Aletaha D, et al. - Experts evaluated achievement of remission as defined by Boolean criteria, Simplified Disease Activity Index (SDAI), Clinical Disease Activity Index (CDAI), and 28-joint Disease Activity Score using C-reactive protein (DAS28[CRP]) and ascertained the elements that restrict patients in SDAI, CDAI, or DAS28(CRP) remission from attaining Boolean remission. The majority of patients (61%–66%) who attained SDAI or CDAI remission also achieved Boolean remission. However, DAS28(CRP) remission was most often accomplished, 74%–77% of patients in DAS28(CRP) remission did not succeed in Boolean remission. Patients in SDAI or CDAI remission though not Boolean remission had higher PGA scores in comparison with patients in Boolean remission, while patients with DAS28(CRP) remission although not Boolean remission had greater joint counts, and Patient's/Physician's Global Assessment scores. In conclusion, variations in PGA restrict patients in SDAI/CDAI remission from meeting the Boolean remission criteria, implying that these criteria otherwise can be utilized reciprocally. On the contrary, patients in DAS28(CRP) remission are restricted by variations in various disease activity measures from obtaining Boolean remission.