A 70-yeаr-оld wоmаn presents with а 4-week histоry of progressive bilateral shoulder and hip stiffness. She reports morning stiffness lasting more than 60 minutes that improves slightly with movement. She denies hand or wrist pain or swelling. She also reports fatigue and low-grade fever. On examination, there is limited active range of motion of the shoulders due to pain, but no joint swelling or deformities are noted. Laboratory studies reveal elevated ESR and CRP. What is the most likely diagnosis?