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Table 1 Assessment of risk of bias (adapted to Cochrane approach Study Quality Guide [20])

From: Incidence of lower extremity amputation in the diabetic compared to the non-diabetic population: a systematic review protocol

Assessment items Lower risk of bias Higher risk of bias
Measurement and definition of outcomes LEA Precise definition and description of how the LEA were recorded No definition and description of how the LEA were recorded
Diagnostic criteria of diabetes Documented by physician (clinical diagnosis, ICD) Self-reported DM
Statistical methods: IR, CumI, RR Presented as age-sex adjusted estimates; reported with CI Crude rates; reported without CI
Time trends Time trends reported using multivariate regression models Time trends reported only descriptive
Duration of the observation perioda 5 years and more Less than 5 years
  1. CI confidence interval, CumI cumulative incidence, DM diabetes mellitus, ICD International Statistical Classification of Diseases and Related Health Problems, IR incidence rate, RR relative risk
  2. aRelevant for studies reporting time trend