Table 2.

Summary of findings with GRADE.

Outcomes	Results	No of participants (Studies) Follow-up range	Quality of the evidence (GRADE)e
Mortality (meta-analysis)	HR: 1.04 (1.03–1.05) for 0.01 change in FI-Lab	11,032 (11 studies) 6 months–7 years	⊕ ⊕ ⊕ ⊖ MODERATE Due to indirectnessa
Mortality (meta-analysis—81+ years of age)	HR: 1.04 (1.03–1.05) for 0.01 change in FI-Lab for age 81+ years old	7,079 (9 studies) 6 months–7 years	⊕ ⊕ ⊕ ⊕ HIGH
Mortality (whole subgroup)	High FI-Lab scores were associated with increased risk of mortality in all studies	69,691 (23 studies) 6 months–18 years	⊕ ⊕ ⊕ ⊖ MODERATE Due to indirectnessa
Adverse health outcomes	High FI-Lab scores were associated with increased risk of at least one adverse health outcome in 94% of studies	36,526 (18 studies) 1 month–18 years	⊕ ⊕ ⊕ ⊖ MODERATE Due to indirectnessb
Sex differences	No clear association between FI-Lab and sex was found across all studies; 5 studies found no sex difference in FI-Lab scores, 3 found higher FI-Lab scores in males, 2 found higher FI-Lab scores in females and 1 found an age dependent sex effect	48,274 (13 studies) N/A	⊕ ⊖ ⊖ ⊖ VERY LOW Due to indirectnessa Risk of biasc Inconsistencyd

^aThe studies are not wholly representative of our target age range of 20+ years.

^bThe studies are not wholly representative of our target age range of 20+ years. Each study identified a different adverse outcome.

^cRisk of bias due to studies including men and women but not reporting sex-based analyses.

^dInconsistency in results across studies. More evidence is needed to make conclusions about sex differences.

^eScores out of 4. ⊕ indicates a point. ⊖ indicates the absence of a point.