Differing Definitions of First-Ever Stroke Influence Incidence Estimates More Than Trends: A Study Using Linked Administrative Data

Youens, David
Katzenellenbogen, Judith
Srinivasa Ragavan, Rathina
Sodhi-Berry, Nita
Carson, Jennie
Zemedikun, Dawit
Thrift, Amanda G
Feigin, Valery
Nedkoff, Lee
Item type
Journal Article
Degree name
Journal Title
Journal ISSN
Volume Title
S. Karger AG

Introduction Researchers apply varying definitions when measuring stroke incidence using administrative data. We aimed to investigate the sensitivity of incidence estimates to varying definitions of stroke and lookback periods, and to provide updated incidence rates and trends for Western Australia (WA).

Methods We used linked state-wide hospital and death data from 1985-2017 to identify incident strokes from 2005-2017. A standard definition was applied which included strokes coded as the principal hospital diagnosis or the underlying cause of death, with a 10-year lookback used to clear prevalent cases. Alternative definitions were compared against the standard definition by percentage difference in case numbers. Age-standardised incidence rates were calculated, and age- and sex-adjusted Poisson regression models used to estimate incidence trends.

Results The standard definition with a 10-year lookback period captured 31,274 incident strokes. Capture increased by 19.3% when including secondary diagnoses, 4.1% when including nontraumatic subdural and extradural haemorrhage, and 8.1% when including associated causes of death. Excluding death records reduced capture by 11.1%. A 20-year lookback reduced over-ascertainment by 2.0% and a 1-year lookback increased capture by 13.3%. Incidence declined 0.6% annually (95% confidence interval -0.9, -0.3). Annual reductions were similar for most definitions except when death records were excluded (-0.1%, CI -0.4, 0.2) and with the shortest lookback periods (greatest annual reduction).

Conclusion Stroke incidence has declined in WA. Differing methods of identifying stroke influence estimates of incidence to a greater extent than estimates of trends. Reductions in stroke incidence over time are primarily driven by declines in hospitalised stroke.

4206 Public Health , 42 Health Sciences , Stroke , Brain Disorders , 2.4 Surveillance and distribution , 2 Aetiology , Stroke , 1109 Neurosciences , 1117 Public Health and Health Services , Epidemiology , 3202 Clinical sciences , 3209 Neurosciences , 4202 Epidemiology
Neuroepidemiology, ISSN: 1423-0208 (Print); 1423-0208 (Online), S. Karger AG. doi: 10.1159/000534242
Rights statement
© 2023 The Author(s). Published by S. Karger AG, Basel. Open Access License / Drug Dosage / Disclaimer. This article is licensed under the Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC). Usage and distribution for commercial purposes requires written permission.