Table 2.
Risk and quality assessment of eligible studies
| Appraisal questions for cohort studies | Bryer and Wasserman 2012 | Villiers et al. 2009 | Klemperer et al. 2014 | |
| 1 | Were the groups similar and recruited from the same population? | Yes | Yes | Yes |
| 2 | Were the exposures measured similarly to assign people to both exposed and unexposed groups? | Yes | Yes | Yes |
| 3 | Was the exposure measured in a valid and reliable way? | Yes | Yes | Yes |
| 4 | Were confounding factors identified? | Yes | Yes | Yes |
| 5 | Were strategies to deal with confounding factors stated? | No | No | Yes |
| 6 | Were the groups/participants free of the outcome at the start of the study (or at the moment of exposure)? | Yes | Yes | Yes |
| 7 | Were the outcomes measured in a valid and reliable way? | Yes | Yes | Yes |
| 8 | Was the follow up time reported and sufficient to belong enough for outcomes to occur? | Yes | No | Yes |
| 9 | Was follow-up complete, and if not, were the reasons to loss to follow-up described and explored? | NA | NA | NA |
| 10 | Were strategies to address incomplete follow-up utilised? | NA | NA | NA |
| 11 | Was appropriate statistical analysis used? | Yes | Yes | Yes |
| Critical appraisal questions for case series study | Naima Chtaou et al. 2016 | |||
| 1 | Were there clear criteria for inclusion in the case series? | Yes | – | – |
| 2 | Was the condition measured in a standard, reliable way for all participants included in the case series? | Yes | – | – |
| 3 | Were valid methods used for identification of the condition for all participants included in the case series? | Yes | – | – |
| 4 | Did the case series have consecutive inclusion of participants? | Yes | – | – |
| 5 | Did the case series have complete inclusion of participants? | Yes | – | – |
| 6 | Was there clear reporting of the demographics of the participants in the study? | Yes | – | – |
| 7 | Was there clear reporting of clinical information of the participants? | Yes | – | – |
| 8 | Were the outcomes or follow up results of cases clearly reported? | Yes | – | – |
| 9 | Was there clear reporting of the presenting site(s)/clinic(s) demographic information? | No | – | – |
| 10 | Was statistical analysis appropriate? | Yes | – | – |
| 11 | Were there clear criteria for inclusion in the case series? | Yes | – | – |