Table 3.
Assessment of risk of bias of the included papers, using the MMAT risk assessment tool18
| Study design and studies | Assessment criteria | Total score | |||
| Qualitative | Relevant to research question | Analysis relevant for objective | Findings related to context | Findings related to researcher’s influence | |
| Howes et al 23 | y/n | y | y/n | y/n | 2.5 |
| Quantitative randomised (randomised controlled trials) | Clear description of randomisation | Clear description of allocation concealment | 80% or more outcome data | Withdrawal/drop-out less than 20% | |
| Bonds et al 34 | n | n | y | y | 2 |
| Hemming et al 36 | y | y | y | y | 4 |
| Quantitative non-randomised | Selection bias minimised | Measurements appropriate | Study groups comparable or differences accounted for | Outcome data 80% or above, or response rate 60% or above, or acceptable follow-up rate | |
| Cottrell et al 35 | n | y | n | y | 2 |
| Quantitative descriptive | Sampling strategy relevant to research question | Sample representative of the population | Measurements appropriate | Response rates 60% or above | |
| Bannerjee et al 19 | y | y | y | y | 4 |
| Bankart et al 20 | y | y | y | y | 4 |
| de Burgos-Lunar et al 21 | y | y | y | y | 4 |
| Byrd et al 22 | 3 | ||||
| Johnson et al 24 | y | y | y | y | 4 |
| MacDonald and Morant25 | y/n | y | y | y | 3.5 |
| Mancia et al 26 | n | y | y | y | 3 |
| Nazroo et al 27 | y | y | y | y/n | 3.5 |
| Pallares-Carratalá et al 28 | y/n | y | y | y | 3.5 |
| Patel et al 29 | y/n | y/n | y | y | 3 |
| Shah and Cook30 | y | y/n | y | y | 3.5 |
| Soljak et al 31 | y | y | y | y | 4 |
| Wallace et al 32 | y | y | y | y | 4 |
| Zhao et al 33 | y/n | y | y | y | 3.5 |
MMAT, Mixed Methods Appraisal Tool; n, criterion not met; y, criterion met; y/n, one assessor assigned criterion as met, the second assessor as not met.