Related Experiment Videos
Interobserver agreement in the classification of stroke in the physicians' health study
K Berger1, C S Kase, J E Buring
1Department of Medicine, Brigham and Women's Hospital, Boston, Mass, USA.
Insights
Interobserver agreement for stroke classification is high for major types and hemorrhagic subtypes but varies for ischemic subtypes. Periodic reclassification is recommended for long-term prospective studies to ensure diagnostic consistency.
Area of Science:
- Neurology
- Epidemiology
- Clinical Trials
Background:
- Prospective studies often rely on medical records for cerebrovascular endpoint evaluation.
- Ensuring diagnostic consistency over time and adequate medical record information is crucial.
- The Physicians' Health Study assessed aspirin's effect on cardiovascular events, including stroke.
Purpose of the Study:
- To evaluate interobserver agreement for stroke classification within the Physicians' Health Study.
- To address challenges in medical record adequacy and diagnostic consistency.
- To assess the reliability of stroke endpoint classification in a large prospective trial.
Main Methods:
- Stroke events (1982-1988) were classified by subtype, severity, and diagnostic certainty from medical records.
- Independent reclassification of 216 stroke events occurred in 1994.
- Kappa statistics were used to compare initial and subsequent classifications.
Main Results:
- Excellent agreement was found for major stroke types (kappa = 0.81) and hemorrhagic stroke subtypes (kappa = 0.95).
- Agreement for ischemic stroke subtypes showed wide variation (kappa = 0.13 to 0.96).
- Substantial agreement was observed for stroke severity (kappa = 0.71), but fair for diagnostic certainty (kappa = 0.33).
Conclusions:
- Interobserver agreement is high for major stroke types and hemorrhagic subtypes based on medical records and imaging.
- Classification of ischemic stroke subtypes demonstrates significant interobserver disagreement.
- Periodic reclassification of endpoints in long-term studies may mitigate misclassification.
Background And Purpose:
The evaluation of cerebrovascular end points in prospective studies is often based exclusively on medical record examination and may be made by more than one observer over time. To address the issues of adequacy of medical record information and consistency in diagnosis over time, we evaluated interobserver agreement for the main items of the stroke classification system used in the Physicians' Health Study. This trial included 22,071 physicians randomly assigned in 1982 to receive either aspirin or placebo to assess the subsequent risk of cardiovascular events, including stroke.
Methods:
Stroke subtype, stroke severity, and certainty of diagnosis were first classified from medical records from the years 1982 through 1988. The 216 stroke events reported in this period were independently reclassified in 1994 and compared with the initial classification using kappa statistics.
Results:
Overall agreement in major stroke types (hemorrhagic, ischemic, undetermined stroke) as well as in hemorrhagic stroke subtypes was excellent (kappa = 0.81 and kappa = 0.95, respectively). A wide range of values for the ischemic stroke subtypes (kappa = 0.13 to kappa = 0.96) was obtained. Agreement was substantial in assessment of stroke severity (kappa = 0.71), and it was fair (kappa = 0.33) for certainty of diagnosis.
Conclusions:
Interobserver agreement is high for major stroke types as well as for categories of hemorrhagic stroke on the basis of review of medical records and results of imaging data. The classification of ischemic stroke subtypes, however, is subject to substantial interobserver disagreement. Periodic reclassification of random samples of end points might be considered in long-term prospective studies to assess potential misclassification of events by different observers.