Parkinson's Disease Questionnaire-39
Also known as: PDQ-39, Parkinson's Disease Questionnaire, PDQ
The PDQ-39 is the most widely used patient-reported outcome measure for Parkinson's disease quality of life. Developed by Crispin Jenkinson and colleagues in 1997, this 39-item self-report questionnaire comprehensively assesses how Parkinson's symptoms affect daily functioning, emotional well-being, stigma, social support, and cognitive-communication abilities. It is the recommended instrument in major Parkinson's disease clinical trials and forms a core component of outcome measurement in movement disorders.
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When to use it
The PDQ-39 is indicated for measuring quality of life across the Parkinson's disease spectrum: at baseline to establish disease burden and identify areas for intervention, during clinical trials as a co-primary or secondary endpoint to assess treatment benefit beyond motor symptom control, in routine clinical practice to monitor functional decline and guide supportive and pharmacologic decisions, in research investigating long-term outcomes and psychosocial factors, and in health economic analyses to estimate quality-adjusted life years (QALYs). A shorter version (PDQ-8) exists for brief screening. The PDQ-39 is less suitable for non-Parkinson's movement disorders, though some researchers use it off-label.
Strengths & limitations
- Comprehensive multidimensional assessment—eight domains capture the breadth of Parkinson's impact: motor (mobility, ADL), emotional (well-being, stigma), social, and cognitive dimensions
- Extensively validated—used in hundreds of clinical trials and observational studies with demonstrated strong psychometric properties (Cronbach's α 0.70-0.90 across domains), test-retest reliability (r > 0.75), and sensitivity to disease progression and treatment effects
- Patient-derived content—developed directly from Parkinson's patient interviews, ensuring items reflect lived experience and priorities
- International standardization—validated in 40+ languages with published translation protocols, enabling global research and comparisons
- Free and widely available—unrestricted access for research and clinical use, with downloadable forms, scoring guides, and reference data from the Oxford Parkinson Disease Centre
- Responsive to change—sensitive to both decline and improvement, including effects of medication adjustments, deep brain stimulation, and rehabilitation interventions
- Length and completion burden—39 items require 10-15 minutes, potentially problematic for patients with advanced Parkinson's, cognitive decline, or severe motor slowing; shorter versions (PDQ-8) sacrifice detail
- Motor confounding—patients with severe tremor, bradykinesia, or dysarthria may struggle with questionnaire completion; paper versions are less accommodating than digital with assistive features
- Limited cognitive assessment—Cognitive dimension covers self-reported confusion and memory but does not quantify cognitive decline objectively; supplementary cognitive testing (MMSE, MoCA) needed for formal cognitive assessment
- Score interpretation requires context—no universal clinical cutoffs for intervention; interpretation relies on comparison to population norms, previous assessments, and clinical judgment rather than absolute thresholds
- Weak motor-QoL correlation—PDSI often correlates modestly with objective motor severity (UPDRS), reflecting that functional capacity depends on coping, medication optimization, and psychological factors as much as motor signs
Frequently asked
How do I interpret a PDQ-39 domain score of 45 in Stigma versus 20 in Mobility?
The Stigma score of 45 indicates moderate to severe perceived social stigma and embarrassment about Parkinson's in public; this patient likely restricts social activity and worries about others' perceptions. The Mobility score of 20 indicates minimal mobility impairment. This pattern—high stigma, low motor impairment—suggests a patient with relatively preserved physical function but significant psychological burden; psychological intervention, support groups, and stigma-reduction counseling may be more impactful than motor-focused therapy.
Should I use PDQ-39 or PDQ-8 for routine clinical monitoring?
PDQ-8 (shorter, 8 items) is appropriate for routine clinic visits and population screening because it samples one item from each dimension and requires only 2-3 minutes. Use full PDQ-39 (39 items) for baseline comprehensive assessment, research studies, and clinical trials where detailed dimensional profiles guide intervention planning. PDQ-8 correlates highly with PDQ-39 overall (r > 0.9) but loses dimensional detail.
How does PDQ-39 relate to UPDRS motor scores?
Correlation is typically weak to moderate (r = 0.20-0.50). A patient with high UPDRS motor score may report low PDQ-39 (good coping, optimized medication) or vice versa (low motor severity but high stigma and emotional distress). This independence justifies using both measures: UPDRS for objective motor assessment, PDQ-39 for subjective quality-of-life impact.
Is PDQ-39 appropriate for patients with dementia (PD-D or DLB)?
PDQ-39 is less reliable in advanced cognitive decline because valid self-report requires intact cognition. For patients with mild cognitive impairment, assess carefully and note limitations. For moderate-severe dementia, consider proxy-reported versions (not standard) or supplementary caregiver burden measures (e.g., Zarit Burden Interview). Combining PDQ-39 with cognitive screening (MoCA, MMSE) helps contextualize responses.
Sources
- Jenkinson, C., Fitzpatrick, R., Peto, V., Greenhall, R., & Hyman, N. (1997). The Parkinson's Disease Questionnaire (PDQ-39): Development and validation of a Parkinson's disease summary index score. Age and Ageing, 26(5), 353-357. DOI: 10.1093/ageing/26.5.353 ↗
- Peto, V., Jenkinson, C., Fitzpatrick, R., & Greenhall, R. (1995). The development and validation of a short measure of functioning and well-being for individuals with Parkinson's disease. Quality of Life Research, 4(3), 241-248. DOI: 10.1007/BF02260863 ↗
- Martínez-Martín, P., Rodríguez-Blázquez, C., Alvarez, M., Arakaki, T., Bergareche, A., Chade, A., ... & Grupo Centros Colaboradores de la Sociedad Española de Neurología para la validación de escalas en neurología. (2009). Expanded and independent validation of the Movement Disorder Society-sponsored unified Parkinson's disease rating scale (MDS-UPDRS). Journal of Parkinson's Disease, 3(3), 271-283. link ↗
How to cite this page
ScholarGate. (2026, June 3). Parkinson's Disease Questionnaire-39. ScholarGate. https://scholargate.app/en/health-outcomes/pdq-39
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