Comparison of readmission and death among cardiac patients in northern vs southern Ontario

Background — Northern Ontarians (residents of the Northeast and Northwest Local Health Integration Networks) have higher population age-standardized mortality rates than the rest of the province, and the majority of deaths in Northern Ontario were attributed to circulatory diseases. It is unknown if differences in hospital-based acute cardiovascular care contribute to the differential outcomes in Northern vs. Southern Ontario.

Objectives — To examine whether mortality and readmission rates differ in Northern and Southern Ontario among patients admitted with acute cardiovascular disease conditions.

Methods — Using the Canadian Institute for Health Information Discharge Abstract Database (CIHI-DAD), we identified index admissions for acute myocardial infarction (MI), heart failure (HF), atrial fibrillation (AF), or stroke, from April 2005 to March 2015. We determined the risk of readmission (using CIHI-DAD) or death (using the Registered Persons Database) for Northern compared to Southern Ontarians, adjusting for validated comorbidity risk models, Johns Hopkins ADG, socioeconomic status, year and season of admission, and distance from home to hospital, using multivariable Cox regression analysis. Physician care was determined using the Ontario Health Insurance Plan (OHIP) database.

Results — We identified 523,029 patients who were admitted with acute MI (n¼183,402), HF (n¼131,374), AF (n¼72,799), and stroke (n¼128,673). Median ages of patients (Northern, Southern) were: 69, 69 years for acute MI; 78, 80 years for HF; 74, 75 years for AF; and 74, 76 years for stroke. Cumulative incidence of mortality over 1 year did not differ in the North vs. the South for acute MI and HF, but there was significantly higher incidence of readmission in the North (Figure). Similar findings were observed for AF and stroke. After multivariable adjustment, the hazard ratio [HR (95%CI)] for mortality in the North was 1.06 (1.03-1.10) for acute MI (p¼0.001), but HRs were 1.02 (0.99-1.06) for HF, 0.95 for AF (0.89-1.02), and 1.00 for stroke (0.97-1.04) compared to the South. However, readmission rate was significantly increased in the North for all conditions (all p < .001): acute MI (HR 1.28, 95%CI; 1.25-1.32), HF (HR 1.20, 95%CI; 1.16-1.23), AF (HR 1.27, 95%CI; 1.21-1.32), and stroke (HR 1.31, 95%CI; 1.26-1.37). In all conditions, early specialist care (cardiologist or neurologist) was significantly less likely in the north with multivariable-adjusted HRs for 30-day specialist consults/visits ranging from 0.51 to 0.70 (p < .001).

Conclusion — Readmissions for cardiovascular conditions were substantially higher in Northern compared to Southern Ontario, while differences in mortality were not different or less pronounced.