Fig 1.
PRISMA diagram outlining the searching and screening process.
Table 1.
Full CASP quality appraisal of all studies assessed for inclusion (including those excluded following quality appraisal).
Table 2.
Policy interventions investigated.
Table 3.
Extract from a translation table on the effects of availability policies.
Table 4.
An example of synthesis table on exclusion programs.
Table 5.
An example of derivation of third-order interpretations.
Table 6.
Characteristics of the included studies.