Quality assessment of included studies (RCTs)
| Cochrane risk of bias tool (for RCTs) | ||||||
| Type of bias | Selection | Performance | Detection | Attrition | Reporting | |
| Author, year | Random sequence generation | Allocation concealment | Blinding of participants and personnel* | Blinding of outcome assessment* | Incomplete outcome data | Selective reporting |
| Arrossi et al, 201521 | Medium† | Low | Low | Low | Low | Low |
| Bais et al, 200722 | Low | Medium‡ | Low | Low | Low | Low |
| Broberg et al, 201423 | Medium‡ | Medium‡ | Low | Low | Low | Low |
| Cadman et al, 201524 | Low | Low | Low | Low | Low | Low |
| Carrasquillo et al, 201825 | Low | Low | Low | Low | Low | Low |
| Darlin et al, 201327 | Medium‡ | Medium‡ | Low | Low | Low | Medium†† |
| Giorgi Rossi et al, 201130 | Low | Low | Low | Low | Low | Low |
| Giorgi Rossi et al, 201529 | Low | Low | Low | Low | Low | Low |
| Gok et al, 201031 | Low | Medium | Low | Low | Low | Low |
| Gök et al, 201232 | Low | Medium‡ | Low | Low | Low | Medium†† |
| Gustavsson et al, 201833 | Low | Low | Low | Low | Low | Low |
| Haguenoer et al, 201434 | Low | Low | Low | Low | Low | Low |
| Ivanus et al, 201835 | Low | Low | Low | Low | Low | Low |
| Kellen et al, 201836 | Low | High§ | Low | Low | Low | Low |
| Lazcano-Ponce et al, 201138 | Medium¶ | Low | Low | Low | Low | Medium†† |
| Modibbo et al, 201739 | High** | Medium | Low | Low | Low | Medium†† |
| Moses et al, 201540 | Low | Low | Low | Low | Medium | Low |
| Murphy et al, 201641 | Low | Low | Low | Low | Low | Low |
| Piana et al, 201142 | Low | Medium‡ | Low | Low | Medium | High††‡‡ |
| Racey et al, 201654 | Low | Low | Low | Low | Medium | Low |
| Sancho-Garnier et al, 201343 | Medium‡ | Medium‡ | Low | Low | Low | Medium†† |
| Sewali et al, 201544 | Low | Low | Low | Low | Low | Low |
| Sultana et al, 201645 | Low | Low | Low | Low | Low | Medium |
| Szarewski et al, 201146 | Medium3 | Medium3 | Low | Low | Low | Low |
| Tranberg et al, 201847 | Low | Low | Low | Low | Low | Low |
| Tranberg et al, 2018 (subanalysis)48 | Low | Low | Low | Low | Low | Low |
| Virtanen et al, 201150 | Low | Medium‡ | Low | Low | Low | Low |
| Viviano et al, 201751 | Low | Low | Low | Low | Low | Low |
| Wikström et al, 201152 | Medium‡ | Medium‡ | Low | Low | Low | Low |
| Zehbe et al, 201653 | Medium† | Medium | Low | Low | Medium | Medium |
Green: low risk of bias; yellow: medium risk of bias; red: high risk of bias.
*Given the intervention of interest (self-sampling for HPV testing), blinding was not possible for participants and personnel, nor was it possible to blind for outcome assessment. However, the measured outcomes (uptake of cervical cancer screening, frequency of HPV testing, social harms/adverse events and linkage to care) are unlikely to be influenced by lack of blinding. For uptake, the outcome was measured by lab/medical records (number of kits sent in for testing and number of patients who got the Pap smear or VIA), not by self-report. For linkage to care, the outcome was measured through medical records, not by self-report.
†Cluster-randomised community health workers or communities to self-sampling and control arms.
‡Details of the randomisation and/or allocation process are not documented.
§Timing of screening invitation was different for the intervention group compared with the control group.
¶Non-random factor is included in design (eg, women randomised to the self-sampling arm who were not at home when visited by researcher were reassigned to control/conventional cytology).
**Randomisation occurred after enrolment.
††Intention to treat was not reported.
‡‡Women in the self-sampling arm could opt out; those who did were excluded from the analysis (possibly leading to an artificially high participation rate in the self-sampling arm).
HPV, human papillomavirus; RCT, randomised controlled trial; VIA, visual inspection with acetic acid.