Objectives: To show the effect of clinical, angio and demographic traits on late survival of Coronary Artery Surgery Study (CASS) patients following coronary artery bypass grafting (CABG) and introduce Hazard Function analysis to CASS survival data.
Methods: Patients were reached by mail survey with 94% response. By National Death Index, vital status was obtained in 99.7% (n = 8221) with a mean follow up of 15 years. Cox proportional hazard and Blackstone Hazard Function regressions were used to assess effects of preoperative traits.
Results: Ninety percent of patients were alive at 5, 74% at 10 and 56% at 15 years. Of those age 65 and age 75 at operation, 74% and 59% were living at 10 years and 54% and 33% at 15 years (now age 90), survival exceeding the matched U.S. population. Hazard Function falls rapidly after CABG to 9 to 12 months, then rises, doubling by 15 years. Young patients, below age 35, had lower late survival. The time-segmented Cox model (divided at time suggested by the Hazard Function) identified traits showing predictive power early, throughout and late. Female sex, small body surface, ischemic symptoms and emergency status affected survival early. Heavier weight, infarct(s), diuretics, diabetes, smoking, left main and LAD stenosis and use of vein grafts only increased hazard late only.
Conclusions: There are still lessons from the CASS database. CABG in the elderly is supported by the survival pattern of our patients age 75 at operation. Time-segmented Cox analysis and Hazard Function analysis separate baseline variables into those that predict early mortality and those that predict long survival.