Case-control

Case-control

1. Variables

   • Antidiabetic drug use
   • Risk of renal carcinoma

2. Patients

   • Cases
     • All individuals in the base population younger than the age of 90 years between January 1995 and December 2013 who had an incident diagnosis of RCC in their record.
   • Controls
     • Individuals with no evidence for RCC
   • Excluded
     • All patients with a recorded diagnosis of HIV, alcoholism, or any malignancy, as well as those with less than 3 years of medical history in the CPRD computer record before the diagnosis date.

3. Confusing variables

4. Statistical tests

   • Conditional logistic regression analyses using SAS Statistical Software, version 9.4 (SAS Institute Inc., Cary, North Carolina, USA) to calculate relative risk estimates as odds ratios (OR) with 95% confidence intervals (CIs).

5. Sample size

   • A total of 3506 cases with incident RCC and 21 038 matched controls between January 1995 and December 2013.

6. Biases

   • The date on which the cancer diagnosis was recorded most likely does not correspond to the actual onset of the disease.
   • Misclassification of RCC cases
   • Number of unknown values for BMI

7. Conflicts of interest

   • There are no conflicts of interest.

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