Introduction Canadian emergency departments (EDs) are struggling under the weight of increased use by a growing population of elderly patients; those who lack proper housing; and those who lack family physicians to provide primary care. The Canadian Foundation for Healthcare Improvement projected a possible ED service utilization increase in Canada at a rate of 40% over three decades. This calls for local-level information on the time trends to understand demographic and temporal variations in the different geographical locations in the country. This study sought to identify and quantify acuity level-based per capita ED visit annual time trends for the 10-year period of 2006-2015 (by age, gender, and housing status). The aim is to provide detailed information on the time trends for demographically targeted ED planning locally. The lengthy record of data allows examining the changing directions in different time segments. Material and methods Administrative data from the largest emergency department in Halifax (Nova Scotia, Canada) was analyzed. Per capita adult ED visit rates (EDVR) based on Canadian Triage Acuity Scale (CTAS), age, gender, and housing status were analyzed. Trends in the age-gender-based standardized rates using 2011 census city population data were also estimated in order to account for the population increase in the city. Results No study in Canada has documented the possibility of flattening the escalating ED visit trend by maintaining an annual declining trend in low-acuity-level visits or documented a threshold rate of decline to be maintained. This study observed that the annual linear per capita non-homeless EDVR increment trend (328/year, CI:245-411, per 100,000) for all-acuity-level visits - noted for a ten-year period - would become stable when low-acuity-level CTAS4-5 visit declining trends (427/year, CI:350-503 and 121/year, CI:79-163, per 100,000) - noted for the period of 2012-2015 - were maintained at the same magnitude and direction. Alarming annual emergent (high acuity level of CTAS2) EDVR increase equivalent to 335/year (CI:280-391, per 100,000) was noted for all combined visits, from all age, gender, and housing groups visits. The highest incremental rate noted among above-50-year-olds (521/year, per 100,000, 95% CI:433-608) was neither driven by overall increasing population census numbers nor by increasing aging population numbers. We found statistically similar age-gender standardized rates (294/year, CI: 207-382) for all ED visits and (316/year, CI:261-372) for CTAS2 level visits, when adjusted for annual population increase. Homeless ED visits did not contribute to the overall ED visit incremental trend. The highest annual homeless increment rate was shown for 50-year-old patients. Our findings suggest one way to make this escalating ED visit rates stable in the future is by maintaining the declining semi-urgent and non-urgent visit trends at the same rates estimated within the years 2012-2015. These findings highlight the potential directions for ED services planning to keep up with the growing demand for high-acuity-level ED services by the aging population.
