Inclusion and exclusion criteria for study selection based on PICOS
| Selection criteria | Inclusion criteria | Exclusion criteria |
| Population | Adults living in mainland China | Residents outside mainland China or children or adolescent living in mainland China |
| Intervention | Internal migration (either rural-to-urban, urban-to-rural or rural-to-rural, urban-to-urban) | International migration |
| Comparator | Any population groups, including rural/urban residents or general population | No eligible comparison group |
| Outcome | All types of NCD risk factors, including behavioural, metabolic, environmental) All types of NCD outcomes (diagnosis, treatment, control) | No NCD risk factors or NCD outcomes |
| Study design | All study designs except for qualitative study, systematic reviewand commentary | Qualitative study, systematic review or commentary |
NCD, non-communicable disease.