Objective: To explore the psychometric properties of the PD-PSS.

Background: Evaluating pain in PD patients can be a difficult issue in the everyday clinical practice. To overcome this challenge we developed a dedicated questionnaire. Its main focus is to differentiate PD from non-PD related pains by means of three questions which correspond to the definition of PD-related pain (positive temporal relationship with PD, modified by motor fluctuations, or relieved by antiparkinsonian medications). If a PD related pain can be assumed due to a positive answer to at least one of the questions, the questionnaire allows to subdivide it into 3 different groups (musculoskeletal, neuropathic, or psychomotor restlessness pain) according to the character and the localisation. A final score including intensity, frequency as well as impact allows to rate the individual pain experience.

Methods: 100 non-demented PD patients (in the ON-condition) were included in this interim report. Pain was assessed by the PD-PSS, DN4, Brief Pain Inventory (BPI) and McGill Pain Questionnaire short-form (MPQ-SF). Patients were also assessed by UPDRS III and IV, clock test, PDQ-8, HADS anxiety and Depression (HADS-A and HADS-D) and Wearing-off Questionaire 9 (WOQ-9).

Results: 63 patients were males, mean±SD age was 63.2±12.1 ys, mean UPDRS III score in ON-state was 36.9±13.2. PD-unrelated pain was found in 19% of patients, musculoskeletal (MS) pain in 59%, neuropathic pain in 16% and psychomotor pain in 23%. Floor effects were observed in 12%, 0%, 26% and 36% of cases for MS, neuropathic, psychomotor subscores, and PD-PDSS total scores respectively. Ceiling effect was observed only in 7% of cases for MS pain. MS, neuropathic and psychomotor scores did not correlate significantly with each other. DN4 scores were higher in patients with neuropathic compared to MS (delta±SEM= 0.8±0.07 p<0.01) or psychomotor pain (0.7±0.09 p<0.01). MS and PD-PDSS total scores correlated significantly with BPI and MPQ scores (r=0.20-0.42 all p<0.05). Neuropathic pain score correlated with HADS-A (r=0.20 p<0.05) and HADS-D (r=0.18 p<0.07), psychomotor pain with WOQ-9 score (r=0.28 p<0.01). Intra- and inter-rater ICCs were 0.75 (n=7 p<0.02) and 0.65 (n=4 p=0.1).

Conclusions: Interim results suggest good psychometric attributes for the PD-PSS, including adequate acceptability, acceptable reliability and criterion and construct validity.

References: Mylius V, Ciampi de Andrade D, Cury RG, Teepker M, Ehrt U, Eggert KM, Beer S, Kesselring J, Stamelou M, Oertel WH, Möller JC, Lefaucheur JP. Pain in Parkinson’s Disease: Current Concepts and a New Diagnostic Algorithm. Mov Disord Clin Pract, 2015;2:357–364. Cury RG, Galhardoni R, Fonoff ET, Perez Lloret S, Dos Santos Ghilardi MG, Barbosa ER, Teixeira MJ, Ciampi de Andrade D. Sensory abnormalities and pain in Parkinson disease and its modulation by treatment of motor symptoms. Eur J Pain. 2016;20:151-65.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/validation-of-the-parkinsons-disease-pain-symptoms-scale-pd-pss-an-interim-report/