In event-time data, interval-censoring occurs when the time to an event of interest, such as recurrence of cancer, is not directly observed but is known to lie within an interval. The existing stintcox command fits semiparametric interval-censored Cox proportional hazards models. In Stata 18, stintcox allows time-varying covariates.
stintcox now supports multiple-record-per-subject interval-censored data, which include a record for each examination time for each subject. This format makes it easy to accommodate time-varying covariates; the data record the values of the covariates at each examination time. Multiple-record-per-subject data also provide a convenient way to specify current status data.
stintcox also has new options tvc(varlist_t) and texp(exp)that provide a convenient way to include time-interacted covariates, which are formed by the interaction between covariates specified in tvc() and a deterministic function of time specified in texp().
After fitting a model, the standard and special-interest postestimation features are available and appropriately account for the time-varying covariates. You can use the new estat gofplot command to produce a goodness-of-fit plot. You can predict the relative hazard. And you can use stcurve to plot survivor and related functions. When you have multiple record data, you can use the new stcurve option attmeans to evaluate the function at time-specific means of the covariates or the new option atrame(framename) to evaluate the function at values of variables specified in the framename frame.