CORONARY-ARTERY BYPASS-GRAFTING IN ALBERTA FROM 1984 TO 1989

OBJECTIVE: To examine the geographic and temporal trends in the perfor mance of coronary artery bypass grafting (CABG) in the province of Alb erta. This examination was designed to improve understanding of the ge ographic distribution and temporal changes in the incidence of the pro cedure. DESIGN: A cohort of all individuals (2.4 million) registered w ith the Alberta Health Care Insurance Plan (AHCIP) was followed for th e five-year period from April 1, 1984 to March 31, 1989. No new member s were admitted to the cohort and an attrition rate averaging 6% per y ear was observed. SETTING: Data from the claims administrative databas e of the AHCIP were used. The AHCIP includes the records of all regist ered residents of the province and is virtually complete. PARTICIPANTS : Participants included all 2963 members of the cohort (2413 males, 55 0 females) who underwent CABG over the study period. MAIN RESULTS: The overall mean surgical rate was 28.8 per 100,000 (46.7 for males, 10.8 for females; chi2=1172.8, df=1, P<0.0001). The mean age at surgery wa s 59.6 years (57.9 for males, 61.4 for females), with 70 and 76% of pr ocedures occurring between the ages of 60 and 70 years for males and f emales, respectively. The largest increases in incidence were in males (223%) and females (148%) aged 70 years or older. Both males (chi2lin earity=25.95, df=3, P<0.01) and females (chi2linearity=8.34, df=3, P<0 .05) displayed an increasing trend over the study period. Data were ag gregated across the five-year study period to assess geographic variat ions. No difference was noted across census divisions for either sex. CONCLUSIONS: The similarity in rates across census divisions implies c onsistent use of criteria for the performance of this procedure. Also, the results imply that research, in Alberta, should focus more on ind ications for the procedure and its outcomes, than on geographic dispar ities.