* Want to select only patients for whom drug1 was given before drug2. * Raynald Levesque rlevesque@videotron.ca 2001/05/09. *I assume your data file has one drug per case. DATA LIST LIST /id(F) drug(A8) dtgiven(ADATE11). BEGIN DATA 1 'drugA' '01/01/2000' 1 'drugB' '01/02/2000' 1 'drugC' '01/03/2000' 2 'drugB' '01/07/2000' 2 'drugA' '01/09/2000' 2 'drugC' '01/15/2000' 2 'drugB' '01/20/2000' END DATA. LIST. * Save the original data file. SORT CASES BY id. SAVE OUTFILE='c:\\temp\\mydata.sav'. * Select patients where drug1 was first given before drug2. * I assume drug1 is never given the same day as drug2. * Define a macro to do the job. */////////////////////////////////. DEFINE !drug (drug1=!TOKENS(1) /drug2=!TOKENS(1)) GET FILE='c:\\temp\\mydata.sav'. * Keep only the 2 relevant drugs. SELECT IF ANY(drug,!drug1, !drug2). SORT CASES BY id dtgiven. MATCH FILES FILE=* /BY=id /first=first. * First=1 means this is the first drug administered. * next line keeps only id of patients for whom first drug was drug1. SELECT IF (first=1) and (drug=!drug1). MATCH FILES /FILE='c:\\temp\\mydata.sav' /TABLE=* /RENAME (drug dtgiven = d0 d1) /BY id /DROP= d0 d1. * Keep only patients where drug1 was given before drug2. SELECT IF first=1. EXECUTE. !ENDDEFINE. */////////////////////////////////. **************************************. * Test the macro with the data given above. **************************************. * This selects only patient with id=1. !drug drug1='drugA' drug2='drugB'. LIST. * This selects both patients. !drug drug1='drugB' drug2='drugC'. LIST. * This selects only patient with id=2.. !drug drug1='drugB' drug2='drugA'. LIST. EXECUTE.