Cohort Study of Pioglitazone and Bladder Cancer in Patients with Type II Diabetes

Study type

• Study topic:
  Disease /health condition

  Human medicinal product
• Study type:
  Non-interventional study
• Scope of the study:
  Disease epidemiology

  Other
• If ‘other’, further details on the scope of the study:
  Association between pioglitazone and bladder
• Data collection methods:
  Secondary use of data

Non-interventional study

• Non-interventional study design:
  Case-control

  Cohort

Study drug and medical condition

• Medical condition to be studied:
  Type 2 diabetes mellitus

Population studied

• Short description of the study population:
  Patients diagnosed with diabetes, who were age 40 or older and were still members of Kaiser Permanente on January 1, 1997.
• Age groups:
  • Adults (18 to < 46 years)
  • Adults (46 to < 65 years)
  • Adults (65 to < 75 years)
  • Adults (75 to < 85 years)
  • Adults (85 years and over)
• Special population of interest:
  Other
• Special population of interest, other:
  Diabetes mellitus patients
• Estimated number of subjects:
  193099

Study design details

• Main study objective:
  The main objective of this study was to assess the potential association between pioglitazone and bladder cancer compared with non-pioglitazone users among patients with type 2 diabetes mellitus.
• Outcomes:
  The primary outcome for this study was the incident diagnosis of bladder cancer identified from the Kaiser Permanente Northern California cancer registry from 01 January 1997 to 31 December 2012.
• Data analysis plan:
  Continuous and categorical variables were compared with the Wilcoxon rank sum test and chisquare test or Fisher’s exact test, respectively. For the cohort study, Cox proportional hazards models were used for all calculations of the relative hazard (HR) of bladder cancer with pioglitazone, adjusted for the covariates.. Other categories of diabetes medications were included in the baseline model to assess both for confounding and the association of the other medications with bladder cancer. To test for confounding, we separately added the other potential confounding variables to the baseline model to assess for a change in the hazard ratio for pioglitazone or for change in the highest category of pioglitazone exposure in models of dose and duration.