reviews [see Table C.22] and GRADE criteria for quality assessment of randomised controlled trials and observational studies [see Table C.3]). C.1: Designations of levels of evidence according to type of research question Level Intervention Diagnostic accuracy Prognosis Aetiology Screening intervention I Systematic review of A systematic review A systematic review of A A systematic review of level II studies of level II studies level II studies systematic level II studies review of level II studies II A randomised A study of test A prospective cohort A A randomised controlled accuracy with an controlled independent, cohort blinded comparison study with a valid reference standard, among consecutive persons with a defined clinical presentation III-1 Pseudo-randomised A study of test All or none All or none Pseudo-randomised accuracy with controlled trial independent, (ie alternate allocation blinded comparison or some other method) with a valid reference standard, among persons with a defined clinical presentation III-2 A comparative study A comparison with Analysis of prognostic A A comparative study with concurrent reference standard factors amongst with concurrent controls: that does not meet persons in a single arm cohort controls: the criteria required of a randomised study Non-randomised Non-randomised, • ▪ for Level II and III-1 controlled experimental trial experimental evidence Cohort study Cohort study • ▪ • Case-control ▪ Case-control study • Interrupted time series with control group A comparative study Diagnostic A retrospective cohort A A comparative study III-3 without concurrent study study without concurrent controls: study controls: ▪ Historical control Historical control study study Two or more single arm Two or more single study ▪ arm ▪ Interrupted time series without parallel control IV Case series with of diagnostic Case series, or cohort A Case series either post-test or yield (no reference of persons at pre-test/post-test standard) different stages of study or outcomes disease case series Source: (NHMRC 2009). Table C.2: Assessment of quality of systematic literature reviews Considerations in assessing quality of systematic reviews Questions and methods clearly stated Search procedure sufficiently rigorous to identify all relevant studies Review includes all the potential benefits and harms of the intervention Review only includes randomised controlled trials Methodological quality of primary studies assessed Data summarised to give a point estimate of effect and confidence intervals
reviews [see Table C.22] and GRADE criteria for quality assessment of randomised controlled trials and observational studies [see Table C.3]). C.1: Designations of levels of evidence according to type of research question Level Intervention Diagnostic accuracy Prognosis Aetiology Screening intervention I Systematic review of level II studies A systematic review of level II studies A systematic review of level II studies A systematic review of level II studies A systematic review of level II studies II A randomised controlled A study of test accuracy with an independent, blinded comparison with a valid reference standard, among consecutive persons with a defined clinical presentation A prospective cohort A cohort study A randomised controlled III-1 Pseudo-randomised A study of test accuracy with independent, blinded comparison with a valid reference standard, among persons with a defined clinical presentation All or none All or none Pseudo-randomised controlled trial (ie alternate allocation or some other method) III-2 A comparative study with concurrent controls: • Non-randomised experimental trial • Cohort study • Case-control • Interrupted time series with control group A comparison with reference standard that does not meet the criteria required for Level II and III-1 evidence Analysis of prognostic factors amongst persons in a single arm of a randomised controlled A cohort study A comparative study with concurrent controls: ▪ Non-randomised, experimental ▪ Cohort study ▪ Case-control study III-3 A comparative study without concurrent controls: ▪ Historical control study ▪ Two or more single arm ▪ Interrupted time series without parallel control Diagnostic study A retrospective cohort study A study A comparative study without concurrent controls: Historical control study Two or more single arm study IV Case series with either post-test or pre-test/post-test outcomes of diagnostic yield (no reference standard) Case series, or cohort of persons at different stages of disease A study or case series Case series Source: (NHMRC 2009). Table C.2: Assessment of quality of systematic literature reviews Considerations in assessing quality of systematic reviews Questions and methods clearly stated Search procedure sufficiently rigorous to identify all relevant studies Review includes all the potential benefits and harms of the intervention Review only includes randomised controlled trials Methodological quality of primary studies assessed Data summarised to give a point estimate of effect and confidence intervals
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