Evaluating test-retest reliability of patient-reported outcome measures in cancer patients: a protocol for a methodological systematic review.

Abstract

Background: Patient-Reported Outcomes (PROs) are increasingly important in oncology, providing a unique patient perspective for evaluating treatment efficacy, symptom burden, and quality of life. The psychometric properties of Patient-Reported Outcome Measures (PROMs), particularly test-retest reliability, form the cornerstone of ensuring the stability and credibility of their measurement results. However, the clinical status of cancer patients often fluctuates rapidly due to disease progression or treatment side effects, posing unique methodological challenges for assessing test-retest reliability, especially in determining appropriate retest intervals and evaluating patient stability. Currently, there is a lack of systematic reviews on methodological elements of test-retest reliability studies for PROMs in cancer populations.

Objective: This study aims to systematically search, summarize, and critically appraise published studies on test-retest reliability of PROMs in cancer patients, focusing on their methodological quality and key design elements, including retest intervals, sample size, patient stability assessment, and statistical analysis methods.

Methods: This protocol adheres to the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) guidelines. A comprehensive literature search will be conducted across five electronic databases (PubMed, EMBASE, CINAHL, PsycINFO, Web of Science) and two supplementary sources (ClinicalTrials.gov and PROQOLID) from their inception to December 2025. All original studies reporting test-retest reliability assessments of PROMs for adult cancer patients will be included. Two reviewers will independently conduct literature screening, data extraction, and methodological quality assessment. Extracted data will include basic study information, PROMs characteristics, patient characteristics, and detailed information on test-retest reliability design. Methodological quality will be appraised using the COSMIN Risk of Bias checklist, while reporting completeness will be evaluated against the COSMIN reporting guideline (version 2.0). Due to study heterogeneity, we will perform a narrative synthesis, summarizing results in tables and figures.

Discussion and significance: This study will be the first to comprehensively depict the current status of test-retest reliability assessment of PROMs in oncology, identifying strengths and weaknesses in current practices. The findings will provide evidence-based methodological recommendations for designing and reporting PROMs validation studies in cancer populations. By enhancing the rigor of PROMs validation studies, this research ultimately aims to improve the quality of patient-centered evidence in cancer clinical research and practice.

Systematic review registration: PROSPERO CRD420251070381.