Interaction patterns amongst risk factors for bladder cancer in adults with type 2 diabetes managed in primary care

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 diabetes patients. 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 vs >74 years) and sex emerged as primary and secondary factors in differentiating the risk of bladder cancer sequentially. Among middle-old males (62 to 74 years) and youngest males (≤58 years), smoking (aHR for ever vs never smoker: 1.96, 95% CI 1.49–2.58) and chronic kidney disease (aHR for presence vs absence: 2.92, 95% CI 1.21–7.02) appeared as dominant risk factor for bladder cancer respectively. Conclusion This study identified the interaction patterns among age, sex, smoking, and chronic kidney disease 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.