Abstract
Background
Previous studies have shown that patients with type 2 diabetes have a higher risk of developing bladder cancer than the general population. However, little is known about how different risk factors interact to influence the risk of bladder cancer among patients with diabetes.
Aim
To explore the interaction patterns among factors associated with the risk of bladder cancer incidence among patients who received diabetes management in primary care.
Design & setting
A retrospective cohort study was performed using territory-wide electronic health records of Hong Kong. Patients who received diabetes care in general outpatient clinics between 2010 and 2019, without cancer history, were included and followed up until December 2019.
Method
The interaction patterns among factors associated with the risk of bladder cancer incidence were examined using conditional inference survival tree analysis.
Results
A total of 382 770 patients were included. During a median follow-up of 6.2 years, 644 patients developed bladder cancer. Age (≤74 years versus >74 years) and sex emerged as primary and secondary factors in differentiating the risk of bladder cancer sequentially. Among males aged 62–74 years and males aged ≤58 years, smoking (adjusted hazard ratio [aHR] for ever versus never smoking: 1.96, 95% confidence interval [CI] = 1.49 to 2.58) and chronic kidney disease (CKD; aHR for presence versus absence: 2.92, 95% CI = 1.21 to 7.02) appeared as dominant risk factors for bladder cancer, respectively.
Conclusion
This study identified the interaction patterns among age, sex, smoking, and CKD on the risk of bladder cancer incidence, providing potential targets for public health cancer prevention strategies in primary care for patients with type 2 diabetes.