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.
*

Historical ECAs refer to patients in SATs and ECAs are drawn from difference time periods.

**

For example, one system may consist of a set of hospitals from which SAT patents are drawn whereas the other consists of an entirely different set of hospitals from which ECA patients are drawn.

SAT: single arm trial; ECA: external control arm; SoC: standard-of-care.

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.