Table 3. Key characteristics of included studies.
| Source study | Country | Study design | Sample setting cases | Sample setting control | Sample size (% IDD) | IDD diagnostic method | Primary outcome | Risk of bias |
|---|---|---|---|---|---|---|---|---|
| Autism | ||||||||
| Almansour, 2013 [28] | Saudi Arabia | Case-control | Hospital & support service | Hospital | 100 (50%) | Clinical diagnosis | Depression& anxiety | Medium |
| Gong, 2015 [29] | China | Case-control | Mental Health centre | School | 302 (62%) | Clinical diagnosis | Depression & anxiety | Medium |
| Ingersoll, 2010 [30] | USA | Case-control | Online portal | Online portal | 165 (43%) | Parental report | Depression | Medium |
| Lai, 2015 [31] | Singapore | Case-control | Specialised service | Student health centre | 135 (54%) | Clinical diagnosis | Depression & anxiety | Medium |
| Riahi, 2010 [32] | Iran | Case-control | Hospital | Hospital | 61 (53%) | Clinical diagnosis | Depression & anxiety | High |
| Yang, 2015 [33] | China | Case-control | Mental Health centre | School | 1,682 (43%) | Clinical diagnosis | Depression | Medium |
| Cerebral Palsy | ||||||||
| Altindag, 2007 [34] | Turkey | Case-control | Not reported | Not reported | 119 (44%) | Clinical diagnosis | Depression & anxiety | Medium |
| Basaran, 2013 [35] | Turkey | Case-control | Not reported | Not reported | 203 (70%) | Clinical diagnosis | Depression & anxiety | Medium |
| Cheshire, 2010 [36] | UK | Case-control | Specialised service | University advert | 140 (50%) | Parental report | Depression & anxiety | Medium |
| Kaya, 2010 [37] | Turkey | Case-control | Hospital | Hospital | 141 (57%) | Clinical diagnosis | Depression | Medium |
| Ones, 2005 [38] | Turkey | Case-control | Hospital | Hospital | 92 (50%) | Clinical diagnosis | Depression & anxiety | Medium |
| Unsal-Delialioglu, 2009 [39] | Turkey | Case-control | Hospital | Hospital | 99 (49%) | Clinical diagnosis | Depression | Medium |
| Yilmaz, 2013 [40] | Turkey | Case-control | Hospital | Hospital | 230 (51%) | Clinical diagnosis | Depression & anxiety | Medium |
| Multiple IDD: Combineda | ||||||||
| Cantwell, 2015 [41] | Republic of Ireland | Case-control | School & support service | University advert | 173 (67%) | Parental report | Depression | Medium |
| Norlin, 2013 [42] | Sweden | Case-control | Support service | Online portal | 423 (25%) | Parental report | Depression | Medium |
| Olsson, 2008 [43] | Sweden | Case-control | Support service | Online portal | 430 (26%) | Parental report | Depression | Medium |
| Multiple IDD: Disaggregateda | ||||||||
| Lach, 2009 [44] | Canada | Cross-sectional | Nationwide survey | Nationwide survey | 8,400 (14%) | Clinical diagnosis | Depression | Medium |
| Muammer, 2013 [45] | Turkey | Case-control | Specialised service | Not reported | 76 (74%) | Clinical diagnosis | Depression | High |
| Intellectual Disability | ||||||||
| Gogoi, 2017 [46] | India | Case-control | Mental Health centre | Regional survey | 120 (50%) | Clinical diagnosis | Depression & anxiety | Medium |
a Studies in which multiple IDDs are represented in one sample. ‘Multiple IDD: Combined’ indicates that outcome data is combined across the sample. ‘Multiple IDD: Disaggregated’ indicates that the researchers have disaggregated outcome data by IDD type.