Factor structure and measurement invariance of the Women's Health Initiative Insomnia Rating Scale.

Abstract

As part of the Women's Health Initiative Study, the 5-item Women's Health Initiative Insomnia Rating Scale (WHIIRS) was developed. This article summarizes the development of the scale through the use of responses from 66,269 postmenopausal women (mean age = 62.07 years, SD = 7.41 years). All women completed a 10-item questionnaire concerning sleep. A novel resampling technique was introduced as part of the data analysis. Principal-axes factor analysis without iteration and rotation to a varimax solution was conducted for 120,000 random samples of 1,000 women each. Use of this strategy led to the development of a scale with a highly stable factor structure. Structural equation modeling revealed no major differences in factor structure across age and race-ethnic groups. WHIIRS norms for race-ethnicity and age subgroups are detailed.

The relative importance of specific risk factors for insomnia in women treated for early‐stage breast cancer

“…Regarding alcohol intake, 16% reported none, 71% averaged ≤ 1 drink/day, 9% averaged 1−2 drinks/day, 4% averaged > 2 drinks/day. In terms of insomnia, the women averaged 7.6 ± 4.7 on the WHI-IRS, which is 15% higher than the mean of 6.6 ± 4.5 for 66 269 postmenopausal women from the WHI Study [61]. Table 1 compares high vs low WHI-IRS groups on the 10 WHI-SDS sleep items.…”

“…The WHI-SDS has shown evidence of internal consistency reliability (Cronbach's α = 0.68 in our data set). An overall insomnia score for the 5-item WHI Insomnia Rating Scale (WHI-IRS) can be calculated as the average of scores for trouble falling asleep, waking several times, waking early, trouble resuming sleep, and overall sleep quality [61]. Scores ≥ 9 indicate clinically significant insomnia; between group differences of 0.50 SD are meaningful [62].…”

“…While other cut-points on the WHI-IRS can be used, Levine et al recommend a score of 9 to minimize false-positives while maintaining acceptable sensitivity [62]. The WHI-IRS was validated in 66 269 postmenopausal women [61] and a clinical trial involving 850 postmenopausal women [40]. The WHI-IRS has a stable factor structure [61]; excellent internal consistency (Cronbach's α = 0.79 in our data set and in the validation study [62]) and test-retest (r = 0.84 for 8−14 days) reliability [62]; and, validity [41,62].…”

Menstrual pain and quality of life in women with primary dysmenorrhea: Rationale, design, and interventions of a randomized controlled trial of effects of a treadmill-based exercise intervention

“…This five-item scale was developed for evaluating insomnia symptoms [44][45][46]. Questions one through four is answered using a five-point, Likert-type scale in which 0 indicates the problem has not been experienced in the past 4 weeks, while four denotes a problem that occurs at least five times a week.…”

Effects of Conjugated Equine Estrogen on Health-Related Quality of Life in Postmenopausal Women With Hysterectomy

“…35 Items in this survey referenced sleep during the past 4 weeks. Four items assessed sleep initiation and maintenance using a 5-point response scale (not in past 4 weeks; Ͻ1 time/wk; 1-2 times/wk; 3 or 4 times/wk; Ն5 times/ wk).…”