 shown in [TABLE 0](#pone-0000000-t000){ref-type="table"}.  00.0000/journal.pone.0000000.t000  ###### Demographic characteristics of the study populations.  ![](pone.0000000.t000){#pone-0000000-t000-0}                                                          COPD; n = 000,000 (000%)   Controls; n = 000,000 (000%)   ---------------------------------------------------- -------------------------- ------------------------------   *