Table 2.
Quality assessment of included studies. Items are derived from Cochrane Collaboration Tool for bias assessment.
| Reference | Population | Tryptophan depletion | Challenge test | Statistical analysis | Dropouts | Selective reporting and incomplete outcome data | Randomisation | Double blind fashion | Outcome assessor blind | Judgmenta |
|---|---|---|---|---|---|---|---|---|---|---|
| Healthy volunteers | ||||||||||
| Smith et al. 1987 (47) | High | Low | Not applicable | Low | High | Low | Low | Low | Low | Good |
| Benkelfat et al. 1994 (45) | Low | Medium | Not applicable | Medium | Medium | Low | Low | Low | Low | Medium |
| Park et al. 1994 (48) | High | Low | Not applicable | Low | High | Low | Medium | Low | Low | Medium |
| Cleare and Bond 1995 (46) | High | Low | Not applicable | Low | High | Medium | Medium | Low | Low | Poor |
| Goddard et al. 1995 (41) | Medium | Medium | Low | Medium | Low | Medium | Low | Low | Low | Poor |
| Kent et al. 1996 (30) | Low | Low | Low | Low | Medium | Medium | Low | Medium | Low | Poor |
| Koszycki et al. 1996 (31) | Low | Low | Low | Medium | High | Low | Low | Low | Low | Good |
| Klaassen et al. 1998 (32) | Low | Low | Low | Low | Low | Medium | Low | Low | Low | Poor |
| Miller et al. 2000 (43) | Low | Low | Low | Low | High | Medium | Low | Low | Low | Poor |
| Monteiro-dos-Santos et al. 2000 (33) | Medium | Medium | Low | Low | Low | Low | Medium | Low | Low | Medium |
| Shansis et al. 2000 (42) | Low | Medium | Low | Medium | Low | Medium | Low | Low | Low | Poor |
| Colasanti et al. 2011 (35) | Low | Low | Low | Low | High | Medium | Low | Low | Low | Poor |
| Robinson et al. 2012 (29) | Low | Low | Low | Medium | High | Low | Low | Low | Low | Good |
| Remitted patients | ||||||||||
| Bell et al. 2002 (38) | Low | Low | Low | Medium | High | Medium | Low | Low | Low | Poor |
| Argyropoulos et al. 2004 (39) | Low | Medium | Low | Medium | High | Low | Low | Low | Low | Medium |
| Davies et al. 2006 (36) | Medium | Low | Low | Low | High | Low | Low | Low | Low | Good |
| Tõru et al. 2006 (28) | Low | Low | Medium | Low | High | Medium | Low | Low | Low | Poor |
| Hood et al. 2010 (37) | Low | Low | Low | Low | Low | Low | Low | Low | Low | Good |
| Bell et al. 2011 (44) | Low | Low | Low | Medium | Low | Medium | Low | Low | Low | Poor |
| Current patients | ||||||||||
| Goddard et al. 1994 (40) | Medium | Low | Not applicable | Medium | High | Medium | Low | Low | Low | Poor |
| Kent et al. 1996 (30) | Please see under healthy volunteers | |||||||||
| Miller et al. 2000 (43) | Please see under healthy volunteers | |||||||||
| Schruers et al. 2000 (34) | Low | Low | Low | Medium | Low | Low | Low | Low | Low | Good |
aStudies were judged to be of ‘good’ quality when using a double-blind randomised design, tryptophan depletion was well executed and reported, and the pre- and post ATD outcome measures were reported. In ‘medium’ quality studies one of the previous items was insufficiently reported. In ‘poor’ quality studies the pre- and post ATD scores nor the differences scores were reported.