Study characteristics and demographics | Study quality characteristics | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Author (year) | Country | No. of cases | No. of controls | Source of controls | Controls matched for: | Methods of diagnosis defined | Diagnosis based on recognized criteria | Urban/rural defined | Urban population >10,000 | Time of exposure | Multiple levels of exposure |
Ulcerative Colitis | |||||||||||
Parrello 1997[26] | Italy | 509 | 657 | Attending orthopedic and surgical clinics | Sex, age, year of diagnosis | Yes | Yes | No | No | Time of data collection | No |
Feeney 2002[17] | UK | 137 | 137 | Functional GI Disorders | Sex, age | Yes | Yes | No | No | Childhood (age 0–5) | No |
Bernstein 2007[27] | Canada | 137 | 310 | Manitoba Health Population Registry | Sex, age | No | N/A | No | No | N/A | No |
Jiang 2007[28] | China | 177 | 177 | Neighbours or colleagues | Sex, age | Yes | Yes | No | No | Childhood | No |
Radon 2007[54] | Germany | 304 | 1481 | Strabismus surgery | Age | No | N/A | No | No | Time of data collection | No |
Martinez Salmeron 1994[46] | Spain | 63 | 63 | Hospital | Sex, age | Yes | Yes | Yes | No | Time of data collection | No |
Ekbom 1990[8] | Sweden | 164 | 328 | Live births between 1924–1957 in Uppsala County | Date of birth, sex, and maternal age or parity | Yes | Yes | Yes | No | Time of birth | No |
Crohn’s Disease | |||||||||||
Feeney 2002[17] | UK | 139 | 139 | Functional GI disorders | Sex, age | Yes | Yes | No | No | Childhood (age 0–5) | No |
Bernstein 2007[27] | Canada | 235 | 310 | Manitoba Health Population Registry | Sex, age | No | N/A | No | No | N/A | No |
Ponsonby 2009[53] | Australia | 278 | 998321 | Live births from 1983–1998 in Victoria | Age | Yes | No | Yes | No | Childhood (age 0–6) | No |
Malekzadeh 2009[16] | Iran | 196 | 207 | IBS treated by an expert gastroenterologist | Age | Yes | Yes | No | No | Childhood (before 16th birthday) | No |
Radon 2007[54] | Germany | 444 | 1481 | Strabismus surgery | Age | No | N/A | No | No | Time of data collection | No |
Thompson 1998[29] | England, Wales | 291 | 1682 | Same GP | Sex, age | No | N/A | No | No | N/A | No |
Wurzelmann 1994[13] | United States | 322 | 262 | Closest neighbour | Sex, age, race | No | N/A | No | No | Childhood (age 0–5) | Yes |
Martinez Salmeron 1994[46] | Spain | 30 | 30 | Hospital | Sex, age | Yes | Yes | Yes | No | Time of data collection | No |
Ekbom 1990[8] | Sweden | 93 | 186 | Live births between 1924–1957 in Uppsala County | Date of birth, sex, and maternal age or parity | Yes | Yes | Yes | No | Time of birth | No |