Validation of the General <i>Health Questionnaire</i> (GHQ-12) adapted to a work-related context

doi:10.4236/ojpm.2011.12007

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Vol.1, No.2, 44- 48 (2011)

doi:10.4236/ojpm.2011.12007

Open Journal of Preventive Medicine

Validation of the General Health Questionnaire (GHQ-12)

adapted to a work-related context

Francois-Xavier Lesage1,2*, Sonia Martens-Resende2, Frédéric Deschamps2, Sophie Berjot1

1Laboratory of Applied Psychology-LPA-(EA4298), Reims, France; *Corres ponding a uthor: fxlesage@chu-reims.fr

2Occupational Health Department, Faculty of Medicine, Hôpital Sébastopol, Reims, France.

Received 25 May 2011; revi sed 14 July 2011; accepted 31 July 2011.

AB S TRAC T

Introduction: the aim of this study is to test the

factorial structure and the internal consistency

of the 12-items General Health Questionnaire

adapted to work-related psychological distress

(GHQW). Methods: a validated French versi on of

the GHQ-12 was used and transformed to re-

mind of the occupational context. A sample of

1014 workers completed the GHQW. Internal

consistency was assessed by Cronbach’s α

coefficient. The factorial structure was extracted

with an exploratory factorial analysis (EFA).

Results: th e EF A run on t he data yield to a on e-

factor structure explaining 60.5% of the total

variance of the scale. The Cronbach’s alpha

showed a very good internal consistency of the

scale (α = 0.94). Conclusion: the findings

support that the GHQW is a reliable and valid

instrument for measuring work-related psycho-

logical distress in workers. This work-related

version could find some applications in epide-

miological research at work, in the study of

psychosocial risk factors and in the occupa-

tional health physician’s daily activity.

Keywords: Occupational Health; Mental Health;

Questionnaires; Factor Analysis; Statistical; General

Health Questionnaire; Validity

1. INTRODUCTION

The 12-item General Health Questionnaire (GHQ-12)

is a self-report measure of psychological morbidity, in-

tended to detect psychiatric disorders in community set-

tings and non-psychiatric settings [1]. It is widely used

in clinical practice, epidemiological research and for

research in psychology [2-4].

The original GHQ is co mposed of 60 items. However,

different shortened validated versions of this instrument

are currently available (e.g., 30, 28, and 12-items).

The 12-items version, due to its brevity, is probably

the most popular and so, has been extensively evaluated

in terms of its validity and reliability as a one-dimen-

sional indicator of the severity of psychological morbid-

ity [5-9].

Respondents had to indicate, on a -points scale an-

chored with 1) less than usual, 2) no more than usual, 3)

rather more than usual, 4) much more than usual how

frequently they experienced recently the different symp-

toms listed on the scale. The general version of the scale

does not precise to participants any context in which the

symptoms have been experienced. Each item is rated on

a four-point scale, using one of two most common scor-

ing methods: dichotomous (0-0-1-1) or Likert-like type

(0-1-2-3).

The GHQ-12 is a well-known instrument for measur-

ing minor psychological distress and has been translated

into a variety of languages. If the GHQ-12 is not a tool

for indicating a specific diagnosis (e.g. depression, anxi-

ety, etc.), it is more useful and adapted in the work con-

text in the way that it can serve as an general indicator o f

distress and/or potential problems.

The GHQ-12 was desig ned and is u sed routinely as a n

unidimensional measure of psychological morbidity.

Many studies, however, have reported that the GHQ-12

is not unidi mensio nal, but in st ead assesse s ps ycholo gical

morbidity in two (positive and negative items) or three

dimensions (“anxiety and depression”, “social dysfunc-

tion” and “loss of confidence”) [10-19].

Considering the GHQ-12 to be a brief, simple and

easy to complete instrument, and thefact that its applica-

tion in research settings as a screening too l is well docu-

mented, we decidedto check its psychometric properties

in a work -related version.

This version could find so me applicatio ns in epidemi-

ological research at work, in the study of psychosocial

risk factors and in the occupational health physician’s

daily activity.

F.-X. Lesage et al. / Open Journal of Preventive Medicine 1 (2011) 44-48

2. MATERIAL S AND METHODS

2.1. Participants

One thousand and fourteen workers were randomly

selected in an occupational health center (In the French

occupational health organization, every workers have a

systematic medical examination annually or biennially).

At their arrival at the center, the authors, after having

informed the participants about the study objectives, ask

for their voluntary and anonymous participation in the

study, précising that they could withdraw at any time.

Both oral and written instructions were given to ensure

that the items were understood, and participants were

reassured that their responses were confidential.

2.2. Instrument

A modified version of the GHQ-12 validated French

scale was used [12]. The first modification was made on

the instructio ns, which (orally and written) asked whether

the participants experienced recently at work the symp-

toms and/or behaviors listed on the scale. The second

modification was made on the items of the scale. For

each item is now précised the work context. For example:

“Felt constantly under strain at work”. The occupational

context was reminded in the items. Each item is rated on

a four-point scale (less than usual, no more than usual,

rather more than usual, or much more than usual). The

Likert scoring method (0-1-2-3) was used for this study.

A higher score indicates a greater degree of psychologi-

cal distress.

2.3. Statistical Analysis

We performed exploratory factor analysis (EFA) to

explore the structure of the in strument, with the principal

components method. The cutoff of factor loading adopted

was >0.5 [20].

The reliability of the measure was examined in rela-

tion to the instrument’s internal consistency by calculat-

ing the Cronbach’s α co efficie nt a nd the homoge neit y of

the scale (mean inter-item correlations). A Cronbach’s α

coefficient of 0.70 or greater and mean inter-item corre-

lations situated in a 0.20 to 0.40 range were considered

as satisfactory [21]. The means and the variances of all

items were computed with 95% confidence limits.

3. RESULTS

3.1. Descriptive Statistics

One thousand and fourteen workers, aged 18 - 63

years (Mean = 41.5; SD = 10.3) entered the study. Fifty

three percent were male. Demographics of workers who

responded to our questionnaire, and comparison with the

French working population are shown in Table 1.

Table 2 presents the mean scores (m), standard devia-

tion (SD), and correlations between items of the General

Health Questionnaire at Work (GHQW). The item’s

means range from 0.50 (item 11) to 1.20 (items 1 and 5).

The means inter-item correlations of the total set of

items was ranged from 0.42 (items 7 and 4) to 0.79 (item

10 and 9).

3.2. Factor Structure

Table 2 presents the factor loading produced by the

EFA with the principal component method. This analysis

identified a single factor model (factor loadings ranging

from 0.68 to 0.89), explaining 60.5% of the total vari-

ance of the scale.

3.3. Homogeneity and Reliabilit y

The 12 items of the GHQW showed good homogene-

ity. The average inter-item correlation was 0.57. The

items-total correlations were ranged from 0.62 to 0.86

indicating a good contribution to the total score.

The internal consistency of the questionnaire was

measured using the Cronbach’s α coefficient. This coef-

ficient was found to be 0.94.

4. DISCUSSION

The current study aimed at exploring the structure and

reliability of the GHQ-12 adapted to a work-related

context (GHQW). We have tried to adapt the GHQ-12,

the shorter version of the GHQ, to a work-related con-

text. It could be a very helpful tool in the field of occu-

pational psychology.

There are significant difference between the subjects

and French workers. The ratio of the youngest workers is

more important in our sample. In fact, there is some dif-

ferences in the different parts of France. Whatever, there

is no influence on the validation. Most of the validation

studies was done with sample s of stud ents. We prefer an

Table 1. Demographics of subjects and comparison with the

French workers.

Subjects (n = 1014) Frenc h workers*

(n = 27,600,000) p

Age

(mean,(SD)) 41.5 y (10.3) 40.2 y ns

<30 years 19.8% 13.5% <0.01

30 - 39 y 26.3% 31.9% <0.01

40 - 49 y 28.1% 27.6% ns

>49 y 25.7% 27% ns

Gender

male 53% 53.6% ns

*According the «institut national de la statistique et des études économi-

ques»; ns: p > 0.05.

F.-X. Lesage et al. / Open Journal of Preventive Medicine 1 (2011) 44-48

Table 2. Means (m), Standard Deviation (SD) and correlations between items, item-total correlations, and exploratory factorial analy-

sis (EFA) of the General Health Questionnaire at Work (GHQW).

Item 1 Item 2 Item 3Item 4 Item 5 Item 6Item 7Item 8Item 9Item 10Item 11Item 12 Item-total

correlations* EFA:

Factor I

Item 1 1.00 0.72 0.77

Item 2 0.59 1.00 0.74 0.78

Item 3 0.52 0.47 1.00 0.62 0.71

Item 4 0.56 0.40 0.54 1.00 0.62 0.69

Item 5 0.55 0.66 0.46 0.43 1.00 0.74 0.78

Item 6 0.59 0.70 0.50 0.51 0.67 1.00 0.81 0.84

Item 7 0.46 0.43 0.51 0.42 0.51 0.481.00 0.62 0.68

Item 8 0.58 0.52 0.49 0.56 0.48 0.590.481.00 0.68 0.74

Item 9 0.62 0.71 0.56 0.52 0.73 0.770.560.581.00 0.86 0.89

Item 10 0.66 0.66 0.55 0.56 0.63 0.750.470.600.791.00 0.84 0.87

Item 11 0.55 0.56 0.54 0.50 0.58 0.660.440.520.690.781.00 0.75 0.80

Item 12 0.53 0.51 0.56 0.46 0.57 0.540.650.500.660.580.561.00 0.71 0.76

Mean

score 1.20 1.00 1.11 0.99 1.20 0.831.171.140.790.640.501.15 60.5%**

SD 0.62 0.98 0.73 0.65 0.95 0.940.680.651.010.960.880.68

*Aver age inter-item correlation: 0.57; Cronbach’s α coefficient: 0.94, **total variance of the scale explained by the one factor structure.

“ecological” validation with a worker sample. There is

some differences in age structure but our sample is near

the French workers’ one.

4.1. Factor Structure

Although the GHQ-12 was designed as a unidimen-

sional scale, two- and three-factor models have been

frequently reported. Currently, the factor structure of the

GHQ-12 remains under debate. The World Health Or

ganization study of psychological disorders in general

health care in 15 different centers indicated that there is

substancial factor variation between centers for the

GHQ-12 [22].

The inconsistent findings might be partly due to the

statistical methods used (principle component analysis

with varimax rotation or confirmatory factor analysis),

and wording effects (positively and negatively worded

items) [23].

But the context might be an important cause of these

inconsistent findings. The factor structure of the GHQ-

12 is often explored in various and specific population,

such as elderly adults, students, or physician population.

These specific populations refer to their own environ-

ment to answer to this q uestionnaire. An item or a set of

items of the GHQ-12 have probably not the same mean-

ing in elderly adults, unemployed population, or students.

Moreover, each of these populations can refer to differ-

ent life events (whether occupational, whether private)

for the meaning of the items.

In this study, the structure and reliability of the GHQ-

12 is explored in a large and almost representative popu-

lation of French workers, and the items remind the ref-

erence context. This work-related version induces a

more homogeneous meaning of the set of items, and so

probably contributes to the single factor structure and the

high reliability of the GHQW.

We use a n EFA b ecause we do no t have stro ng theor y

about the construct underlying responses to our meas-

ures in an occupational context. A second study could

follow up with a Confirmatory Factor Analysis (CFA) to

confirm the factor structure of the GHQW. This CFA

cannot be done using the same data set. W hatever, a CFA

performed in a large sample of workers is useful.

The high factor loading and its homogeneity consoli-

date the use of the GHQW as a unidirectional measure.

The score of the GHQW can be the sum of the items,

without weightin g some items.

4.2. Reliabil ity

In general, the most research findings throughout the

world show satisfactory reliabilities. Cronbach’s alpha in

our study was 0.94. The internal consistency of the

GHQW is over the original French translation of the

GHQ-12. (0.78), and close to two French GHQ-28 item

alpha, respectively 0.91 and 0.95 [24,25].

We have data from more than 80 subjects for every

measured variable in the model, which is widely over the

10 subjects recommended per variable [26]. This large

sample provides a good reliability in our parameter es-

timates.

The specific context of work-related psychological

context increases the homogeneity of the GHQW. The

findings reported in the current study support the psy-

chometric appropriateness of the GHQW.

We have study the possib ility to provide a shorter ver-

sion of the GHQW. But the good homogeneity of the

item-total correlations does not allow it (Table 2).

5. CONCLUSIONS

The current study provides some evidences that the

F.-X. Lesage et al. / Open Journal of Preventive Medicine 1 (2011) 44-48

GHQW is a reliable version (Cronbach’s α coefficient:

0.94) and valid instrument for measuring work-related

psychological distress The findings reported support a

single factor structure, as in the original Goldberg’s ver-

sion.

This version could find so me applicatio ns in epidemi-

ological research at work, in the study of psychosocial

risk factors and in the occupational health physician’s

daily activity.

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APPENDIX: LIST OF THE ITEMS OF THE

GHQ-12

1- Able to concentrate

2- Lost sleep over worry

3- Play usef ul part in things

4- Capable of making decisions

5- Constant l y unde r strai n

6- Could not overcome difficulties

7- Enjoy day-to-day activities

8- Face up problems

9- Feeling unhappy and depressed

10- Losing confidence in self

11- Thinking of self as worthless

12- Reasonable happy