بررسی تاثیرپذیری سلامتی کوتاه مدت و پرسشنامه بیماری پارکینسون در بیماران مبتلا به بیماری پارکینسون Responsiveness of the short-form health survey and the Parkinson’s disease questionnaire in patients with Parkinson’s disease

Background Parkinson’s disease (PD) is a progressive neurodegenerative disorder; therefore, measuring the patient’s healthrelated quality of life (HRQoL) to reflect the progression of PD is important. HRQoL refers to the status of one’s health in the physical, emotional, and social well-being [1]. Soh et al. [2] reported that the 36-item Short-Form Health Survey (SF-36) is the most frequently used generic HRQoL instrument, and that the 39-item Parkinson’s Disease Questionnaire (PDQ-39) is the most frequently used disease-specific HRQoL instrument. Both measures have good internal consistency, stability, and discriminant validity [3, 4], and both are recommended by the Movement Disorder Society [4, 5]. The responsiveness of a measurement instrument is important because it reflects the extent to which the instrument can detect changes in the progression of a disease and whether it can show longitudinal validity [6, 7]. Two major types of responsiveness have been recommended: internal and external [8]. Internal responsiveness refers to the ability of an instrument to detect change at two different time points. External responsiveness refers to the ability of an instrument to change relative to the change of a reference measure. These two types of responsiveness provide different but complementary information: internal responsiveness reflects patient-level changes, and external responsiveness reflects a different view of patient status using another available measure. Although the responsiveness of HRQoL instruments has been examined in several studies [9, 10], few have examined the comparative responsiveness of the SF-36 and the PDQ-39 in patients with PD. Schrag et al. [11] reported that the PDQ-39 was acceptably responsive to small changes in PD progression during a 1-year follow-up, independent of any intervention or external measure. Using self-reported changes in health status as external criteria, Brown et al. [12] reported that the SF-36 was more responsive than was the PDQ-39 in an 18-month follow-up. However, neither study [11, 12] included clinician-judged motor evaluation or psychological measures as external criteria to evaluate the responsiveness of the HRQoL instrument. We assessed and compared the internal and external responsiveness of the SF‐36 and PDQ-39 in patients with PD. Evaluations of motor signs and motor difficulties of daily living and a measure of depressive symptoms were used as external criteria. Many interventions for patients with PD have targeted motor problems and depression [13, 14], but few have examined the comparative responsiveness of the SF-36 and the PDQ-39 against these external criteria to determine which one to use in longitudinal outcome research in patients with PD.