Table 1.
Stratified analysis of the association between pioglitazone use and risk of bladder cancer based on adjusted data from observational studies
| Number of studies | Odds ratio (95%CI) | I 2 (%) | P for heterogeneity | |
|---|---|---|---|---|
| Overall | 19 | 1.13 (1.03, 1.25) | 31.3 | – |
| Smoking adjusted | ||||
| Yes | 6 | 1.28 (1.02, 1.61) | 43.1 | 0.07 |
| No | 13 | 1.03 (0.98, 1.08) | 0 | |
| Region of study | ||||
| Europe | 8 | 1.17 (1.00, 1.36) | 67.6 | 0.77 |
| United States | 9 | 1.03 (0.78, 1.36) | 0 | |
| Asia | 2 | 1.11 (0.92, 1.34) | 0 | |
| Source of funding | ||||
| Industry (Takeda) | 5 | 1.00 (0.85, 1.19) | 0 | 0.17 |
| Other | 14 | 1.20 (1.05, 1.36) | 43.8 | |
| Type of comparators | ||||
| Never use of Thiazolidinedione | 3 | 1.62 (1.27, 2.08) | 0 | 0.43 |
| Never use of Pioglitazone | 13 | 1.04 (0.99, 1.09) | 0 | |
| Rosiglitazone | 1 | 1.14 (0.79, 1.65) | – | |
| Insulin | 1 | 0.92 (0.63, 1.34) | – | |
| Placebo | 1 | 0.65 (0.33, 1.28) | – | |
| Design of study | ||||
| Cohort studies | 12 | 1.12 (1.00, 1.24) | 40.1 | 0.69 |
| Case–control studies | 7 | 1.21 (0.96, 1.56) | 7.5 | |
| Sex | ||||
| Men | 3 | 1.12 (0.96, 1.31) | 67.3 | 0.47 |
| Women | 3 | 1.01 (0.98, 1.08) | 0 | |
| Cumulative dose‐1a | ||||
| ≤10.5 g | 6 | 1.17 (0.99, 1.39) | 0 | 0.04 |
| 10.5–28 g | 4 | 1.27 (1.05, 1.54) | 0 | |
| >28 g | 4 | 1.66 (1.32, 2.07) | 0 | |
| Cumulative dose‐2a | ||||
| ≤14 g | 2 | 0.96 (0.79, 1.17) | 0 | 0.80 |
| 14–40 g | 2 | 1.07 (0.86, 1.32) | 0 | |
| >40 g | 2 | 0.92 (0.58, 1.44) | 43.5 | |
| Cumulative duration‐1a | ||||
| ≤1 years | 9 | 1.07 (0.92, 1.23) | 33.9 | 0.01 |
| 1–2 years | 7 | 1.25 (1.11, 1.40) | 0.2 | |
| >2 years | 7 | 1.49 (1.21, 1.84) | 57.5 | |
| Cumulative duration‐2a | ||||
| ≤1.5 years | 2 | 0.97 (0.78, 2.82) | 0 | 0.53 |
| 1.5–4 years | 2 | 0.94 (0.73, 1.22) | 20.5 | |
| >4 years | 2 | 1.11 (0.85, 1.44) | 0 | |
a
Some studies provide the results by cumulative dose (≤10.5 g vs. 10.5–28 g vs. >28 g;) or cumulative duration (≤1 year vs. 1–2 years vs. >2 years), while other studies provide the data based on cumulative dose (≤1.5 year vs. 1.5–4 years vs. >4 years) or cumulative duration (≤14 g vs. 14–40 g vs. >40 g).