Table 3.

Subgroup analyses for the association between ultra-processed food consumption and risk of breast cancer.

Study characteristic	Category	No. of studies	RR (95%CI)	p-values	Heterogeneity
					p-values for within groups	I 2 (%)	p-values for between groups
Study design	Case-control	3	1.13 (1.01–1.26)	0.028	0.167	44.1	0.002
	Cohort	3	1.10 (0.90–1.34)	0.347	0.080	60.5
Exposure assessment	24 h dietary recall	2	1.26 (0.92–1.72)	0.144	0.35.6	35.6	0.090
	FFQ	4	1.08 (0.97–1.20)	0.155	0.003	78.4
Outcomes	Pre-menopausal breast cancer	6	1.12 (0.97–1.29)	0.138	0.004	71.0	0.666
	Post-menopausal breast cancer	5	1.03 (0.96–1.11)	0.435	0.156	39.8
Study area	Developed countries	4	1.08 (0.96–1.20)	0.188	0.013	72.1	0.041
	Developing countries	2	1.15 (0.91–1.45)	0.239	0.067	70.2
Sample size	<5,000	2	1.17 (1.02–1.35)	0.028	0.130	56.3	0.001
	>5,000	4	1.04 (0.93–1.16)	0.456	0.162	41.6
Alcohol intake	Adjusted	4	1.08 (0.96–1.20)	0.188	0.013	72.1	0.041
	Unadjusted	2	1.15 (0.91–1.45)	0.239	0.067	70.2

FFQ, Food frequency questionnaire; RR, relative risk; CI, confidence interval.