Table 2

Proportion of study participants with anaemia before and after RYGB surgery

		Before surgery		6 months		12 months		24 months		36 months		Δ6 month	Δ12 month	Δ24 month	Δ36 month
Year	Author	No	Per cent	No	Per cent	No	Per cent	No	Per cent	No	Per cent	(Per cent)	(Per cent)	(Per cent)	(Per cent)	Definition of anaemia
2009	Toh SY	7/113	6.0		–	10/58	17.0	–	–	–	–	–	11.0	–	–	Hb: men <13.0 g/dL; women <11.9 g/dL
2011	von Drygalski A	125/1037	12.0	70/559	12.5	43/371	11.6	35/153	22.9	–	–	0.5	−0.4	10.9	–	Hb: men <13.0 g/dL; women <12.0 g/day L
2011	Cable CT	156/1009	15.5	–	–	259/720	36.0	–	–	–	–	–	20.5	–	–	Hb: men <14.0 g/dL; women <12.0 g/dL
2012	Blume CA	11/170	6.5	37/170	21.8	32/170	18.8	58/170	34.1	57/170	33.5	15.3	12.3	27.6	27.0	Hb: men <13.0 g/day L; women <12.0 g/dL
2012	Aarts EO	27/377	7.2	50/377	13.3	71/377	18.8	–	–	–	–	6.1	11.6	–	–	Hb: men <13.5 g/dL; women <11.9 g/dL
2012	Dallal RM	97/590	16.4	–	–	162/590	27.5	–	–	–	–	–	11.1	–	–	Hct: men <39%; women <35%
2013	Moizé V	65/294	22	61/294	20.8	59/294	19.9	46/259	17.7	35/203	17.2	−1.2	−2.1	−4.3	−4.8	Hb: men <13.7 g/dL; women <12.2 g/dL
2014	Salgado W Jr	22/102	21.6	–	–	25/97	25.8	26/85	30.6	27/89	30.3	–	4.2	9.0	8.7	Hb: men <13 g/dL; women <12 g/dL
2014	Ledoux S	9/144	6.0	–	–	17/144	12.0	–	–	15/115	13.0	–	6.0	–	7.0	Hb: men <11.5 g/dL; women <11.5 g/dL
Summary estimate (95% CI)		12.2 (8.8 to 15.6)		16.6 (12.1 to 21.0)		20.9 (14.7 to 27.1)		25.9 (17.9 to 33.8)		23.1 (13.6 to 32.7)		4.8 (−1.1 to 10.8)	8.4 (2.8 to 14.0)	10.8 (−3.3 to 24.8)	9.4 (−4.7 to 23.5)
I²		89.8		79.6		93.8		81.9		87.6		81.9	88.2	91.7	91.3