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Psychosomatic Medicine 67:98-104 (2005)
© 2005 American Psychosomatic Society

ORIGINAL ARTICLES

Validation of the Women’s Health Initiative Insomnia Rating Scale in a Multicenter Controlled Clinical Trial

Douglas W. Levine, PhD, Margaret E. Dailey, PhD, Beverly Rockhill, PhD, Diane Tipping, MS, Michelle J. Naughton, PhD and Sally A. Shumaker, PhD

From the University of South Carolina, Columbia, South Carolina (D.W.L.); Wake Forest University School of Medicine, Winston-Salem, NC (M.E.D., M.J.N., S.A.S.); the University of North Carolina, Chapel Hill, North Carolina (B.R.); and Tipping Associates, Green Lane, PA (D.T.).

Address correspondence and reprint requests to Douglas W. Levine, PFRC, University of South Carolina, 1334 Sumter St., Columbia, SC 29201. E-mail: levined{at}gwm.sc.edu


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 METHOD
 RESULTS
 DISCUSSION
 NOTES
 REFERENCES
 
Objective: The objective of this study was to evaluate the construct validity of the five-item Women’s Health Initiative Insomnia Rating Scale (WHIIRS) by comparing women taking hormone therapy (HT) versus those taking a placebo and by comparing women known to differ in vasomotor symptoms.

Methods: The WHIIRS was included in two phase III randomized trials intended to evaluate the efficacy of a combination estradiol plus and norethindrone acetate transdermal delivery system in reducing vasomotor symptoms. In all, 850 healthy postmenopausal women participated in these studies. Both trials were double-blind, one was placebo-controlled and the other was positive-controlled. The former trial admitted women with ≥8 hot flashes/day and lasted 12 weeks with data collected on the WHIIRS at baseline, 4, 8, and 12 weeks. The other trial had no entry criteria pertaining to hot flashes and lasted 52 weeks with WHIIRS data collected at baseline, 12, 24, and 52 weeks.

Results: The WHIIRS was sensitive to the effect of HT on sleep disturbance over time. The WHIIRS also detected differences in self-reported sleep disturbance between women with mild vasomotor symptoms compared with those with moderate to severe symptoms. As expected, the study using a positive control revealed that sleep improved over time (p <.0001). Also as predicted, the study using a placebo control found that sleep disturbance in the treatment groups improved at a faster rate than in the control groups (p = .035).

Conclusion: The construct validity of the WHIIRS was supported because it was successfully used to detect self-reported sleep disturbance differences in women taking HT versus those taking a placebo as well as in groups known to differ in severity of their vasomotor symptoms.

Key Words: construct validity • hormone therapy • insomnia scale • quality of life • randomized clinical trial • sleep

Abbreviations: ANOVA = analysis of variance; CES-D = Center for Epidemiologic Studies Depression Scale; E2 = estradiol 50 µg; HT = hormone therapy; NETA = norethindrone acetate; RPR = Rhône-Poulenc Rorer; WHI=Women’s Health Initiative; WHIIRS=Women’s Health Initiative Insomnia Rating Scale.


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
METHOD
 RESULTS
 DISCUSSION
 NOTES
 REFERENCES
 
Sleepdisturbance and insomnia are highly prevalent in society. It has been estimated that 60 million Americans suffer from insomnia annually, and this number is expected to grow to 100 million by the middle of the 21st century (1). Epidemiologic studies often show that women and older people are more likely to have accompanying psychologic distress, somatic anxiety, major depression, and multiple health problems (2–6). Given the prevalence and importance of sleep disorders, many clinical and observational trials now assess sleep difficulties as an essential element of quality of life.

The need for a brief, reliable, and well-validated measure of sleep disorders prompted the Women’s Health Initiative (WHI) Behavioral Advisory Committee to develop its own set of items in the early 1990s at a time when there was no widely used valid short scale. The WHI is one of the world’s largest investigations of the determinants of common causes of morbidity and mortality in postmenopausal women. A total of 161,809 women were enrolled in the various arms of the study. The purpose of the current study is to evaluate the construct validity of the Women’s Health Initiative Insomnia Rating Scale (WHIIRS), a measure of perceived insomnia symptoms. The WHIIRS was first validated using a WHI sample (7,8), but this is the first investigation of this scale in a non-WHI sample.

Psychometric work on the WHIIRS was conducted using a sample of almost 70,000 WHI participants (7,8). The five-item WHIIRS was developed using a novel resampling method. In this resampling study, 120,000 separate factor analyses were conducted with 1000 women in each sample. The factor analyses showed the WHIIRS has desirable measurement properties. The scale has a stable one-factor solution, and multigroup structural equation modeling found that the factor structure was stable across age and race/ethnic groups. The internal consistency averaged 0.78. Short-term test–retest reliability was excellent. Content validity was assessed by comparing the WHIIRS against the definitions of insomnia in the major nosologies (9–11). This assessment revealed that the WHIIRS items corresponded to the majority of insomnia characteristics noted in the nosologies and the literature. In addition, the content of the WHIIRS was compared with other sleep measures. Construct validity was investigated by examining the relationships between the WHIIRS and measures known to be related to sleep (eg, the Center for Epidemiologic Studies–Depression [CES-D]), which were found to be in the predicted directions. Norms for this scale were based on 66,269 women and were provided by age and race/ethnic groups.

In a different sample of 459 WHI women (8), responses on the WHIIRS were compared against objective measures of sleep as measured by a wrist activity recorder. The women wore the recorder for a week to monitor sleep and wakefulness both at home and while active in the community. Results showed that differences in sleep latency, sleep efficiency, and wake-after-sleep-onset, as measured by the recorder, could be detected by the WHIIRS. These results were taken as supporting the construct validity of the instrument.

Neither of the previous psychometric studies of the WHIIRS (7,8) included interventions that could affect sleep. The current study investigates the validity of the WHIIRS in two clinical trials that assessed sleep disturbance in postmenopausal women who received hormone therapy (HT).

Self-reports from women indicate that they perceive increased sleep disturbance during menopause (12–23). There is a growing body of work indicating that vasomotor and other climacteric symptoms are associated with sleep disturbance (8,24–27). This is such a common observation that Empson and Purdie (28), echoing the view of many researchers, commented, "It is widely assumed that the disturbed sleep is a consequence of arousals triggered by night sweats" (p. 142). The association between vasomotor symptoms and reported sleep disturbance has led researchers to investigate whether HT can improve sleep. In general, these studies found that self-reported sleep complaints are reduced by HT (29–31). The most convincing findings regarding the effect of HT on self-reported sleep come from randomized, double-blind, placebo-controlled clinical trials. Most of these clinical trials indicated that HT was associated with improved subjective sleep compared with those not given HT (32–40). Clinical trials that did not find effects of HT on self-reported sleep have had small samples, used single-item sleep measures (eg, respondent checked "insomnia" on a symptom checklist), and/or the participants did not exhibit sleep disruption at baseline so their sleep could not be improved (41–43).

One recent clinical trial is particularly relevant to the current investigation because it used the WHIIRS (33). The reported results come from the estrogen plus progestin component of the WHI primary prevention trial, which was designed to assess the major health benefits and risks of estrogen plus progestin. The main outcomes were coronary heart disease and invasive breast cancer. This was not a trial to investigate the effects of HT on vasomotor symptoms and, in fact, "Women who reported moderate or severe menopausal symptoms during the washout period were discouraged from participating in the study but were not excluded." (33). Thus, inclusion in the WHI trial was not based on menopausal symptomatology. This study nevertheless found a small but statistically significant improvement in sleep in women enrolled in the HT group compared with the placebo group. For the subset of 564 women 50 to 54 years old who reported moderate or severe vasomotor symptoms, the effect was larger, although the effect size was small. These results are consistent with the other clinical trials cited here and indicate some effect of HT on self-reported sleep, especially in women reporting vasomotor symptoms.

How HT improves sleep in peri- and postmenopausal women is uncertain. It is alternatively hypothesized that 1) HT indirectly affects sleep by reducing the climacteric symptoms that cause nighttime wakefulness, 2) hormones participate directly in sleep regulation, or 3) HT both directly and indirectly affects sleep (19,20,25,27,44–47). The exact nature of the causal relationships among HT, vasomotor symptoms, and sleep quality, although of obvious biologic and clinical concern, is not of primary concern in this scale validation study. Validation of the WHIIRS as a measure of perceived insomnia symptoms does not depend on whether the causal relationships are direct or are mediated by other variables. The literature cited indicates that self-reported sleep should improve in women taking HT, and evidence for construct validity is obtained if the scale detects that change.

As noted, the cited literature also indicates that women who experience greater vasomotor symptoms report more sleep disruption. Although it may be that sleep disruption is a consequence of the temperature-regulating disruption of hot flashes and night sweats, this assumption is not necessary to validate the scale. If sleep is disrupted in women who have vasomotor symptoms for reasons other than temperature regulation, construct validity is evidenced if the WHIIRS can detect the sleep differences between women with and without vasomotor symptoms.

Some of the most powerful evidence of construct validity (48) is based on either experimental intervention (eg, drug/placebo studies) or from groups known to differ on the construct under investigation (eg, those with and without vasomotor symptoms should differ in sleep disturbance); both of these design components were included in the current study. The two Rhône-Poulenc Rorer (RPR) phase III randomized trials of the combination patch estradiol/norethindrone acetate (CombiPatch) reported here provided an opportunity to investigate the construct validity of the WHIIRS in women who 1) were randomly assigned to hormone therapy conditions (experimental groups) and 2) differed in the severity of their vasomotor symptoms (known natural groups).

In this investigation, then, construct validity is supported by findings that: 1) yield differences in reported sleep disturbance between those known to have mild vasomotor symptoms versus those with moderate-to-severe symptoms; 2) show improvements in self-reported sleep across time (ie, pre- vs. post-HT use) for women in all trial 1 treatment groups because all participants in this trial received HT; and 3) show improvements in self-reported sleep over time for women in the trial 2 active treatment groups compared with the placebo groups in this trial (ie, a treatment group by time interaction).


   METHOD
TOP
 ABSTRACT
 INTRODUCTION
 METHOD
RESULTS
 DISCUSSION
 NOTES
 REFERENCES
 
Sleep Measure
The WHIIRS consists of five items (see Table 1). Four of these items are related either to initiation insomnia, maintenance insomnia, or early morning awakening; the last item is related to sleep quality (see (7) for more on the development and use of the scale).


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  		TABLE 1. Items Used in the WHI Insomnia Rating Scale

 

Participants
In total, 850 women participated in the two phase III multicenter longitudinal investigations of the efficacy and safety of CombiPatch. Table 2 shows the number of women participating in each trial as well as their average ages. All trials were reviewed by Institutional Review Boards and conformed to the Declaration of Helsinki. The major eligibility criteria common to both studies were: healthy postmenopausal women aged 40 to 70 years with an intact uterus; no menses for at least 1 year; follicle-stimulating hormone level above 40 mIU/mL and serum estradiol levels <20 pg/mL; normal pelvic, PAP smear, and mammogram examinations; no major contraindications to estrogen therapy; ability and willingness to complete daily diary records; and ability to understand fully all study procedures and provide written informed consent. Unique eligibility criteria are described in the appropriate subsequent sections.


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  		TABLE 2. Characteristics of the CombiPatch Studies

 

The major exclusion criteria were: current endometrial hyperplasia; unexplained vaginal bleeding; any use of HT with estrogens or progestins taken in the 4 weeks preceding the baseline screening visit; any nonhormonal therapy for hot flashes or menopausal symptoms in the 2 weeks before the screening visit; any use of lipid-lowering drugs within the 3 months before baseline; allergic dermatitis or eczema; intolerance of estrogen or progestin or any patch; known or suspected malignancies or carcinoma; and documented or active thrombophlebitis or active coagulation disorders.

The major postadmission exclusion criteria were: a serious drug-related adverse event; development of endometrial hyperplasia; chronic systemic glucocorticoid therapy; or withdrawal of patient’s consent.

Procedures
The characteristics of these two trials are summarized in Table 2. Because these data were collected as part of an investigation of the safety and efficacy of CombiPatch, the two trials shared numerous common features. CombiPatch consisted of 50 µg/day 17-ß estradiol (E2) and one of the following doses of norethindrone acetate (NETA): 140, 250, or 400 µg/day. The trials also included either a placebo or a positive control group. Placebo patches were made in the size and shape of the E2 and each of the three CombiPatches. The administration of these patches is described subsequently for each trial. The positive control groups consisted of E2 alone (Vivelle or Menorest). Patches were placed on a clean, dry spot on one side of the lower abdomen below the waistline and left there for 3.5 days. If a patch fell off, a replacement patch was applied to the same location and removed according to the original schedule. After 3.5 days, a new patch was applied to the other side of the abdomen for the prescribed time. This procedure was repeated throughout the duration of the trial.

Daily diaries were completed to assess the presence and number of hot flashes. These diaries were begun several weeks before the baseline visit and were continued through the completion of the study. Quality-of-life questionnaires (including the WHIIRS) were completed at baseline and at several times during the trials.

Trial 1
This was a randomized, double-blind, positive-controlled, multicenter study of the effects of three doses of CombiPatch on endometrial hyperplasia and vasomotor symptoms in postmenopausal women. CombiPatch was worn continuously, meaning that either an E2 transdermal patch (positive control) or one of three CombiPatches (E2/NETA; 50/140, 50/250, or 50/400) was worn for all 28 days of each cycle. The study lasted 13 28-day cycles or 52 weeks. To ensure that the investigation remained double-blind, women in the control group wore a matching placebo CombiPatch and women in the combination patch group wore a placebo E2 patch. Because the different CombiPatches differed in size, there were three control groups, one corresponding to each treatment group. This was true of both trials. There was no inclusion criterion related to the number of vasomotor symptoms. Daily diaries began 2 weeks before baseline and continued throughout the trial. The WHIIRS was completed in the clinics at baseline, 12, 24, and 52 weeks.

Trial 2
This was a 12-week (three 28-day cycles), randomized, double-blind, placebo-controlled, multicenter study. To be included in the trial, women were required to have moderate-to-severe menopausal symptomatology (≥8 hot flashes/day in the past 2 weeks). The method was the same as trial 1 except that the positive control (E2) was replaced by a placebo control. Before baseline and randomization, women completed a 28-day run-in period using placebo patches. The daily diaries started during this period and continued through the end of the study. The WHIIRS was completed in the clinics at baseline, 4, 8, and 12 weeks.

Statistical Analyses
Analyses of Dropouts and Check on Vasomotor Status
One-way analysis of variance (ANOVA) was used to compare women who dropped out with women who remained in the trial.

Merging Transdermal CombiPatch Groups
To reduce the number of analyses presented here, we desired to combine the three transdermal combination treatment groups (ie, CombiPatch 50/140, 50/250, 50/400) because HT was known to affect vasomotor symptoms. We also desired to combine the three associated control groups used in each of the studies. A mixed-model repeated-measures analysis was used to determine whether treatment groups could be combined into one treatment group and whether the placebo groups could be combined into a single placebo group. If we observed statistically significant CombiPatch group by time interactions, that would indicate that the groups should not be combined.

Validity Analyses
Groups Differing in Vasomotor Symptoms (ie, Known Groups)
A one-way ANOVA was used to examine whether the WHIIRS could detect sleep disturbance in groups known to differ in vasomotor symptoms. The baseline responses of women in trial 1 (ie, no vasomotor inclusion criteria) were compared with the baseline responses of those in trial 2 (ie, inclusion criterion of ≥8 hot flashes/day in the 2 weeks before baseline). The women in this latter trial were expected to have, on average, more vasomotor symptoms than those in the former trial and hence should report more disturbed sleep. Only baseline WHIIRS scores were compared because HT eliminates vasomotor symptoms quickly; thus, WHIIRS scores were not expected to differ across treatment groups at later time points.

Effect of Hormone Therapy (ie, Experimentally Manipulated Groups)
These analyses were intended to examine whether the WHIIRS could detect the effect of the HT on self-reported sleep over time. We expected that those receiving HT would show improvements in reported sleep and in vasomotor symptoms over time. To examine the validity of the WHIIRS, we used an HT treatment group by time mixed-model repeated-measures analysis that tested the treatment effect over time on hot flashes and the WHIIRS. Because a positive control group was used in trial 1, we expected that analyses of these data would yield only a time main effect for both number of hot flashes and WHIIRS scores. For trial 2, which included a placebo control, the most important effect expected was an HT group by time interaction. This interaction would indicate that HT and placebo groups differed in the pattern of reported sleep disruption or vasomotor symptom relief across time. Main effects for time and HT group were also possible, although these effects would not be important in light of an HT group by time interaction. In the presence of a statistically significant HT group by time interaction, we examined the differences between the treatment groups at each time point (ie, the simple effects) to isolate the source of the interaction effect (49).

All statistical tests were two-sided at an {alpha} level of 0.05. For the mixed-model analyses, the degrees of freedom were adjusted using the Huynh-Feldt estimator of Box’s epsilon. This adjusts for the degree to which the circularity assumption may have been violated (49). For the simple-effects analyses, degrees of freedom were based on the smaller of those yielded by the Huynh-Feldt adjustment or the Satterthwaite approximation (49). This somewhat conservative approach ensures that the type I error is maintained at or below its nominal level (ie, {alpha} = 0.05).


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 METHOD
 RESULTS
DISCUSSION
 NOTES
 REFERENCES
 
Comparisons of Dropouts With Participants
Table 3 presents the percentage of patients not continuing in the trials. The majority of these dropouts were the result of adverse events associated with the drug. For example, in trial 1, Table 3 shows that 624 women were randomly assigned to one of the drug groups. Across all four conditions, 24% of women discontinued treatment over the course of the yearlong study; 17.31% stopped because of an adverse event. Not surprisingly, more women dropped out of the yearlong trial 1 than dropped out of the 12-week trial 2. For the purposes of investigating the validity of the WHIIRS, we analyzed whether there were baseline differences on both the WHIIRS and the average number of hot flashes between those who dropped out of the trial and those that did not. In trials 1 and 2, there were no statistically significant differences between the means on either the WHIIRS or the number of hot flashes for those who dropped out and for those did not.


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  		TABLE 3. Number Dropping Out of the Trial by Time and Reason (Adverse Reaction vs. Other)

 

Merging Transdermal Combination Groups
As discussed previously, both trials included three CombiPatch treatment groups and three control groups. To simplify the presentation of results, we investigated whether the treatment groups could be combined. To do this, we compared the treatment groups over time and then separately did the same with the control groups. In the 8 separate analyses (ie, using hot flashes and the WHIIRS scores as the dependent variables, treatment and control groups were analyzed separately, and this was done for both trials independently), there were no statistically significant group-by-time interactions for either hot flashes or the insomnia scale, which indicated that within each trial, the treatment groups could be combined and the control groups could be merged for both vasomotor and insomnia scores.

Validity Analyses
Two main hypotheses regarding the WHIIRS were investigated. First, the introduction of hormone therapy should reduce sleep complaints. Second, those women known to have more severe vasomotor symptoms should report more sleep disturbance on the WHIIRS.

Effect of Hormone Therapy
These analyses were intended to examine whether the WHIIRS could detect the effect of HT over time. For trial 1 (no entry criterion, positive control), the analysis revealed, as expected, no interaction and a diminution in symptoms over time (ie, a time main effect) for both number of hot flashes (p <.0001) and WHIIRS (p <.0001). The top two panels in Figure 1 show the means for the WHIIRS and the number of hot flashes plotted across time for this trial. The curves for the active control and treatment groups were fairly parallel across time and this was especially true for the hot flashes. The difference between the mean of the treatment group at baseline and at the end of trial was 2.5 (standard deviation [SD] = 4.0) for hot flashes and 1.8 (SD = 4.5) for the WHIIRS. The mean differences for the control group were: 1.9 (SD = 3.2) for hot flashes and 0.7 (SD = 4.5) for the WHIIRS.



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  		Figure 1. Changes in outcomes over time by treatment condition and by trial.

 

Trial 2 used a placebo control rather than a positive control group. In this case, the results were again as predicted. The bottom two panels in Figure 1 show the means for the WHIIRS and the number of hot flashes. It is evident that symptoms were more severe in this trial, which is not surprising because participants needed to meet the entry criterion. Another notable aspect of the lower two panels is that the curves are no longer parallel across time. This is, of course, what produced the statistically significant HT group by time interactions (hot flashes: p <.0001; WHIIRS: p = .035). These interactions indicated that the active treatment groups were improving at a faster rate than the placebo control groups. The difference between the mean of the treatment group at baseline and end of trial was 8.96 (SD = 3.3) for hot flashes and 4.79 (SD = 5.0) for the WHIIRS. The mean differences for the control group were smaller: 5.42 (SD = 3.6) for hot flashes and 2.97 (SD = 3.8) for the WHIIRS. The analyses of simple effects revealed that the control group and the treatment groups differed at all time points except baseline on both number of hot flashes and the WHIIRS (eg, at 12 weeks, for hot flashes, p <.0001; for the WHIIRS, p = .046).

Groups Differing in Vasomotor Symptoms
The average number of hot flashes at baseline was 2.58 (SD = 3.9) for trial 1 (no entry criterion group) and 10.44 (SD = 3.4) for trial 2 (≥8 hot flashes/day group). The difference between these means was statistically significant (p <.0001).

To determine whether the WHIIRS could detect differences between known groups with varying vasomotor symptoms, we compared baseline scores for trials 1 and 2. This analysis revealed that women known to have mild vasomotor symptoms had on average a lower self-reported insomnia score (mean = 7.56, SD = 5.0) compared with women known to have more severe vasomotor symptoms (mean = 10.37, SD = 5.1); the difference between these means was statistically significant (p <.0001). In addition, the difference between these means was approximately 0.56 of a SD, which is above the approximate guide of one half a SD that Levine et al. (8) suggested might indicate a clinically meaningful difference on the WHIIRS.


   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 METHOD
 RESULTS
 DISCUSSION
NOTES
 REFERENCES
 
The results of this study provide support for the construct validity of the WHIIRS. The scale detected differences in self-reported sleep disturbance in the active HT therapy versus a placebo control group. The WHIIRS also detected differences in self-reported sleep between those known to have mild vasomotor symptoms versus those with moderate to severe symptoms. Equally important, the WHIIRS did not detect differences that should not exist. A positive control was used in trial 1 and, thus, there should have been no differences between treatment and control groups on the WHIIRS. None was found. These findings are consistent with the literature showing HT improves sleep disturbance and also with the literature showing that vasomotor symptoms are associated with sleep disturbance. The construct validity of the WHIIRS is bolstered by these results.

This research focused on the validity of the WHIIRS as a measure of perceived insomnia. We did not explore the mechanism underlying the association between HT and sleep improvement in women experiencing climacteric symptoms. That is, we did not investigate whether HT affects sleep directly, indirectly, or both directly and indirectly. This study also did not, for example, address the assumption of many sleep researchers that there is a causal relationship between vasomotor symptoms and self-reported sleep (ie, sleep disruption is a consequence of the temperature-regulating disruption of hot flashes and night sweats). Addressing this assumption is not, however, necessary to validate the scale. If sleep is disrupted in women who have vasomotor symptoms for reasons other than temperature regulation, construct validity is nonetheless supported by results that indicate that the WHIIRS can detect the sleep differences between women with and without vasomotor symptoms as would be expected based on the literature (24–27). Such evidence was found in this study.

When quality-of-life measures such as the WHIIRS are used in clinical research, the clinical significance of the obtained effect sizes is not always clear. To estimate a clinically meaningful effect size using the WHIIRS, Levine et al. (8) compared women who either met or did not meet the common operational definition of insomnia, ie, sleep-onset latency greater than 30 minutes and an accompanying sleep efficiency lower than 85% (50,51). They found the mean difference on the WHIIRS between the two groups was approximately 0.48 of the pooled SD, with the insomnia group reporting worse sleep. As a consequence, Levine et al. (8) suggested one half a SD might indicate a clinically meaningful difference on the WHIIRS. In the current study, we compared women known to have more severe vasomotor symptoms with those known to have mild vasomotor symptoms, and the between-group mean difference on the WHIIRS was approximately 0.56 of a SD. Thus, in clinical trials using the WHIIRS as an outcome, it appears that a between-group difference of approximately one half a SD may be clinically meaningful. Further research is needed to determine whether smaller differences are also meaningful.

The implications for using the WHIIRS directly in the clinic are less clear. The WHIIRS is not a diagnostic tool but rather a measure of perceived insomnia symptoms. These symptoms are described in the definitions of insomnia (9–11) and in the article describing the development of the scale (7). The WHIIRS, like other sleep scales that measure the intensity of insomnia symptoms, does not distinguish between primary and secondary diagnoses. Such diagnoses are difficult to make even in a clinical setting. Much of this difficulty stems from the complex nature of insomnia and the fact that the various nosologies do not agree in their definitions of insomnia (4,5,52–55). Although the use of sleep questionnaires in research is common (56), their use as tools to assist clinicians in assessing the severity of insomnia symptoms is less frequent, and it remains uncertain how much they add to diagnostic accuracy of treatment outcome in routine clinical use (5,55,57). Some researchers, nonetheless, believe that using questionnaires as screening instruments would be valuable in clinical care (26). If the WHIIRS were used in the clinic with women 50 years of age and older, results indicate that scores above 9.0 may warrant more in-depth evaluation (8). This is a tentative recommendation and requires replication. We expect, however, that this instrument will be used primarily in clinical research rather than as a screening tool for individuals.

One limitation of this study is that women had not been classified by clinical diagnosis or by objective sleep criteria as having insomnia. Previous research with the WHIIRS has examined women who met the operational criteria for insomnia (8) and so the WHIIRS has already been shown to detect differences between women with and without insomnia. A greater limitation to this study is that only older females were included. This was a consequence of studying hormone replacement therapy in postmenopausal women. Although this study examined the use of the insomnia scale with participants who had a slightly lower age range than women in the WHI (minimum age in these trials was 40 years vs. the 50-year minimum age in the WHI), future research needs to explore the reliability and validity of the WHIIRS in younger women as well as in men.

In summary, the WHIIRS appears to be a reliable and valid instrument that can be used successfully in a non-WHI population. The WHIIRS is a measure of perceived insomnia symptoms and is not a diagnostic tool. Measures of this type can provide an overview of a complaint of persistent insomnia but cannot substitute for a face-to-face consultation (57). This measure can, for example, be used in evaluating the outcomes of interventions designed to ameliorate sleep disorders (58) or can be used as a covariate in studies examining the many health conditions associated with sleep difficulties (59).


   NOTES
TOP
 ABSTRACT
 INTRODUCTION
 METHOD
 RESULTS
 DISCUSSION
 NOTES
REFERENCES
 
Received for publication February 11, 2004; revision received August 10, 2004.

DOI:10.1097/01.psy.0000151743.58067.f0


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 METHOD
 RESULTS
 DISCUSSION
 NOTES
 REFERENCES
 

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