Causality of the effect of bDMARDs on spinal radiographic progression in the available literature
| Study design | Assumption | |||
| Exchangeability | Positivity | Consistency | Causality | |
| Equal exposure No comparator | – | – | + | Very unlikely |
| Equal exposure Comparator | +/– | – | – | Unlikely |
| Variable exposure Comparator | + | +/– | – | Likely |
Assumption is very unlikely (–), unlikely (+/–) and likely (+) to be met.