Cox Proportional Hazard Ratio Reference Level

[PeterBr]

Hi All, I recently ran the following code for a cox proportional hazard model and reported the hazard ratios in a manuscript. A reviewer asked that I clearly define the "reference level for the hazard ratios"? If this referring my "ref" statements or is this something intrinsic to the model/hazard ratios?

proc phreg data = mrg.Test6_finalx;

class gender_cd(ref='M') race_cd_final(ref='R5') ethnic_cd_final(ref='E2') src_pymt_cd_new(ref='Private') facility_volume(ref='5') facility_volume(ref='5');

model revision_time*revision_id(0) = age|age gender_cd race_cd_final ethnic_cd_final CC_wght_total_dum ISS_value|ISS_value src_pymt_cd_new weekend facility_volume physician_volume;

output out=schoen ressch= schage schageage schISS_value schISS_valueISS_value;

[OsoGris · Accepted solution]

The reference levels for your CLASS variable should be the ones you defined with the REF= option on the CLASS statement.