     Age                                               P                                 0.00              0.00   b coefficient                                     \[00%CI\]                                         AMD category (0 or 0--0)                          P                                 0.00              0.00   b coefficient                                     \[00%CI\]                                        Coefficients that were not statistically significant are not shown.  Discussion {#s0} ==========  In the present study, we 