Coronary artery bypass grafting in Alberta from 1984 to 1989

To examine the geographic and temporal trends in the performance of coronary artery bypass grafting (CABG) in the province of Alberta. This examination was designed to improve understanding of the geographic distribution and temporal changes in the incidence of the procedure.

A cohort of all individuals (2.4 million) registered with the Alberta Health Care Insurance Plan (AHCIP) was followed for the five-year period from April 1, 1984 to March 31, 1989. No new members were admitted to the cohort and an attrition rate averaging 6% per year was observed.

Data from the claims administrative database of the AHCIP were used. The AHCIP includes the records of all registered residents of the province and is virtually complete.

Participants included all 2963 members of the cohort (2413 males, 550 females) who underwent CABG over the study period.

The overall mean surgical rate was 28.8 per 100,000 (46.7 for males, 10.8 for females; chi 2 = 1172.8, df = 1, P < 0.0001). The mean age at surgery was 59.6 years (57.9 for males, 61.4 for females), with 70 and 76% of procedures occurring between the ages of 60 and 70 years for males and females, respectively. The largest increases in incidence were in males (223%) and females (148%) aged 70 years or older. Both males (chi 2 linearity = 25.95, df = 3, P < 0.01) and females (chi 2 linearity = 8.34, df = 3, P < 0.05) displayed an increasing trend over the study period. Data were aggregated across the five-year study period to assess geographic variations. No difference was noted across census divisions for either sex.

The similarity in rates across census divisions implies consistent use of criteria for the performance of this procedure. Also, the results imply that research, in Alberta, should focus more on indications for the procedure and its outcomes, than on geographic disparities.