S_DISC_S contains the number of sampled state discharges in the strata (STRAT_ST). Beginning in the 1998 NIS, this data element is not included in the data set.

This variable is missing for zero-weight hospitals (see the File Composition for the Nationwide Inpatient Sample for a definition of zero-weight hospitals). Zero-weight hospitals are included in the 1988-1992 data for NIS, Release 1. Because relatively few hospitals were affected and the complexity of including these hospitals entailed considerable processing burden and costs, no zero-weight hospitals are included in the NIS after 1992.