King's Parkinson's disease pain scale, the first scale for pain in PD: An international validation

Abstract

Pain is a key unmet need and a major aspect of non-motor symptoms of Parkinson's disease (PD). No specific validated scales exist to identify and grade the various types of pain in PD. We report an international, cross-sectional, open, multicenter, one-point-in-time evaluation with retest study of the first PD-specific pain scale, the King's PD Pain Scale. Its seven domains include 14 items, each item scored by severity (0-3) multiplied by frequency (0-4), resulting in a subscore of 0 to 12, with a total possible score range from 0 to 168. One hundred seventy-eight PD patients with otherwise unexplained pain (age [mean ± SD], 64.38 ± 11.38 y [range, 29-85]; 62.92% male; duration of disease, 5.40 ± 4.93 y) and 83 nonspousal non-PD controls, matched by age (64.25 ± 11.10 y) and sex (61.45% males) were studied. No missing data were noted, and floor effect was observed in all domains. The difference between mean and median King's PD Pain Scale total score was less than 10% of the maximum observed value. Skewness was marginally high (1.48 for patients). Factor analysis showed four factors in the King's PD Pain Scale, explaining 57% of the variance (Kaiser-Mayer-Olkin, 0.73; sphericity test). Cronbach's alpha was 0.78, item-total correlation mean value 0.40, and item homogeneity 0.22. Correlation coefficients of the King's PD Pain Scale domains and total score with other pain measures were high. Correlation with the Scale for Outcomes in PD-Motor, Non-Motor Symptoms Scale total score, and quality of life measures was high. The King's PD Pain Scale seems to be a reliable and valid scale for grade rating of various types of pain in PD.

Distribution and impact on quality of life of the pain modalities assessed by the King’s Parkinson’s disease pain scale

“…The correlations between number of experienced types of pain and other variables in the study were low or moderate as a whole and lower than the correlations between severity of pains and those variables. 10 The only close association between number of different types of pain and other constructs in the study was observed with the PDQ-8 Index ( r S  = 0.55). Other studies have found relationships between pain and motor complications 13, 20 or disease progression, 21 but no with factors like age at diagnosis, disease duration, motor examination, or PD stage.…”

“…A ratio of patients to controls of 2:1 was estimated and 83 non-spousal, non-PD, age- and sex-matched controls were included. 10 …”

“…In addition to recording sociodemographic data and medical history, the following assessments were applied:The KPPS, 10 a rater-interview-based scale with the patient (helped by the caregiver if needed) addressed to determine localization, intensity, and frequency of pain and its relationships with motor fluctuations or musculoskeletal pain. The KPPS is composed of 14 items divided into seven domains: 1.…”

“…In the United Kingdom, the study was adopted by the National Institute of Health Research Central Research Network (UKCRN No 13344). 10 All participants provided informed consent before their entry to the study.…”

“…In the first validation study, a high correlation was found between the KPPS total score and the summary indexes of a generic (EQ-5D-3L) and a PD-specific (PDQ-8) HRQoL instrument. 10 …”