. 2012 Apr 11;27(8):3305–3314. doi: 10.1093/ndt/gfr806

Table 1.

Study quality scoring system^a

Validity criterion	Explanation	Scoring	Perfusate comments	Urine comments
Participant recruitment	Was recruitment based on presenting symptoms, results from previous tests or fact that participants received index tests^b?	Presenting symptoms = 1	All based on presenting symptoms	All based on presenting symptoms
Participant recruitment		Previous tests or index tests = 0	All based on presenting symptoms	All based on presenting symptoms
Participant sampling	Was its study population a convenience sample or a consecutive series?	Consecutive series =1	Based on convenience sample: 12 [23–34]	Based on convenience sample: 3 [35–37]
Participant sampling		Convenience sample or not stated = 0	Based on convenience sample: 12 [23–34]	Based on convenience sample: 3 [35–37]
Data collection	Was data collection planned before the index test and reference standard were performed prospectively or retrospectively?	Prospective =1	Planned and performed retrospectively: 6 [24, 38–42]	All prospective
Data collection		Retrospective or not stated = 0	Planned and performed retrospectively: 6 [24, 38–42]	All prospective
Reference standard	Was the definition for the reference standard stated^c?	Stated = 1	Not stated: 8 [25, 33, 34, 39–43]	Not stated: 1 [36]
Reference standard	Was the definition for the reference standard stated^c?	Not stated = 0	Not stated: 8 [25, 33, 34, 39–43]	Not stated: 1 [36]
Materials and methods	Were technical specifications of material and methods stated including how and when measurements were taken?	Stated = 1	Not stated: 9 [24, 25, 32, 33, 39–42, 44]	All stated
Materials and methods		Not stated = 0	Not stated: 9 [24, 25, 32, 33, 39–42, 44]	All stated
Participant characteristics	Were the clinical and demographic characteristics of the study population stated?	Stated = 1	Not stated: 17 [23–26, 28–34, 39–42, 44, 45]	Not stated: 3 [35–37]
Participant characteristics		Not stated = 0	Not stated: 17 [23–26, 28–34, 39–42, 44, 45]	Not stated: 3 [35–37]
Blinding	Were readers of the index test and reference standard blinded?	Blinded = 1	Not stated: 20 [23–25, 27, 29, 30, 32–34, 38–48]	Not stated: 5 [35–37, 49, 50]
Blinding		Not blinded or not stated = 0	Not stated: 20 [23–25, 27, 29, 30, 32–34, 38–48]	Not stated: 5 [35–37, 49, 50]
Completion	Was the number of participants that did not undergo index tests stated (no. of tests versus sample size stated)?	Stated = 1	Completion was always stated	Not stated: 1 [36]
Completion		Not stated = 0	Completion was always stated	Not stated: 1 [36]
Diagnostic accuracy and statistical uncertainty	Were estimates of diagnostic accuracy and measures of statistical uncertainty for biomarker results (e.g. 95% confidence intervals) stated?	Stated = 1	Not stated: 20 [23–34, 39–45, 48]	Not stated: 5 [35–37, 49, 50]
Diagnostic accuracy and statistical uncertainty		Not stated = 0	Not stated: 20 [23–34, 39–45, 48]	Not stated: 5 [35–37, 49, 50]
Clinical applicability	Was the clinical applicability of biomarker findings stated?	Stated = 1	Not stated: 7 [24, 25, 33, 34, 40, 41, 44]	Stated in all studies
Clinical applicability		Not stated = 0	Not stated: 7 [24, 25, 33, 34, 40, 41, 44]	Stated in all studies

^aStudy quality scoring system is modified checklist of the STARD criteria [21].

^bIndex test is the biomarker measurement.

^cReference standard is each outcome reported in a study.