Characteristics of each group (mean±SD) and statistical differences between groups.

The effect of pain intensity on PA was compared on age-matched groups, i.e. No Pain vs. Severe Pain in the Middle Age groups and Moderate Pain vs. Severe Pain in the Old Age groups. It can be observed that in the Middle Age groups the mean difference in pain intensity is about 70% while it is only about 35% in the Old Age groups.Diagnosis: SS = spinal stenosis; FBSS = failed back surgery syndrome; CRPS = Complex regional pain syndrome; PVD = peripheral vascular disease; LB = low back and leg pain; PN = polyneuropathy; DA = deafferentation; HD = Herniated disc.