Full text of DOI:10.1207/S15327558IJBM0902_06

INTERNATIONAL JOURNAL OF BEHAVIORAL MEDICINE, 9(2), 155–172
Copyright © 2002, Lawrence Erlbaum Associates, Inc.
Assessment of Functional
Gastrointestinal Disorders
Using the Gastro-Questionnaire
Rolf Leibbrand, Ulrich Cuntz, and Wolfgang Hiller
The purpose was to investigate the reliability and factorial structure of the Gas-
tro-Questionnaire for the screening and psychometric measurement of functional
gastrointestinal disorders (FGDs). The questionnaire contains 27 gastrointestinal
symptom items drawn from the Rome–II criteria, which are rated by frequency and
severity, as well as some items to exclude organic diseases. The questionnaire was ad-
ministered to 259 normal participants and to 69 participants of the annual German
meeting of patients with irritable bowel syndrome. Reliability was good (Cronbach’s
alpha for frequency and severity items: α = .86 and α = .87). Factor analysis yielded a
six-factor solution explaining 60.7% of the variance. Diagnostic frequencies ranged
from 32.8% to 100% for FGDs in general, from 1.3% to 76.8% for irritable bowel syn-
drome, and from 7.0% to 100% for functional dyspepsia, depending on samples and
symptom definitions. The Gastro-Questionnaire is a very economic, reliable, and
content-valid instrument for the assessment of FGDs.
Key words: functional gastrointestinal disorders, assessment, Gastro-Questionnaire,
symptom frequencies, Rome criteria
Functionalgastrointestinaldisorders(FGDs)arereportedtobeverycommon. They
are commonly defined as “a variable combination of chronic or recurrent gastroin-
testinal symptoms not explained by structural or biochemical abnormalities”
(Drossmanetal.,1990).However,thisbasicdefinitionhastoberegardedasprelimi-
nary, because physiological etiology might be verified by future research. In epide-
Rolf Leibbrand, Department of Clinical Psychology, University of Mainz, Germany; Ulrich Cuntz,
Roseneck Center for Behavioral Medicine in Prien, Germany; Wolfgang Hiller, Department of Clinical
Psychology of the University of Mainz, Germany.
Correspondence concerning this article should be addressed to Rolf Leibbrand, Johannes
Gutenberg-Universität Mainz, Psychologisches Institut, Staudingerweg 9, 55099 Mainz, Germany.
E-mail: Rolf.Leibbrand@Uni-Mainz.de

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LEIBBRAND, CUNTZ, AND HILLER
miological studies on irritable bowel syndrome (IBS), which is the most prominent
ofthesedisorders, lifetimeprevalenceratesofabout15%to20%inthegeneralpop-
ulation were observed (Talley, Zinsmeister, van Dyke, & Melton, 1991; Jones &
Lydeard,1992;Longstreth&Wolde-Tsadik,1993).Agréus,Svärdsudd,Nyrén,and
Tibblin (1995) found that 25% of an unselected Swedish adult population fulfilled
diagnostic criteria for functional dyspepsia (FD). In a study by Drossman et al.
(1993), 69% of a sample of 5,430 U.S. householders met the criteria for at least 1 of
20 FGDs; that is, more than two thirds of the U.S. population may be affected by
FGDs.
However, frequencies vary widely. In the study by Drossman et al. (1993),
only 11% of the participants reported symptoms compatible with the diagnosis
of IBS, and prevalence of FD was less than 3%. Sandler (1990) reported find-
ings from the Second National Health and Nutrition Examination survey indicat-
ing that 4.7 million people (2.9% of the U.S. population) had self-reported
diagnoses of IBS (spastic colon or mucous colitis). Talley, Boyce, and Jones
(1996) found IBS in 11.8% and FD in 11.5% of the participants in an Australian
random sample. In a recent study, Herschbach, Henrich, and Von Rad (1999) re-
ported lifetime prevalence rates of about 2% for IBS and 11% for FD in a repre-
sentative sample of the German adult population.
Discrepancies may be explained partly by different diagnostic definitions, as
determined by the Manning criteria (Manning, Thompson, Heaton, & Morris,
1978), Rome criteria (Drossman et al., 1990), and Rome–II criteria (Talley et al.,
1999; Thompson et al., 1999). These are characterized by different symptom
sets and definitions yielding different prevalence rates. Recent epidemiological
studies on IBS were based on the international consensus (Rome) criteria for
FGDs (Drossman et al., 1990). According to the Rome criteria, FGD diagnoses
are based on specific symptom sets and scores. In addition, a distinct threshold
for the persistence of functional gastrointestinal symptoms (FGSs; >12 weeks
during the last year) was defined for most FGDs in a recent revision of the
Rome criteria, the Rome–II criteria (Clouse, Richter, Heading, Janssens, & Wil-
son, 1999; Talley et al., 1999; Thompson et al., 1999; Whitehead et al., 1999).
However, compared with common definitions of psychosomatic disorders (e.g.,
somatoform disorders) according to the Diagnostic and Statistical Manual of
Mental Disorders (4th ed. [DSM–IV]; American Psychiatric Association, 1994)
or the International Classification of Diseases (ICD)–10 (World Health Organi-
zation, 1993), the Rome–II criteria are incomplete. They contain no severity in-
dex (e.g., distress, impairment, illness behavior) or threshold definitions to
differentiate between clinically relevant symptoms and common conditions of
lowered well-being. This problem is very salient for diagnostic definitions in ep-
idemiological studies, because symptom frequencies basically depend on what is
regarded as an abnormal condition. Likewise, this problem is relevant for re-
search and practice of standardized psychological treatments, which need to re-

ASSESSMENT OF GASTROINTESTINAL DISORDERS
157
fer to diagnostically homogeneous populations, as commonly defined by
symptom definitions, severity indexes, and inclusion and exclusion criteria.
Furthermore, standardized psychometric instruments for dimensional measure-
ment of FGD, as required for evaluations of natural course and treatment of FGSs,
havenotbeen availableuntilnow. Manystudies usedsymptom diaries instead. Asa
consequence,Boyce,Gilchrist,Talley,andRose(2000)presentedaninstrumentnot
evaluated yet, the Bowel Symptom Severity Scale. It was used in a pilot study on
cognitive–behavioral IBS treatment to cover dimensional aspects (frequency, dis-
tress, impairment) of IBS symptoms.
Another important issue is that even well-elaborated instruments (e.g., Boyce et
al., 2000; Talley, Boyce, Owen, Newman, & Paterson, 1995; Talley, Phillips,
Wiltgen, Zinsmeister, &Melton, 1990)focusonspecificFGDsfollowingtheRome
classification, insteadofconsideringthefullrangeofFGSs. Subsyndromalvariants
of FGDs, atypical symptom combinations, the significance of the total number of
symptoms, andempiricallybasedcriteriafortheclassificationofFGDwerenotsuf-
ficiently addressed in epidemiological studies (Drossman et al., 1993; Herschbach
etal.,1999;Jones&Lydeard,1992;Sandler;1990;Talley,Boyce,&Jones,1996).
The aim of this study was to investigate the practical use and psychometric prop-
erties of a recently developed self-rating instrument for the screening, dimensional
measurement, and classification of FGD. One particular focus was to determine ef-
fectsofvarioussymptomdefinitionsonfrequenciesofFGDsinnormalparticipants
and patients, to evaluate the practical consequences of the additional severity index
and the symptom definition proposed. Furthermore, the factorial structure of the
questionnaire on the basis of symptom severity items was investigated to determine
the compatibility of its empirical dimensions with the Rome–II classification.
METHODS
Participants
Theinitialsampleconsistedof259participantsfromtheGermangeneralpopulation
randomly recruited in public areas of the cities of Mainz, Cologne, and Frankfurt
(e.g., waiting areas of the Frankfurt airport). This sample was unselected and is not
representative of the German general population. Because participants were not pa-
tients, theyhadnotbeenscreenedsystematicallyforgastrointestinalmedicalcondi-
tions. In addition, 69 participants particularly affected by various combinations of
FGSswererecruitedattheGermanIBSpatientmeeting.Thecommoncharacteristic
of these participants was that they had been told by a specialized physician that their
symptoms were functional after careful examination. They did not necessarily have
to meet Rome–II IBS criteria. Participants were asked to participate, on a voluntary
basis, inascientificstudyonhealthproblemsinthegeneralpopulation. Participants

158
LEIBBRAND, CUNTZ, AND HILLER
completed a self-administered questionnaire on gastrointestinal symptoms, gastro-
intestinal medical conditions, and health care use.
Assessments
FGDswereassessedbyarecentlydevelopedscreeninginstrumentfortheself-rating
of gastrointestinal complaints, the Gastro-Questionnaire. It contains 27 symptoms
(Table 1), which are rated by frequency and severity (defined as subjective distress
or suffering). Symptoms were not selected empirically but were derived on a theo-
retical basis from the Rome–II criteria. For example, IBS and each of its subtypes
can be combined easily from Items 10, 11, 12, 14, 15, 16, 18, 19, 20, 21, 22, and 24;
FDanditssubtypescanbecombinedfromitems2,4,5,6,9,and12.Germantransla-
tions were taken mainly from the IBS Consensus Report of the German Society for
Digestive and Metabolic Diseases (Hotz et al., 1999) and completed by common
medical expressions. Passage of blood is included in the symptom list as an addi-
tional indicator to rule out structural explanations for symptoms. Frequency of each
symptom during the last 12 months is rated on a 4-point scale: 0 (not at all), 1 (from
time to time), 2 (frequently, i.e., >25% of days), and 3 (nearly always, i.e., >75% of
days). Symptom severity is rated on a 5-point scale: 0 (no distress) to 4 (very severe
distress), except for two FGSs that are not associated with bodily sensations (pas-
sageofmucusandstoolresiduesinunderwear).Administrationofthequestionnaire
is very economic and requires less than 15 min. Diagnoses of 20 FGDs according to
the Rome and Rome–II criteria can be derived directly from the Gastro-Question-
naire on the basis of computer algorithms. For some symptoms (e.g., abdominal
pain), additional questions are included to cover the Rome criteria entirely (e.g.,
symptom associated or relieved with defecation, eating, etc.). Furthermore, gastro-
intestinal medical conditions are excluded by several questions on organic disease
andweightchange.Participantssarequestionedexplicitlyonmedicalconditionsdi-
agnosed by a physician. Following the Rome criteria, FGDs (e.g., IBS, FD, func-
tionaldiarrhea)arediagnosedcomorbidlyingeneral,apartfromresidualcategories.
The procedure for specifying FGDs can be varied easily along different symptom
definitions. Sociodemographic and clinical characteristics (job status, educational
level, family status, partner situation, and previous psychotherapeutic treatments)
also were investigated.
Definitions
Symptom sets for FGDs were based on the Rome–II criteria. To analyze FGS
and FGD frequencies, we applied three different thresholds: First, we evaluated
FGS and FGD frequencies without considering either the persistence or the se-
verity of symptoms. In the second step, FGD diagnoses were determined consid-
ering a persistence criterion corresponding to the Rome–II criteria (enduring

ASSESSMENT OF GASTROINTESTINAL DISORDERS
159
symptoms have to be present for at least 12 weeks during the preceding 12
months). We used a criterion of “more than 25% of days during the last 12
months,” which is very similar to the Rome–II definition. However, the defini-
tion used in the Gastro-Questionnaire can be varied easily, because it need not
necessarily refer to a 12-month period. This may be of particular value for re-
peated application of the Gastro-Questionnaire as a dimensional measure in
studies on treatment evaluation and the natural course of FGDs. Third, we ana-
lyzed frequencies of FGDs considering not only the persistence but also the se-
verity of FGSs (i.e., FGDs were diagnosed only if symptoms were associated
with distinct feelings of distress).
Statistical Analyses
Split-half reliability (Spearman–Brown) and internal consistency (Cronbach’s
alpha) were investigated separately for frequency and severity item subscales.
Frequencies of FGS and FGD diagnoses were calculated according to the differ-
ent symptom thresholds defined. Factor analysis was conducted by using
varimax rotation. T tests and chi-square-tests were calculated to analyze associa-
tions of FGDs with age and sex.
RESULTS
The mean age of the participants in the general population sample was 33.5
years (SD = 14.7). Sixty-three percent of the participants were female, 32% were
married, 64% lived in long-term partnerships, 42% had finished secondary
school or had a higher degree, and 78% were employed. Eleven percent of the
participants had received psychotherapy previously on an outpatient basis and
2% on an inpatient basis.
In the sample collected at the German IBS patient meeting, only age and sex
were investigated as sociodemographic characteristics. Sixty-seven percent of
the participants were female. Mean age was 53.4 years (SD = 16.0).
Because the patient sample was not comparable regarding mean age, and
only age and sex were recorded as socioeconomic characteristics, these data
were used only to compare FGS and FGD frequencies in both samples on a de-
scriptive basis. Statistical analyses on reliability, factorial structure, and age and
sex differences were conducted exclusively for the general population sample.
Thirty of 259 participants in the general population sample (12%) and 13 of
69 participants in the sample collected at the German IBS patient meeting (19%)
reported structural or biochemical gastrointestinal conditions incompatible with
FGD diagnoses and were excluded from further analyses.

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LEIBBRAND, CUNTZ, AND HILLER
Split-Half Reliability and Internal Consistency
OverallCronbach’salphawas.86forfrequencyitemsand.87forseverityitems(N=
238) based on the general population sample. For the split-half reliability, we deter-
mined overall Spearman–Brown coefficients of .77 for frequency items and .81 for
severity items.
Factorial Structure of the Gastro-Questionnaire
Factor analysis was conducted on the basis of items statistically generated from
both frequency and distress items. Symptoms present less than 25% of days
were counted 0; otherwise, they were counted 1 and multiplied with the corre-
sponding distress rating. This is of particular importance, because former facto-
rial approaches were based on the frequency or the simple presence of FGSs
instead of considering aspects of distress or suffering.
A varimax-rotated six-factor solution explaining 60.7% of the variance, and
including all FGSs, was revealed as most appropriate model (Table 1). Factor I
includes four symptoms of diarrhea-type IBS, whereas three symptoms of
obstipation-type IBS are located on Factor V. The correlation of .16 between
these two factors is significant but small, indicating that IBS is a very heteroge-
neous syndrome rather than a distinct diagnostic entity. Symptoms of functional
abdominal bloating are located on Factor II, whereas Factors III and IV mainly
involve gastroduodenal and esophageal disorders, respectively. Factor VI con-
sists of only two items and thus is difficult to interpret.
Frequencies of FGSs in Normal Participants and Patients
Almost 99% of the participants in the general population sample reported at
least 1 FGS (of 27) to be present from time to time; 59% reported at least 1
symptom (of 27) persisting more than 25% of the time during the last 12
months, and 37% were affected by symptoms associated with distinct distress
(rated 2 or higher) and persisting more than 25% of days. Frequencies of most
specific symptoms were too small to identify significant differences in age or
sex. Regarding the total range of FGSs, we found no significant differences in
age or sex between participants reporting at least 1 of 27 symptoms and
nonsymptomatic participants. In the patient sample, all participants reported at
least one FGS, regardless of the symptom threshold applied. Most frequent com-
plaints associated with distinct distress were abdominal bloating, feeling of dis-
tension, frequent farting, and abdominal pain, which are IBS symptoms (Table
2).

ASSESSMENT OF GASTROINTESTINAL DISORDERS
161
TABLE 1
Factor Analysis of the Gastro-Questionnaire in a General Population Sample of
229 Participants After Excluding Self-Reported Gastrointestinal Organic Diagnoses
1
2
3
4
5
6
Σ
Variance explained (%)
Eigen value
Abdominal pain
23.4
5.6
.58
10.4
2.5
.22
9.0
2.2
.31
6.5
1.6
.20
6.1
1.5
—
5.4
1.3
.04
60.7
Stools very often
Stool urgency
.83
.77
.78
.11
.23
.30
–.06
.09
.05
.38
.12
.03
.30
.10
.07
.21
.82
.66
.60
.54
.70
.31
–.15
.02
.11
.25
.10
.23
–.01
.13
–.03
–.17
.28
.28
.54
.59
.87
.08
.06
.22
.13
.06
.13
.01
—
.0
.02
.08
–.04
.44
–.02
.10
Loose or watery stools
Abdominal bloating
Feeling of distension
Bowel noises
Feeling of incomplete evacuation
Frequent farting
Regurgitation of food
Difficulty swallowing
Vomiting
Intolerance of several foods
Frequent changing of stool
consistency
.02
.09
.24
.31
.03
.08
.23
.02
–.07
.15
.15
.16
–.02
–.04
–.07
.08
–.02
–.03
.0
–.17
–.11
–.04
.21
.62
.65
.24
Sensation of lump in the throat
Nausea
Heartburn
.24
.34
– .05
.25
.02
.05
–.04
.09
.17
.01
–.15
.09
.20
.08
.24
.13
.06
.28
–.05
.26
–.03
–.06
.03
.66
.47
.69
.70
.66
–.09
.47
.10
.18
–.07
.03
–.12
.18
–.18
.08
.66
.58
.84
—
.09
.08
–.04
.10
–.07
.06
.41
–.05
.69
.84
Chest pain
Pain in the rectum
Stools very rarely
Hard or lumpy stools
Straining during a bowel movement
Abdominal fullness
Fecal soiling
.23
–.02
–.02
.27
–.03
–.09
–.03
.05
Frequencies of FGD in Normal Participants and Patients
When we considered neither the persistence nor the severity of symptoms,
FGDs were found in all participants in the patient sample and nearly all par-
ticipants in the general population sample. When we applied more restrictive
symptom definitions, frequencies of FGDs decreased dramatically. Although
FGDs were detected in 48% of the participants when we used a definition
corresponding to the Rome–II criteria (i.e., considering only those symptoms
that were present more than 25% of days during the last 12 months), this rate
further decreased to 32% when we considered only symptoms associated
with distinct, severe, or very severe distress. Most frequent diagnoses in the
general population sample were functional abdominal bloating, functional

162
LEIBBRAND, CUNTZ, AND HILLER
TABLE 2
Frequency of Gastrointestinal Symptoms in GeneralPopulation and German IBS Patientsa
General Population
Sampleb
IBS Patient Meeting
Samplec
Item
I %
II %
III %
I %
II %
III %
Sensation of lump in the throat
Regurgitation of food
Difficulty swallowing
Nausea
Vomiting
Heartburn
26.6
76.9
8.7
3.5
10.5
1.3
7.0
2.2
5.7
2.2
6.1
14.4
24.5
14.8
8.7
14.8
9.6
7.4
6.6
0.7
10.9
9.6
9.2
3.9
1.7
0.0
7.9
1.3
19.7
5.7
59.0
2.2
3.0
1.3
4.4
1.8
4.4
1.3
4.8
6.5
16.6
11.8
6.5
5.2
4.8
3.9
5.3
0.4
3.0
4.8
6.5
3.1
—
35.7
83.9
25.0
75.0
17.9
35.7
39.3
91.1
85.7
100.0
92.9
96.4
92.9
82.1
30.4
85.7
41.1
96.4
85.7
71.4
58.9
67.9
16.1
89.3
48.2
100.0
53.6
100.0
12.5
33.9
1.8
30.4
3.6
8.9
30.4
1.8
25.0
3.6
64.6
28.0
27.5
27.1
38.4
49.3
81.7
47.1
63.7
75.9
40.2
27.9
53.8
7.0
57.2
52.0
64.7
31.8
18.3
8.7
14.3
21.4
67.9
53.6
92.9
78.6
75.0
75.0
55.4
8.9
64.3
21.4
64.3
67.9
32.1
26.8
26.8
5.4
12.5
19.6
62.5
50.0
92.9
78.6
73.2
71.4
51.8
8.9
57.1
21.4
55.4
60.7
28.6
26.8
—
Chest pain
Intolerance of several foods
Abdominal fullness
Abdominal bloating
Feeling of distension
Abdominal pain
Bowel noises
Stools very often
Stools very rarely
Stool urgency
Fecal soiling
Frequent changing of stool consistency
Loose or watery stools
Hard or lumpy stools
Straining during a bowel movement
Passage of mucus
Passage of blood
—
6.1
—
8.3
3.9
36.7
—
57.1
—
78.6
16.1
100.0
Feeling of incomplete evacuation
Stool residues in underwear
Frequent farting
Pain in the rectum
Any functional gastrointestinal symptom
42.8
20.1
76.9
25.8
98.7
58.9
19.6
82.1
17.9
100.0
Note. Thresholds are as follows: I = Symptom present from time to time; II = Symptom present >
25% of days during the last 12 months; III = Symptom present > 25% of days during the last 12 months
and at least distinct distress.
aSamples of 229 general population participants and 56 German IBS patient participants of the
meeting, after excluding self-reported gastrointestinal organic diagnoses. bN = 229. cN = 56.
constipation, and any form of functional dyspepsia. When we used the most
restrictive symptom definition, FGD frequencies in the general population
sample were 1.3% for IBS and 7.0 for FD, compared with 26.8% for IBS and
75.0% for FD in the patient sample (Table 3).

ASSESSMENT OF GASTROINTESTINAL DISORDERS
163
TABLE 3
Frequencies of Functional Gastrointestinal Disordersa
General Population Sampleb
IBS Patient Meeting Samplec
Functional Gastrointestinal
Disorder
I %
II %
III %
I %
II %
I %
Globus
21.8
27.1
7.4
8.7
0.0
3.1
2.2
4.8
1.3
0.0
1.7
1.3
3.9
1.3
0.0
17.9
39.3
1.8
25.0
0.0
8.9
21.4
5.4
1.8
0.0
7.1
19.6
3.6
1.8
0.0
Functional chest pain
Functional heartburn
Functional dysphagia
Unspecified functional
esophageal disorder
Functional dyspepsia
(ulcer-like)
Functional dyspepsia
(dysmotility-like)
Functional dyspepsia
(reflux-like)
38.4
65.1
19.7
5.2
5.7
2.2
0.4
2.6
4.4
0.9
0.4
1.7
78.6
78.6
33.9
5.4
46.4
26.8
8.9
46.4
25.0
8.9
Functional dyspepsia
(unspecified)
16.1
16.1
Dyspepsia (global)
Aerophagia
78.2
22.7
28.4
65.9
30.1
10.9
0.0
10.0
8.7
3.5
10.0
4.8
24.9
0.0
7.0
2.6
1.3
7.4
0.9
100.0
3.6
76.8
75.0
76.8
0.0
76.8
7.1
75.0
7.1
Irritable bowel syndrome
Functional constipation
Functional diarrhea
Functional abdominal bloating
Unspecified functional bowel
disorder
33.9
32.1
46.4
25.0
0.0
26.8
28.6
41.1
26.8
0.0
15.3
0.0
0.0
Chronic functional abdominal
pain
63.8
1.7
1.7
96.4
17.9
17.9
Functional incontinence
Levator syndrome
Proctalgia fugax
24.5
3.9
9.6
1.7
2.6
0.9
1.7
2.6
0.9
63.4
12.5
21.4
35.7
8.9
3.6
35.7
8.9
3.6
Any functional gastrointestinal
disorder
97.8
48.0
32.3
100.0
100.0
100.0
Note. Threshold levels are as follows: I Symptoms present from time to time; II = Symptoms
present >25% of days during the last 12 months; III = Symptoms present >25% of days during the last 12
months and at least distinct distress.
an = 229. bn = 229. cn = 56.
DISCUSSION
In this study, we investigated the reliability and factorial structure of the recently
developed Gastro-Questionnaire and evaluated effects of various symptom defi-
nitions on frequencies of FGD screening diagnoses.

164
LEIBBRAND, CUNTZ, AND HILLER
Theimplicationsofourresultsarelimitedbythefactthatthesampleinvestigated
was not representative of the general population, the sample size was relatively
small compared with epidemiological studies, and external validity was not deter-
mined. On the other hand, those limitations apply for most studies conducted until
now. Only one carefully conducted large-scale study (Drossman et al., 1993) inves-
tigated the total spectrum of FGDs according to the Rome criteria, and none are
availableonthebasisoftheRome–IIcriteria.Hence,findingsofthisstudymaybeof
particular value for certain neglected aspects of FGD. Obviously, self-rating instru-
ments like the Gastro-Questionnaire cannot replace medical examination or care-
fully conducted standardized diagnostic interviews. However, self-rated
questionnairesareindispensableandwidelyacceptedmeasuresforcourseandtreat-
mentevaluationsaswellasfordiagnosticscreeninginclinicalresearchandpractice.
The particular value of the Gastro-Questionnaire is based on economic administra-
tion, its use in advanced diagnostic decision making, and its applicability for re-
peated dimensional measurement.
Split-half reliability and internal consistency of both frequency and severity
itemsoftheGastro-Questionnaireweregood. Contentvaliditymaybederivedfrom
thefactthatsymptomsandsymptomsetsweredirectlyandliterallyderivedfromthe
Romecriteria,aswellasthesymptomfrequencythresholdof25%ofdaysduringthe
last12months,whichalmostcorrespondstotheRomedefinition(>12weeksduring
the past 12 months). Because we mainly used official symptom translations of the
German Society for Digestive and Metabolic Diseases (Hotz et al., 1999), language
effects on content validity should be limited. Discrimination of some symptoms
(e.g., farting/flatulence vs. bloating) by subjects seems to be more problematic and
mightbeproblematicintheEnglishlanguageaswell. However, investigationofva-
lidity is a concern in general, because standardized instruments for evaluating con-
current validity are not available at present, and the Rome–II criteria themselves
require further validation. At present, application of the Gastro-Questionnaire as a
diagnostic screening instrument is supported mainly by literal use of the Rome–II
symptom items, which also are applied for checklist interviews in clinical research
and practice. Because neither a gold standard nor completely symptom-free normal
samples exist, exact data on sensitivity and specificity are not available. However,
frequenciesofmajorFGDs(likeIBSandFD)inthepatientsamplewereabout10-to
20-fold higher than in the general population sample, independent of the symptom
definitionapplied.Becausegoodsensitivityandspecificitycanbepresumedbutnot
determined on the basis of these preliminary findings, further empirical research on
external validity of the Gastro-Questionnaire is required.
The factor analysis conducted on the basis of severity aspects of FGSs sug-
gests that IBS is not a homogeneous diagnostic entity but rather falls into two
distinct subgroups, characterized by either diarrhea-type or constipation-type
symptoms. Furthermore, the dimensions detected confirm somewhat the upper
grouping of the Rome criteria, whereas the subdivision into more than 20 spe-

ASSESSMENT OF GASTROINTESTINAL DISORDERS
165
cific FGDs is not supported by our results. This subclassification appears to be
overdifferentiated, because psychosomatic treatments require classification
along psychological characteristics and severity dimensions, because evidence
on different organic etiologies of FGD does not exist, and because separate con-
sideration of more than 20 FGDs is a practical and economical concern in re-
search.
Our findings elucidate the outstanding effect of symptom definition on frequen-
cies of FGDs. Compared with previous epidemiological studies on FGDs and IBS
(Drossman et al., 1993; Jones & Lydeard, 1992; Talley et al., 1991), frequencies in
our study were substantially lower when we used a more narrow definition of FGS.
However, using this restrictive definition seems to yield appropriate frequencies of
FGDs, considering that all participants in the patient sample revealed at least one
positiveFGDdiagnosis.Informerstudiesapplyingbroaderdefinitions,itwasfound
that patients with IBS were very heterogeneous regarding psychopathology and
healthcare–seekingbehavior. Onlyaboutonethirdofallpersonswiththediagnosis
of IBS and fewer than one of six with FGD had ever consulted a physician
(Drossmanetal.,1993;Jones&Lydeard,1992;Talleyetal.,1991).Onlyabout50%
of participants with the diagnosis of IBS had elevated levels of psychopathology
(Creed & Guthrie, 1987; Toner, Garfinkel & Jeejeebhoy, 1990). Nonconsulters dif-
fered very little from healthy participants on psychopathology scores, whereas par-
ticipants seeking medical care had higher levels of psychopathology than either of
the two other groups (Drossman et al., 1988; Heaton et al., 1992; Herschbach et al.,
1999; Sandler, Drossman, Nathan, & McKee, 1984; Smith et al., 1990). Conse-
quently, existing prevalence rates for FGD reflect a very large spectrum of severity,
ranging from negligible impairment to very serious illness. Using a more narrow
concept of FGD may yield more homogeneous sample characteristics.
In a critical review of controlled treatment trials, Talley, Owen, Boyce, and
Paterson (1996) emphasize the need to clarify diagnostic criteria and cutoffs for
group definition in future studies. However, one principal problem of classifica-
tion is that FGDs are far from describing diagnostic entities, although some fac-
torial evidence was found for separable subgroups (Talley, Holtman, Agreus, &
Jones, 2000; Taub, Cuevas, Cook, Crowell, & Whiteheat, 1995; Whitehead et
al., 1990). Some FGDs, like functional constipation and IBS, are differentiated
exclusively by symptom cutoffs, whereas others like IBS and FD partly overlap
or like IBS divide into distinct subgroups. The incompatibility of FGD criteria
definition with coexisting classification concepts of functional symptoms in
DSM–IV and ICD–10 is another problematic issue. The concepts of FGD and
somatoform disorders substantially overlap but are not compatible. FGSs some-
times are combined with functional or somatoform symptoms in other anatomic
regions, but their classification as somatoform disorder or FGD is arbitrary in
most cases. Patients suffering from severe bowel symptoms compatible with the
diagnosis of IBS but also complaining about multiple additional somatoform

166
LEIBBRAND, CUNTZ, AND HILLER
symptoms would probably be diagnosed with somatization disorder, which com-
prises two or more gastrointestinal symptoms. On the other hand, someone suf-
fering from symptoms justifying the diagnosis of undifferentiated somatoform
disorder or pain disorder would probably obtain an FGD diagnosis, if symptoms
were mainly situated in the bowel. DSM–IV and ICD–10 provide more distinct
cutoffs and symptom thresholds, yielding convergent prevalence rates between
epidemiological studies and being more appropriate for psychological objec-
tives. However, no appropriate classification category for FGS is available
within the concept of somatoform disorders, whereas specific disorders are de-
fined for pain symptoms, pseudoneurological symptoms, and autonomic symp-
toms (ICD–10). FGSs can be diagnosed only as a part of a somatization
disorder, as undifferentiated somatoform disorder, or as somatoform disorder
not otherwise specified. Hence, an additional category for FGSs would effi-
ciently complete DSM–IV and ICD–10. Conversely, severity indexes combining
symptomatic and psychological aspects are not sufficiently considered in the
Rome criteria at present. In the light of these issues, combining the concepts of
FGD and somatoform disorders and adjusting them stepwise would be useful. At
present, conceptual incompatibility is hindering interdisciplinary research on
FGDs and somatization disorder. Introducing a distinct severity criterion as pro-
posed in this study as well as systematic screening for FGSs could be the first
steps toward adjusting the concepts of FGD and somatoform disorders.
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APPENDIX (CONTINUED)

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APPENDIX (CONTINUED)

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APPENDIX (CONTINUED)