if not necessary该怎么理解？

Most experts agree that an educational or psychoeducational treatment component is useful if not necessary when treating FM as part of a multimodal approach.Burckhardt and colleagues assigned FM patients to an education-only condition, an education plus physical training condition, or a delayed treatment waitlist control.Both active treatment groups improved on subjective ratings and reports of physical activity compared to controls. Rooks et al. completed an RCT with 207 confirmed FM patients who were assigned to one of four groups: (1) an aerobic and flexibility exercise group; (2) a strength training, aerobic, and flexibility exercise group; (3) the FM Self-Help Course (FSHC) (Education group); or (4) a  combination of the previous three groups. The primary outcome was change in physical function from baseline to completion of the intervention, and the combination group showed the greatest  improvement.

FM纤维肌痛