Purpose: To develop and calibrate a cardiovascular disease microsimulation (CVDM) model using the validated cell-based Coronary Heart Disease (CHD) Policy Model and national vital statistics.
Methods: The CVDM was programmed in TreeAge, and states for annual cycles were CVD-free, stroke, coronary heart disease, having both coronary heart disease and stroke, and death. Individual characteristics (sex, age, body mass index, blood pressure, lipid profile, and hypertension treatment, smoking and diabetes) for 35-44 year-olds who were free of CVD were obtained from U.S. National Health and Nutrition Examination Surveys (NHANES) 1999-2008 in order to create nationally-representative simulation cohorts. Annual probabilities of developing the first CVD event or non-CVD death were estimated using multivariate logistic regressions estimated from Framingham Heart Study. Annual risk factor changes and weight gain over time were estimated from NHANES. We calibrated the model by comparing model output with a validated, cell-based Markov model of U.S. adults, the CHD Policy Model, using criteria within 5% of incidence and 1% of mortality rates, as well as visual inspection. Another calibration target was age, sex, and cause-specific mortality rates from 2010 U.S. vital statistics. We simulated 10000 40-year-old male and 10000 female individuals for 30-years or until death. Annual and cumulative CVD incidence, CVD mortality, and non-CVD mortality were computed from the model output.
Results: After CVDM calibration, cumulative 30-year incidence and mortality projections were similar between the CVDM and CHD Policy Model (Table). Within ten-year age intervals between ages 45-74 years, CVDM coronary heart disease and stroke mortality rate estimates were within 1 deaths/1,000 of CHD Policy Model and national vital statistics rates. CVDM coronary heart disease and stroke incidence estimates were within 20 events/1,000 of CHD Policy Model estimates.
Conclusions: Validation is important for positing simulation model accuracy, but nationally representative CVD incidence data are not directly available. An well validated cell-based CVD simulation model can be used in conjunction with national survey and mortality data to validate a new microsimulation model of CVD in U.S. adults.
