Table 2. Characteristics of all included studies (comparison).
| Author & year | Comparison | Patient | PFS (HR) | OS (HR) | |
|---|---|---|---|---|---|
| Exp | Con | ||||
| Tan B 2011 (11) | DM: Metformin vs. Insulin | 39 | 35 | Median 8.4 vs. 4.7 months (NG)* | Median 20.0 vs. 13.1 months (NG)* |
| DM: Metformin vs. Other† | 39 | 25 | Median 8.4 vs. 6.4 months (NG)* | Median 20 vs. 13 months (NG)* | |
| Ahmed I 2015 (12) | DM: Metformin vs. Othera | 20 | 20 | Median 10.1 vs. 19.7 months [1.4 (0.65–3.04)] | Median 14.3 vs. 19.2 months [1.73 (0.78–3.85)] |
| Sayed R 2015 (13) | Non-DM: Metformin vs. no Metformin | 15 | 15 | Median 5.5 vs. 5.0 months (NG) | Median 12.0 vs. 6.5 months (NG) |
| Chen H 2015 (14) | DM: Metformin vs. Other‡ | 44 | 46 | Median 19 vs. 8 months [0.46 (0.28–0.75)]* | Median 32 vs. 23 months [0.44 (0.26–0.76)]* |
| Lin J 2015 (15) | DM: Metformin vs. Other§ | 227 | 122 | NG (NG) | NG [0.77 (0.65–0.92)]* |
| Wink K 2016 (16) | DM: Metformin vs. Othera | 59 | 623 | Median 41 vs. 15 months [0.63 (0.41–0.96)]* | Median 33 vs. 23 months [0.86 (0.57–1.28)] |
| Arrieta O 2016 (17) | DM: Metformin vs. Other¶ | 111 | 75 | NG (NG) | Median 25.6 vs. 13.2 months [0.57 (0.36–0.90)]* |
†, including Sulfonylureas, Acarbose, or Thiazolidinedione; ‡, including Sulfonylureas, Acarbose, Thiazolidinedione, or Insulin; §, including, Sulfonylureas, a-glucosidase inhibitors (including Acarbose), Thiazolidinedione, Insulin, Meglitinides, and dipeptidyl peptidase-4 inhibitors; ¶, including Glibenclamide (one kind of Sulfonylureas), or Insulin; a, no detailed information of what medications or diet-controlled strategies were used instead of Metformin; *, significant difference. Exp, experimental group; Con, control group; DM, patients with diabetes mellitus; Met, Metformin; Non-DM, patients without diabetes mellitus; Other, other diabetes treatments instead of Metformin; OS, overall survival; PFS, progression-free survival; HR, hazard ratio; NG, not given.