Our discussion forums are available to anyone to read, but you must be a member to reply or start new topics. Log-in or register to get started.


Great question! Stages 1.5 and 2.5 were added to the original H&Y scale as refinements – and there are only subtle differences between stages 2 and 2.5 (and 1 and 1.5).

Basically, if someone has bilateral symptoms and is starting to demonstrate some changes to balance but is not yet losing their balance, they are considered stage 2.5. This can be quantified with the retro pull test where maintaining balance in 3 or more steps would be considered stage 2.5 (whereas 1-2 steps is stage 2).

The best explanation is from the American Parkinson Disease Association (https://www.apdaparkinson.org/article/stages-in-parkinsons/):
“In the original H-Y system there were no stages 1.5 and 2.5. These were added later as refinements. In stage 1.5, only one side is affected, but one can see symmetric problems on both sides such as reduced facial expression on both sides, stooped posture on both sides, or reduced arm swing on both sides. In stage 2.5 both sides are involved plus there is a mild impairment of balance, but not loss of balance. To test for this, the patient is told that he will be pulled backward and to take a step back to try to prevent a fall. The patient is then pulled backward firmly. It is considered normal to take one or two steps, but if three or more are taken and balance is recovered, it is considered stage 2.5 (or 1.5 if there are no signs of PD on the better side).”