We thank Dr Lipworth for his response to our article on the safety and tolerability of fluticasone furoate/vilanterol (FF/VI) combination in asthma,1 in which he specifically discusses effects on urinary cortisol. We acknowledge the limitations of urinary cortisol assessment; however, as outlined in the online supplement, the urinary cortisol population in our study specifically excluded subjects with an incomplete urine collection and/or 24-h urinary creatinine levels below the lower limit of the threshold range. Thus, our data are not confounded …