Academic journal article Australian Health Review

Should Diagnosis Codes from Emergency Department Data Be Used for Case Selection for Emergency Department Key Performance Indicators?

Academic journal article Australian Health Review

Should Diagnosis Codes from Emergency Department Data Be Used for Case Selection for Emergency Department Key Performance Indicators?

Article excerpt


There are several existing and proposed key performance indicators (KPIs) at the state and national level that are defined according to diagnosis data collected in the Emergency Department (ED; Table 1). Administrative data can provide a rich resource for healthcare planning and management, as well as for research into healthcare quality and outcomes. However, the quality of administrative data, particularly those collected in the ED, has not been well explored or documented. Of particular relevance to the present study, there has been no formal assessment of ED diagnosis data in Queensland despite problems identified in previous data quality reports; for example, a diagnosis code of 'Z53' ('procedure not required') was used in up to 7% of cases.1 This raises concerns about the quality of discharge diagnosis as assigned in the ED and its suitability for use in the assessment of ED performance. Data quality statements from other jurisdictions raise similar concerns.2-4

In the present study we sought to examine the quality of discharge diagnosis as recorded on Queensland ED data collections (Emergency Department Information System (EDIS)), and its value as the basis for case selection for existing and proposed ED-based KPIs. Comparisons were made between the discharge diagnosis that appeared on the ED records and the principal diagnosis on the Queensland Hospital Admitted Patient Data Collection (QHAPDC). Although it is unreasonable to expect that all patients receive the same diagnosis in both settings, most diagnoses would be expected to be consistent, so any substantial differences between ED and inpatient diagnoses would raise questions over the suitability of ED data for identifying patient cohorts to assess KPIs.


The data were sourced from EDIS and QHAPDC. The EDIS data capture one diagnosis per patient and this represents the diagnosis at discharge from the ED.5 This is coded using a substantially abridged set of International Statistical Classification of Diseases and Health Related Problems, Tenth Revision, Australian Modification (ICD-10-AM)6 codes (~1000 codes compared with ~16 500 in the QHAPDC). The principal diagnosis in the QHAPDC is defined as 'the diagnosis established after study to be chiefly responsible for occasioning an episode of inpatient care (Australian Coding Standard (ACS) 0001)'.7 This is determined at separation from the episode of care and often follows a more detailed clinical assessment than occurs in the ED. The principal diagnosis is recorded along with an unlimited number of 'other' diagnoses8 and is coded using the ICD-10-AM according to a stringent set of rules as defined by the ACS 0001.

Hospital inpatient episodes of care with a principal diagnosis from Table 1 were extracted from the QHAPDC for the year 2010-2011. The ICD code definitions for some indicators were extended to encompass episodes of care with related diagnoses. These are documented in Table 1. Inpatient episodes of care were then matched to the associated EDIS record using the patient's unit record (UR) identifier, along with the dates of inpatient admission and ED presentation. Owing to known issues with recording of times in both ED and admitted patient data, the following criteria were applied to determine a match between an ED presentation and the corresponding hospital admission:

(1) The ED presentation occurred in the same facility as the inpatient admission.

(2) Discharge from the ED must have taken place within 2 calendar days before hospital admission.

(3) Presentation to the ED must not have taken place more than 1 calendar day after hospital admission.

(4) When the hospital admission could be matched to more than one ED presentation, the ED presentation with the shortest time between presentation and hospital admission and with a discharge code of 'Admit to Hospital' was chosen.

Case ascertainment was based entirely on the principal diagnosis (PD) as recorded on the QHAPDC. …

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