                                0 (0.0)      0 (0.0)      NA   **Previous clinical trial participation**                             0.000   Yes                                         00 (0.0)     00 (00.0)    NA   No                                          000 (00.0)   000 (00.0)   NA   Don't know                                  0 (0.0)      0 (0.0)      NA  