Table 3. Association between coffee intake and the risk of hypertension in subgroup meta-analyses.

Factors		No. of studies	Summary RR (95% CI)	Heterogeneity, I2 (%)
Amount of coffee (vs. never or rarely drink)
	Lowest	1215,16,17,18,19,20,21,22,23,24,25	1.02 (0.94–1.10)	85.1
	Moderate	1015,16,17,19,20,22,23,24,25	0.95 (0.90–1.00)	59.4
	Highest	1215,16,17,18,19,20,21,22,23,24,25	0.97 (0.90–1.05)	68.0
Gender
	Female	816,17,19,20,22,24,26	0.96 (0.84–1.09)	78.6
	Male	615,17,19,20,24,26	0.99 (0.88–1.11)	0.0
Region
	Europe	617,18,19,20,21,24	1.10 (0.89–1.35)	76.0
	America	515,16,22,25	0.93 (0.87–0.98)	4.6
	Asia	223,26	0.93 (0.87–1.01)	0.0
Type of coffee (decaffeinated vs. caffeinated)
	Caffeinated	1315,16,17,18,19,20,21,22,23,24,25,26	0.97 (0.90–1.05)	58.0
	Decaffeinated	222,24	0.95 (0.84–1.06)	0.0
Smoking
	Never/ever smoker	317,20,25	1.03 (0.78–1.35)	51.9
	Current smoker	317,20,25	1.00 (0.73–1.39)	0.0
Follow-up, yr
	< 5	222,25	0.94 (0.82–1.08)	46.8
	5–10	518,20,23,24,26	0.97 (0.85–1.11)	48.6
	≥ 10	615,16,17,19,21	1.01 (0.87–1.18)	73.1
Methodological quality
	Low quality	715,16,19,22,23,24	0.92 (0.88–0.96)	0.0
	High quality	617,18,20,21,25,26	1.17 (0.96–1.43)	62.4

RR = relative risk, CI = confidence interval.