Table 2.
Assessment of risk of bias
| Risk of bias questions | Goodchild et al., 2010 [13] | Gudbjörnsson et al., 1993, study 1 [23] | Gudbjörnsson et al., 1993, study 2 [23] | Hilditch et al., 2008 [24] | Theander et al., 2010 [25] | Tishler et al., 1997 [26] | Usmani et al., 2012 [27] | Van Oers et al., 2010 [28] | Walker et al., 2003 [29] |
|---|---|---|---|---|---|---|---|---|---|
| 1. Was the sample representative of the target population? | N | N | N | N | Y | Y | Y | Y | N |
| 2. Were study participants recruited in an appropriate way? | ? | ? | ? | ? | Y | Y | Y | ? | Y |
| 3. Was the sample size adequate? | N | Y | N | N | Y | Y | N | N | Y |
| 4. Were the study subjects and the setting described in detail? | N | Y | N | N | Y | Y | Y | Y | Y |
| 5. Was the data analysis conducted with sufficient coverage of the identified sample? | ? | Y | N | Y | Y | Y | Y | Y | Y |
| 6. Were objective, standard criteria used for the measurement of the condition? | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| 7. Was the condition measured reliably? | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| 8. Was there appropriate statistical analysis? | Y | Y | Y | Y | Y | Y | Y | Y | Y |
| 9. Were all important confounding factors/ subgroups/differences identified and accounted for? | Y | ? | ? | ? | Y | Y | ? | ? | Y |
| 10. Were subpopulations identified using objective criteria? | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A | N/A |
Adapted with permission from Munn et al. [22]. The development of a critical appraisal tool for use in systematic reviews addressing questions of prevalence. Int J Health Policy Manag 2014;3:123–8.
N: no; N/A: not applicable; Y: yes; ?: unclear.