RESUMO
Background: Published data on the epidemiology of interstitial lung disease (ILD) in Asia is scarce. Understanding the epidemiology is important for authorities in the health management planning. This study aimed to estimate the prevalence, incidence, and survival of ILD in Hong Kong from 2005 to 2020 and evaluate the change of trend over time. Methods: In this retrospective cohort study, we identified ILD patients between 2005 and 2020 using a territory-wide electronic health record database. Prevalence, incidence rates, and age- and sex-standardised incidence rates with United Nations population in 2020 as a reference were estimated. Trends in prevalence and incidence were analysed using joinpoint regression and the average annual percent change (AAPC) was estimated. Median survival, and risk factors of mortality were evaluated using Cox proportional hazard regression. Findings: We identified 5924 patients and included 5884 of them for analysis. The prevalence of ILD increased from 24.7 to 33.6 per 100,000 population from 2005 to 2020 with an AAPC of 1.94 (95% confidence interval, CI: 1.69-2.34). The standardized incidence rate decreased from 5.36 to 2.57 per 100,000 person from 2005 to 2020 (AAPC -3.56, 95% CI, -4.95 to -1.78). The median survival of ILD was 2.50 (95% CI, 2.32-2.69) years. Male, older age, higher Charlson comorbidity index, and IIP subtype were associated with increased mortality with statistical significance. Interpretation: This study provided the first epidemiological evaluation of ILD in Hong Kong. Further studies on ILD in multiple Asian cities and countries are warranted. Funding: None.
RESUMO
OBJECTIVE: Large electronic medical record (EMR) databases can facilitate epidemiology research into uncommon diseases such as interstitial lung disease (ILD). Given the rarity and diagnostic difficulty of ILD, the validity of the coding in EMR requires clarification. We aimed to assess the validity of International Classification of Diseases, 9th Revision (ICD-9) code algorithms for identifying ILD in the territory-wide electronic medical health record system of Clinical Data Analysis and Reporting System (CDARS) in Hong Kong. METHOD: Patients who visited the Queen Mary Hospital in 2005-2018 with ILD were identified using the following ICD-9 codes: post-inflammatory pulmonary fibrosis (PPF; ICD-9: 515), idiopathic fibrosing alveolitis (IFA; ICD-9: 516.3), connective tissue disease-associated interstitial lung disease (CTD-ILD; ICD-9: 517.2, 517.8, 714.81), sarcoidosis (ICD-9: 135) and extrinsic allergic alveolitis (EAA; ICD-9: 495). A random selection was conducted in cases with diagnostic code of PPF and IFA, where a relative higher case number was identified. All the cases of CTD-ILD, sarcoidosis and EAA were included in validation for relatively small case number. RESULTS: Two hundred and sixty nine cases were validated using medical record review by a respiratory specialist. The overall positive predictive value (PPV) was 79% (95% CI, 74%-84%). In subgroup analysis, true positive case numbers of PPF, IFA, CTD-ILD, sarcoidosis and EAA were 74/100 (74%), 95/100 (95%), 11/15 (73%), 27/32 (84%) and 6/22 (27%), respectively. CONCLUSIONS: This was the first ICD-9 coding validation for ILD in Hong Kong CDARS. Our study demonstrated that using ICD-9 algorithms 515, 516.3, 517.2, 517.8, 714.81 and 135 enhanced identifications of ILDs with PPV that was reliable to support utility of CDARS database for further clinical research on ILDs. The validity is particularly high with 516.3.