Correction: How Reliable Are Current Data for Assessing the Actual Prevalence of Chronic Obstructive Pulmonary Disease?

[This corrects the article DOI: 10.1371/journal.pone.0149302.].

How Reliable Are Current Data for Assessing the Actual Prevalence of Chronic Obstructive Pulmonary Disease?

BACKGROUND: Estimating COPD occurrence is perceived by the scientific community as a matter of increasing interest because of the worldwide diffusion of the disease. We aimed to estimate COPD prevalence by using administrative databases from a city in central Italy for 2002-2006, improving both the sensitivity and the reliability of the estimate. METHODS: Multiple sources were used, integrating the hospital discharge register (HDR), clinical charts, spirometry and the cause-specific mortality register (CMR) in a longitudinal algorithm, to reduce underestimation of COPD prevalence. Prevalence was also estimated on the basis of COPD cases confirmed through spirometry, to correct misclassification. Estimating such prevalence relied on using coefficients of validation, derived as the positive predictive value (PPV) for being an actual COPD case from clinical and spirometric data at the Institute of Clinical Physiology of the National Research Council. RESULTS: We found that sensitivity of COPD prevalence increased by 37%. The highest estimate (4.43 per 100 residents) was observed in the 5-year period, using a 3-year longitudinal approach and combined data from three sources. We found that 17% of COPD cases were misclassified. The above estimate of COPD prevalence decreased (3.66 per 100 residents) when coefficients of validation were applied. The PPV was 80% for the HDR, 82% for clinical diagnoses and 91% for the CMR. CONCLUSIONS: Adjusting the COPD prevalence for both underestimation and misclassification of the cases makes administrative data more reliable for epidemiological purposes.

[Chronic obstructive pulmonary disease prevalence estimated using a standard algorithm based on electronic health data in various areas of Italy]. / Stima della prevalenza di broncopneumopatia cronico-ostruttiva basata su dati sanitari correnti, mediante l'uso di un algoritmo comune, in differenti aree italiane.

AIM: to estimate the prevalence of chronic obstructive pulmonary disease (COPD) by integrating various administrative health information systems. METHODS: prevalent COPD cases were defined as those reported in the hospital discharge registry (HDR) and cause of mortality registry (CMR) with codes 490*, 491*, 492*, 494* and 496* of the International diseases classification 9th revision. Annual prevalence was estimated in 35+ year-old residents in six Italian areas ofb different sizes, in the period 2002-2004. We included cases observed in the previous four years who were alive at the beginning of each year. RESULTS: in 2003, age-standardized prevalence rates varied from 1.6% in Venice to 5% in Taranto. Prevalence was higher in males and increased with age. The highest rates were observed in central (Rome) and southern (Taranto) cities, especially in the 35-64 age group. HDR contributed 91% of cases. Health-tax exemption registry would increase the prevalence estimate by 0.2% if used as a third data source. CONCLUSIONS: with respect to the National Health Status survey, COPD prevalence is underestimated by 1%-3%; this can partly be due to the selection of severe and exacerbated COPD by the algorithm used. However, age, gender and geographical characteristics of prevalent cases were comparable to national estimates. Including cases observed in previous years (longitudinal estimates) increased the point estimate (yearly) of prevalence two or three times in each area.