# The patient-doctor relationship questionnaire (PDRQ-9). An overview of 20 years of research and a proposal for normalisation of scores. Systematic review

## TL;DR

This paper reviews 20 years of research on the PDRQ-9 questionnaire, which measures patient-doctor relationship quality, and suggests a new way to standardize its scores.

## Contribution

The paper proposes a novel normalization method for PDRQ-9 scores and provides validated cut-off thresholds for relationship quality.

## Key findings

- The PDRQ-9 has a one-dimensional structure confirmed in most studies across 24 countries.
- A T-score normalization method is proposed with cut-off values for challenged, average, and good patient-doctor relationships.
- The questionnaire shows strong validity, correlating with patient understanding, shared decision-making, and treatment adherence.

## Abstract

The Patient-Doctor Relationship Questionnaire (PDRQ-9) was developed as the first questionnaire to establish the quality of the Patient-Doctor Relationship (PDR) from the patient's perspective. It was published in 2004, has been translated and psychometrically tested in many languages, and is used widely.

This study aims to explore the reliability and validity of the PDRQ-9 in various languages and countries, to report norm scores and cut-off scores for an above or below-average relationship, and to propose a novel scoring method for the PDRQ-9 based on the findings.

Eligibility criteria: studies should report on the PDRQ-9 item version for inclusion. Studies were excluded if they were not peer-reviewed, did not provide outcome data or analysis for the PDRQ-9, did not use the recommended scoring method for nine items, developed another questionnaire based on the PDRQ-9, were a protocol publication, or were retracted. Information sources: We searched for articles in Pubmed/Medline/Web of Science/Google Scholar with the terms “patient-doctor relationship questionnaire” OR “PDRQ-9” OR “PDRQ9” OR “PDQR” published between the publication date of the original study in March 2004 up to November 2025. No language restrictions were used. Risk of bias: was assessed by a tool for cross-sectional studies. Synthesis of Results: we present psychometric and factor structure findings and total scores, calculating weighted Means and SD_pooled over studies. We present an approach to convert raw sum scores to standardised, normalised scores.

The search resulted in 66 studies performed in primary care and various specialist general healthcare and mental healthcare settings in up to 24 countries. Twenty-five of those adapted the PDRQ-9 in 15 different languages and reported on its validity. Fourteen studies investigated the factor structure, and in all except one, the one-dimensional structure of the PDQR-9 was confirmed. Based on normalised T-scores, we recommend a cut-off value of ≤ 44 for a challenged PDR, 45 ≤ T ≤ 56 for an average PDR, and T > 56 for a good PDR.

Construct and criterion validity are well supported, with correlations between the PDRQ-9 score and patients reporting that they understood their illness well, experiencing more shared decision-making and adherence to treatment. Limitations: Most studies reported a ceiling effect in the scores with an overrepresentation of high ratings. The risk of bias was considered low to moderate. Most samples were convenience samples.

The PDRQ-9 is an instrument that was psychometrically tested with its validity supported worldwide and fulfils a need. As the PDR is essential in health services, the PDRQ-9 is a highly relevant measure. It provides a good measure of the PDR when total scores are transformed to a metric with a normal distribution, yielding helpful information, especially when the PDR is challenged. Future studies should preferably report normalised sum scores over mean scores of the items, to improve interpretation in view of ceiling effects, and given the provided cut-off score levels, as well as for consistency in the international literature.

https://www.researchregistry.com/browse-the-registry#registryofsystematicreviewsmeta-analyses/, reviewregistry1953.