Table 6

Proportion of study participants with folate deficiency before and after RYGB surgery

Before surgery6 months12 months24 months36 monthsΔ6 monthΔ12 monthΔ24 monthΔ36 monthDefinition of deficiency
YearAuthorNoPer centNoPer centNoPer centNoPer centNoPer cent(Per cent)(Per cent)(Per cent)(Per cent)
2006Madan AK1/622.02/543.03/378.01.06.0NR
2009Toh SY0/650*0/220*0<3.1 ng/mL
2012Blume CA11/1706.58/1704.72/1701.23/1701.81/1700.6−1.8−5.3−4.7−5.9<2.8 ng/mL
2014Ledoux S3/1442.06/1444.01/1151.02.0−1.0<3.0 ng/mL
Summary estimate (95% CI)2.2 (−0.3 to 4.7)4.1 (1.5 to 6.7)1.6 (0 to 3.5)†1.8‡ (0 to 3.8)†0.7 (0 to 1.7)†−0.6 (−4.3 to 3.1)−0.3 (−3.5 to 2.9)−4.7‡ (−8.9 to −0.5)−3.3 (−8.1 to 1.5)
I280.70.067.00.00.067.074.4
  • *Data were included in the analysis with a continuity correction factor of 0.01.

  • †The lower limits of 95% CI were truncated as zero due to negative values.

  • ‡Only one study for the analysis.

  • NR, not reported; RYGB, Roux-en-Y gastric bypass.