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Table 3 The number of studies identified for different treatments

From: The effectiveness of metal on metal hip resurfacing: a systematic review of the available evidence published before 2002

  Number of studies
Assessment Item Yes No Unable to judge Not applicable
Clarity of study question and definition of outcome     
Is the purpose of the study clearly stated? 8 1 1 -
Is the definition of prosthesis failure clear? 7 2 - 1
Is there a clear definition of primary outcome(s)? 7 3 - -
Are standardised outcome measures used? 9 - 1 -
Are the outcome measures used appropriate for the purpose of the study? 9 1 - -
Description of prosthesis and method of fixation     
Is the prosthesis design adequately described? 7 2 - 1
Is the method of fixation adequately described? 7 2 - 1
Description of study sample     
Is the method of selection of the sample adequately described? 2 7 1 -
Are the study exclusion and inclusion criteria stated? 2 7 1 -
Is the baseline sample clearly described in terms of basic characteristics (age, sex etc)? 6 3 1 -
Is the study sample sufficiently homogenous in terms of disease/diagnosis? 5 1 4 -
Is the study sample sufficiently homogenous in terms of co-morbidity? 2 - 8 -
Control of bias in study design     
Is the method of randomisation adequate? - - 1 9
Is the method of masking the patient to the intervention allocated stated? - 2 1 7
Were outcome assessors blind to intervention allocation? - 1 3 6
Are baseline values for groups compared? - 1 1 8
Has the study adequately controlled for confounding factors? 1 7 2 -
Duration and completeness of follow-up     
Are intervals between surgery and follow-up assessment clearly stated? 8 2 - -
Are reasons for loss of patients at follow-up stated? 2 2 2 4
Are those lost to follow-up compared to the rest of the sample? 1 2 3 4
Is there an appropriate length of follow-up? 8 2 - -
Is the length of follow-up at least 5 years? 3 7 - -
Statistical and analytical considerations     
Has the study sample size been justified? - 9 1 -
Are the data clearly presented? 8 2 - -
Was the data analyst masked to interventions? - 5 3 2
Has type of statistical test and actual probability value been stated? 2 1 1 6
Are statistical tests appropriate to study? 2 - 2 6
Is the sample on which failures are assessed adequate? - 2 7 1
Are conclusions justified by evidence? 5 1 3 1