Table 1 Overview of main characteristics and extracted data from articles included in this systematic review

STUDY (Author + Year)

COUNTRY

STUDY DESIGN

N

RECRUITMENT

DIAGNOSIS IBS

Migraineurs with IBS

 Wu (2017) [43]

Taiwan

Cohort

Total cases: 2859 Migraine: 2859 IBS: 239 Controls: 5718

Used data from the National Health Insurance Research Database (NHIRD) of Taiwan

Used disease history records with the International Classification of Disease, 9th Revision (ICD-9-CM), in which IBS has the following code: 564.1

 Lau (2014) [9]

Taiwan

Cohort

Total cases: 14,117 Migraine: 14,117 Controls: 56,468

Randomly selected 1 million people from the Taiwanese insurance claims database in the period of 1996 to 2010

Used the disease history as recorded in the International Classification of Disease, 9th Revision, Clinical Modification (ICD-9-CM), in which IBS has the following code: 564.1

 Penn (2019) [12]

Taiwan

Cohort

Total cases: 17,420 Migraine: 17,420 IBS: 3330 Controls: 69,680

Acquired data from the Longitudinal Health Insurance Database (LHID)

Used disease history records with the International Classification of Disease, 9th Revision (ICD-9-CM), in which IBS has the following code: 564.1

 Warren (2009) [34]

USA

Case–control

Total cases: 313

IBS:

86 Migraine: 112 Controls:313

Three ways. 1.Associations: the Interstitial Cystitis Association and the Interstitial Cystitis Network. 2.Professionals and support groups: urologists, gynaecologists, and regional IC/PBS support groups 3.Advertising: brochures, posters, national meetings, letters, newsletters, blast e-mails, and Website links. Controls were recruited by random digit dialling on a national scale

IBS diagnosis and onset was confirmed through a 6-step process using telephone interviews and medical record reviewing

 Martami (2017) [37]

Italy

Cross-sectional

Total cases: 1574 Migraine: 181 Headache78 Controls: 1315

Individuals that were referred to the Obesity Research Centre of Sina Hospital in the period from 2009 to 2016

Confirmed by a gastroenterology specialist. IBS was characterized according to ROME-III criteria

 Kim (2022) [41]

South Korea

Cross-sectional

Total cases: 781,115 IBS: 43,184 Migraine: 8438

Medical information reported to the Health Insurance Review & Assessment Service (HIRA) was used. Most Koreans are enrolled in this universal health insurance system. The dataset used random stratification based on 5-year interval ages and gender (HIRA-NPS-2018)

Confirmed using Code K58 of the Korean Standard Classification of Disease and Cause of Death-7 (KCD-7)

 Tietjen (2007) [35]

USA

Cross-sectional

Total cases: 171 Migraine: 171 IBS: 52 Controls: 104

Two different institutions: University of Toledo Medical Centre (Toledo, OH) and Duke University Medical Centre (Durham, NC)

Confirmed through a questionnaire that inquired the following self-reported physician-diagnosed conditions: “Have you ever been diagnosed by a doctor with IBS?”

 Grassini (2016) [42]

Sweden

Cross-sectional

Total cases: 151 Migraine: 151 IBS:

80 Controls: 3255

Acquisition of a representative sample of the general population from the county of Veasterbotten. Random selection from the population registry took place after stratification for sex and age

Used the Patient Health Questionnaire 15-Item Somatic Symptom Severity Scale (PHQ-15) and asking the question: “Have you been diagnosed with this disease by a physician?” The diseases included were fibromyalgia, IBS, CFS, exhaustion syndrome, depression

 Lankarani (2017) [40]

Iran

Cross-sectional

Total cases: 755 Migraine: 246 IBS:

184 Controls: 1609

Took place in Baladeha village near Kazerun, which is in the west of Fars province, Iran. Each individual older than 15 years was invited to participate in a medical interview at the health care center in this region

Used three-dimensional questionnaire which was completed during the physicians’ interview. The third dimension contained questions on gastrointestinal functional disorders symptoms in accordance with the ROME-III criteria

 Lee (2017) [39]

South Korea

Case–control

Total cases: 336 Migraine: 168 Headache168 Controls: 336

Clinical big data analytic solution Smart CDW from Hallym University Medical Centre (HUMC) was used of patients with common primary headaches (including migraines and TTH), and controls from January 2006 to August 2016 at the Chuncheon Sacred Heart Hospital of HUMC

Confirmed by physician after work-ups for patients who visited the gastroenterology centre more than 2 times consecutively

 Li (2017) [38]

China

Cross-sectional

Total cases: 1052 Migraine: 287 IBS: 312 Controls: 287

Used data of patients from the internal medicine and emergency departments of three hospitals (General Hospital of PLA, Rocket Army General Hospital, and the 316th Hospital of PLA) from June 2014 until 2016

IBS diagnosis was confirmed via the use of the ROME-III criteria

 McLean (2017) [36]

UK

Cross-sectional

Total cases: 1,468,404 Migraine: 9370 IBS: 52,333 Controls: 1,459,034

Data obtainment from the Primary Care Clinical Informatics Unit at the University of Aberdeen of patients that were permanently registered at one of 314 Scottish general practices on March 31, 2007

IBS diagnosis was confirmed through information in register

IBS patients with Migraine

 Ladabaum (2012) [30]

USA

Cross-sectional

Total cases: 141,295 IBS: 141,295 Migraine: 80,266 Control: 141,294

Recruitment from 1995 to 2005, of all individuals who were enrolled in KPNC. This population is demographically representative of the general population of northern California

Patients who had at least received 1 diagnosis from a medical doctor between 1995–2005

 Poitras (2007) [27]

Canada

Cross-sectional

Total cases: 167 IBS: 71 Migraine: 174 Control: 67

Patients followed by the gastroenterology department of the Hospital Saint-Luc, which is a tertiary care university hospital

E-mail questionnaire based on ROME-II criteria

 Vandvik (2004) [25]

Norway

Cross-sectional

Total cases: 208 IBS: 208 Migraine: 25 Control: 1240

Norwegian general practices. The study was executed during 2001 in nine practices in the county of Oppland

GPs reported on abdominal complaints using a paper questionnaire. Those who reported abdominal complaints within the past 3 months, were diagnosed according to the ROME-II criteria

 Cole (2006) [26]

USA

Cross-sectional

Total cases: 97,593 IBS: 97,593 Migraine: 6501 Control: 27,402

Data from eight different states with the largest concentration of health plan membership, primarily in mid/west and south/south-eastern United States

IBS diagnosis was established by using the ICD-9 CM. The corresponding code is 564.1

IBS patients with Headache

 Tuteja (2019) [32]

USA

Cross-sectional

Total cases: 413 IBS:

148 Control: 47

Data from list of GW Veterans from the Gulf War Registry of the Veterans Affairs Medical Centres in Salt Lake City, Utah and Gainesville (Florida). Data of 655 Veterans and 3.350 Veterans respectively. Other methods to recruit veterans was via advertisments

Previously validated Talley's Bowel Disease Questionnaire (BDQ) to assess current GI symptoms based on ROME-III criteria

 Przekop (2012) [29]

USA

Cross-sectional

Total cases: 598 IBS: 366 Headache: 3782 Control: 3213

Data drawn from the Biopsychosocial Religion and Health Study (BRHS). BRHS investigators randomly sampled individuals who participated in the Adventist Health Study 2 (AHS-2, 2002–2007)

Used the BRHS questionnaire. Physical symptom frequency in the past month was assessed by means of questions about how frequently participants experienced headache, indigestion, constipation, diarrhoea, and incontinence

 Whitehead (2007) [28]

USA

Cross-sectional

Total cases: 3724 IBS: 3153 Control: 3153

Used data of the Group Health Cooperative of Puget Sound (GHC). This is a large staff-model HMO that serves approximately 550.000 residents in Washington. GHC provides comprehensive health care primarily on a capitated basis

IBS was diagnosed using the ICD9-CM codes listed in the administrative database previously identified by the clinician at the time of clinic visit

 Tan (2003) [24]

Malaysia

Cross-sectional

Total cases: 533 IBS: 84 Headache: 228

Assessed the self-report questionnaires that were administered to a population of medical students from the Faculty of Medicine, University of Malaya

Questionnaire based on the Rome I criteria. It was defined as abdominal pain or discomfort for at least 3 months, which was relieved with defecation, associated with a change in frequency and consistency of stool

 Yanartas (2019) [33]

Turkey

Cross-sectional

Total cases: 207 IBS: 51 Headache 164 Control: 67

Gastroenterology and internal medicine outpatient clinic from March 2017 to September 2018 at Marmara University School of Medicine (Istanbul, Turkey)

IBS diagnosis was confirmed according to ROME-IV criteria

 Patel (2015) [31]

UK

Cross-sectional

Total cases: 840 IBS: 840 Headache 544 Control: 2137

Individuals who were newly referred from primary care to secondary care for investigation of GI symptoms. This took place at either McMaster University Medical Centre or St. Joseph’s Healthcare, both hospitals located in Hamilton (Ontario, Canada)

Data collected via the validated ROME-III diagnostic questionnaire for adult functional GI disorders. Through this the following information was recorded using a Likert scale: the frequency of individual lower GI symptoms, including lower abdominal pain or discomfort, stool frequency, stool consistency, bloating or abdominal distension, tenesmus and urgency

STUDY (Author + Year)

DIAGNOSIS MIGRAINE

DIAGNOSIS HEADACHE

MEAN AGE

QUALITY SCORE

HR/OR

Migraineurs with IBS

 Wu (2017) [43]

By means of the International Classification of Diseases 9th Revision (ICD-9-CM) with code 346 for migraine

Cases: 46.5 Controls: 46.1

71.4% Female 28.6% Male

9

HR: 1.58 (1.33–1.87)

 Lau (2014) [9]

Disease history records with the International Classification of Disease, 9th Revision, Clinical Modification (ICD-9-CM), in which Migraine’s code is: 346

Total: 42.5 Migraine: 42.5 Controls: same migraine

72.6% Female, 27.4% Male

8

HR: 1.95 (1.75–2.18)

 Penn (2019) [12]

Patients with a history of migraine (ICD-9-CM code 346)

Total cases: 44.5 Migraine: 44.5 Controls: 44.2

73.4% Female, 26.6% Male

10

HR: 1.36 (1.17 to 1.58)

 Warren (2009) [34]

Through telephone interview which was used to identify 7 syndromes in total. This interview included expert consensus criteria for the following categories: CFS, IBS, panic, and migraine

Cases: 42.3 Controls: 42.9

100% Female

9

OR: 3.6 (2.3–5.6)

 Martami (2017) [37]

Confirmed by a neurologist according to the international classification of headache disorders-III (ICHD-III-β)

TTH diagnosis was confirmed by a neurologist according to the international classification of headache disorders-III (ICHD-III-β)

Total cases: 37.44 Migraine: 38.39 Headache 41.08 Controls: 37.10

83.5% Female, 16.5% Male

8

OR: 4.90 (2.00–12.01)

 Kim (2022) [41]

Used Code G43 of the Korean Standard Classification of Disease and Cause of Death-7 (KCD-7)

elderly (≥ 65 years) than in the adult group (≥ 20 and

50.1% Female, 49.9% Male

7

OR: 2.18 (2.04–2.33)

 Tietjen (2007) [35]

Defined by the second International Classification of Headache Disorders (ICHD-II) criteria, through completion of the digital Headache Impact TestTM (HIT6)

Total cases: 39.1 Migraine: 37.6 Controls: 40.6

100% Female

9

OR: 2.7 (1.2–6.1)

 Grassini (2016) [42]

Self-report on a received diagnosis of migraine by a physician

Total cases: 48.2 Migraine: 48.2 Controls: 51.4

64.6% Female, 35.4% Male

4

OR: 3.12 (1.60–6.06)

 Lankarani (2017) [40]

Through the three-dimensional questionnaire completed during the physicians’ interview. The second dimension included questions on presence of headache symptoms based on criteria of International Headache Society

Total cases: 34.3

56.4% Female, 43.6% Male

8

OR: 3.43 (2.40–4.89)

 Lee (2017) [39]

Reference to the International Classification of Headache Disorders (ICHD) second or third edition ( ICHD II or ICHD 3-beta)

Reference to the International Classification of Headache Disorders (ICHD) second or third edition ( ICHD II or ICHD 3-beta)

Range 19–80

83.9% Female, 16.1% Male

9

OR: 3.04 (0.50–18.35)

 Li (2017) [38]

Based on the International Classification of Headache Disorders 3rd edition (ICHD-3-beta)

Total cases: 41.5 Migraine: 41.3 IBS: 40.2 Controls: 40.9

67.9% Female, 32.1% Male

8

OR: 1.07 (1.02–1.12),

 McLean (2017) [36]

Based on whether patients had four or more anti-migraine prescriptions in the previous 12 months

Total cases: 48.8 Migraine: 50.5 Controls: 47.0

67.8% Female, 32.2% Male

7

OR: 2.22 (2.08–2.37)

IBS patients with Migraine

 Ladabaum (2012) [30]

Based on patients who had at least received 1 diagnosis from a medical doctor between 1995–2005

Total cases: 53 IBS: 53 Control: 53

73.6% Female, 26.4% Male

9

OR: 2.31 (2.27–2.35)

 Poitras (2007) [27]

E-mail questionnaire which also contained extra-GI related questions

Total cases: 43 IBS: 46.8 Control: 42.2

100% Female

9

OR: 2.4 (1.29–4.47)

 Vandvik (2004) [25]

Self-administered questionnaires which had to be completed at the first visit

Total cases: 50.3 IBS: 50.3

67% Female, 33% Male

7

OR: 2 (1.2–3.5)

 Cole (2006) [26]

Diagnosed by a physician, any past hospitalization associated migraine or outpatient prescriptions associated with anti-migraine drugs (e.g. ergot alkaloid or triptan). Both the diagnosis and the prescription criteria had to be fulfilled to be clasified withing the migraine group

aged 18 and older

75% Female, 25% Male

7

OR: 1.6 (1.4 – 1.7)

IBS patients with Headache

 Tuteja (2019) [32]

Used the Somatic Symptom Checklist (SSC). The checklist was used to detect the following extra‐intestinal symptoms: headache, backache, wheeziness, insomnia, bad breath, fatigue, general stiff‐ ness, dizziness, weakness, sensitivity to hot and cold, palpitation, and tightness in chest

Range 32–78 Total cases: 47

10.5% Female, 89.5% Male

6

OR: 2.33 (1.36‐3.99)

 Przekop (2012) [29]

Used the BRHS questionnaire. Physical symptom frequency in the past month was assessed by means of questions about how frequently participants experienced headache, indigestion, constipation, diarrhea, and incontinence

Total cases: 63.1 IBS: 64.9 Control: 62.4

100% Female

4

OR: 0.52 (0.2–1.38)

 Whitehead (2007) [28]

Used the ICD9-CM codes listed in the administrative database previously identified by the clinician at the time of clinic visit

aged 18 and older

68.7% Female,

31.3% Male

9

OR: 2.40 (2.07–2.78)

 Tan (2003) [24]

Via questionnaire evaluating also other aspects of inquiry including alcohol intake, smoking, chili consumption, fibre intake, the presence anxiety, depression, insomnia, headache, and health-seeking behaviour

Total cases: 22

57% Female, 43% Male

5

OR: 1.7 (1.0–2.8)

 Yanartas (2019) [33]

Used the Bradford Somatic Inventory (BSI) which is a multi-ethnic inventory of functional somatic complaints associated with anxiety and depression. It measured a wide range of somatic symptoms during the previous month

Total cases: 35.1 IBS: 36 Control: 32.1

72.2% Female, 27.8% Male

10

OR: 2.21 (1.05–4.65)

 Patel (2015) [31]

Data obtained through the PHQ-12 questionnaire (excluded 3 GI questions). It asks about the presence of somatic symptoms over the last 4 weeks

Total cases: 43.3 IBS: 38.3 Control: 48.3

74.5% Female, 25.5% Male

7

OR: 2.58 (2.13–3.13)