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Table 1 Grade Criteria

From: When a parent dies – a systematic review of the effects of support programs for parentally bereaved children and their caregivers

Grade I (Strong evidence)
 RCTs or review of RCTS
  IA Calculation of sample size and accurate standard definition of appropriate outcome variables
  IB Accurate and standard definition of appropriate outcome variables
  IC Neither of the above
Grade II (Fairly strong evidence)
 Prospective study with a comparison group (non-randomized controlled trial, good observational study or retrospective study that controls effectively for confounding variables)
  IIA Calculation of sample size and accurate, standard definition of appropriate outcome variables and adjustment for the effects of important confounding variables
  IIB One or more of the above
Grade III (Weaker evidence)
 Retrospective or observational studies
  IIIA Comparison group, calculation of sample size, accurate and standard definition of appropriate outcome variables
  IIIB Two or more of the above
  IIIC None of these
Grade IV (Weak evidence)
 Cross-sectional study, Delphi exercise, consensus of experts
  1. Cancer Guidance Subgroup of the Clinical Guidance Outcomes Group. Improving outcomes in breast cancer – the research evidence. Leeds: NHS Executive, 1996 [20]