Open Access
Table 1
Two main sources of biases threatening internal validity of SAT/ECA studies.
Patient-level | Inconsistent measurement of endpoints (e.g., uneven follow-up time of long-term progression events and overall survival)/prognostic risk factors between SATs and ECAs. |
Non-random missingness of data. | |
Differences in observed baseline characteristics that make it challenging to define SoC for ECAs as a comparator. | |
Differences in unobserved baseline characteristics. | |
Use of historical (vs. concurrent) ECAs* in which practice may deviate from that in SATs. | |
System-level | Underlining heterogeneity among the systems**. |
−Population-level disease burdens. | |
−Practice style, experience, reimbursement policy, clinical guideline. |
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