Table 4

 Pioglitazone cumulative duration of use and cumulative dosage and risk of bladder cancer among cases of bladder cancer and matched controls*

VariablesNo (%) of cases (n=376)No (%) of controls (n=6699)Crude rate ratio (95% CI)Adjusted rate ratio (95% CI)†
Never use of any thiazolidinediones319 (84.8)5856 (87.4)1.00 (reference)1.00 (reference)
Cumulative duration of pioglitazone:
 ≤12 months1 (0.3)27 (0.4)0.69 (0.09 to 5.11)0.56 (0.07 to 4.42)
 13-24 months2 (0.5)11 (0.2)2.99 (0.61 to 14.59)3.03 (0.63 to 14.52)
 >24 months16 (4.3)153 (2.3)2.00 (1.16 to 3.45)1.99 (1.14 to 3.45)
P=0.050 for trend
Cumulative dosage of pioglitazone:
 ≤10 500 mg7 (1.9)70 (1.0)1.63 (0.72 to 3.69)1.58 (0.69 to 3.62)
 10 501-28 000 mg6 (1.6)68 (1.0)1.75 (0.75 to 4.07)1.66 (0.70 to 3.94)
 >28 000 mg6 (1.6)53 (0.8)2.44 (1.02 to 5.84)2.54 (1.05 to 6.14)
P=0.030 for trend

*Matched on year of birth, year of cohort entry, sex, and duration of follow-up.

†Adjusted for excessive alcohol use, obesity, smoking status, HbA1c, previous bladder conditions, previous cancer (other than non-melanoma skin cancer), Charlson comorbidity score, and ever use of other antidiabetic agents (metformin, sulfonylureas, insulin, and other oral hypoglycaemic agents).