validation of the spanish version of the perceived stress questionnaire
TRANSCRIPT
Validation of the Spanish version of the Perceived Stress Questionnaire
C. Sanz-Carrilloa, J. Garcıa-Campayob,c,*, A. Rubiod, M.A. Santede, M. Montorof
aDepartment of Psychiatry, San Jorge Hospital, Huesca, SpainbDepartment of Psychiatry, Miguel Servet University Hospital, Zaragoza, Spain
cUniversity of Zaragoza, Zaragoza, SpaindDepartment of Family Medicine, San Jorge Hospital, Huesca, Spain
eDepartment of Psychology of Personality and Psychological Assessment and Treatment,
Universidad Nacional de Educacion a Distancia, Madrid, SpainfDepartment of Gastroenterology, San Jorge Hospital, Huesca, Spain
Received 5 March 2001; accepted 28 June 2001
Abstract
Objective: To validate in Spanish the Perceived Stress
Questionnaire (PSQ), a questionnaire to assess stress for research
purposes in psychosomatic patients. Method: The test was
administered to a healthy population (N= 174) of nursing students
and health workers and to a clinical sample (N= 80) of patients
attending a psychiatric outpatient consultation. Results: Con-
current validity: General and Recent PSQ scores correlated high
with trait anxiety (r= .65), moderate with depression (r= .46) and
psychological disturbance (r = .51) and poor with state anxiety
(r = .22). Predictive validity: PSQ scores were higher in
‘‘psychiatric cases’’ than in ‘‘psychiatric noncases’’ (P < .01),
and correlated highly with somatic symptoms of psychological
origin (r= .62) in the clinical subsample. Internal consistency was
0.9 for the General and 0.87 for the Recent PSQ. Test– retest
reliability of the General PSQ was 0.80. Discussion: The Spanish
version of PSQ presents good psychometric properties and it
seems to be a valuable instrument for psychosomatic researchers.
D 2002 Elsevier Science Inc. All rights reserved.
Keywords: Questionnaire; Perceived stress; Validation; Psychosomatics; Spanish
Introduction
The relationship between stress and the onset of med-
ical and psychiatric disorders has been widely studied in
psychiatric literature [1], however, there is no clear con-
sensus on how to measure stress [2,3]. Some of the
approaches used by researchers has been to evaluate
different aspects of this construct such as: (a) external
stressors in the form of ‘‘life events’’ [4], (b) the cumu-
lative minor stresses or hassles [5,6] and (c) the coping,
i.e., the individual’s sense of control [7]. All of these
systems of evaluation present important drawbacks that
limit their usefulness in research.
The Perceived Stress Questionnaire (PSQ) of Levenstein
et al. [8] is specifically designed to measure stress in clinical
psychosomatic research. It consists of 30 items developed
by experienced clinicians and has been validated in Italian
and English languages in a population (N = 230) of psychi-
atric inpatients, outpatients, students and health workers.
The validation study showed excellent psychometric prop-
erties [8], and it has been used in research, demonstrating
good predictive value in stress-related diseases such as
ulcerative colitis [9,10].
In the context of a high-scale study of somatization and
somatoform disorders [11–14], we needed to use a scale to
measure stress in psychosomatic disorders so we selected
PSQ. The objective of this paper is to translate into Spanish
and validate the PSQ.
Method
The questionnaire was translated from English into
Spanish by two native Spanish-speaking psychiatrists
working independently of each other and, in a second
step, they agreed on a final common translation. After that,
0022-3999/02/$ – see front matter D 2002 Elsevier Science Inc. All rights reserved.
PII: S0022 -3999 (01 )00275 -6
* Corresponding author. Avda. Cesareo Alierta 47, 2� B, 50.008
Zaragoza, Spain. Fax: +34-976-254006.
E-mail address: [email protected] (J. Garcıa-Campayo).
Journal of Psychosomatic Research 52 (2002) 167–172
the Spanish version of PSQ was back-translated into
English by unaware native English-speaking people, and
differences between the original test and the Spanish
version were resolved. Finally, the questionnaire was
administered to bilingual persons in English and Spanish
versions to detect possible differences.
The Spanish version of PSQ was validated in two
different populations: (1) A healthy sample of 176 persons,
of which 128 were first and second year nursing students at
the University of Huesca, Spain, and 48 were health
professionals (doctors and nurses) working in San Jorge
Hospital in Huesca. The sociodemographic characteristics
of the sample were the following: In relation to sex, females
clearly predominated (N = 133, 75.6%) over males (N = 43,
24.4%), and the mean age was 27.9 years (standard devi-
ation: 12.4 years, range:18–65). (2) A clinical sample
(N = 80) of first-time patients attending the outpatient psy-
chiatric consultations of Miguel Servet University Hospital
in Zaragoza, Spain. The SPPI psychiatric interview clas-
sified the sample into two subgroups: 49 psychiatric cases
and 31 psychiatric noncases. The sociodemographic char-
acteristics of the whole sample were the following: pre-
dominance of women (N = 51, 63.7%) and middle-aged
patients (mean: 45.8 years; standard deviation: 18.8 years;
range: 18–66). Psychiatric cases were primarily depressive
and anxiety disorders, while nonpsychiatric cases were
subthresold minor psychiatric disorders and couple distur-
bances. In both samples, all the participants were Cauca-
sian, and their native language was Spanish.
Construct validity was performed through comparison
with other measures of stress. The most specific question-
naire for comparison, Cohen et al.’s Perceived Stress Scale
[15], has not been validated in Spanish, so it had to be
rejected. We used three scales validated in our country: (1)
the State–Trait Anxiety Inventory (STAI) [16,17] also
used in the original paper; (2) the Beck Depression
Inventory [18,19] and (3) the General Health Question-
naire-28 items (GHQ-28) [20,21], a patient-rated question-
naire of psychological distress.
Predictive validity was assessed by two different meth-
ods, based on the paper by Levenstein et al.: (1) Compar-
ison of PSQ scores in first time patients attending a
psychiatric outpatient consultation divided into two sub-
groups: ‘‘psychiatric cases’’, as defined by the psychiatric
interview SPPI [22], an interview widely used by our group
[11–14] that allows DSM-IV and ICD-10 psychiatric dia-
gnosis. These patients were compared with ‘‘psychiatric
noncases’’, as defined by the same interview. (2) In the
population of ‘‘psychiatric noncases’’, correlation of the
PSQ scores with the section of somatic symptoms of
psychological origin of the psychiatric interview SPPI
[22], a section that allows scores ranging from 0 to 35,
which can be used as a scale. The reason to reject the
subsample of ‘‘psychiatric cases’’ was to avoid confusing
somatic symptoms produced by stress with those produced
by the psychiatric disorder itself [23].
In addition, internal consistency analysis, analysis by
demographic characteristics, test–retest reliability and fac-
tor analysis were also carried out.
Data analyses were performed using SPSS 9th version
for Windows. Whole-scale reliability (internal consist-
ency) was estimated using coefficient alpha [24], test–
retest reliability and analysis by demographic character-
istics were tested using the Spearman r, and factor
analysis of PSQ was performed using principal compon-
ent analysis with the Varimax transformation, in its
oblique solution.
Results
PSQ index was obtained according to Levenstein et al.’s
[10] indications, i.e., PSQ= (raw score� 30) / 90. Overall
mean scores were 0.35 (S.D. = 0.14) for the General and 0.37
(S.D. = 0.15) for the Recent form, with scores ranging from
0.08 to 0.86 and from 0.01 to 0.93, respectively. Table 1
shows PSQ scores (General form) by age and sex distri-
bution. Scores of � 0.25 fell into the lowest quartile for the
validation sample as a whole, 0.25–0.34 in the second
quartile, 0.35–0.44 in the third quartile and � 0.45 in the
upper quartile for both forms.
We studied correlation between age and PSQ and we
found a Spearman r of � .04 (P = .55) for the General and
Table 1
Age and sex distributions of the PSQ scores (General form) in healthy
population (N= 176)
Mean Standard deviation
Sex
Male (N= 43) 0.3366 0.1353
Female (N= 133) 0.3604 0.1418
Age
18–24 years (N= 110) 0.3681 0.1485
25–39 years (N= 33) 0.3384 0.1230
> 39 years (N= 33) 0.3259 0.1251
Entire sample (N= 176) 0.3546 0.1403
Table 2
Specific items varying at a P < .05 level with age or sex (N = 176)
Age
(7) You feel you are doing things you really like.
(9) You fear you may not manage to attain your goals.
(17) You feel safe and protected.
(20) You feel discouraged.
(21) You enjoy yourself.
(22) You are afraid for the future.
(30) You feel under pressure from deadlines.
Sex
(23) You feel you are doing things because you have to not because you
want to.
C. Sanz-Carrillo et al. / Journal of Psychosomatic Research 52 (2002) 167–172168
.11 (P = .12) for the Recent form. PSQ index did not vary
by gender, and t test yielded t (174) =� 0.96 (P = .33) for
the General form, and t (174) =� 1.23 (P = .22) for the Re-
cent form. Table 2 summarizes specific items varying at a
P < .05 level with age or sex.
All individual items in both the General and the Recent
PSQ correlated in the predicted direction with their cor-
responding PSQ index, i.e., all items showed a positive
correlation except items 1, 7, 10, 13, 17, 21, 25 and 29,
which showed a negative correlation with PSQ index. The
highest correlation of any item with any other single item
was r= .59. The mean for each item was between 1.35 and
2.93 in all cases, and the standard deviation always
exceeded 0.6.
Table 3 summarises concurrent validity of the General
and the Recent PSQ in relation with other questionnaires.
Both correlate highly with trait anxiety and somatic symp-
toms of psychological origin, moderately with depression
and psychological disturbance in general, and poorly with
state anxiety.
In relation to predictive validity, the General Index was
significantly higher (P < .01) in psychiatric cases than in
psychiatric noncases. In addition, in the ‘‘nonpsychiatric’’
clinical sample, correlation between PSQ and the somatic
section of the SPPI was good as can be seen in Table 3.
Internal consistency, as measured by coefficient alpha,
was 0.9 for the General and 0.87 for the Recent PSQ. Test–
retest reliability of the General PSQ, after an interval of
13.12 ± 2.05 days (mean ± S.D.), was 0.80.
Table 4 summarises principal component analysis, with
the Varimax transformation in its oblique solution, of the
General PSQ scores of the healthy sample (N = 174). The
analysis yielded seven factors with eigenvalues greater
than 1. Factor names were assigned appropriate to the
contributing items: tension– fatigue, conflict – social
acceptance, overload–harrassment, energy–joy, self-real-
isation–satisfaction, fear–anxiety and Factor 7. This
solution explained 58% of the variance. According to
empirical criteria, we have grouped in the same subscale
those items that presented the highest loading in the
same factor. The only exception was Item 29, which
showed the highest loading in Factor 7. However, as in
this factor, no other item presented its highest loading,
the subscale has been deleted, and Item 29 has been
included into Factor 4 (energy–joy) in which loading
was .3.
The Spanish version of the questionnaire is attached as
an annex at the end of the paper. The approximate time
needed for administration of the Spanish version of the PSQ
ranges from 10 to 15 min.
Discussion
The present data demonstrate the favourable psychomet-
ric characteristics of the Spanish version of the PSQ in
relation to the different psychometric properties that should
define a valid and reliable test. In addition, the patients,
health professionals and students evaluated confirm that the
Spanish version of the questionnaire is easy to understand
and quick to administer, supporting the feasibility of the test
in the everyday clinical practice.
Concurrent validity demonstrates good correlation with
trait anxiety and somatic symptoms of psychological origin,
moderate correlation with depression and psychological
disturbance in general, and poor correlation with state
anxiety. These data, quite similar to those found by Leven-
stein et al. [8], were expected.
Predictive value has been assessed by confirming that in
people without psychiatric disorders, as evaluated by SPPI
psychiatric interview, PSQ is well correlated with minor
physical symptomatology. In addition, PSQ scores are
significantly higher in ‘‘psychiatric cases’’ compared with
‘‘psychiatric noncases’’ from a sample of people attending
psychiatric outpatient consultations. These data are coherent
with those described by Levenstein et al. [8]. Further data
confirming the predictive value of the PSQ will be obtained
from the research on somatoform disorders in progress.
Other psychometric measures such as internal consist-
ency (Cohen’s a coefficient = 0.9) and test–retest reliability
(0.80) were also satisfactory and similar to the original study.
One of the expectations of a stress questionnaire is a
minimal correlation with sex and age. In fact, the PSQ
Spanish version seems to be more independent than the
original version from these sociodemographic character-
istics: In our study, we found no correlation in either
variable, while Levenstein et al. did not find a correlation
with sex but they did with age (Spearman r=.22, P < .001
for the General form). In addition, the specific PSQ items
that showed P < .05 in relation with sex and age were less
numerous in our study compared with the study by
Levenstein et al. Therefore, Spanish validation shows
better psychometric properties related to the specific aspect
of correlation with sex and age. In general, PSQ scores are
lower in our sample than in the original sample by
Levenstein et al. We think the explanation is the predom-
inance in our study of students in which stress is supposed
to be lower.
Table 3
Concurrent validity of the PSQ with other measures
General PSQ Recent PSQ
State anxiety (STAI) (N = 80) 0.22 0.28
Trait Anxiety (STAI) (N= 80) 0.65*** 0.69***
Depression (BDI) (N= 80) 0.46** 0.49**
Psychological disturbance
(GHQ-28) (N= 80)
0.51** 0.55**
Somatic symptoms (SPPI
somatic section) (N= 31)
0.62*** 0.67***
** P < .01 by Spearman’s r.
*** P < .001 by Spearman’s r.
C. Sanz-Carrillo et al. / Journal of Psychosomatic Research 52 (2002) 167–172 169
Table 4
Factor analysis of the Spanish version of PSQ
Item
Tension–
irritability– fatigue
Conflict–
social acceptance
Factor
overload
Energy–
joy
Self– realization
satisfaction
Fear–
anxiety
Factor 7 (deleted
and included in
energy– joy)
(3) You are irritable or grouchy .60
(8) You feel tired .51 .36 .44
(10) You feel calm .63
(14) You feel tense .73
(15) Your problems seem to be pilling up .48 .32 .42
(16) You feel you’re in a hurry .53 .45
(26) You feel mentally exhausted .38 .32 .31
(27) You have trouble relaxing .67
(30) You feel under pressure from deadlines .52 .35
(5) You feel lonely or isolated .65
(6) You find yourself in situations of conflict .55 .30
(12) You feel frustrated .54
(17) You feel safe and protected .58 .39
(19) You are under pressure from other people .57 .36
(20) You feel discouraged .55
(24) You feel criticized or judged .53
(2) You feel that too many demands are being
made on you
.66
(4) You have too many things to do .33 .58 .37 .37
(11) You have too many decisions to make .73
(18) You have many worries .57 .31
(1) You feel rested .35 .34 .60
(13) You are full of energy .68
(21) You enjoy yourself .64 .30
(25) You are lighthearted .56
(29) You have enough time for yourself .30 .60
(7) You feel you’re doing things you really like .75 .35
(9) You fear you may not manage to attain your goals .30 .56
(23) You feel you’re doing things because you have to
not because you want to
.72
(22) You are afraid for the future .75
(28) You feel loaded down with responsibility .61
Eigenvalue 7.89 2.71 1.83 1.38 1.27 1.15 1.14
Percent of total variance explained by factor 12.27 9.75 9.42 8.96 6.35 6.05 5.17
Percent cummulated variance 12.27 22.03 31.46 40.43 46.78 52.84 58.01
The highest loading for each item is included. Loading < .3 have been omitted.
C.Sanz-C
arrillo
etal./JournalofPsych
osomatic
Resea
rch52(2002)167–172
170
The main difference between the Spanish and the
original English version of the PSQ is the factorial
structure, which can be seen in Table 5. In the Spanish
version, only six factors have been obtained, one less
than in the original. In addition, in the Spanish version
the number of items in each subscale is quite variable
(range 2–10) compared to the English version (range of
items in each subscale: 2–7), but the variance explained
for each subscale is rather more balanced in the Spanish
version (range 5–12%) compared with the original ver-
sion (range 2–15%).
Differences in factor analysis between different valida-
tion studies is frequent. The six subscales we have
obtained from the analysis show great conceptual coher-
ence (in addition to empirical coherence) and respond to
the name used. We have included all the items in each
subscale with loadings equal or higher than .3. Levenstein
et al.’s original validation [10] had included several items
in subscales with loadings as low as � .15 (Item 7), .18
(Item 18) or .19 (Items 11 and 12). For this reason,
factorial structure of the Spanish version seems coherent
from a psychometric point of view.
In summary, the Spanish version of PSQ seems to be an
accurate instrument to assess stress in psychosomatic
research and deserve to be used in clinical practice.
Acknowledgments
The authors want to thank Dr. Susan Levenstein, San
Camillo-Forlanini Hospital, Rome, Italy, for her valuable
comments on a draft of the paper. This research was carried
out with the support of grants 98/1017 and 00/0991 from
the Spanish ‘‘fondo de investigaciones sanitarias de la
seguridad social’’ (FISSS).
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Table 5
Factors and items according to factor analysis in the original English
version and the Spanish version
Original english version Spanish version
Harrassment (2, 6, 19, 24) Harrassment– social acceptance
(5, 6, 12, 17, 19, 20, 24)
Overload (4, 11, 28, 29) Overload (2, 4, 11, 18)
Irritability (3, 10) Irritability– tension– fatigue
(1, 3, 8, 10, 14, 15, 16, 26, 27, 30)
Lack of joy (5, 7, 16, 17,
21, 23, 25)
Energy– joy (1, 13, 21, 25, 29)
Fatigue (1, 8, 13, 15) –
Worries (9, 18, 20, 22, 30) Fear–anxiety (22, 28)
Tension (12, 14, 26, 27) –
– Self-realisation–satisfaction (7, 9, 23)
C. Sanz-Carrillo et al. / Journal of Psychosomatic Research 52 (2002) 167–172 171
Appendix A. Cuestionario de estres percibido
A.1. Instrucciones para la forma general
En cada pregunta marque un cırculo en el numero que mejor describa con que frecuencia se aplica esta cuestion a su vida en
general durante los ultimos uno o dos anos. Responda rapidamente, sin intentar comprobar las respuestas y teniendo cuidado
en describir lo ocurrido en un perıodo largo de tiempo.
A.2. Instrucciones para la forma reciente
En cada pregunta marque un cırculo en el numero que mejor describa con que frecuencia se aplica esta cuestion a su
vida en general durante el ultimo mes. Responda rapidamente, sin intentar comprobar las respuestas y teniendo cuidado en
describir lo ocurrido exclusivamente en el ultimo mes.
Casi
nunca
A
veces
A
menudo
Casi
siempre
(1) Se siente descansado 1 2 3 4
(2) Siente que se le hacen demasiadas peticiones 1 2 3 4
(3) Esta irritable o malhumorado 1 2 3 4
(4) Tiene demasiadas cosas que hacer 1 2 3 4
(5) Se siente solo o aislado 1 2 3 4
(6) Se encuentra sometido a situaciones conflictivas 1 2 3 4
(7) Siente que esta haciendo cosas que realmente le gustan 1 2 3 4
(8) Se siente cansado 1 2 3 4
(9) Teme que no pueda alcanzar todas sus metas 1 2 3 4
(10) Se siente tranquilo 1 2 3 4
(11) Tiene que tomar demasiadas decisiones 1 2 3 4
(12) Se siente frustrado 1 2 3 4
(13) Se siente lleno de energıa 1 2 3 4
(14) Se siente tenso 1 2 3 4
(15) Sus problemas parecen multiplicarse 1 2 3 4
(16) Siente que tiene prisa 1 2 3 4
(17) Se siente seguro y protegido 1 2 3 4
(18) Tiene muchas preocupaciones 1 2 3 4
(19) Esta bajo la presion de otras personas 1 2 3 4
(20) Se siente desanimado 1 2 3 4
(21) Se divierte 1 2 3 4
(22) Tiene miedo del futuro 1 2 3 4
(23) Siente que hace cosas por obligacion, no porque quiera hacerlas 1 2 3 4
(24) Se siente criticado o juzgado 1 2 3 4
(25) Se siente alegre 1 2 3 4
(26) Se siente agotado mentalmente 1 2 3 4
(27) Tiene problemas para relajarse 1 2 3 4
(28) Se siente agobiado por la responsabilidad 1 2 3 4
(29) Tiene tiempo suficiente para usted 1 2 3 4
(30) Se siente presionado por los plazos de tiempo 1 2 3 4
C. Sanz-Carrillo et al. / Journal of Psychosomatic Research 52 (2002) 167–172172