| Methods |
RCT |
| Participants |
USA: Dayton, Seattle, Fitchburg, Franklin, Charleston, Georgetown |
| Interventions |
Ceiling + Co‐insurance |
| Outcomes |
Medicine use; cost |
| Notes |
Health Insurance Study grant from the US Department of Health and Social Services, Washington, DC |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Low risk |
Random sequence generation is described and adequate |
| Allocation concealment (selection bias) |
Low risk |
Allocation of concealment is adequately done |
| Baseline outcome measurement similarity |
Low risk |
Outcomes are measured before the intervention, and no important differences are detected among groups |
| Baseline characteristics similarity |
Low risk |
Baseline characteristics of intervention and control groups are similar |
| Protection against contamination |
Low risk |
It is unlikely that the control group received the intervention |
| Intervention independent of other changes |
Unclear risk |
Not applicable (RCT) |
| Shape of the intervention effect pre‐specified |
Unclear risk |
Not applicable (RCT) |
| Intervention unlikely to affect data collection |
Unclear risk |
Not applicable (RCT) |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
No outcome data are missing |
| Blinding of outcome assessment (detection bias)
All outcomes |
Low risk |
Outcomes are objective |
| Selective reporting (reporting bias) |
Low risk |
All relevant outcomes in the Methods section are reported in the Results section |
| Other bias |
High risk |
Only 4 out of 6 study sites are included in the analysis |
