Test–Retest Reliability of the Generalized Pain Questionnaire in Patients with Rheumatoid Arthritis and Preliminary Reference Values for Non-Clinical and Several Clinical Samples

Abstract

Introduction

Generalized pain hypersensitivity is a characteristic feature in many different types of chronic pain. Recently, a 7-item self-reported Generalized Pain Questionnaire (GPQ) was developed to evaluate the presence and severity of generalized pain hypersensitivity in chronic pain patients. Here, we evaluate the test–retest reliability of the GPQ and report on preliminary reference values for various patient groups and healthy subjects.

Methods

Eighty-five patients diagnosed with Rheumatoid Arthritis (RA) completed the GPQ twice over a 2-week interval. Relative and absolute indicators of reliability were determined using data of 69 patients (81.2% retest response rate). Using readily available datasets, preliminary reference data were established in two nonclinical populations (NCP1; N = 30 and NCP2; N = 111), and for patients diagnosed with RA (N = 114), gout (N = 97), fibromyalgia (N=98), or neuropathy (N = 25), or participants in a pain rehabilitation program (N = 33).

Results

Total GPQ scores had an ICC of 0.78 (95% CI: 0.67 to 0.86). While no systematic or proportional differences were found for the GPQ total score; two (near-)significant systematic differences were observed for the individual questions. The standard error of measurement and minimal detectable change were 2.22 and 6.2, respectively. Mean ± SD scores were found to be 0.8 ± 1.2 (NCP1), 4.0 ± 4.6 (NCP2), 6.4 ± 5.5 (Gout), 6.5 ± 5.1 (RA), 8.1 ± 4.5 (Neuropathy), 13.6 ± 4.0 (Rehabilitation) and 16.0 ± 5.0 (Fibromyalgia).

Discussion

This study shows that the GPQ has acceptable reliability to be used as a tool to evaluate the presence and intensity of generalized pain hypersensitivity. The absolute measures of reliability and the preliminary reference values reported here aid in the interpretation of future studies with the GPQ.

Keywords:

• generalized pain hypersensitivity
• widespread pain
• preliminary reference values
• reliability
• face validity

Data Sharing Statement

The dataset of the experiments reported here is available upon request to the corresponding author (Niels Jansen) of this paper.

Ethical Approval

All experiments were approved by the Medical research Ethics Committees United (MEC-U; NL73282.100.20) and in accordance with the 1964 Helsinki Declaration and its later amendments.

Code Availability

Code required to perform the analyses reported here is available upon request to the corresponding author of this paper.

Consent for Publication

All authors have approved of the manuscript and agreed to submit to Journal of Pain Research.

Consent to Participate

All participants provided written informed consent and were rewarded for participation in the experiment.

Disclosure

Prof. Dr. Harald Vonkeman reports grants from Galapagos, Boehringer Ingelheim; personal fees from Novartis, Pfizer, UCB, and Janssen, outside the submitted work. The authors declare that they have no other conflicts of interest in this work.

Additional information

Funding

This work was supported by internal funding from the University of Twente and Medisch Spectrum Twente.