Table 4.

Grades of evidence used to assess the frailty literature

Direction of association§	Methodological Quality§
	1. Very Poor†	2. Poor†	3. Good
A. Clear evidence of positive association (i.e. increased risk)	1A	2A	3A
B. Clear evidence of negative association (i.e. protective, preventive)	1B	2B	3B
C. Absence of Evidence (i.e. H0 not rejected or wide CIs)	1C	2C	3C
D. Statistically significant association, but not clinically relevant	1D	2D	3D

§ Rows: Clarity and Direction of Evidence; Columns: Methodological Quality of the study

† The cells highlighted in bold do not provide good quality evidence on the question under study.