Table 3.
VOC models.
| ID | Year | Article | Aim | Number of compounds | Study population | Result |
|---|---|---|---|---|---|---|
| Disease versus healthy | ||||||
| Inflammatory bowel disease | ||||||
| 1 | 2014 | [34] | IBD vs HV | NA | IBD 101 HV 46 | Acc: Mean 79%; IBD 78%; HV 80% |
| 2 | 2016 | [41] | IBD vs HV | NA | IBD 54 HV 22 | Sens: 74%, Spec: 75%, AUC: 0⋅82 |
| Crohn's disease | ||||||
| 3 | 2015 | [53] | CD R vs HV | 6 | CD 191 CDR NA HV 110 | Acc: 92⋅3%, Sens: 96%, Spec: 99%, AUC: 0⋅99 |
| 4 | 2015 | [53] | CD A vs HV | 7 | CD 191 CDA NA HV 110 | Acc: 97⋅3%, Sens: 96%, Spec: 97%, AUC: 0⋅98 |
| 5 | 2015 | [44] | CD vs HV | 6 | CD 18 HV 18 | OSC-PLS-DA: Clear separation groups. Sens: 94⋅4%, Spec: 94⋅4%, AUC: 0⋅864 |
| 6 | 2016 | [41] | CD vs HV | NA | CD 25 HV 22 | Sens: 69%, Spec: 67%, AUC: 0⋅77 |
| 7 | 2014 | [38] | Faeces: CD vs HV | NA | CD 24 HV 20 | Acc: 85%, Sens: 93%, Spec: 78%, AUC: 0⋅97 |
| Ulcerative colitis | ||||||
| 8 | 2007 | [42] | UC vs HV | 32 | UC 18 HV 30 | DS: Clear separation groups. Acc: 100 (96)% |
| 9 | 2015 | [44] | UC vs HV | 6 | UC 20 HV 18 | Sens: 90⋅5%, Spec: 94⋅4%, AUC: 0⋅742 |
| 10 | 2016 | [41] | UC vs HV | NA | UC 29 HV 22 | Sens: 61%, Spec: 62%, AUC: 0⋅70 |
| 11 | 2014 | [38] | Faeces: UC vs HV | NA | UC 19 HV 20 | Acc: 58%, Sens: 43%, Spec: 69%, AUC: 0⋅54 |
| Irritable bowel syndrome | ||||||
| 12 | 2013 | [32] | IBS vs HV | 49 | IBS 30 HV 109 | Acc: IBS 70 (68)%; HV 95 (94)%, Sens: 90 (82)%, Spec: 80 (78)%, AUC: 0⋅94 (0⋅92) |
| 13 | 2014 | [34] | IBS vs HV | NA | IBS 34 HV 46 | Acc: Mean 54%; IBS 46%; HV 58% |
| 14 | 2016 | [24] | IBS vs HV | 16 | IBS 170 HV 153 | PCA: Clear separation groups. Acc: Positive 84%; Negative: 81.5%, Sens: 89⋅4%, Spec: 73⋅3%, AUC: 0⋅83 |
| 15 | 2014 | [38] | Breath: IBS vs HV | NA | IBS 28 HV 20 | Acc: 58%, Sens: 41%, Spec: 72%, AUC: 0⋅44 |
| 16 | 2014 | [38] | Faeces: IBS vs HV | NA | IBS 28 HV 20 | Acc: 61%, Sens: 51%, Spec: 71%, AUC: 0⋅63 |
| 17 | 2014 | [38] | Urine: IBS vs HV | NA | IBS 28 HV 20 | Acc: 64%, Sens: 38%, Spec: 80%, AUC: 0⋅53 |
| Active disease versus disease in remission | ||||||
| Crohn's disease | ||||||
| 18 | 2015 | [53] | CD A vs CD R | 10 | CD 191 CDA NA CDR NA | Acc: CD A 81⋅5%; CD R 86⋅4%, Sens: 81%, Spec: 80%, AUC: 0⋅88 |
| Disease versus disease | ||||||
| Inflammatory bowel disease and irritable bowel syndrome | ||||||
| 19 | 2013 | [32] | IBS vs active IBD | 60 | IBS 30 IBD 110 | Acc: IBS 80 (70)%; IBD 96 (95)%, Sens: 96 (80)%, Spec: 80 (62)%, AUC: 0⋅98 (0⋅76) |
| 20 | 2014 | [34] | IBS vs IBD | NA | IBS 34 IBD 101 | Acc: Mean 76%; IBS 68%; IBD 82%, Sens: 76%, Spec: 88% |
| Crohn's disease and ulcerative colitis | ||||||
| 21 | 2015 | [44] | CD vs UC | 6 | CD 18 UC 20 | Sens: 88⋅9%, Spec: 90⋅0%, AUC: 0⋅828 |
| 22 | 2016 | [41] | UC vs CD | NA | CD 25 UC 29 | Sens: 67%, Spec: 67%, AUC: 0⋅70 |
| Irritable bowel syndrome and Crohn's disease | ||||||
| 23 | 2013 | [32] | IBS vs CD | 44 | IBS 30 CD 62 | Acc: IBS 80 (80)%; CD 100 (97)%, Sens: 94 (90)%, Spec: 82 (80)%, AUC: 0⋅97 (0⋅93) |
| Irritable bowel syndrome and ulcerative colitis | ||||||
| 24 | 2013 | [32] | IBS vs UC | 44 | IBS 30 UC 48 | Acc: IBS 87 (83)%; UC 94 (92)%, Sens: 96 (90)%, Spec: 80 (80)%, AUC: 0⋅96 (0⋅88) |
| Irritable bowel syndrome and coeliac disease | ||||||
| 25 | 2014 | [33] | IBS vs coeliac disease | NA | IBS 20 Coeliac 27 | Heat map: Clear separation groups. Sens: 85%, Spec: 85%, AUC: 0⋅91 |
| Inflammatory bowel disease and non-inflammatory bowel disease | ||||||
| 26 | 2016 | [40] | IBD vs non-IBD | 4 | IBD 35 Non-IBD 6 | AUC: 0⋅81 |
| Combinations | ||||||
| Crohn's disease and ulcerative colitis and healthy | ||||||
| 27 | 2011 | [65] | CD vs UC vs HV | NA | CD 15 UC 4 HV 8 | PCA: Clear separation groups |
| 28 | 2013 | [66] | CD vs UC vs HV | NA | CD 24 UC 24 HV 14 | PCA: Clear separation groups. Acc: >75% |
| 29 | 2016 | [45] | CD vs UC vs HV | NA | CD 117 UC 100 HV 109 | PCA: Clear separation CD A, CD R and HV; Clear separation ileal and colon CD; Unclear separation UC A, UC R and HV |
| Crohn's disease and ulcerative colitis and irritable bowel syndrome and healthy | ||||||
| 30 | 2017 | [36] | IBS vs CD vs UC vs HV | NA | IBS 28 CD 36 UC 49 HV 41 | PCA: Clear separation CD A and IBS; Clear separation UC A and UC R; Unclear separation IBD A and IBD R Acc: Ranging between 75% and 100%†, Sens: NA, † Spec: NA, † AUC: NA, † |
| 31 | 2014 | [38] | Faeces: CD vs HV and UC and IBS | NA | IBS 28 CD 24 UC 19 HV 20 | Acc: 79%, Sens: 68%, Spec: 83% AUC: 0⋅65 |
| 32 | 2014 | [38] | Urine: CD vs HV and UC and IBS | NA | IBS 28 CD 24 UC 19 HV 20 | Acc: 72%, Sens: 48%, Spec: 81%, AUC: 0⋅59 |
| Other | ||||||
| 33 | 2015 | [53] | CD A vs CD R vs HV | 17 | CD 191 CDA NA CDR NA HV 110 | PCA: Clear separation groups. Acc: 86⋅7% |
| 34 | 2017 | [67] | UC A vs UC R vs non-IBD colitis | 11 | UC 76 UCA NA UCR NA Non-IBD 22 | PCA: Clear separation groups. Sens: 92%, Spec: 77%, AUC: 0⋅94 |
| Interventional | ||||||
| Irritable bowel syndrome | ||||||
| 35 | 2017 | [35] | Low FODMAP baseline model | 15 | Response 35 Non-response 9 | PCA: Clear separation groups. Acc: treat 97%; plac 40⋅9%, Sens: treat 100%; plac 62⋅5%, Spec: treat 88%; plac 28⋅6% |
| 36 | 2017 | [35] | Probiotic baseline model | 10 | Response 29 Non-response 16 | PCA: Clear separation groups. Acc: treat 89%; plac 45⋅5%, Sens: treat 93%; plac 75%, Spec: treat 82%; plac 28⋅6% |
| 37 | 2017 | [35] | Low FODMAP end treatment model | 9 | Response 30 Non-response 9 | PCA: Clear separation groups. Acc: 96%, Sens: 100%, Spec: 82% |
| 38 | 2017 | [35] | Probiotic end of treatment model | 11 | Response 29 Non-response 16 | PCA: Clear separation groups. Acc: 91%, Sens: 92%, Spec: 90% |
A = active disease; CD = Crohn's disease; CV = cross validation; DS = discriminant score; HV = healthy volunteer; IBD = inflammatory bowel disease; IBS = irritable bowel syndrome; NA = not available; OSC-PLS-DA = partial least squares discriminant analysis with orthogonal signal correction; PCA = principal component analysis; R = disease in remission; UC = ulcerative colitis.
Results are shown as: visual (PCA, heat map, OSC-PLS-DA, DS); Acc = accuracy% (after CV); Sens = sensitivity% (after CV); Spec = specificity% (after CV); AUC = area under the curve (after CV); treat = treatment; plac = placebo.
†This article has elaborate tables which are not included in this paper. After double cross-validation, the most clinically important findings were the accuracy of CD-A versus IBS (87%), and IBS versus HV (78%).