Population-based stroke surveillance using big data: state-wide epidemiological trends in admissions and mortality in New South Wales, Australia.

OBJECTIVES: Epidemiological trends for major causes of death and disability, such as stroke, may be monitored using administrative data to guide public health initiatives and service delivery.

METHODS: We calculated admissions rates for ischaemic stroke, intracerebral haemorrhage and subarachnoid haemorrhage between 1 January 2005 and December 31st , 2013 and rates of 30-day mortality and 365-day mortality in 30-day survivors to 31 December 2014 for patients aged 15 years or older from New South Wales, Australia. Annual Average Percentage Change in rates was estimated using negative binomial regression.

RESULTS: Of 81,703 eligible admissions, 64,047 (78.4%) were ischaemic strokes and 13,302 (16.3%) and 4,778 (5.8%) were intracerebral and subarachnoid haemorrhages, respectively. Intracerebral haemorrhage admissions significantly declined by an average of 2.2% annually (95% Confidence Interval = -3.5% to -0.9%) ( p < 0.001). Thirty-day mortality rates significantly declined for ischaemic stroke (Average Percentage Change -2.9%, 95% Confidence Interval = -5.2% to -1.0%) ( p = 0.004) and subarachnoid haemorrhage (Average Percentage Change = -2.6%, 95% Confidence Interval = -4.8% to -0.2%) ( p = 0.04). Mortality at 365-days amongst 30-day survivors of ischaemic stroke and intracerebral haemorrhage was stable over time and increased in subarachnoid haemorrhage (Annual Percentage Change 6.2%, 95% Confidence Interval = -0.1% to 12.8%), although not significantly ( p = 0.05).

DISCUSSION: Improved prevention may have underpinned declining intracerebral haemorrhage rates while survival gains suggest that innovations in care are being successfully translated. Mortality in patients surviving the acute period is unchanged and may be increasing for subarachnoid haemorrhage warranting investment in post-discharge care and secondary prevention.