Performance of the Palliative Prognostic Index for cancer patients: A systematic review and meta-analysis

• Published in: Palliative Medicine 2023-09, Vol.37 (8), p.1144-1167
• Main Authors: Yoong, Si Qi, Porock, Davina, Whitty, Dee, Tam, Wilson Wai San, Zhang, Hui
• Format: Article
• Language: English
• Subjects: Adults; Analysis; Bias; Cancer; Clinical medicine; Delirium; Medical prognosis; Meta-analysis; Observational studies; Palliative care; Prediction models; Risk assessment; Systematic review; Thresholds; Validation studies
• ISSN: 0269-2163; 1477-030X; 1477-030X
• DOI: 10.1177/02692163231180657

Background: Clinician predicted survival for cancer patients is often inaccurate, and prognostic tools may be helpful, such as the Palliative Prognostic Index (PPI). The PPI development study reported that when PPI score is greater than 6, it predicted survival of less than 3 weeks with a sensitivity of 83% and specificity of 85%. When PPI score is greater than 4, it predicts survival of less than 6 weeks with a sensitivity of 79% and specificity of 77%. However, subsequent PPI validation studies have evaluated various thresholds and survival durations, and it is unclear which is most appropriate for use in clinical practice. With the development of numerous prognostic tools, it is also unclear which is most accurate and feasible for use in multiple care settings. Aim: We evaluated PPI model performance in predicting survival of adult cancer patients based on different thresholds and survival durations and compared it to other prognostic tools. Design: This systematic review and meta-analysis was registered in PROSPERO (CRD42022302679). We calculated the pooled sensitivity and specificity of each threshold using bivariate random-effects meta-analysis and pooled diagnostic odds ratio of each survival duration using hierarchical summary receiver operating characteristic model. Meta-regression and subgroup analysis were used to compare PPI performance with clinician predicted survival and other prognostic tools. Findings which could not be included in meta-analyses were summarised narratively. Data sources: PubMed, ScienceDirect, Web of Science, CINAHL, ProQuest and Google Scholar were searched for articles published from inception till 7 January 2022. Both retrospective and prospective observational studies evaluating PPI performance in predicting survival of adult cancer patients in any setting were included. The Prediction Model Risk of Bias Assessment Tool was used for quality appraisal. Results: Thirty-nine studies evaluating PPI performance in predicting survival of adult cancer patients were included (n = 19,714 patients). Across meta-analyses of 12 PPI score thresholds and survival durations, we found that PPI was most accurate for predicting survival of