Instrument Information

  • A 33-item Parkinson’s Disease (PD) specific health-related quality of life (HRQoL) measure.

  • Developed in the US [Welsh et al, 2002] for use in individuals diagnosed with idiopathic PD.

  • PD-specific motor symptoms not directly assessed as the instrument is intended to be a complement to the UPDRS which provides a comprehensive assessment of motor symptomatology.

  • Initial psychometric testing of the instrument was conducted in a convenience sample of outpatient clinic attendees with physician-confirmed idiopathic PD. The subjects were selected from 13 outpatient movement disorder clinics in the US and Canada.

  • Factor analysis with varimax rotation supported a seven-factor solution. Three of the original four domains used as the conceptual framework during the qualitative data collection and four additional domains emerged.

  • Mean age of the total sample was 65.4, 62% were male, 98% were Caucasian, and the average educational level was 14.7 years. 82% of the subjects were in mid-stage disease.

  • Subjects self-administered an instrument packet containing demographics questions, the PDQUALIF, SF-36 and Sickness Impact. Associations between the PDQUALIF total and subscale scores and those of the SF-36 and SIP were all highly significant with associations tending to be stronger with the SIP than with the SF-36.

  • Final version of the PDQUALIF© consists of seven domains: social/role function (nine items), self-image/sexuality (seven items), sleep (three items), outlook (four items), physical function (five items), independence (two items), urinary function (two items), and global HRQoL (one item).

  • The scale showed good internal reliability with Cronbach's α=0.89 and the range for the seven subscales was 0.55 to 0.85. Four of seven subscales, however, had Cronbach’s α estimates of less than 0.70 (0.55-0.62) which may have resulted from the small number of items in those subscales.

  • Overall test-retest reliability was good (r=0.88). Test-retest reliability was shown to be good for all subscales.

  • Support for item convergence and discrimination was provided by the multitrait scaling analysis.

  • All subscales demonstrated reasonable score variability with the exception of the Independence subscale which had a noticeable floor effect (78.9%) and the Sleep subscale which demonstrated minor floor effects (8.7%).

  • Completion time for the scale is 10 to 15 minutes.


Instrument Information


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Parkinson Study Group

The Parkinson Study Group (PSG) is a non-profit group of physicians and other health care providers from medical centers in the United States, Canada and Puerto Rico experienced in the care of Parkinson patients and dedicated to clinical research of Parkinson disease.

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