“…Within individuals, pain was positively associated with NA variables across studies of mixed chronic pain [44,45], back pain [46,47], fibromyalgia [48][49][50], rheumatoid arthritis [51][52][53], osteoarthritis [54,55], mixed rheumatic disease [56][57][58], IBS [59], CRPS [60], and migraine [61]. Several studies also found pain to be negatively associated with PA in general chronic pain [44,62], fibromyalgia [48,49,63], rheumatoid arthritis [52,53,64,65], osteoarthritis [55,66], and mixed rheumatic disease [56,58]. Additionally, a higher ratio of PA to NA was associated with less pain in patients with osteoarthritis [55,67].…”