Validation of Diagnostic Coding for Asthma in an Electronic Health Record System in Hong Kong

Abstract

Background: Electronic health record (EHR) databases can facilitate epidemiology research into various diseases including asthma. Given the diagnostic challenges of asthma, the validity of the coding in EHR requires clarification. We aimed to assess the validity of International Classification of Diseases, 9th Revision (ICD-9) code algorithms for identifying asthma in the territory-wide electronic medical health record system of the Clinical Data Analysis and Reporting System (CDARS) in Hong Kong. Methods: Adult patients who had the diagnosis of asthma input from all public hospitals in Hong Kong and those from Queen Mary Hospital in 2011-2020 were identified using the ICD-9 code of 493 (493.0, 493.1, 493.2, and 493.9) by CDARS. Patients' clinical record and spirometry were reviewed by two respiratory specialists to confirm the presence of asthma in the randomly selected cases. Results: There were 43,454 patients who had the diagnostic code of asthma among all public hospitals in Hong Kong and 1852 in Queen Mary Hospital in the same period. A total of 200 cases were randomly selected and validated using medical record and spirometry review by a respiratory specialist. The overall positive predictive value (PPV) was 85.0% (95% CI 80.1−89.9%). Conclusion:This was the first ICD-9 code validation for CDARS (EHR) in Hong Kong on asthma. Our study demonstrated that using ICD-9 code (493.0, 493.1, 493.2 and 493.9) to identify asthma can result in a PPV that was reliable to support the utility of the CDARS database for further research on asthma among the Hong Kong population.

Projecting the 10-year costs of care and mortality burden of depression until 2032: a Markov modelling study developed from real-world data

“…The database has been widely used in depression-related epidemiological studies 13 , 15 , 19 with reliable and validated diagnostic codes. 24 , 25 In this study, we identified a cohort of patients aged above 10 years with newly diagnosed depression (ICD-9-CM: 296.2, 300.4, 311) between 2014 and 2016 from the database (the “2014–2016 cohorts” thereafter). New diagnosis was ascertained by reviewing diagnosis records since 1993, when the database was first available.…”

Statins and risks of dementia among patients with heart failure: a population-based retrospective cohort study in Hong Kong

“…We traced patients' records back to 3 years before the index date. Demographics including age at index date, sex; lifestyle factors including alcohol consumption and smoking; The comorbidities were defined based on the combination of ICD9/ICD10 codes which had been previously validated 24 , 25 , 26 and medications prescribed, including hypertension, diabetes, obesity, stroke, anaemia, coronary artery disease (CAD), peripheral vascular disease (PVD), dyslipidaemia, atrial fibrillation (AF), other arrhythmias, cirrhosis, chronic renal failure (CRF), hearing loss, head injury, cancer, Parkinson's disease, rheumatism, depression, sleep apnea; Medications including antiplatelets, angiotensin-converting enzyme inhibitors (ACEI), angiotensin receptor blocker (ARB), beta-blockers, calcium channel blockers (CCB), diuretics, statins, insulin, and other anti-diabetics; Education status (SES) including less than primary, primary, secondary, tertiary and higher education were retrieved from CDARS. Baseline drug use was defined as ≥90 days of consecutive drug use within 3 years before the index date.…”

Real-World Effectiveness Study of Nirmatrelvir-Ritonavir or Molnupiravir in Hospitalized Unvaccinated Patients with Chronic Respiratory Diseases and Moderate COVID-19 at Presentation

“…24 Patients with underlying COPD, asthma, bronchiectasis and ILD were identified using the following ICD-9 diagnostic codes of 493.x, 496.x, 494.x and 516.3/517.2/517.8/714.81/495, respectively. [25][26][27] Patients who had a previous history of COVID-19, who received MOL or NMV-r in an outpatient setting before hospitalization, who received remdesivir treatment, received both MOL and NMV-r in the same index admission (simultaneous or sequential) and those requiring supplementary oxygen upon admission were excluded. The cohort was followed-up until 30th June 2023.…”