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Indian Journal of Gastroenterology ISSN 0254-8860Volume 33Number 3 Indian J Gastroenterol (2014)33:265-273DOI 10.1007/s12664-014-0447-1

Prevalence of irritable bowel syndromeand functional dyspepsia, overlappingsymptoms, and associated factors in ageneral population of Bangladesh

Irin Perveen, Mufti Munsurar Rahman,Madhusudan Saha, MohammadMasudur Rahman & MohammadQuamrul Hasan

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ORIGINAL ARTICLE

Prevalence of irritable bowel syndrome and functional dyspepsia,overlapping symptoms, and associated factors in a generalpopulation of Bangladesh

Irin Perveen & Mufti Munsurar Rahman &

Madhusudan Saha & Mohammad Masudur Rahman &

Mohammad Quamrul Hasan

Received: 31 July 2013 /Accepted: 12 February 2014 /Published online: 26 March 2014# Indian Society of Gastroenterology 2014

AbstractBackground This community-based survey aimed to find outthe prevalence of irritable bowel syndrome (IBS), functionaldyspepsia (FD), overlapping symptoms, and associated fac-tors for overlap.Method By cluster sampling method, 3,000 (1,523 male)randomly selected adult subjects in the Sylhet district ofBangladesh were interviewed by a questionnaire based onROME III criteria. Multivariate logistic regression analyseswere done to find out the factors for overlap with significancelevel set at ≤0.05.Results The mean age of the study population was 33.9±16.4 years. Prevalence of IBS and FD and IBS-FD were12.9 % (n=387), 8.3 % (n=249), and 3.5 % (n=105), respec-tively. Approximately 27.1 % of IBS patients and 42.1 % ofFD patients had overlapping IBS-FD. The odds ratio for IBS-FD overlap was 6.3 (95 % CI, 4.8–8.4). Mean age (p=0.011)and epigastric pain (p=0.002) were more in overlap patientsthan FD alone, whereas epigastric pain syndrome subtype

(p<0.009) was more prevalent in lone FD subjects. In themultivariate logistic analysis, early satiety (OR, 3.0; 95 % CI,1.2–7.5; p=0.018) and epigastric pain (OR, 14.5; 95 % CI,5.0–42.1; p=0.000) in FD patients appeared as independentrisk factors for overlap. Bloating (p=0.026), <3 stools perweek (p=0.050), abdominal pain reduced by defecation (p=0.002), abdominal pain severity score (p=0.004), and overallsymptom frequency score (p=0.000) were more in overlappatients than IBS-alone patients. In IBS patients, bloating(OR, 3.6; CI, 2.0–6.5; p=0.000) was found as potential symp-tom associated with IBS-FD overlap.Conclusion FD was a less prevalent disorder than IBS in ourcommunity, and significant overlap existed between the twodisorders. Early satiety, epigastric pain, and bloating wereimportant factors associated with overlap.

Keywords Abdominal pain . Associations . Bloating .

Constipation . Diarrhea . Functional bowel disorder

Introduction

Overall prevalence rates of irritable bowel syndrome (IBS) andfunctional dyspepsia (FD) in the general population are similar(10 % and 20 %, respectively) in most industrialized countries[1–6] as well as in Asian countries [7–11]. Significant overlapexists between these two disorders [5, 12–17]. Longitudinalstudies showed that with time, 18 % of the subjects with FDand 8 % of the subjects with IBS evolved into alternativediagnosis [5]. As both the conditions could share commonpathophysiologic disturbances, researchers suggested that FDand IBS represent different manifestations of a single entity[18, 19]. Based on epidemiological data, 13 % to 87 % ofpatients with either diagnosis fulfill the criteria for the other

I. Perveen (*) :M. Q. HasanDepartment of Gastroenterology, Enam Medical College,Dhaka 1340, Bangladeshe-mail: [email protected]

M. M. RahmanDepartment of Medicine, Enam Medical College, Dhaka,Bangladesh

M. SahaDepartment of Gastroenterology, North East Medical College,Sylhet, Bangladesh

M. M. RahmanDepartment of Gastroenterology, Shaheed Suhrawardy MedicalCollege, Dhaka, Bangladesh

Indian J Gastroenterol (May–June 2014) 33(3):265–273DOI 10.1007/s12664-014-0447-1

Author's personal copy

diagnosis [5, 11–17]. In patient-based series, IBS-FD overlapprevalence is even higher [7, 14–17]. IBS patients are oftenmislabeled and mismanaged as dyspeptic patients [12] as theyfrequently share common features [8, 10, 20, 21]. The magni-tude of the problem of mislabeling is even higher in Asia thanin the West [7–11].

Prevalence and patient characteristic of IBS and FD varydepending on the definitional criteria used and populationinvolved [1–7, 16–21]. Past diagnostic criteria for IBS mainlyfocused on bowel disturbances and lower abdominal pain, anddid not consider the association with postprandial pain. Thesymptomatic characteristics of IBS and FD have presentlybeen changed based on pathophysiologically relevant symp-toms on Rome III criteria. Better-defined terms such as pain,burning sensation, postprandial fullness, and early satiety arenow used to describe dyspepsia rather than the ambiguousterm discomfort used in the previous Rome criteria [22].Besides, sensitivity and specificity of the Rome III classifica-tion in discriminating functional gastrointestinal disorders(FGIDs) from organic diseases are reasonably high [5, 12].

We have limited data on IBS and FD in Bangladesh, andoverlapping symptoms of IBS and FD were not properlyaddressed in our previous studies [10, 23]. Knowledge onthe prevalence of these two disorders and clinical overlap ofFD and IBS may provide clues and new insights for betterdiagnosis and management of these patients. Reasonably, thisstudy aimed to find out the prevalence of FD and IBS and todetermine the prevalence and associated factors for the clinicaloverlap between FD and IBS by Rome III criteria.

Materials and Methods

Study setting

This population-based observational study was conductedduring the months of August to December 2011 in the Sylhetdistrict of Bangladesh. This study was approved by the EthicsCommittee of Enam Medical College and Hospital.

Sample size calculation

We are lacking in data on the prevalence of FD or FD-IBSoverlap. According to established formula: sample size(n)=(Z1−α)

2{(1−P)/ε2P}, where (a) Z1−α=Z0.95=1.96, (b)anticipated population proportion p=30 %, and (c) ε (relativeprecision, 25 % to 35 %)=10 % (of 30 %)=0.1; a sample sizeof 896 would be needed [24]. For a cluster sampling strategy,the design effect might be estimated as 2. Therefore, for aconfidence level of 95 %, a sample size of 896×2=1,792would be needed. We included 3,000 participants, and expect-ed that was sufficient for estimating the prevalence of IBS,FD, and FD-IBS overlap.

Subjects and survey methods

Ten mahallas (1 mahalla=1 cluster) out of 207 in the citycorporation and 10 villages (1 village=1 cluster) out of 3,052outside the city were selected as clusters. A total of 3,000subjects, selected by cluster sampling method, wereinterviewed in a home setting by trained data collectors underthe supervision of two physicians. Informed consent wastaken from the participants. Apparently, healthy subjects hav-ing no organic gastrointestinal (GI) disorders, neuropsychiat-ric, or other major organic disorders and not taking drugsaffecting GI secretion or motility were included in the study.

Questionnaire

A previously validated questionnaire based on Rome III diag-nostic criteria for adult functional dyspepsia and irritablebowel syndrome [25] was used for data collection. Bengalitranslation of the questionnaire was performed by the methodof forward and backward translation and tested for reproduc-ibility in a sample of 50 patients over a period of 2 weeks. Theintraclass correlation coefficient of the translated question-naire for adult FD and IBS was 0.89 (95 % CI, 0.85–0.94).

Study definitions

For the study, IBS and FD was defined according to Rome IIIcriteria www.romecriteria.org/criteria. IBS patients weresubtyped according to their predominant stool pattern as: (1)IBS with constipation (IBS-C)—hard/lumpy stools (Bristolstool types 1 and 2) occurring at least 25 % of defecationsand loose/watery stools (Bristol stool types 6 and 7) occurringnever or rarely; (2) IBS with diarrhea (IBS-D)—loose/waterystools occurring at least 25 % of defecations and hard/lumpystools occurring never or rarely; (3) mixed IBS (IBS-M)—alternating hard and loose stools, each occurring at least 25 %of defecations; and (4) unsubtyped IBS (IBS-U)—hard orloose stools occurring never or rarely. The frequency of nineabnormal bowel habits were scored based on a 5-pointscale—0, never or rarely; 1, about 25 % of the time; 2, about50 % of the time; 3, about 75 % of the time; and 4, always,100% of the time. An overall abnormal bowel habit score wascalculated by summing the frequency score of each symptom.

FD patients were classified according to their symptoms aspostprandial distress syndrome (PDS) alone, epigastric painsyndrome (EPS) alone, or coexisting PDS and EPS (PDS+EPS) subtypes. The severity of postprandial fullness, earlysatiation, epigastric pain, epigastric burning, and abdominalpain/discomfort relieved by defecation or associated with analtered bowel habit were scored based on a 5-point scale [22,23] (1—very mild, could be easily ignored without effort; 2—mild, could be ignored with effort, but would not influencedaily activities; 3—moderate, could not be ignored and

266 Indian J Gastroenterol (May–June 2014) 33(3):265–273


http://www.romecriteria.org/criteria

occasionally limited daily activities; 4—severe, could not beignored and often limited concentration on daily activities;and 5—very severe, could not be ignored and markedlylimited daily activities and often required rest). An overallFD symptom score was calculated by summing the severityscore of each symptom.

Statistical analysis

Statistical analysis was performed with a SPSS16.0 program(SPSS Inc., Chicago, IL, USA). Student’s t test and Pearson’schi-square test were used to compare the distribution of con-tinuous variables and categorical variables, respectively. Abivariate logistic regression analysis was done to measurethe association between FD and IBS. Variables having a p-value of 0.2 (cutoff point) in the univariate analysis wereincluded in the multivariate logistic regression analysis toidentify the risk factors for FD-IBS overlap. Odds ratios with95 % confidence intervals (CIs) were computed. During com-parison, significance level was set at 0.05 or less.

Results

Out of the 2,555,000 population of Sylhet district, 1,523(51 %) men and 1,477 (49 %) women with an age range of15–97 years were interviewed.

Irritable bowel syndrome

Table 1 showed that IBS prevalence varied with age, educa-tion, occupation, and economic condition but not with sex(p=0.481). Mean±SD age of the male (M) and female (F) IBSpatients (43.5±20.2 vs. 41.3±16.3; p=0.233) were compara-ble. Prevalence of IBS-C (M=45, F=59; p=0.101), IBS-U(M=9, F=8; p=0.469), IBS-D (M=70, F=65; p=0.246), andIBS-M (M=60, F=51; p=0.130) were comparable in bothsexes. In subjects with IBS, the distribution of IBS-C (59[27.1 %] vs. 45 [26.6 %]; p=1.00) and IBS-D (76 [34.9 %]vs. 64 [37.9 %]; p=0.594) were similar between older(>35 years) and younger age groups (<35 years) in both sexes.

Among the bowel symptoms, abdominal pain relieved bydefecation was present in 85.5 % (M=157, F=174;p=0.382) cases. Loose stools (69.4 % vs. 60.4 %;p=0.039) and frequent bowel motion (62.1 % vs. 53.3 %;p=0.049) were significantly more in men, but no significantsex difference was noted in other bowel symptoms. Bowelsymptoms were comparable in older (>35 years) and youn-ger (<35 years) IBS patients. The majority (66.6 %) of theIBS subjects had upper GI symptoms with heartburn in 258(M=122, F=136; p=0.033), nocturnal abdominal pain(uninvestigated) in 13 (3.3 %, M=8, F=5; p=.409), andvomiting in 57 (14.7 %, M=18, F=39; p=0.031).

Functional dyspepsia (FD)

Prevalence of FD was more in older age group, illiterate/loweducation group, and lower socioeconomic group (Table 1).Prevalence rates of FD (8.7% vs. 8.0%; p=0.350) were similarin both sexes with comparable mean age of male and femaleFD patients (42.3±18.4 vs. 39.8±17.2; p=0.264). Business-men, farmers, and day laborers were more vulnerable to FD(Table 1). Prevalence of PDS-EPS (M=66, F=78; p=0.201)and PDS (M=32,F=38; p=0.484) subgroupswere comparablein both sexes (Table 3), whereas EPS (M=25, F=10; p=0.006)subgroup was more in men. Dyspeptic symptoms of postpran-dial fullness (47 vs. 51; p=0.407), early satiation (77 vs. 84;p=0.295), and epigastric pain (79 vs. 89; p=0.173) weresimilar in both sexes whereas epigastric burning (48 vs. 64;p=0.041) was more in women than men.

Functional dyspepsia-Irritable bowel syndrome overlap

The prevalence of FD-IBS overlap was 3.5 % (n=105). Ap-proximately 27.1 % of the patients with IBS and 42.1 % of thepatients with FD fulfilled the diagnostic criteria of the otherdisorder. The odds ratio of having IBS of those with FD andwithout FD and vice versa was 6.384 (95 % CI, 4.825–8.448).

IBS-FD overlap and IBS alone cases had similar demo-graphic pattern (Table 2). Symptoms of abdominal bloating(p=0.026) and <3 stools/week (p=0.050) were more frequentin overlap patients than in lone IBS cases. In comparison toIBS-alone patients, overall IBS symptom frequency score(13.8±4.3 vs. 10.6±4.9; p<0.01) as well as individual symptomfrequency score of a number of bowel symptoms were more inoverlap patients. The distribution of IBS subtypes was almostsimilar in IBS-FD overlap and IBS alone patients (Table 2).

FD-IBS overlap patients were older (p=0.011) than lone FDpatients (Table 3). FD patients (both groups) mostly belonged toPDS-EPS subtype and PDS subtype thanEPS subtype (Table 3).Alternatively, IBS was more common in PDS alone than in EPSalone (50.0 % vs. 29.6 %; p=0.039). Distribution of dyspepticsymptoms was similar in both the groups except epigastric pain,which was more frequent in IBS-FD overlap cases than FDalone. Overall symptom severity score and individual symptomseverity score of the two groups (Table 3) were comparable.

Prevalence rates of IBS alone (p=0.708), IBS-FD (p=0.552)and FD alone (p=1.00) were similar in both sexes (Tables 2 and3). No sex difference was noted in the prevalence of different IBSsubtypes and bowel symptoms among lone IBS and overlap casesexcept loose stools (M=71.4%, F=58.5%; p=0.025) and urgen-cy (M=57.9%,F=45.8%; p=0.044), whichweremore prevalentin male IBS alone cases. Distribution of PDS-EPS and PDSsubtypes were similar in both sexes in both the groups whereasEPS subtype was more prevalent in male lone FD patients (7.9 %vs. 2.1 %; p=0.030). Dyspeptic symptoms pattern were similaramong FD alone and IBS-FD overlap cases in both sexes.

Indian J Gastroenterol (May–June 2014) 33(3):265–273 267


Risk factors for overlap

Table 2 summarizes the comparison of variables in FD-IBSoverlap patients vs. IBS alone. Mean age (p=0.195), <3 bowelmotions/week (p=0.050), straining (p=0.090), bloating (p=0.026), incomplete bowel evacuation (p=0.063), abdominalpain decreased by defecation (p=0.003), abdominal pain sever-ity score (p=0.004), and over all symptom frequency score (p=0.000) were included in the multivariate logistic regressionanalysis. Only bloating (p=0.000; OR, 3.659; 95 % CI, 2.037–6.574) and presence of abdominal pain decreased by defecation(OR, 1.610; 95 % CI, 0.589–4.396) appeared as statisticallysignificant and independent factor for overlap (Table 4).

Table 3 summarizes the comparison of variables in patientswith FD-IBS overlap relative to those with FD alone. Vari-ables having p-value ≤0.2 (Table 3), such as mean age (p=0.011), education (p=0.198), economic condition (p=0.083),occupation (0.159), early satiation (p=0.066), postprandialdistress (p=0.053), epigastric pain (p=0.002), PDS alonesubtype (p=0.078), EPS alone subtype (p=0.009), and overallsymptom severity score (p=0.121) were included in the mul-tivariate logistic regression analysis. Of these, early satiation(OR, 3.029; 95 % CI, 1.598–8.115; p=0.018) and epigastricpain (OR, 14.59; 95 % CI, 5.08–42.19; p=0.000) had astatistically significant and independent effect on the proba-bility of having overlap (Table 5).

Table 1 Sociodemographic characteristics of patients with functional dyspepsia and irritable bowel syndrome

IBS Non-IBS p-value FD Non-FD p-valueN (%) N (%) N (%) N (%)

Mean age 42.4±18.3 32.6±15.7 0.000 41.0±17.8 33.2±16.1 0.000

Prevalence

Total 387 (12.9) 2,613 (87.1) 0.513 249 (8.3) 2,715 (91.7) 0.691Male 190 (12.4) 1,333 (51.0) 126 (8.7) 1,400 (50.9)

Female 197 (13.6) 1,280 (49.0) 123 (8.0) 1,351 (49.1)

Age distribution

15–20 Years 45 (5.8) 735 (94.2) 0.000 32 (4.1) 748 (95.9) 0.00021–30 Years 83 (9.6) 785 (90.4) 57 (6.5) 811 (93.4)

31–40 Years 81 (15.8) 432 (84.2) 48 (9.4) 465 (90.6)

41–50 Years 71 (18.1) 320 (81.8) 49 (12.5) 342 (87.4)

51–60 Years 40 (18.3) 178 (81.6) 32 (14.6) 186 (85.3)

61–70 Years 41 (24.7) 125 (75.3) 17 (10.2) 149 (89.7)

>71 Years 26 (40.6) 38 (59.3) 14 (21.8) 50 (78.1)

Education

Illiterate 163 (17.5) 769 (82.5) 0.000 121 (12.9) 811 (87.0) 0.000Primary 170 (13.2) 1,113 (86.7) 93 (7.2) 1,190 (92.8)

SSC 40 (7.9) 463 (92.0) 23 (4.6) 480 (95.4)

HSC 7 (3.7) 181 (96.3) 5 (2.7) 183 (97.3)

Graduate 4 (4.7) 80 (95.3) 7 (8.3) 77 (91.7)

Postgraduate 3 (30) 7 (70.0) 0 10 (100.00)

Economic condition

Poor 113 (18.1) 735 (81.9) 0.000 81 (12.9) 544 (87.0) 0.000Lower class 195 (13.0) 1,302 (87.0) 101 (6.7) 1,396 (93.2)

Middle class 63 (9.5) 597 (90.5) 48 (7.3) 612 (92.)

Upper class 16 (7.3) 202 (92.7) 19 (8.7) 199 (91.3)

Occupation

Service holder 19 (11.0) 154 (89.0) 0.006 13 (7.5) 160 (92.5) 0.000Business man 56 (11.6) 426 (88.4) 49 (10.2) 433 (89.8)

Student 14 (3.9) 341 (96.1) 12 (3.4) 343 (96.6)

Housewife 169 (15.3) 936 (84.7) 99 (9.0) 1,006 (91.0)

Day laborer 22 (13.4) 142 (86.6) 18 (10.9) 146 (89.03)

Farmer 30 (15.8) 160 (84.2) 20 (10.5) 170 (89.5)

Others 77 (14.5) 454 (85.5) 38 (7.1) 493 (92.8)

N number, IBS irritable bowel syndrome, FD functional dyspepsia, SSC school secondary certificate, HSC higher secondary certificate



Table 2 Comparison of irritable bowel syndrome and irritable bowel syndrome–functional dyspepsia overlap

IBS-FD overlapN (%)

IBS aloneN (%)

p-value

Demography

Mean age±SD 44.4±17.620 41.71±18.64 0.195

Sex

Male 50 (47.6) 140 (49.6) 0.405

Female 55 (52.4) 142 (50.4)

Education

Below SSC 94 (28.2) 239 (71.8) 0.252

SSC and above 11 (20.4) 43 (79.6)

Economic condition

Lower class 83 (29.6) 225 (73.1) 0.888

Upper class 22 (27.8) 57 (72.2)

Occupation

Day laborer/farmer 12 (23.1) 40 (76.9) 0.615

Others 93 (27.8) 242 (72.2)

Abdominal pain severity score 2.87±0.971 2.44±1.083 0.004

Abdominal pain decreased by defecation N (%) 99 (94.3) 232 (82.3) 0.002

Bowel symptoms and symptom frequency score N (%)Score

p-value

Hard stools 60 (57.1) 155 (55.0) 0.395

1.83±1.110 1.53±0.785 0.040

Loose stools 68 (64.76) 183 (64.89) 0.452

1.32±0.558 1.25±0.544 0.320

>3 bowel motions/day 60 (57.14) 163 (57.80) 0.499

1.23±0.50 1.17±0.492 0.410

<3 bowel motions/week 54 (51.43) 173 (61.35) 0.050

1.94±1.02 1.6±0.701 0.010

Straining 76 (72.38) 182 (64.54) 0.090

1.83±0.97 1.59±0.81 0.046

Mucus with stool 66 (62.86) 169 (59.93) 0.343

1.39±0.63 1.21±0.45 0.012

Bloating 72 (68.57) 161 (57.09) 0.026

3.68±0.95 2.82±0.94 0.000

Incomplete bowel evacuation 59 (56.19) 132 (46.81) 0.063

1.58±0.70 1.42±0.69 0.142

Urgency 67 (63.8) 171 (60.6) 0.327

1.263±0.54 1.215±0.502 0.469

Overall bowel symptom frequency score 10.01±4.173 8.162±3.841 0.000

IBS subtypes (prevalence) N (%) p-value

IBS-C 30 (28.6) 74 (26.2) 0.367

IBS-D 38 (36.2) 102 (36.2) 0.544

IBS-M 30 (28.6) 81 (28.7) 0.542

IBS-U 7 (6.7) 25 (8.9) 0.320

N number, IBS-FD irritable bowel syndrome–functional dyspepsia, SSC school secondary certificate, IBS-C IBS with constipation, IBS-D IBS withdiarrhea, IBS-M mixed IBS, IBS-U unsubtyped IBS



Table 3 Comparison of functional dyspepsia alone and functional dyspepsia–irritable bowel syndrome overlap

IBS-FDN (%)

FD-aloneN (%)

p-value

Demography

Mean age±SD 44.44±17.620 38.64±17.66 0.011

Prevalence

Male 50 (47.6) 73 (50.7) 0.363

Female 55 (52.4) 71 (49.3)

Education

Below SSC 94 (43.1) 120 (56.1) 0.198

SSC and above 11 (31.4) 24 (68.6)

Economic condition

Lower class 83 (45.6) 99 (54.4) 0.083

Upper class 22 (32.8) 45 (67.2)

Occupation

Day laborer/farmer 12 (31.6) 26 (68.4) 0.159

Others 93 (44.1) 118 (55.9)

FD symptoms and symptom severity score N (%)Score

p-value

Early satiation 74 (70.5) 87 (60.4) 0.066

3.80±0.97 3.75±1.073 0.755

Postprandial distress 48 (45.7) 50 (34.7) 0.053

3.21±1.73 3.06±1.12 0.419

Epigastric pain 82 (78.1) 86 (59.7) 0.002

3.28±1.008 3.38±1.094 0.516

Epigastric burning 49 (46.7) 63 (43.8) 0.371

3.78±0.941 3.86±0.865 0.646

Overall FD symptom severity score 9.84±3.98 9.042±3.0 0.121

FD subtypes N (%)Score

p-value

PDS 35 (33.3) 35 (24.3) 0.078

EPS 8 (7.6) 27 (18.8) 0.009

PDS-EPS 62 (59.0) 82 (56.9) 0.420

IBS-FD irritable bowel syndrome–functional dyspepsia, PDS postprandial distress syndrome, EPS epigastric pain syndrome, SSC school secondary certificate

Table 4 Factors for irritable bowel syndrome–functional dyspepsia overlap in irritable bowel syndrome patients

Risk factors for IBS-FD overlap B (Crude OR) Significance (p) OR 95 % CI

Age 0.005 0.474 1.005 0.992–1.019

Abdominal pain severity score 0.165 0.217 1.179 0.908–1.531

Bloating 1.297 0.000 3.659 2.037–6.574

< 3 motions per week −1.036 0.008 0.355 0.165–0.761

Straining during defecation 0.566 0.107 1.762 0.885–3.508

Feeling of incomplete evacuation −0.171 0.670 0.843 0.383–1.852

Abdominal pain↓ by bowel motion 0.476 0.353 1.610 0.589–4.396

IBS overall symptom frequency score 0.094 0.055 1.099 0.998–1.210

OR odds ratio (adjusted), CI confidence interval, IBS-FD irritable bowel syndrome-functional dyspepsia



Discussion

Overlapping symptoms of IBS and FD is a least investigatedproblem in our country. In the present study, 27.1 % of thepatients with IBS and 42.1 % of the patients with FD fulfilledthe diagnostic criteria for the alternative disorder. Early satiety,epigastric pain, and bloating were found as independent asso-ciations for overlap.

FD (8.3 %) was found less prevalent than IBS (12.9 %) inour community which is contrary to the reports from otherAsian countries [7–11, 26, 27]. A symptom recall period of3 months was considered to be sufficient for diagnosis of FDin Asia [26]. The prevalence of dyspepsia was found toincrease with decreasing frequency of symptoms in our study,eg. with a symptom frequency of two to three times permonth, FD prevalence raised to 34.4 %. A low prevalence ofuninvestigated dyspepsia (UD) (6.7 %) in comparison to IBS(22.1 %) is also reported in Japan [28]. Besides definitionalcriteria involved, sociocultural and dietary factors of a partic-ular population may be responsible for low prevalence of FD.No gender difference was found in the prevalence of FD orIBS in the present study which is consistent with otherpopulation-based studies from Asia [7–11, 26]. But in a Jap-anese study, UD was found discordantly high in males [26].

Apparently, more IBS patients (8.2 %) remained to beunclassified in our study by using Rome III than Asian criteria[11]. By Asian criteria [11], out of the 32 unsubtyped IBS(IBS-U) subjects, 14 remained to be unclassified, 6 fell underIBS with diarrhea (IBS-D), 4 under IBS with constipation(IBS-C), and 8 under mixed IBS (IBS-M). These 14unsubtyped patients had only changes in stool frequency notin stool form. Reports from other Asian countries also showedthat a large proportion of IBS patients remained to be unclas-sified using a stool frequency-based criteria [8, 11]. IBS-Dwas the most prevalent subtype in our study which is inaccordance with previous urban study (58 %) [23] but in

contrast to rural survey (0.8%) [10]. However, others reportedalmost equal prevalence of diarrhea- and constipation-predominant IBS [27, 29]. The high prevalence of IBS-D inthis particular population may be related to dietary habit,cultural factors, fast gut transit time [30], and post-infectiousIBS—the prevalence of which is presently unknown.

Panigrahi et al. have shown that stool frequency decreasesamong females with advancing age [30]. But in our study,hard/lumpy stools (p=0.257), less than three bowel motionsweekly (p=0.603), and IBS-C prevalence rates (26.6 % vs.27.1 %; p=1.00) were similar between older (>35 years) andyounger IBS patients (<35 years) in both sexes.

Masud et al. (Rome I) [10] and Perveen et al. (Rome II)[23] reported a high prevalence of upper GI symptoms (up to72.6 %) in IBS patients. But none of them specifically eval-uated the association of FD with IBS using standard defini-tional criteria [10, 23]. In the present study, we evaluated two-way associations between FD vs. FD-IBS and IBS vs. FD-IBSusing Rome III criteria. Like Wang et al. [27], a strongassociation (OR, 6.38) was found between these two disor-ders. The presence of symptoms rather than the severity ofsymptoms or symptom subtypes appeared as potential factorsfor overlap. A good number of IBS subjects had heartburn inour series. These patients might have gastroesophageal refluxdisease (GERD) and IBS overlap. Existence of considerableGERD-IBS overlap has recently been highlighted [11, 17, 31].

Clinical overlap between IBS and FD is frequently encoun-tered. The prevalence of FD varies between 29 % and 87 %among IBS patients, and the prevalence of IBS in FD subjectsranges within 13 % to 29 % [5, 11–17, 21, 26]. In Asia, 14 %to 58 % subjects with IBS had one or more dyspeptic symp-toms [7, 10, 11, 16, 17, 23, 28]. In our study, persons havingIBS or FD were six times more vulnerable to have the alter-native diagnosis. The authors concluded that this FD-IBSoverlap is not a chance occurrence, as estimated overlap rateswere higher than the expected overlap prevalence [5, 12].

Table 5 Factors for functional dyspepsia–irritable bowel syndrome overlap in functional dyspepsia patients

Risk-factors FD-IBS overlap B (crude OR) Significance (p) OR 95.0 % CI

Age 0.017 0.099 1.017 0.997–1.037

Low education (below SSC) −0.069 0.901 0.934 0.317–2.752

Low economic condition −0.649 0.104 0.523 0.239–1.144

Laborer and farmer −1.312 0.009 0.269 0.101−0.719PDS sub-type −1.884 0.013 0.152 0.034−0.672EPS sub-type −1.176 0.074 0.309 0.085−1.122Postprandial fullness 0.177 0.775 1.194 0.355−4.009Early satiation 1.108 0.018 3.029 1.211−7.578Epigastric pain 2.681 0.000 14.594 5.084−42.191FD overall symptom severity score 0.358 0.000 1.440 1.292−1.584

OR odds ratio (adjusted), CI confidence interval, FD-IBS functional dyspepsia-irritable bowel syndrome, PDS postprandial distress syndrome, EPSepigastric pain syndrome, SSC school secondary certificate



FD patients mostly with dysmotility subtype and withnonpainful symptoms of postprandial fullness, nausea, andvomiting were more likely overlap [5, 6, 9, 16]. Wang et al.[27] reported that more patients with lone PDS overlappedwith IBS than with lone EPS and overlap patients mostlybelonged to PDS-EPS subtype. Patients with PDS-EPS sub-type and PDS alone were also found to be more vulnerable tooverlap than with EPS alone in our series. Besides earlysatiation, epigastric pain appeared as a potential risk factorfor overlap but not the FD subtype.

Overlap patients usually have more symptoms [6, 8, 16].Compared to other dyspeptic symptoms, epigastric pain (p=0.002) was more in our overlap patients than in lone FDpatients. IBS patients are often mislabeled as dyspeptic pa-tients as they frequently present with upper abdominal pain,postprandial pain (50 %) [20], and precipitation of pain byfoods that are commonly implicated in dyspepsia [21].Mislabeling is even more in Asia as majority of the IBSpatients present with upper abdominal pain [7–9] and theyhave milder degree of defecatory or stool disturbances.

Shared, common, and generalized pathophysiologic distur-bances of the gut are suggested mechanisms [16, 32] foroverlapping diagnoses of functional GI disorders. IBS patientshaving dysmotility-type symptoms [17, 33] and constipation-predominant IBS [17] were more likely to overlap with FDthan other variety. Corsetti et al. [32] and Stanghellini et al.[16] showed that only FD-IBS overlap patients had delayedgastric emptying and heightened visceral sensitivity to gastricdistension not in patients with lone IBS. In the present series,IBS-Cwas not found as an independent risk factor for overlap,but abdominal bloating was found as potential risk factor foroverlap. Evidence regarding the role of these different patho-genic factors remains controversial, and researchers found itdifficult to establish a causal relationship between any of thesefactors and the symptoms [34].

The severity of symptoms of functional GI disorders isrelated to pathophysiological mechanism [32]. IBS-FD over-lap patients usually suffer from more severe dyspeptic symp-toms in comparison to patients with FD alone [16, 27] and thatcould be a predictor of consultation-seeking behavior [12]. Inthe clinic-based study [27], patients with FD-IBS overlapwere found to have higher severity score for postprandialfullness and overall FD symptom score. In our community-based study, the symptom severity score were comparablebetween FD alone and FD-IBS overlap cases. Compared toIBS alone patients, overall symptom frequency score wasmore in overlap patients, but the symptom frequency had nosignificant effect on the potential for overlap.

Past studies from Bangladesh reported that 35.0 % to65.5 % [10, 23] of IBS subjects ever consulted a physician.Age, sex, and number of symptoms had no influence onhealthcare-seeking behavior [10]. In the present study, consul-tation behavior of the IBS or FD patients was not assessed.

Studies showed that coexisting IBS-FD increases the likeli-hood of medical consultation [19], referral for specialist as-sessment [35], and even unnecessary surgery [12] in IBSpatients. The recognition of overlapping symptoms of IBS-FD therefore has potentially profound therapeutic importancein reducing mismanagement [12, 19].

IBS-FD patients usually have a worse quality of life (QOL)than with lone disorder [36, 37]. According to Lee et al.,depressive mood was significantly related to FD and FD-IBS overlap, but not to IBS alone [37]. Authors suggestedthat psychobehavioral conditions may affect the developmentof functional GI symptoms, regardless of the subtype ofFGIDS, and can explain the high proportion of overlap amongthe subtypes [38].

Differentiations between different FGIDS are challengingand using clinical features are not so reliable and some appro-priate tests are warranted [34]. Because of significant degreeof symptom overlap between FD, IBS and GERD investiga-tors hypothesized that patients with overlapping disordershave an irritable gut [5, 39].

This community-based study likely to represent the trueprevalence of IBS and FD as direct interview of the subjectshelped in better interpretation of questionnaire with selection ofmore appropriate answers. Community-level patients not seek-ing health care usually have less severe symptoms and trueaccount of their sufferings may not be available. That mayaffect epidemiological features. Some important domain likehealth-related-QOL, psychosocial makeup, consultation behav-ior, effects of previous treatment/surgery, and dietary habits ofthe patients remained unexplored. Investigations of the FD orIBS patients were not feasible in our setting. Despite theshortcomings, it was a good initiative to find out the prevalenceand risk factors for FD and IBS overlap in our community.

In conclusion, IBS was found to bemore prevalent than FDin our community with existence of significant clinical over-lap between these two disorders. A strong association betweenFD and IBS was proved. It is evident from the present studythat more patients with FD had overlapping IBS than the IBShaving overlapping FD. Patients with PDS alone and PDS-EPS subtypes were more likely to overlap. Besides abdominalbloating, early satiation and epigastric pain were found aspotential factors for overlap. We hope that this data will helpour clinician to avoid misdiagnosis and mismanagement ofoverlap patients and will instigate further studies with appro-priate investigations and QOL survey.

Acknowledgments Wewould like to thank Incepta Pharmaceuticals Ltd.and Beximco Pharma Ltd., Bangladesh who partly financed this study. Wealso would like to thank theDepartment of Statistics, Shahjalal University ofScience and Technology, Sylhet, Bangladesh for the statistical analysis.

Conflicts of interest Irin Perveen,MuftiMunsurar Rahman,MadhusudanSaha, Mohammad Masudur Rahman, and Mohammad Quamrul Hasandeclare that they have no conflict of interest.



Ethics statement The authors confirm that the study was performed in amanner that conforms with the Helsinki Declaration of 1975, as revised in2000 and 2008 concerning Human and Animal Rights, and the authorsfollowed the policy concerning InformedConsent as shown on Springer.com

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