There are several different rating scales that may be used to assess the stage of Parkinson’s disease (PD) in an individual. The two most commonly used are the Hoehn and Yahr scale and the Unified Parkinson’s Disease Rating Scale.

The Hoehn and Yahr scale

The Hoehn and Yahr scale, named for its authors, was published in 1967 and was the first rating scale to describe the progression of PD. The Hoehn and Yahr scale describes five stages to PD progression:

1. Stage One of Parkinson’s Disease – In stage one, the earliest stage, the symptoms of PD are mild and only seen on one side of the body (unilateral involvement), and there is usually minimal or no functional impairment. The symptoms of PD at stage one may be so mild that the person doesn’t seek medical attention or the physician is unable to make a diagnosis. Symptoms at stage one may include tremor, rigidity, or slowness of movement in the arm or leg on one side of the body, or one side of the face may be affected, impacting the expression.
2. Stage Two of Parkinson’s Disease – Stage two is still considered early disease in PD, and it is characterized by symptoms on both sides of the body (bilateral involvement) or at the midline without impairment to balance. Stage two may develop months or years after stage one. Symptoms of PD in stage two may include the loss of facial expression on both sides of the face and decreased blinking. Speech abnormalities may be present, such as soft voice, monotone voice, fading volume after starting to speak loudly, or slurring speech. There also may be stiffness or rigidity of the muscles in the trunk that may result in neck or back pain, stooped posture, and general slowness in all activities of daily living. Diagnosis may be easy at this stage if the patient has a tremor, however, if stage one was missed and the only symptoms of stage two are slowness or lack of spontaneous movement, PD could be misinterpreted as only advancing age.
3. Stage Three of Parkinson’s Disease – Stage three is considered mid-stage and is characterized by loss of balance and slowness of movement. Balance is compromised by the inability to make the rapid, automatic, and involuntary adjustments necessary to prevent falling, and falls are common at this stage. All other symptoms of PD are also present at this stage, and generally diagnosis is not in doubt at stage three. An important clarifying factor of stage three is that the patient is still fully independent in their daily living activities, such as dressing, hygiene, and eating.
4. Stage Four of Parkinson’s Disease – In stage four, PD has progressed to a severely disabling disease. Patients with stage four PD may be able to walk and stand unassisted, but they are noticeably incapacitated. Many use a walker to help them. At this stage, the patient is unable to live an independent life and needs assistance with some activities of daily living.
5. Stage Five of Parkinson’s Disease – Stage five is the most advanced and is characterized by confinement to a bed or wheelchair. People with stage five PD may be unable to rise from a chair or get out of bed without help, they may have a tendency to fall when standing or turning, and they may freeze or stumble when walking. Around-the-clock assistance is required at this stage to reduce the risk of falling and help the patient with all daily activities. At stage five, the patient may also experience hallucinations or delusions.^1,2

While the symptoms worsen over time, it is worth noting that some patients with PD never reach stage five. People with PD may also never experience some of the above symptoms. In addition, there are treatments available that can help at every stage of the disease.

Unified Parkinson’s Disease Rating Scale

The Unified Parkinson’s Disease Rating Scale (UPDRS) has four parts. Each part has multiple points that are individually scored, using zero for normal or no problems, 1 for minimal problems, 2 for mild problems, 3 for moderate problems, and 4 for severe problems. These scores are tallied to indicate the severity of the disease, with 199 points being the worst and total disability and 0 meaning no disability.³

In 2001, the Movement Disorder Society (MDS) updated the rating scale with involvement from patients and caregivers. The updated scale is referred to as the UPDRS-MDS, and it was published in 2008. It now includes the following sections:³

Part 1: Intellectual function, mood, behavior

• Forgetfulness, disorientation in time and space
• Vivid dreaming
• Hallucinations
• Delusions and paranoia
• Depressed mood
• Anxious mood
• Apathy
• Features of dopamine dysregulation syndrome
• Nighttime sleep problems
• Daytime sleepiness
• Pain and other sensations
• Urinary problems
• Constipation problems
• Lightheadedness on standing
• Fatigue

Part 2: Activities of daily living

• Speech: difficulty being understood
• Salivation and drooling
• Chewing and swallowing
• Cutting food
• Small handwriting
• Needing help with getting dressed, buttons, arms in sleeves
• Requires assistance with bathing, brushing teeth
• Trouble doing hobbies and other activities
• Difficulties with turning in bed
• Tremor impact on activities
• Getting in and out of bed
• Walking, balance, falling
• Freezing

Part 3: Motor examination

• Speech – volume, diction
• Reduced facial expressions
• Rigidity
• Finger tapping
• Slowed hand movements
• Rapid alternating movements of hands (pronation-supination)
• Toe tapping
• Leg agility – when tapping heel on the ground, is it slowed, early fatiguing
• Arising from a chair – degree of difficulty
• Gait – shuffling, walking with difficulty
• Freezing of gait
• Postural stability – difficulty recovering balance
• Posture – stooped
• Global spontaneity of movement (body bradykinesia) – slowness of movement, lack of movement
• Tremor at rest

Part 4: Motor complications

• Dyskinesia, including time spent with dyskinesia, functional impact of dyskinesia, and painful off-state dystonia
• Motor fluctuations, including time spent in the off state, functional impact of fluctuations, and complexity of motor fluctuations