Table 5.
Quality assessment.
| Item | First author, publication year, reference | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
| |||||||||||||
| Helenius et al. (2005) (22) | Sezer et al. (2012) (25) | Chang et al. (2013) (26) | Keller et al. (2013) (28) | Pischon et al. (2010) (24) | Londoño et al. (2013) (20) | Suppiah et al. (2013) (27) | Bisanz et al. (2016) (21) | Bautista-Maulano et al. (2017) (19) | Kang et al. (2015) (23) | Schmalz et al. (2018) (30) | Ziebolz et al. (2018) (29) | ||
| 1.1 | The study addresses an appropriate and clearly focused question | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| 1.2 | The cases and controls are taken from comparable populations | No | No | No | Yes | No | No | Yes | Yes | Yes | Yes | Yes | Yes |
| 1.3 | The same exclusion criteria are used for both cases and controls | Cannot say | Yes | Cannot say | Cannot say | Yes | No | No | No | Yes | Yes | Yes | Yes |
| 1.4 | What percentage of each group (cases and controls) participated in the study? | Cannot say | Cannot say | Cannot say | Not applicable | Cannot say | Cannot say | Cases: 72.1%; controls: 34.7% |
Cannot say | Cannot say | Cannot say | Cannot say | Cannot say |
| 1.5 | Comparison is made between participants and non-participants to establish their similarities or differences | No | No | No | Not applicable | No | No | No | Not applicable | Not applicable | Not applicable | No | No |
| 1.6 | Cases are clearly defined and differentiated from controls | Yes | Yes | Yes | Yes | Yes | Cannot say | Yes | Yes | Yes | Yes | Yes | Yes |
| 1.7 | It is clearly established that controls are non-cases | Yes | Yes | Cannot say | Yes | Cannot say | Cannot say | Yes | Yes | Yes | Yes | Yes | Yes |
| 1.8 | Measures will have been taken to prevent knowledge of primary exposure influencing case ascertainment | Cannot say | No | Cannot say | Not applicable | No | Cannot say | Cannot say | Cannot say | Cannot say | Cannot say | Cannot say | Cannot say |
| 1.9 | Exposure status is measured in a standard, valid and reliable way | Yes | Yes | Cannot say | Yes | Yes | Cannot say | Yes | Yes | Yes | Yes | Yes | Yes |
| 1.10 | The main potential confounders are identified and taken into account in the design and analysis | No | Yes | Cannot say | Yes | Yes | Yes | Cannot say | Yes | Yes | Yes | Yes | Yes |
| 1.11 | Confidence intervals are provided | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
| 1.12 | How well was the study done to minimize the risk of bias or confounding? | + | ++ | − | + | + | − | + | + | + | + | + | + |
| 1.13 | Do you think there is clear evidence of an association between the exposure group and outcome? | No | No | No | Yes | Yes | Yes | No | No | Yes | Yes | Yes | Yes |
| 1.14 | Are the results of this study directly applicable to the patient group targeted by this guideline? | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |