Stages of Disease

Three PD rating scales are widely used to rate the stage of PD. It is important for dental providers to realize these scales stage the disease at “a given moment in time” and individuals’ scores can vary from day-to-day or even hour-to-hour.

  • The Unified Parkinson Disease Rating Scale measures (1) mental functioning, behavior, and mood; (2) activities of daily living, (3) motor function, and (4) complications. Scores range from 0 to 195, with higher scores indicating greater disability. Although widely used, this scale is very complicated and would not be a good fit for most dental practices.

  • The Schwab and England Activities of Daily Living Scale36 (Table 1) measures the abilities of individuals with PD relative to their complete independence. The scale stages the disease from 0% (vegetative state) to 100% (completely independent). This scale is relatively simple and could be utilized by dental practices.

  • The Hoehn and Yahr Scale (Table 2) measures motor symptoms to determine the level of disease.37 It is important for dental providers to recognize this scale is not linear. The amount of time spent in each stage varies from patient-to-patient and is different for each level. Patients may begin at stage II if involvement is generalized or bilateral. They may not reach stage V. Stages do not represent specific amounts of brain pathology.38 A modified form of this scale, that divides the disease into smaller increments, is also available. This scale is also relatively simple and could be utilized by dental practices.
Table 1. The Schwab and England Activities of Daily Living Scale.36
Stage Level of Independence
100% Completely independent. Able to do all chores without slowness, difficulty, or impairment.
90% Completely independent. Able to do all chores with some slowness, difficulty, or impairment. May take twice as long.
80% Independent in most chores. Takes twice as long. Conscious of impairment.
70% Not completely independent. More difficulty with chores. Three to 4 times as long on chores for some. May take large part of day for chores.
60% Some dependency. Can do most chores, but very slowly and with much effort. Errors, some chores impossible.
50% More dependent. Help with ½ of chores. Difficulty with everything.
40% Very dependent. Can assist with all chores but accomplish few alone.
30% With effort, now and then does a few chores alone or begins alone. Much help needed.
20% Nothing alone. Can occasionally provide slight help with chores.
10% Totally dependent, helpless.
0% Vegetative; functions such as swallowing, bladder and bowel are not functioning. Bedridden.
Table 2. The Hoehn and Yahr five stages of Parkinson’s disease scale.37
Stage Symptoms
I Unilateral involvement only, usually with minimal or no functional impairment.
II Bilateral or midline involvement, without impairment of balance.
III First signs of impaired righting reflexes. This is evident as the patient turns or is demonstrated when he or she is pushed from standing equilibrium with the feet together and eyes closed.
IV Fully developed, severely disabling disease; the patient is still able to walk and stand unassisted but is markedly incapacitated.
V Confinement to bed or wheelchair unless aided.