Systematic review of the diagnostic accuracy, reliability, and safety of the sharp-purser test

Introduction: The Sharp-Purser Test (SPT) is used to assess for atlantoaxial instability (AI) in patients with rheumatoid arthritis (RA). The test is commonly used by clinicians; however, many experts argue it lacks reliability and validity along with concerns of safety. The primary purpose of this review is to determine the diagnostic accuracy of the SPT to detect AI. Methods: A search of five databases was performed from inception to 19 December 2018 using search terms related to the SPT. Studies were eligible for inclusion if the SPT was used on a patient/participant. Methodological quality assessment of diagnostic studies was performed with the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) for studies that reported data to calculate sensitivity (SN), specificity (SP), positive likelihood ratio (+LR), and negative likelihood ratio (-LR). Results: The search yielded 1009 articles, and 32 studies met the inclusion criteria for analysis. Meta-analysis on diagnostic accuracy studies assessing the SPT was not possible due to statistical heterogeneity. Six diagnostic accuracy studies assessed the SN of the SPT ranging from 0.19 to 1.00. Four of the studies assessed SP of the SPT ranging from 0.71 to 0.98. The +LR was identified in 4 studies was 0.655, 1.73, 22, and 17.25. The -LR was 1.14, 0.799, 0.571, and 0.323. Seven RCTs utilized the SPT to screen for AI, and the SPT was used in 18 case reports. Conclusion: The SPT may be inappropriate to use due to inconsistent validity, poor inter-rater reliability, and potential to cause harm.