Candidate for the Lee B. Lusted Student Prize Competition
Purpose: To evaluate the role of aspirin together with the combined management of hyperlipidemia and hypertension in patients with type 2 diabetes.
Method: We present a Markov decision process model to determine the optimal start times for the combination of aspirin and the most common cholesterol and blood pressure medications for patients with type 2 diabetes. Health states were defined by cholesterol, blood pressure, A1c, and other risk factors used by the United Kingdom Prospective Diabetes Study risk model. Transition probabilities and treatment effects were estimated from a longitudinal clinical dataset from the Mayo Clinic electronic medical record. Cost parameters and disutilities were taken from secondary sources. The objective of the model was to maximize expected rewards over the course of the patient’s lifetime. Rewards were defined by the difference in benefits of increased quality-adjusted life years (QALYs) to first event (including stroke, CHD, gastrointestinal bleed, and death from all causes) based on a societal willingness-to-pay factor, minus costs of medication. One-way sensitivity analysis was performed for the risk reduction factors for stroke and CHD, and the probability of gastrointestinal bleed.
Result: We computed the optimal treatment guidelines assuming availability of aspirin, statins, fibrates, ACE Inhibitors, Thiazides, and Beta-Blockers. For the base case the average incremental effect of adding aspirin is an increase of 0.736 QALYS and a decrease of $291 for males, and an increase of 0.434 QALYs and a decrease of $675 for females. Depending on individual CHD and stroke risk, females should initiate aspirin between the ages of 40 and 48; males should initiate aspirin at age 40, regardless of risk. Relative to the baseline, varying risk reduction for stroke from 0.85 to 1.06 resulted in a change in QALYs from 0.212 to -0.228. Varying risk reduction for CHD from 0.75 to 0.90 resulted in a change in QALYs from 0.215 to -0.230. Varying annual probability of gastrointestinal bleed from 0.0002 to 0.0005 resulted in a change in QALYs from 0.057 to -0.104. Across all cases the latest start times for males and females are 45 and 54 respectively.
Conclusion: Aspirin is beneficial for all patients with type 2 diabetes. The optimal time for initiation depends on the patient’s individual risk level and assumptions about aspirin effectiveness and risk of gastrointestinal bleeding.