Hoehn and Yahr Scale
Top Contributors - Ahmed M Diab, Shreya Pavaskar, Vidya Acharya, Aminat Abolade, Safiya Naz and Alexandra Stead
Introduction
The Hoehn and Yahr (H&Y) scale was first described by Margaret Hoehn and Melvin Yahr in 1967 in the journal Neurology, covering stages 1 through 5.[1] It remains one of the most widely used staging systems for Parkinson's disease (PD), valued for its brevity and broad clinical acceptance. The modified version, which added the intermediate stages 1.5 and 2.5, was introduced to better capture transitional disease states, though these stages were not part of the original publication. The scale is used alongside the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) to provide a more complete picture of disease severity. The MDS-UPDRS includes the H&Y as a sub-component (part V), and higher H&Y stages have been shown to correspond with progressively higher MDS-UPDRS scores across all four subscales.[2]
Purpose
The H&Y scale was designed to describe the broad progression of motor impairment and functional disability associated with PD. It provides a standardised framework for characterising disease severity, facilitating communication between clinicians and enabling stratification of patient cohorts in research settings.[3] Because the scale integrates both impairment (e.g., unilateral vs bilateral involvement) and disability (e.g., physical independence), it offers a practical global overview that is particularly useful for defining inclusion and exclusion criteria in clinical trials.[3] However, its broad categories limit its sensitivity as an outcome measure for detecting the effects of specific interventions.[3]
Technique
The H&Y scale is a clinician-rated observational assessment, typically conducted by a neurologist or movement disorder specialist. It is not a patient-reported outcome. The clinician assigns a stage based on direct observation of motor function, including assessment of laterality of symptoms and postural stability via the pull test. The rating should reflect what the clinician observes at the time of examination and should incorporate any comorbidities that influence motor performance, as per MDS Task Force guidance.[3] It is important to note that the H&Y stage should ideally be recorded in context-specifically, whether the patient was in a medication 'on' or 'off' state-as motor performance can differ substantially between states, particularly in patients on dopaminergic therapy. The examination does not require any specialist equipment. The core assessment involves:
- Observation of the distribution of motor symptoms (unilateral, axial or bilateral)
- Assessment of postural stability using the pull test
- Clinical judgement of the patient's level of physical independence
Staging Criteria
| Stage | Hoehn and Yahr Scale | Modified Hoehn and Yahr Scale |
|---|---|---|
| 1 | Unilateral involvement only usually with minimal or no functional disability | Unilateral involvement only |
| 1.5 | - | Unilateral and axial involvement |
| 2 | Bilateral or midline involvement without impairment of balance | Bilateral involvement without impairment of balance |
| 2.5 | - | Mild bilateral disease with recovery on pull test |
| 3 | Bilateral disease: mild to moderate disability with impaired postural reflexes; physically independent | Mild to moderate bilateral disease; some postural instability; physically independent |
| 4 | Severely disabling disease; still able to walk or stand unassisted | Severe disability; still able to walk or stand unassisted |
| 5 | Confinement to bed or wheelchair unless aided | Wheelchair bound or bedridden unless aided[4] |
Clinimetric Properties
Reliability
Direct clinimetric testing of the H&Y scale has been limited, and earlier reviews noted only moderate inter-rater reliability.[5] However, the first systematic clinimetric evaluation of the modified H&Y embedded within the MDS-UPDRS,[5] conducted in an international sample of 3,109 patients, demonstrated satisfactory acceptability, reproducibility and convergent validity. Content validity was identified as relatively weak, primarily because the scale does not address non-motor aspects of PD. The MDS Task Force noted that the scale fulfils at least some criteria for reliability and validity, particularly for the mid-range stages (2-4), where the staging criteria are more clearly defined.[3] Reliability is less consistent at the extremes of the scale.
Validity
Convergent validity is supported by strong correlations between H&Y stage and other established PD measures. In a large cross-sectional study of 3,206 patients, MDS-UPDRS subscores across all four parts increased significantly with each H&Y stage, providing robust support for construct validity.[3] Higher H&Y stages correlate with neuroimaging findings and with quality of life deterioration.[6]
Evidence
The MDS Task Force concluded that, while the H&Y scale has clear strengths including widespread adoption and correlation with neuroimaging findings, the modified scale (with half-point stages) should not be used until formal clinimetric testing is completed. They recommended retaining the original five-point scale for group description and using it primarily to define inclusion/exclusion criteria in research.[3]
A landmark validation study by Martínez-Martín et al. (2018), using data from 3,109 patients across multiple countries (the QUALPD cohort), provided the first systematic clinimetric evidence for the modified H&Y as embedded within the MDS-UPDRS. The study confirmed satisfactory reproducibility and convergent validity, while identifying weak content validity as a persistent limitation, which is consistent with the scale's focus on motor laterality and postural instability alone.[5]
A large cross-sectional study demonstrated that all four MDS-UPDRS subscale scores increased significantly across H&Y stages 1 through 5, as well as over five-year increments of disease duration during the first 15 years of illness. This supports the H&Y scale's utility as a marker of disease burden across the disease spectrum.[2]
Research examining staging combined with non-motor symptoms (Santos García et al., 2021; n = 603, COPPADIS cohort) demonstrated that H&Y motor staging alone does not adequately capture disability and quality-of-life burden. A composite staging approach incorporating non-motor symptom burden provided significantly greater discrimination of disability and quality-of-life outcomes. This further supports the use of H&Y in combination with, rather than instead of, more comprehensive instruments.[6]
Clinical Relevance for Physiotherapy
The H&Y stage provides a rapid, standardised orientation to a patient's level of motor disability, which can inform physiotherapy planning. Clinically relevant thresholds include:
• H&Y stage 1-2 (early disease): rehabilitation goals focus on maintaining physical function, activity levels, and exercise participation. Early signs of gait and balance decline are present even in the prodromal period, with a high prevalence of non-motor symptoms, supporting early physiotherapy initiation as a secondary prevention strategy.[7] The APTA Clinical Practice Guideline recommends physiotherapy be initiated early, focusing on aerobic, resistance, balance, and flexibility training to maintain function and reduce disability.[8]
• H&Y stage 3 (moderate disease): The APTA Clinical Practice Guideline recommends balance training progressively shift from preventive strategies in earlier stages to compensatory strategies in later stages.[8]
• H&Y stage 4-5 (advanced disease): at H&Y stages IV-V, patients become severely dependent on caregivers, and symptom burden is often profound.[9]
Recommended outcome measures
Since the H&Y scale is a broad, ordinal, and non-linear staging tool with limited responsiveness to change, it must not be used in isolation to evaluate physiotherapy outcomes. The APTA Clinical Practice Guideline identifies the following as recommended outcome measures for tracking physiotherapy response in PD: the MDS-UPDRS Part II (motor experiences of daily living) and Part III (motor examination); the Berg Balance Scale (BBS); the Timed Up and Go (TUG) test; the 10-Metre Walk Test (10MWT); and the Six-Minute Walk Test (6MWT) for aerobic endurance. These instruments provide the sensitivity to change that the H&Y stage alone lacks.[8]
References
- ↑ Hoehn MM, Yahr MD. Parkinsonism: onset, progression, and mortality. Neurology. 1967 May;17(5):427-.
- ↑ 2.0 2.1 Skorvanek M, Martinez‐Martin P, Kovacs N, Rodriguez‐Violante M, Corvol JC, Taba P, Seppi K, Levin O, Schrag A, Foltynie T, Alvarez‐Sanchez M. Differences in MDS‐UPDRS scores based on Hoehn and Yahr stage and disease duration. Movement disorders clinical practice. 2017 Jul;4(4):536-44.
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Goetz CG, Poewe W, Rascol O, Sampaio C, Stebbins GT, Counsell C, Giladi N, Holloway RG, Moore CG, Wenning GK, Yahr MD. Movement Disorder Society Task Force report on the Hoehn and Yahr staging scale: status and recommendations the Movement Disorder Society Task Force on rating scales for Parkinson's disease. Movement disorders. 2004 Sep;19(9):1020-8.
- ↑ Scanlon BK, Katzen HL, Levin BE, Singer C, Papapetropoulos S. A formula for the conversion of UPDRS-III scores to Hoehn and Yahr stage. Parkinsonism & related disorders. 2008 May 1;14(4):379-80.
- ↑ 5.0 5.1 5.2 Martinez‐Martin P, Skorvanek M, Rojo‐Abuin JM, Gregova Z, Stebbins GT, Goetz CG, QUALPD Study Group. Validation study of the hoehn and yahr scale included in the MDS‐UPDRS. Movement Disorders. 2018 Apr;33(4):651-2.
- ↑ 6.0 6.1 Santos García D, de Deus Fonticoba T, Paz González JM, Cores Bartolomé C, Valdés Aymerich L, Muñoz Enríquez JG, Suárez E, Jesús S, Aguilar M, Pastor P, Planellás LL. Staging Parkinson’s disease combining motor and nonmotor symptoms correlates with disability and quality of life. Parkinson’s Disease. 2021;2021(1):8871549.
- ↑ Ellis TD, Colón-Semenza C, DeAngelis TR, Thomas CA, Saint Hilaire MH, Earhart GM, Dibble LE. Evidence for early and regular physical therapy and exercise in Parkinson's disease. InSeminars in neurology 2021 Apr (Vol. 41, No. 02, pp. 189-205). Thieme Medical Publishers, Inc..
- ↑ 8.0 8.1 8.2 Osborne JA, Botkin R, Colon-Semenza C, DeAngelis TR, Gallardo OG, Kosakowski H, Martello J, Pradhan S, Rafferty M, Readinger JL, Whitt AL. Physical therapist management of Parkinson disease: a clinical practice guideline from the American Physical Therapy Association. Physical therapy. 2022 Apr 1;102(4):pzab302.
- ↑ Rosqvist K, Schrag A, Odin P, CLaSP Consortium. Caregiver burden and quality of life in late stage Parkinson’s disease. Brain Sciences. 2022 Jan 14;12(1):111.