Table 23: PICO characteristics of review question Population People with chronic kidney disease (excluding patients on dialysis) and suspected heart failure in a community or outpatient setting. Index diagnostic test + treatment NT-proBNP assay (at any reported threshold) Treatment/next step in pathway: Echocardiography Comparator index diagnostic tests + treatment BNP assay (at any reported threshold) Treatment/next step in pathway: Echocardiography Outcomes Efficacy outcomes: All-cause mortality Quality of life Unplanned hospitalisation Process outcomes: Number of people receiving echocardiography, i.e., including people who may not have needed it such as those with false positive results Repeat testing / additional testing Secondary accuracy outcomes: Sensitivity / specificity and other test accuracy measures Study design Systematic Review RCT 5.3.3 Clinical evidence A search was conducted for single gate studies assessing the diagnostic test accuracy of BNP or NT- proBNP to identify the presence of heart failure (as indicated by the reference standard) in people with chronic kidney disease and suspected heart failure in a community or outpatient setting. A search was also conducted for diagnostic RCTs comparing outcomes in patients tested with BNP versus NT-proBNP. One diagnostic accuracy study was included in the review319, 375 ; it is summarised in Table 24 below. The index test was BNP. The study was downgraded for serious indirectness as the reference standard did not fully match the protocol, but was included in the review in the absence of any direct evidence. Evidence from this study is summarised in the clinical evidence summary in Table 25 below. No diagnostic RCTs meeting the protocol were identified. See also the study selection flow chart in Appendix C, sensitivity/specificity forest plots in Appendix E, study evidence tables in Appendix F and excluded studies list in Appendix I. 