In Google, I could find only 22 examples of "'all patients treated' analysis", so I do not think there has been a 定訳 yet.

The following sites give partial definitions of "'all patients treated' analysis":

http://www.annals.org/issues/v132n2/full/200001180-00002.htm...
An all-patients-treated analysis, which included patients with a baseline visit and at least one post-randomization visit, was performed.

http://www.stfm.org/fmhub/Fullpdf/may99/special5.pdf
An "all patients treated" analysis was conducted on efficacy data for all patients who received at least one dose of study drug after the baseline phase and had at least one observation taken while receiving study medication.

Considering these two, I suggest those above. Since the original is a clause, I purposely used "すべての患者を治療する" in my first suggestion. You may not use quotations.