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Brief communication
The Short Form Health Survey (SF-36): Translation and validation study of
the Iranian version
Ali Montazeri
1
, Azita Goshtasebi
1
, Mariam Vahdaninia
1
& Barbara Gandek
2
1
Iranian Institute for Health Sciences Research, Tehran, Iran (E-mail: ali@jdcord.jd.ac.ir);
2
Health
Assessment Lab, Waltham, MA, USA
Accepted in revised form 22 June 2004
Abstract
This was a large population-based study to develop and validate the Iranian version of the Short Form
Health Survey (SF-36) for use in health related quality of life assessment in Iran. A culturally comparable
questionnaire was developed and pilot tested. Then, the Iranian version of the SF-36 was administered to a
random sample of 4163 healthy individuals age d 15 years and over in Tehran. The mean age of the
respondents was 35.1 (SD ¼ 16.0) years, 52% were female, mostly married (58%) and the mean years of
their formal education was 10.0 (SD ¼ 4.5). Reliability was estimated using the internal con sistency and
validity was assessed using known groups comparison and convergent validity. In addition factor analysis
was performed. The internal consistency (to test reliability) showed that all eight SF-36 scales met the
minimum reli ability standard, the Cronbach’s a coefficients ranging from 0.77 to 0.90 with the exception of
the vitality scale (a ¼ 0.65). Known groups comparison showed that in all scales the SF-36 discriminated
between men and women, and old and the young respondents as anticipated (all p values less than 0.05).
Convergent validity (to test scaling assumptions) using each item correlation with its hypothesized scale
showed satisfactory results (all correlation above 0.40 ranging from 0.58 to 0.95). Factor analysis identified
two principal components that jointly accounted for 65.9% of the variance. In general, the Iranian version
of the SF-36 performed well and the findings suggest that it is a reliable and valid measure of health related
quality of life among the general population.
Key words: Health status, Iran, Population-based study, Quality of life, The SF-36
Introduction
The Short Form Health Survey (SF-36) is a well-
known generic health-related quality of life
instrument that has been developed in the United
State of America and translated into a variety of
languages. Psychometric analyses of the translated
versions provide evidence that the SF-36 is a reli-
able and valid measure in multiple populations.
[17]. Although cross-cultural studies are time
consuming, it is suggested that there is increasing
need for international standards to measure health
status in a man ner that allows comparison across
countries, but which also are relevant within
individual cultures. Thus, it was decided to devel-
op the SF-36 Iranian version to respond to this
increasing demand and provide a validated generic
quality of life instrument. In Iran there are
increasing demand by researchers and health
professionals to include a validated quality of life
questionnaire in their research or clinical investi-
gations. In Asia a few studi es have been carried
out to trans late and culturally adapt the SF-36
into different languages [812], but at present
there is no an agreed or a validated generic quality
of life instrument in Iran. This paper reports the
development of the Iranian version of the SF-36
Health Survey and the results of its psychometric
testing among the general population in Tehran,
the capital of Iran.
Quality of Life Research (2005) 14: 875882 Ó Springer 2005
Methods
The questionnaire
The SF-36 is a general quality of life instrument
that measures eight health related concepts: phys-
ical functioning (PF-10 items), role limitations due
to physical problems (RP-4 items), bodily pain
(BP-2 items), general health perceptions (GH-5
items)), vitality (VT-4 items), social functioning
(SF-2 items), role limitations due to emotional
problems (RE-3 items), and pe rceived mental
health (MH-5 items). In addition a single item that
provides an indication of perceived change in
general health status over a one-year period (health
transition) is also included in the SF-36 [13].
Translation
Permission was asked from the International
Quality of Life Assessment (IQOLA) Project and
the IQOLA translation methodology was followed
to translate the SF-36 from English into Persian,
the Iranian language [14]. Two independent health
professionals translated the items and two others
translated the response categories. Then a con-
solidated forward version was produced. This
questionnaire then was backward translated into
English by two professional translators to check
for differences between the Iranian versi on and the
original questionnaire. After a careful review and
cultural adaptation few changes have been made
and the provisional version of the questionnaire
was provided. In general there were no difficulties
in translating response categories but in items
regarding activities bowling and playing golf have
been changed to light sport activities, mile has
been changed to kilometer, and walking one block
or walking several blocks have been changed to
walking one alley or several alleys to refer to a
similar distance in Iranian language. Subsequently
the provisional forward translated questionnaire
was pilot tested and administered to a sample of 50
healthy individuals. The mean time to complete
the SF-36 was 9.6 (SD ¼ 6.6) min, 70% stated that
did not have any difficulties completing the que s-
tionnaire and 98% indicated that there were no
upsetting questions. The results of pilot testing
were reported to the IQOLA Project Director and
after her review a few more changes have been
made. There were difficulties in translation of
feelings such as ‘full of pep’, ‘felt so down’ and ‘felt
downhearted and blue’. These all carefully con-
verted to Iranian equivalence and the final version
was provided and used in this study.
Data collection and statistical analysis
This was a population-based study and the SF-36
was administered to a random sample of healthy
individuals aged 15 years and over living in Teh-
ran. To select a representative sample of the general
population a stratified multi-stage area sampling
was applied. Every household within 22 different
districts in Tehran had the same probability to be
sampled. A team of trained interviewers collected
data and all participants were interviewed in their
home. According to the IQOLA Project to test
psychometric properties of the SF-36 Iranian ver-
sion several tests were performed [15, 16]. To test
reliability the internal consis tency for each scale
was estimated using Cronbach’s alpha coefficient
and alpha equal to or greater than 0.70 was c on-
sidered satisfactory [17]. Validity was assessed
using known groups comparison to test how well
the questionnaire discr iminates between sub-
groups of the study sample that differed in gender
and age. It was expected that women and old
people would have lower scores than men and
young people in all measures. In addition conver-
gent validity (to test scaling assumptions) was as-
sessed using the correlation of each item with its
hypothesized scale. The Pearson product moment
statistic (Pearson correlation coefficient) of 0.40 or
above was considered satisfactory [18]. Further-
more the factor structure of the questionnaire was
extracted by performing principal component
analysis using oblique factor solution.
Results
The study sample
In all 4804 healthy individual were approached
and 4163 (87%) were agreed to be interviewed.
The mean age of the respondents was 35.1
(SD ¼ 16.0), 52% were female, mostly married
(58%), and the mean year of their formal education
876
was 10.0 (SD ¼ 4.5). The characteristics of
the respondents are shown in Table 1. Of those
who did not participate in the study 230 individ-
uals were female and the remaining 411 were male.
The main reason for this was due to the fact that
after two approaches most of these individuals
were not available in their home. Only a few
individuals refused to respond to the question-
naire.
Descriptive statistics and reliability
The descriptive statistics for the eight SF-36 scales
for the whole population are shown in Table 2. In
addition the Cronbach’s a coefficient to indicate
item internal consistency reliability for each mea-
sure is presented and all measures but vitality
showed satisfactory results. All scales met or ex-
ceeded the 0.70 level recommended for group
comparison with the exc eption of the vitality scale
(Cronbach’s a ¼ 0.65). In addition the percentage
of respondents scoring at the highest level (i.e.,
ceiling effect) was substantial for scales measuring
physical functioning, role physical, bodily pain,
social functioning, and role emotio nal. In contrast
the percent age of respondents scoring at the lowest
level (i.e., floor effect) was minimal for all scales
but role emotional. Inter-scale correlation analy-
sis also indicated that the scale constructs for the
SF-36 Iranian version were generally distinct
although fairly strong relationships between scales
(correlations greater than 0.50) were observed in
the expected directions. The results are shown in
Table 3.
Known groups comparison
This was to test the scale validity. It was hypoth-
esized that women and older people would have
poorer health status than men and the younger
respondents. The analysis showed that the females
and the older respon dents significantly had lower
scores in all measures as expected (Tables 4 and 5).
This indicated that the SF-36 well discriminated
between sub-groups of people who differed in
gender and age.
Table 1. The characteristics of the study sample (n = 4163)
No. (%)
Age group ( year)
1524 1420 (34)
2544 1614 (39)
4564 882 (21)
P65 247 (6)
Mean (SD) 35.1 (16.0)
Gender
Male 1997 (48)
Female 2166 (52)
Marital status
Single 1601 (38)
Married 2406 (58)
Widowed/divorced 156 (4)
Educational level
Primary 755 (18)
Secondary 2595 (62)
Higher 812 (20)
Mean year (SD) 10.0 (4.5)
Employment status
Employed 1482 (35)
Housewife 1225 (30)
Student 801 (19)
Unemployed 407 (10)
Retired 248 (6)
Table 2. Descriptive statistics and reliability statistics for the SF-36 scales
Mean (SD) Cronbach’s a Floor (%) Ceiling (%)
Physical functioning (PF) 85.3 (20.8) 0.90 0.6 38.6
Role physical (RP) 70.0 (38.0) 0.85 0.15 53.5
Bodily pain (BP) 79.4 (25.1) 0.83 1.1 42.7
General health (GH) 67.5 (20.4) 0.71 0.3 4.7
Vitality (VT) 65.8 (17.3) 0.65 0.2 1.8
Social functioning (SF) 76.0 (24.4) 0.77 1.2 32.4
Role emotional (RE) 65.6 (41.4) 0.84 22.5 52.9
Mental health (MH) 67.0 (18.0) 0.77 0.1 1.9
877
Test of scaling assumptions (convergent validity)
Table 6 presents the item-scale correlation matrix
between each item and the eight SF-36 scales. All
of the correlations between each item and its
hypothesized scale showed satisfactory results
suggesting that the items had a substantial asso-
ciation with the scale representing the concept.
Each of the eight scales measured a distinct
domain of functioning and well being as demon-
strated by higher item-scale correlations. Pear-
son correlation coefficient exceeded the 0.40 level
recommended ranging from 0.58 (GH3) to 0.95
(BP1).
Factor structure
The principal component analysis with oblique
rotation solution was performed and as expected a
two-factor structure (physical and mental compo-
Table 3. Inter-scale correlation for the SF-36 scales
PF RP BP GH VT SF RE MH
Physical functioning (PF)
Role physical (RP) 0.56
Bodily pain (BP) 0.53 0.55
General health (GH) 0.46 0.45 0.54
Vitality (VT) 0.46 0.44 0.52 0.55
Social functioning (SF) 0.47 0.51 0.61 0.51 0.56
Role emotional (RE) 0.34 0.52 0.41 0.39 0.41 0.51
Mental health (MH) 0.33 0.34 0.42 0.051 0.65 0.56 0.46
Table 4. Comparison of the SF-36 scores for the general population by gender
Male Female p*
mean (SD) mean (SD)
Physical functioning (PF) 87.8 (19.0) 82.9 (22.1) <0.0001
Role physical (RP) 73.8 (36.4) 66.5 (39.1) <0.0001
Bodily pain (BP) 82.7 (23.4) 76.4 (26.2) <0.0001
General health (GH) 70.2 (19.6) 65.0 (20.8) <0.0001
Vitality (VT) 68.9 (16.2) 62.9 (17.8) <0.0001
Social functioning (SF) 78.0 (23.5) 74.2 (25.1) <0.0001
Role emotional (RE) 70.1 (39.7) 61.4 (42.4) <0.0001
Mental health (MH) 69.2 (17.1) 65.0 (18.6) <0.0001
*The t-test result.
Table 5. Comparison of the SF-36 scores for the general population by age groups
1524 2544 4564 P65 p*
Mean (SD) Mean (SD) Mean (SD) Mean (SD)
Physical functioning (PF) 93.8 (12.9) 87.9 (17.2) 75.1 (22.4) 54.9 (29.2) <0.0001
Role physical (RP) 81.0 (30.8) 73.2 (30.3) 56.4 (40.6) 34.2 (40.9) <0.0001
Bodily pain (BP) 87.2 (19.7) 80.6 (23.8) 71.0 (27.3) 56.9 (30.2) <0.0001
General health (GH) 75.5 (17.6) 68.3 (18.9) 58.6 (20.0) 49.0 (21.9) <0.0001
Vitality (VT) 70.2 (15.2) 66.2 (16.8) 61.5 (17.7) 53.0 (20.3) <0.0001
Social functioning (SF) 82.9 (20.6) 76.5 (23.7) 69.0 (24.9) 58.4 (30.4) <0.0001
Role emotional (RE) 73.4 (37.3) 65.0 (41.8) 59.1 (43.3) 47.6 (44.2) <0.0001
Mental health (MH) 71.1 (16.3) 65.9 (18.2) 63.7 (18.7) 62.2 (18.6) <0.0001
*The result of one-way analysis of variance.
878
nents) was loaded that jointly accounted for 65.9%
of the variance. However, this was not exactly
similar to the struc ture seen for the original ques-
tionnaire. The results are shown in Table 7.
Discussion
Cross-cultural validation studies although very
difficult to be carried out, their results might be
Table 6. Item-scale correlation matrix for the eight SF-36 measures
Item PF RP BP GH VT SF RE MH
Physical functioning (PF)
PF1 0.65 0.41 0.39 0.41 0.38 0.34 0.25 0.25
PF2 0.74 0.45 0.41 0.41 0.36 0.36 0.28 0.26
PF3 0.71 0.41 0.40 0.35 0.35 0.31 0.24 0.24
PF4 0.80 0.47 0.44 0.36 0.38 0.38 0.28 0.27
PF5 0.77 0.39 0.37 0.27 0.31 0.33 0.24 0.22
PF6 0.75 0.43 0.44 0.34 0.37 0.35 0.29 0.27
PF7 0.81 0.45 0.43 0.38 0.36 0.39 0.28 0.26
PF8 0.82 0.44 0.40 0.32 0.32 0.37 0.26 0.23
PF9 0.77 0.37 0.33 0.26 0.27 0.32 0.21 0.19
PF10 0.59 0.27 0.25 0.20 0.23 0.24 0.19 0.18
Role physical (RP)
RP1 0.46 0.81 0.45 0.38 0.38 0.40 0.42 0.27
RP2 0.44 0.83 0.44 0.38 0.38 0.41 0.45 0.31
RP3 0.50 0.83 0.47 0.37 0.36 0.44 0.42 0.29
RP4 0.46 0.84 0.46 0.37 0.36 0.43 0.43 0.27
Bodily pain (BP)
BP1 0.49 0.50 0.95 0.52 0.48 0.56 0.37 0.39
BP2 0.51 0.53 0.91 0.49 0.50 0.60 0.40 0.40
General health (GH)
GH1 0.47 0.45 0.50 0.71 0.45 0.44 0.35 0.39
GH2 0.25 0.29 0.36 0.69 0.39 0.33 0.26 0.35
GH3 0.22 0.18 0.23 0.58 0.25 0.23 0.16 0.23
GH4 0.24 0.24 0.28 0.66 0.27 0.29 0.24 0.34
GH5 0.41 0.39 0.49 0.78 0.51 0.45 0.33 0.43
Vitality (VT)
VT1 0.29 0.29 0.32 0.31 0.64 0.33 0.24 0.29
VT2 0.36 0.34 0.39 0.42 0.77 0.41 0.31 0.52
VT3 0.33 0.32 0.41 0.44 0.69 0.42 0.32 0.52
VT4 0.29 0.27 0.33 0.35 0.67 0.38 0.27 0.47
Social functioning (SF)
SF1 0.43 0.46 0.59 0.45 0.49 0.91 0.47 0.49
SF2 0.41 0.47 0.52 0.47 0.52 0.90 0.45 0.53
Role emotional (RE)
RE1 0.28 0.44 0.36 0.35 0.35 0.43 0.87 0.40
RE2 0.27 0.44 0.34 0.32 0.35 0.43 0.87 0.39
RE3 0.34 0.47 0.37 0.36 0.37 0.47 0.88 0.39
Mental health (MH)
MH1 0.16 0.19 0.26 0.32 0.38 0.36 0.28 0.69
MH2 0.22 0.25 0.30 0.41 0.43 0.41 0.36 0.74
MH3 0.24 0.26 0.32 0.36 0.49 0.39 0.30 0.69
MH4 0.24 0.25 0.30 0.35 0.49 0.43 0.38 0.77
MH5 0.31 0.29 0.35 0.39 0.56 0.42 0.32 0.72
879
considered worthwhile. First, providing standard
health measures make health status comparison
between countries possible. Second, they provide
validated instruments to monitor population
health, to estimate bur den of disease and to
investigate outcomes in clinical practice and to
evaluate treatment effects. This study provided
evidence that the SF-36 is a valid measure of
population health status and quality of life in Iran.
As it was suggested the results indicated that the
SF-36 version meet at least two of the prerequisites
for cross-cultural use of health status question-
naires, namely, cultural appropriateness and
comparability of content [19].
The SF-36 was basically designed to be a
self-administered questionnaire but it can be
completed through an interview in person, com-
puterized administration, or by telephone [20]. To
collect data this study used face-to-face inter-
views. Thus there were no missing data and the
problem of illiterate individuals was not encoun-
tered. Furthermore the study used a relatively
large sample of the general population. Therefore
as it has been suggested [16] the result of this
study could be considered as Iranian normative
data for the SF-36 Health Survey and might be
used as a basis for comparison with specific
populations in the future studies. However, one
might argue that a sample from the urban capital
is not necessarily representative of the entire
country. In general this is true but since Tehran
has became a multicultural metropolitan area it
has been suggested that a sample from the general
population in Tehran at least could be regarded
as a representati ve sample of urban population in
Iran.
In general all psychometric tests of the SF-36
Iranian version showed satisfactory results. Reli-
ability of the questionnaire as measured by the
Cronbach’s a coefficient for all eight scales but the
vitality scale exceeded the recommended level. The
fact that the vitality scale performed differently
from other scale s might reflect the difficulty
encountered in translating vitality items from
English to Persian. Even trans lating the word
‘vitality’ from English to Persian was somewhat
difficult. However in translating vitality items it
was decided to use very similar vocabularies to
indicate what we are exactly asking for. Known
groups analys is also indicated that the SF-36 could
discriminate well between sub-group of people that
differed in gender an d age. The findings showed
that women and old people had poorer health as
compared to men and the younger respondents.
This suggests that in study of health status and
using the SF-36 in Iran the contribution of age and
gender to the findi ngs should be considered.
Studies using the SF-36 in other countries also
reported similar results [21].
The multi-item analysis of the SF-36 Iranian
version showed promising results. For all eight
scales satisfactory results were observed indicating
that each item strongly correlated with its
hypothesized scale. In additi on the resul t showed
that items were stronger measures of their
hypothesized co nstructs than of other constructs.
Table 7. Hypothesized association between the SF-36 scales and the actual factor loading obtained in this study
Hypothesized association Factorial analysis: Rotated principal component
Physical Mental Correlation with Variance explained
Physical Mental
Physical functioning (PF) + ) 0.81 0.18 0.69
Role physical (RP) + ) 0.83 0.22 0.73
Bodily pain (BP) + ) 0.68 0.42 0.65
General health (GH) * * 0.45 0.60 0.56
Vitality (VT) * * 0.31 0.78 0.71
Social functioning (SF) * + 0.50 0.63 0.65
Role emotional (RE) ) + 0.46 0.50 0.45
Mental health (MH) ) + 0.10 0.90 0.83
+Strong association (r>0.70), *Moderate association (0.30< r < 0.70), )Weak association (r < 30).
880
Items in the bodily pain (BP) and social func-
tioning (SF) scales correlated most strong ly with
their own scale than with other scales.
The factor analysis of the SF-36 clearly indi-
cated that the questionnaire includes two under-
lying factors namely physical and mental
components, although the findings was not exactly
similar to the original hypothesized association.
The vitality scale (VT) was strongly correlated
with mental component than physical component.
Also the role emotional scale (RE-role limitations
due to emotional problems) showed a moderate
association with physical and mental components
while one expects a weak association with physical
component and strong association with mental
component. It is argued that these might be due to
the cultural differences that exist between Asia and
Western countries rather than structural defect
since the criteria of validity of items and scales
were satisfactory [8, 11, 12]. Perhaps this indicates
the strength of physical and emotional dimensions
of quality of life for Iranians and the fact that
general health loads more strongly on mental
health than physical he alth. However, one should
be aware that in the present study the factor
analysis was carried using oblique rotation method
while the instrument developers used the varimax
method [22]. In this study a two-factor structure
(physical and mental components) jointly ac-
counted for 65.9% of the variance that was a rel-
atively better factor loading reported from Asian
countries such as China (56.3%), Taiwan (60%)
and Lebanon (62.9%) [1012].
In conclusion, although the present study does
not provide evidence on test-retest reliability or on
responsiveness, the findings however provide fur-
ther evidence that the translation of the SF-36 is
feasible in Asia and could be used as a reliable and
valid instrument for measuring health related
quality of life. The Iranian version of the SF-36 is
being used in several academic research projects
and further results from its validity are awaited.
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Address for correspondence: Ali Montazeri, Iranian Institute for
Health Sciences Research, P.O. Box 13185-1488, Tehran, Iran
E-mail: ali@jdcord.jd.ac.ir
882
