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Coding accuracy of hospital discharge data for elderly survivors of myocardial infarction
A R Levy1, R M Tamblyn, D Fitchett
1St Joseph's Hospital, Hamilton, Canada. levya@mcmaster.ca
Insights
Hospital discharge databases accurately identify myocardial infarction (MI) patients but under-report comorbidities. This impacts the accuracy of comorbidity indices like the Charlson index when using these databases for research on MI survivors.
Area of Science:
- Health Informatics
- Cardiology
- Epidemiology
Background:
- Hospital discharge databases are crucial for epidemiological research.
- Accurate coding of diagnoses is essential for reliable data analysis.
- Myocardial infarction (MI) coding accuracy in these databases requires validation.
Purpose of the Study:
- To evaluate the accuracy of primary and secondary discharge diagnoses for myocardial infarction (MI).
- To assess coding accuracy within the Quebec hospital discharge database for elderly MI patients.
- To compare the reliability of hospital discharge databases versus medical charts for MI diagnosis.
Main Methods:
- Retrospective chart review conducted in six Montreal hospitals.
- Comparison of diagnoses between medical charts and the hospital discharge database.
- Calculation of the Charlson comorbidity index using both data sources for each patient.
Main Results:
- The positive predictive value for coding MI in the database was high at 0.96 (95% CI 0.94, 0.98).
- Comorbid conditions and MI complications were significantly under-reported in the discharge database.
- The Charlson comorbidity index was, on average, 0.71 units lower when based on the discharge database compared to medical charts.
Conclusions:
- Hospital discharge databases are highly reliable for identifying patients with myocardial infarction (MI).
- However, there is substantial under-reporting of comorbid medical conditions in these databases.
- Researchers must weigh the benefits of using discharge databases against the limitations in data quality for comorbidities.
Objective:
To assess the coding accuracy of primary and secondary discharge diagnoses in the Quebec hospital discharge database for elderly persons with myocardial infarction (MI).
Design:
Retrospective chart review in a convenience sample of six Montreal hospitals. The diagnoses listed in the medical chart were compared with those listed in the hospital discharge database. For each subject, the Charlson comorbidity index was calculated twice, once based on the medical chart and again based on the hospital discharge database.
Patients:
Subjects aged 65 years and over who had an MI coded as the primary discharge diagnosis in the hospital discharge database and who were discharged alive.
Main Results:
For 234 MI survivors, the positive predictive value (ie, probability that a patient with MI reported in the hospital discharge database had an MI diagnosed by the discharging physician) for coding MI was 0.96 (95% CI 0.94, 0.98). Comorbid medical conditions and complications of the MI were under-reported in the hospital discharge database, which meant that the Charlson index based on the hospital discharge database was an average of 0.71 units lower than the Charlson index based on the medical chart.
Conclusions:
When studying survivors of MI by using hospital discharge databases, the advantages must be weighed against potential drawbacks in the quality of the information. Hospital discharge databases are almost as reliable as medical charts for identifying MI patients, but there is substantial under-reporting of comorbid medical conditions.
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