The GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach was primarily designed for clinical practice guidelines. No formal guidelines exist for applying these to systematic reviews of prevalence (72). We have adapted Iorio's et al. (73) suggestions for operationalization of the GRADE approach for prognosis estimates. The Tables 1, 2 in Supplementary File 5 presents the GRADE scoring for pooled estimation of each comorbid condition. The findings are summarised below.
