Table 1. Patient demographics for the studies included in the pooled analysis.
| Study | Nation or region of origin | Included study dates | Median follow-up (months) | Number of patients | Mean ± SD or median (range) age (years) | Female sex, n (%) | Mean BMI ± SD (kg/m2) or n (%) with BMI ≥ 40 kg/m2 | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Surgery | Control | Surgery | Control | Surgery | Control | Surgery | Control | ||||
| Arterburn [25] | US | 2000–2011 | 60 | 2,500 | 7,462 | 52 ± 8.8 | 53 ± 8.7 | 651 (26%) | 1,920 (26%) | 47 ± 7.9 | 46 ± 7.3 |
| Backman [26] | Sweden | 2007–2012 | 55 | 18,418 | 175,138 | 39 ± 10.5 | 39 ± 10.5 | 14,518 (79%) | 138,082 (79%) | 42.2 ± 5.8 | — |
| Bailly [35] | France | 2008–2016 | 44 | 102,627 | 225,882 | 37.3 ± 10.5 | 44.0 ± 11.7 | 88,464 (86%) | 151,566 (67%) | 47,516 (46.3%) | 37,948 (16.8%) |
| Ceriani [36] | Lombardy region, Italy | 1999–2008 | 144 | 472 | 1,405 | 43.1 ± 10.6 | 43.5 ± 12.5 | 354 (75%) | 995 (71%) | 47.3 ± 7.5 | 46.8 ± 3.8 |
| Douglas [37] | UK | Up to 2014 | 36 | 3,882 | 3,882 | 45 ± 11 | 45 ± 11 | 3,126 (81%) | 3,166 (82%) | 44.7 ± 8.8 | 42.1 ± 6.5 |
| Eliasson [38] | Sweden | 2007–2014 | 60 | 6,132 | 6,132 | 48.5 ± 9.8 | 50.5 ± 12.7 | 3,678 (61%) | 3,768 (61%) | 42.0 ± 5.7 | 41.4 ± 5.7 |
| Flum [39] | Washington State, US | 1987–2001 | 120 | 3,328 | 62,781 | 43.1 ± 10.1 | 47.0 ± 6.2 | 2,679 (81%) | 40,368 (64%) | — | — |
| Johnson [40] | South Carolina, US | 1996–2009 | 60 | 2,580 | 13,371 | 47.5 ± 10.6 | 52.1 ± 12.8 | 1,987 (77%) | 9,012 (67%) | — | — |
| Kauppila [41] | Nordic countries | 1980–2012 | 48 | 49,977 | 494,842 | — | — | 37,247 (75%) | 334,407 (68%) | — | — |
| Moussa [42] | UK | Up to 2017 | 129 | 3,842 | 177,973 | — | — | — | — | — | — |
| Moussa [27] | UK | Up to 2017 | 60 | 4,073 | 4,073 | 50 (42–58) | 50 (43–58) | — | — | 40.2 (37.0–45.2) | 40.4 (36.7–45.6) |
| Perry [28] | US | 2001–2014 | 18 | 11,903 | 11,901 | — | — | 9,237 (78%) | 9,236 (78%) | — | — |
| Persson [29] | Sweden | 1987 onwards | 44 | 22,295 | 25,564 | 40.7 ± 10.7 | 44.3 ± 13.2 | 16,921 (76%) | 17,077 (67%) | — | — |
| Pontiroli [30] | Lombardy region, Italy | 1995–2001 | 59 | 385 | 681 | 39.2 ± 10.4* | 40.2 ± 12.0* | 292 (76%) | 509 (75%) | 41.1 ± 5.4* | 40.9 ± 7.3* |
| Singh [31] | UK | 1990–2018 | 43 | 5,170 | 9,995 | — | — | 4,158 (80%) | 8,105 (81%) | 3,634 (70.3%) | 6,780 (67.8%) |
| Reges [32] | Israel | 2005–2014 | 48 | 8,385 | 25,155 | 46 (37–54) | 46 (37–54) | 5,490 (66%) | 16,470 (66%) | 4,980 (59%) | 14,940 (59%) |
| Thereaux [33] | France | 2008–2015 | 72 | 15,650 | 15,650 | 38.9 ± 11.2 | 39.4 ± 11.2 | 13,241 (85%) | 13,241 (85%) | 9,449 (60%) | 9,449 (60%) |
| Thereaux [34] | France | 2009 | 72 | 8,199 | 8,199 | 39.9 ± 11.5 | 40.5 ± 11.6 | 6,728 (82%) | 6,728 (82%) | 6,092 (74%) | 6,092 (74%) |
*Study subgroup with no type 2 diabetes at baseline.