Regression Analysis in Interval-Censored Multistate Models // Estimates regression coefficients in proportional hazards models for interval-censored multistate data. Individuals may be observed at irregular times and their states may be partially observed. Allowable transitions and transition- specific covariate effects can be specified. The numerical estimation is implemented in 'C++' using 'RcppArmadillo'. The method implemented in this package is described in You, Liu, and Krischer (2024) doi:10.1002/sim.10079.