleep measure. The instrument can be used to assess important aspects of sleep perceived by adults in the general population or participating in clinical studies.

Introduction

Sleep is an active and highly organized biological process that is an important component of life. For example, quantity of sleep has been found to be associated with quality of social interaction [1], but sleep is a multi-dimensional construct that includes how long it takes to fall asleep, the duration and quality of the sleep, and the extent to which sleep is perceived to be adequate.

A 12-item self-report sleep measure was developed in the Medical Outcomes Study (MOS) to provide a concise assessment of important dimensions of sleep, including initiation, maintenance, respiratory problems, quantity, perceived adequacy, and somnolence [2]. The MOS sleep scale was developed at the same time and is similar, but not identical, in content to the Pittsburgh Sleep Quality Index, a measure that includes several more questions about sleep disturbance and a total of seven more items overall [3]. Preliminary support for the MOS sleep measure was provided in the developmental sample of 3445 individuals with chronic illness who participated in the cross-sectional phase of the MOS. Analyses of this data set showed that insomnia had about an equal independent association with worse SF-36 scores as was found for chronic conditions such as congestive heart failure and clinical depression [4]. Similarly, a study of 70 African–Americans over the age of 65 years found that HRQOL scores of persons with sleep apnea were similar to patients with depression and chronic obstructive pulmonary disease [5]. Manocchia et al. [6] reported that sleep problems reported on the MOS Sleep measure by chronically ill patients were associated with poorer mental health, diminished work productivity and lower work quality.

This study extends this work by evaluating the psychometric properties of the measure in the US general population and in a sample of individuals with neuropathic pain participating in a clinical trial.