A reliable method to retrieve accident & emergency data stored on a free-text basis

Abstract

Accident & Emergency (A & E) data on asthma-related attendances are useful for studies on the effectiveness of asthma interventions, and to determine the relationship of environmental factors to asthma and asthma epidemics. The final diagnoses made in the A & E departments are not usually coded when entered into hospital databases in the U.K., although the "presenting complaint' can be retrieved from the computerized Hospital Information & Support Systems (HISS), from a free-text attendance diagnosis field entered by the reception clerk when the patient arrives at the A & E department. The validity of this as an indication of the final diagnosis is unevaluated. The aim of this study was to measure the validity of the string "asth' in the A & E attendance diagnosis field for identifying patients attending the A & E departments of two hospitals for asthma-related conditions. A list of patients who attended the A & E department of two hospitals was retrieved from the HISS along with the attendance diagnosis field. If the attendance diagnosis field contained the text string "asth', mentioned wheeze or breathing problems, or the patients were referred by their GP without any diagnostic information entered on HISS, the records were selected for evaluation. The remaining attendances, which were not evaluated further, were attributed to another diagnosis based on the evidence of the recorded attendance diagnosis. The results indicated that the string "asth' in the attendance diagnosis field had a sensitivity of 80.3% (95% CI 75.1-85.5%) and a specificity of 96.7% (95% CI 95.6-97.8%) for a final diagnosis of asthma. It is concluded that free-text attendance diagnosis fields in hospital databases can be searched with suitable strings to obtain reliable data on attendance with asthma. As part of another investigation, the present authors attempted to retrieve a list of the attendances with asthma at the same two A & E departments at a time that was reportedly associated with an epidemic of asthma following a thunderstorm. On this occasion, the string "asth' proved to be significantly less sensitive. The possible reasons for this and the implications for using this method for identifying cases are discussed.

A major outbreak of asthma associated with a thunderstorm: experience of accident and emergency departments and patients' characteristics

“…Secondly, we believe that the criteria for identifying affected patients were sensitive and specific. In one study a presenting complaint of asthma was 80% sensitive and 98% specific for asthmatic patients in accident and emergency departments outside the epidemic,9 but this complaint was of low sensitivity during the epidemic. To ensure sensitivity we identified patients with complaints such as shortness of breath, and to maintain specificity we checked patients' records.…”

Clustered randomised trial of an intervention to improve the management of asthma: Greenwich asthma study

“…We retrieved accident and emergency attendances16 and hospital admissions related to asthma from the hospital information support system. We obtained quarterly prescribing data from the health authority.…”

Reattendance at hospital for asthma in two Australian states, 2000–2003

“…Inconsistencies in coding may introduce error in the identification of presentations for asthma. However, it has been shown elsewhere that provisional ED diagnoses are reasonably accurate for the purpose of identifying people presenting with asthma 31 . Indigenous status reporting is also considered to have poor reliability in Victoria and New South Wales, and the findings in this study regarding Indigenous status should be interpreted with caution.…”