Validation of a Revised Visual Analog Scale for Premenstrual Mood ...

Original Research
Validation of a Revised Visual Analog Scale for
Premenstrual Mood Symptoms: Results From
Prospective and Retrospective Trials
Meir Steiner, MD, PhD, FRCPC 1 , David L Streiner, PhD 2 ,Ba Pham, MSc 3
Objective: Previous studies have demonstrated that visual analog scales (VASs) are valid
and reliable instruments for measuring the severity of premenstrual symptoms. Most of
these studies, though, predate the introduction of DSM-IV diagnostic criteria for
premenstrual dysphoric disorder (PMDD). Our objective was to assess the reliability and
validity of VASs that were revised to better reflect the DSM-IV definition of PMDD.
Methods: Concurrent information from the well-validated Premenstrual Tension
Syndrome-Observer (PMTS-O) rating scale was used to evaluate the revised VASs. Data
from 4 randomized controlled trials (n = 1208) evaluating the efficacy of paroxetine for the
treatment of PMDD were used. Cronbach’s alpha coefficient was used to evaluate the
internal consistency of the core VAS mood items. Pearson’s correlation between scores
from the 2 scales was used to assess reliability.
Results: The internal consistency among the core VAS mood items (Cronbach’s > 0.90
across trials) was high. Luteal VAS scores and corresponding PMTS-O scores were
moderately correlated at baseline (P < 0.01). Luteal VAS change scores and corresponding
PMTS-O change scores were strongly correlated (P < 0.01). These results did not differ
regardless of whether the PMTS-O data were collected prospectively or retrospectively.
Conclusion: The revised VASs, which approximate the current DSM-IV definition of
PMDD, provide a valid and reliable measure of the severity of premenstrual symptoms
when evaluated against the validated PMTS-O scale. Our results also suggest that, whether
observers assessed severity of PMDD symptoms retrospectively or prospectively using the
PMTS-O scale, the correlations with the patient-reported VAS scores were comparable.
(Can J Psychiatry 2005;50:327–332)
Information on funding and support and on author affiliations appears at the end of the
article.
Clinical Implications
The revised visual analog scale presented here approximates DSM-IV diagnostic criteria for
premenstrual dysphoric disorder (PMDD).
Contrary to DSM-IV diagnostic criteria for PMDD, which require prospective daily symptom
charting, our data indicate that using a retrospective data collection approach may be as valid.
Limitations
At present, there is still no consensus on diagnostic criteria for severe premenstrual syndrome
(PMS) and PMDD.
Further studies are needed to validate the possibility of circumventing the need for prospective
daily charting in establishing the diagnosis of PMS or PMDD.
Key Words: premenstrual dysphoric disorder, visual analog scales, VAS
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The Canadian Journal of Psychiatry—Original Research
The diagnostic criteria for premenstrual dysphoric disorder
(PMDD), as defined in the DSM-IV, are much stricter
than those for premenstrual syndrome (PMS) (1). To apply the
DSM-IV criteria for PMDD, women must prospectively chart
symptoms daily for at least 2 consecutive symptomatic cycles,
and their chief complaints must include 1 of the 4 core mood
symptoms (that is, irritability, tension, dysphoria, and lability
of mood) and at least 5 of the 11 total symptoms. The charting
of symptoms should clearly demonstrate premenstrual worsening
and remission within a few days after the onset of menstruation
(“on-offness”) (2). A change in symptoms from the
follicular to the luteal phase of at least 50% is suggested for
the diagnosis of PMDD (3,4).
Results from a study of women with PMS who sought medical
attention suggest that the DSM-IV criteria for PMDD may be
too strict (5). Subjects failing to meet the criteria may still
have substantial premenstrual worsening of symptoms.
Prospective daily self-rating of symptoms, using reliable and
valid instruments, is essential in making the diagnosis. To
date, there is still no consensus among investigators as to the
best instrument for confirming prospectively the diagnosis of
PMDD, nor is there consensus as to the most appropriate
instrument to measure treatment effects in clinical trials (6).
Previous studies have shown that using a single-item visual
analog scale (VAS) for each of the 4 core premenstrual mood
symptoms is a reliable and valid method of prospective data
collection (3,4). Most of these studies, though, predate the
introduction of the DSM-IV diagnostic criteria for PMDD,
and previous VASs are not aligned with these criteria. We further
report here on the reliability and validity of the VASs that
were revised to better reflect the DSM-IV definition of
PMDD.
Methods
The analysis used concurrent data from women’s scores on
the revised VASs and the validated Premenstrual Tension
Syndrome Observer (PMTS-O) rating scale collected in 4 randomized
controlled trials (n = 1208) evaluating the efficacy of
different treatment options with paroxetine. In all these trials,
women with premenstrual symptoms that fulfilled the
DSM-IV diagnostic criteria for PMDD signed a written
informed consent form that was approved by the institutional
review board at participating centres.
The validated PMTS-O scale allows an observer to assess
symptoms in 10 domains: irritability or hostility, tension, efficiency,
dysphoria or moodiness, motor coordination, mental–cognitive
functioning, eating habits, sexual drive and
activity, physical symptoms, and social impairment (7).
VASs, together with the PMTS-O scale, have been shown to
be a valid, reliable, and sensitive measure for the severity of
premenstrual symptoms (3). The PMTS-O scale has also been
328
used in subjects with premenstrual symptoms to establish
symptom severity for inclusion in clinical studies (8–11) and
to evaluate treatment response in clinical trials (12–15).
In 3 trials with regular visits scheduled during the follicular
phases (that is, each within 3 days after onset of menses), 1030
participants were randomized to treatment groups of continuous
treatment with paroxetine (12.5 mg daily), paroxetine (25
mg daily), or placebo (16). The trials were conducted according
to an identical protocol with minor language adaptations
for different geographic regions of Europe and North America.
Participants completed a self-rating set of 11 VASs daily
throughout 6 menstrual cycles (2 screening, 1 baseline, and 3
treatment cycles). Single-item VASs were used to measure
each of the 4 core mood symptoms (depressed mood, tension,
affective lability, and irritability), as well as the 7 additional
clusters of symptoms (decreased interest in usual activities,
difficulty with concentration, lack of energy, change in appetite,
change in sleep pattern, feeling out of control, and physical
symptoms), in accordance with the DSM-IV criteria for
PMDD (1). During regular visits, independent observers also
assessed participants by using a retrospective data collection
approach with the PMTS-O scale, prompting for the severity
of premenstrual symptoms associated with the late luteal
phase of the preceding menstrual cycles.
In one trial with regular visits scheduled during the luteal
phases, 178 participants were randomized to treatment groups
receiving continuous treatment with paroxetine (20 mg daily),
intermittent treatment with paroxetine (20 mg daily during the
luteal phase only), or placebo (17). Participants completed a
self-rating, slightly modified (that is, a Swedish version) set of
10 VASs daily for 6 cycles. Single-item VASs were used to
measure each of the 4 core mood symptoms (depressed mood,
tension, affective lability, and irritability) as well as 6 additional
clusters of symptoms (mood swings, bloatedness,
breast tenderness, lack of energy, food cravings, and menstrual
pain). A single observer used a prospective data collection
approach with the PMTS-O scale to assess participants
during their luteal phases.
In all trials, each VAS consisted of a 100-mm horizontal line
with vertical line anchors at each end. The anchors were 0 =
“not at all” (that is, “the way you normally feel when you don’t
have premenstrual symptoms”) and 100 = “extreme symptoms”
(that is, “the way you feel when your premenstrual
symptoms are at their worst”).
Data Analysis
All analyses were based on intention-to-treat. For the analyses,
data from the 3 trials with follicular phase visits were
pooled on the basis of their identical protocols and the homogeneous
results from the reliability analyses of individual trial
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Validation of a Revised Visual Analog Scale for Premenstrual Mood Symptoms: Results From Prospective and Retrospective Trials
Table 1 Baseline VAS and PMTS-O scores a
VAS mood score
(mm)
Late luteal
phase
Placebo
(n = 349)
Mean (SD)
data. Data from the trial with luteal phase visits were analyzed
separately.
The VAS scores on the 4 core symptoms were averaged to create
a mean score to represent mood symptoms (that is, VAS
mood score) (4). We calculated the VAS total scores (average
of 11 symptom scores) only for the trials with follicular phase
visits. For the trial with luteal phase visits, the VAS total
scores (average of 10 symptom scores) were not derived
because they were not comparable with those derived from the
other trials. We calculated a late luteal phase score (that is,
VAS mood or VAS total), using the average daily VAS scores
of the 5 days prior to menses, and a follicular phase score,
using the average of daily VAS scores from postmenses days
6to10.
The PMTS-O scale scores 10 domains (outlined above) with
severity ranging from 0 to 4 in 8 subscales and 0 to 2 in 2
domains, for a maximum score of 36. A PMTS-O mood
subscore includes items from question 1 (irritability or hostility),
question 2 (tension), and question 4 (dysphoria or moodiness)
and ranges from 0 to 12.
Change scores from both VAS and PMTS-O scales were used
to assess sensitivity to symptom worsening or improvement.
A change score was derived by subtracting a baseline score
from the corresponding score at study end (that is, the third
treatment cycle in all trials). For participants who dropped out,
we used the score of the last cycle before early termination.
Trials with follicular phase visits Trial with luteal phase visits
Paroxetine
12.5 mg
(n = 333)
Mean (SD)
Paroxetine
25 mg
(n = 348)
Mean (SD)
Placebo
(n = 59)
Mean (SD)
Intermittent treatment
with 20 mg paroxetine
(n = 60)
Mean (SD)
Continuous treatment
with 20 mg paroxetine
(n = 59)
Mean (SD)
55 (23) 57 (23) 51 (23) 48 (23) 48 (21) 47 (22)
Follicular phase 6 (7) 6 (7) 6 (9) 5 (7) 5 (7) 9 (10)
VAS total score
(mm)
Late luteal
phase
PMTS-O
52 (23) 48 (22) 53 (23) NA NA NA
Follicular phase 6 (7) 6 (8) 6 (8) NA NA NA
Mood score 9 (2) 9 (2) 9 (2) 8 (2) 8 (2) 8 (2)
Total score 23 (5) 22 (5) 22 (5) 22 (5) 21 (5) 19 (4)
a
VAS mood score is the average of the 4 core mood symptoms (that is, depressed mood, tension, affective lability, and irritability) according to DSM-IV definition
of PMDD. VAS total score is the average from the VAS score of 11 symptoms according to DSM-IV definition of PMDD.
NA = not available (VAS total scores from the trial with luteal phase visits were not comparable with those from the 3 trials with follicular visits.)
Cronbach’s alpha coefficient was used at baseline to evaluate
the internal consistency of the VAS mood items. Baseline
VAS scores were summarized for the late luteal and follicular
phases across treatment options. To evaluate construct validity,
we compared VAS mood scores for subgroups of participants
with varying premenstrual symptom severity according
to a priori defined PMTS-O thresholds. A PMTS-O total score
greater than 27 has been suggested for severe symptoms,
between 18 and 27 for moderate symptoms, and between 10
and 17 for mild symptoms (18,19). Analysis of variance was
used to compare subgroups.
Pearson’s correlation was used to compare the DSM-IV VAS
and PMTS-O scores. Both absolute scores at baseline and
change scores were compared. Individual items, mood
domain scores, and total scores were compared.
To examine the construct validity of the VAS items relative to
those of the PMTS-O scale, pairwise correlation coefficients
were examined between the 4 core mood symptoms in the
VAS scale and the corresponding 3 symptoms from the
PMTS-O scale. Correlation coefficients from 0.3 to 0.5 indicated
moderate association; from 0.5 to 0.7, strong association;
and above 0.7, excellent association (20).
Results
Data from 1208 participants were used in the analyses. In the
trials with follicular phase visits, 1030 participants contributed
data to the baseline analyses and 934 (88%) to the change
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The Canadian Journal of Psychiatry—Original Research
score analyses. For the trial with luteal phase visits, the corresponding
figures were 178 and 165 (93%), respectively
(Tables 1 and 2).
The internal consistency coefficient for the luteal VAS mood
score was 0.90 with data from the 3 trials with follicular phase
visits (ranging from 0.90 to 0.91 across trials) and 0.88 with
data from the trial with luteal phase visits. The corresponding
coefficients for the follicular VAS mood score were 0.94
(ranging from 0.92 to 0.96 across trials) and 0.91, respectively.
These results indicate a high level of internal consistency
among the 4 core mood symptoms.
The VAS mood scores captured the “on-offness” of the conditions,
with the mean VAS mood score ranging from 47 to 57
across treatment options for the late luteal phase and from 5 to
9 for the subsequent follicular phase. Similar results were
observed with the VAS total scores (Table 1).
According to the construct validity criterion, 15% (n = 153) of
participants in the trials with follicular phase visits experienced
mild premenstrual symptoms; 68% (n = 682), moderate
symptoms; and 17% (n = 171), severe symptoms. The mean
VAS mood score was 41 (95%CI, 38 to 44) for participants
with mild symptoms, 54 (95%CI, 52 to 55) for those with
moderate symptoms, and 70 (95%CI, 66 to 73) for those with
severe symptoms. The mean VAS mood score was significantly
different across symptom severities (F2,1003 = 75.7, P <
0.0001).
Luteal phase VAS scores and corresponding PMTS-O scores
were moderately correlated at baseline (P < 0.01) (Table 2).
330
Table 2 Correlation between luteal phase VAS scores and PMTS-O scores a
Correlation between Baseline
(n = 1030)
VAS depressed mood and PMTS-O dysphoria or
moodiness
VAS affective lability and PMTS-O dysphoria or
moodiness
Trials with follicular phase visits Trial with luteal phase visits
The correlation coefficient between VAS mood and PMTS-O
mood scores was 0.48 for the 3 trials with follicular phase visits
(ranging from 0.42 to 0.50 across individual trials) and 0.46
for the trial with luteal phase visits. Luteal phase VAS change
scores and corresponding PMTS-O change scores were
strongly correlated (P < 0.01), indicating similar sensitivity to
premenstrual symptom change by both scales. Whether
observers assessed symptom severity retrospectively or prospectively,
the correlations between the patient-reported VAS
scores and the PMTS-O scores were comparable (Table 2).
Corresponding items from the 2 scales (for example, VAS
depressed mood and PMTS-O dysphoria or moodiness)
always attained relatively higher correlation values when
compared with correlation between noncorresponding items
(for example, VAS depressed mood and PMTS-O tension),
suggesting further evidence of the construct validity of VAS
items.
Discussion
Change b
(n = 934)
Baseline
(n = 178)
Change b
(n = 165)
0.48 0.52 0.46 0.43
0.46 0.54 0.40 0.35
VAS tension and PMTS-O tension 0.49 0.56 0.64 0.54
VAS irritability and PMTS-O irritability or hostility 0.36 0.57 0.36 0.56
VAS mood and PMTS-O mood 0.47 0.63 0.47 0.51
VAS mood and PMTS-O total 0.45 0.63 0.41 0.46
VAS total and PMTS-O total 0.48 0.63 NA NA
a
VAS mood score is the average of the 4 core mood symptoms (that is, depressed mood, tension, affective lability, and irritability) according to DSM-IV definition
of PMDD. VAS total score is the average from the VAS scores of eleven symptoms according to DSM-IV definition of PMDD.
b
Change scores from baseline to trial end (that is, baseline score – end of treatment score).
NA = not available (VAS total scores from the trial with luteal phase visits were not comparable with those from the 3 trials with follicular visits.)
Data collected from 4 treatment trials of women with severe
premenstrual symptoms indicate that using the revised VASs
(which better reflect the current DSM-IV definition of
PMDD) provides a reliable measure of premenstrual symptoms
when evaluated against the well-validated PMTS-O
scale. The results also suggest similar concurrent validity
between the daily rating of symptom severity using the
patient-reported revised VAS and the observers’ rating scale
(PMTS-O), regardless of whether the observers assessed the
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Validation of a Revised Visual Analog Scale for Premenstrual Mood Symptoms: Results From Prospective and Retrospective Trials
premenstrual symptoms with a prospective or retrospective
data collection approach.
The DSM-IV requires women to prospectively chart symptoms
daily for a minimum of 2 symptomatic cycles to qualify
for the diagnosis of PMDD and hence meet inclusion criteria
in clinical trials. It has recently been suggested that this may
be impractical as a diagnostic tool in a busy primary care practice.
Not only has it been shown that the requirement for prospective
charting may act as a deterrent for seeking help, it
may also indicate that patients who participate in clinical trials
are very different from typical PMDD patients seen in primary
care (21).
The revised VAS better reflects the current DSM-IV diagnostic
criteria for PMDD, and it is also more user-friendly. As
such, it can potentially increase the accurate identification of
sufferers and also improve their compliance with treatment.
Most women with severe PMS or PMDD are likely to seek
treatment from their obstetrician-gynecologist or other primary
health care provider. At present, there is still no consensus
on diagnostic criteria for severe PMS and PMDD (22).
Recent attempts at circumventing the need for a prospective
daily paper and pencil charting are promising (23,24); however,
further validation studies are needed. The data presented
here seem to also indicate that, in women with clear-cut severe
PMS and (or) PMDD, retrospective assessment may be a clinically
acceptable alternative to strict DSM-IV research diagnostic
criteria.
Funding and Support
Funding for the project was provided by GlaxoSmithKline.
Acknowledgements
The authors thank Brian Hunter, Timothy Rolfe, and Reid Robson
for their input and support during the project; Tina Haller, Theresa
Chua, and Jenny Huang for their assistance with the data analysis;
and Carol Ballantyne and Cindy Tasch for their expert help in preparing
the manuscript.
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Manuscript received April 2004, revised, and accepted July 2004.
1
Professor, Department of Psychiatry and Behavioural Neurosciences and
Department of Obstetrics and Gynecology, McMaster University,
Hamilton, Ontario.
2
Assistant Vice President, Research and Director, Baycrest Centre for
Geriatric Care; Professor, Department of Psychiatry, University of
Toronto, Toronto, Ontario.
3
Statistician, BioMedical Data Sciences, GlaxoSmithKline, Oakville,
Ontario.
Address for correspondence: Dr M Steiner, Department of Psychiatry and
Behavioural Neurosciences, McMaster University, Hamilton, ON
L8N 4A6
e-mail: mst@mcmaster.ca
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332
Résumé : Validation d’une échelle visuelle analogique révisée des symptômes de
l’humeur prémenstruelle : résultats d’essais prospectifs et rétrospectifs
Objectif : Des études antérieures ont démontré que les échelles visuelles analogiques (EVA) sont des
instruments valides et fiables pour mesure la gravité des symptômes prémenstruels. La plupart de ces
études, cependant, datent d’avant l’introduction des critères diagnostiques du DSM-IV pour le trouble
dysphorique prémenstruel (TDPM). Notre objectif était d’évaluer la fiabilité et la validité des EVA
qui ont été révisées pour mieux refléter la définition du DSM-IV du TDPM.
Méthodes : L’information concurrente de l’échelle de mesure bien validée de l’observateur du
syndrome de tension prémenstruelle (PMTS-O) a servi à évaluer les EVA révisées. Les données de 4
essais contrôlés randomisés (n = 1 208) évaluant l’efficacité de la paroxétine pour le traitement du
TDPM ont été utilisées. Le coefficient alpha de Cronback a servi à évaluer la cohésion interne des
principaux items sur l’humeur des EVA. La corrélation de Pearson entre les scores aux 2 échelles a
servi à évaluer la fiabilité.
Résultats : La cohésion interne des principaux items sur l’humeur des EVA (alpha de Cronback >
0,90 dans tous les essais) était élevée. Les scores lutéaux aux EVA et les scores correspondants à la
PMTS-O étaient modérément corrélés à la base (P < 0,01). Les scores de changement lutéaux aux
EVA et les scores de changement correspondants à la PMTS-O étaient fortement corrélés (P < 0,01).
Ces résultats ne différaient pas, que les données de la PMTS-O soient recueillies prospectivement ou
rétrospectivement.
Conclusion : Les EVA révisées, qui s’approchent de la définition actuelle du TDPM du DSM-IV,
offrent une mesure valide et fiable de la gravité des symptômes prémenstruels, quand elles sont
évaluées par rapport à l’échelle PMTS-O validée. Nos résultats suggèrent également que les
corrélations avec les scores aux EVA déclarés par les patients étaient comparables, que les
observateurs aient évalué la gravité du TDPM prospectivement ou rétrospectivement.
Can J Psychiatry, Vol 50, No 6, May 2005