using a nearly complete set of hospital discharge abstracts for michigan in 1980 , the authors offer evidence that the shifts in diagnostic and procedure coding ( from hicda-2 to icd-9-cm ) and associated class definitions may have affected both estimates of surgical/nonsurgical use rates and expected lengths of stay of operated versus nonoperated patients as defined using commission on professional and hospital activities length-of-stay texts .
C0184661
procedure
C0543467
surgical