Box-wisker plots of the percentage changes of VA per litre of expired volume (Delta VA/VE) in healthy individuals and in COPD patients

<p><b>Copyright information:</b></p><p>Taken from "Assessment of the alveolar volume when sampling exhaled gas at different expired volumes in the single breath diffusion test"</p><p>http://www.biomedcentral.com/1471-2466/7/18</p><p>BMC Pulmonary Medicine 2007;7():18-18.</p><p>Published online 19 Dec 2007</p><p>PMCID:PMC2235885.</p><p></p> The horizontal lines represent the 50th percentile (median); limits of boxes are the 25th and 75th percentiles; the wiskers are the 10th and 90th percentiles. More than 90% of patients with COPD showed significant changes in alveolar volume when sampled at different intervals of lung volume. This suggests a different time constant of lung units coupled with a non-homogeneous distribution of ventilation

Graphic representation of the alveolar volume calculated by the two methods in COPD patients

<p><b>Copyright information:</b></p><p>Taken from "Assessment of the alveolar volume when sampling exhaled gas at different expired volumes in the single breath diffusion test"</p><p>http://www.biomedcentral.com/1471-2466/7/18</p><p>BMC Pulmonary Medicine 2007;7():18-18.</p><p>Published online 19 Dec 2007</p><p>PMCID:PMC2235885.</p><p></p> The bars represent the mean values and the lines above the bars represent one standard deviation from the mean values. The alveolar volume calculated by the quintile method appears significantly different from that calculated using the standard method for all quintiles, except for the second one. It is evident that the alveolar volume, measured on the instantaneous CH4 fraction of each quintile, progressively increases from the beginning to the end of exhalation from total lung capacity (TLC) to residual volume (RV)

Graphic representation of the alveolar volume calculated by the two methods in healthy individuals

<p><b>Copyright information:</b></p><p>Taken from "Assessment of the alveolar volume when sampling exhaled gas at different expired volumes in the single breath diffusion test"</p><p>http://www.biomedcentral.com/1471-2466/7/18</p><p>BMC Pulmonary Medicine 2007;7():18-18.</p><p>Published online 19 Dec 2007</p><p>PMCID:PMC2235885.</p><p></p> The bars represent the mean values and the lines above the bars represent one standard deviation from the mean values. The alveolar volume calculated by the quintile method appears significantly different from that calculated by the ERS-ATS standard (the left hand image is taken from reference 18) from the third quintile, corresponding to 40% of exhaled volume, to residual volume (RV) from total lung capacity (TLC)

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.]

Graphic representation of the relation between the mean values of alveolar volume, calculated by the quintile method, and those of the corresponding DLCO, in healthy individuals (panel A) and in COPD patients (panel B), at different expired volumes

<p><b>Copyright information:</b></p><p>Taken from "Assessment of the alveolar volume when sampling exhaled gas at different expired volumes in the single breath diffusion test"</p><p>http://www.biomedcentral.com/1471-2466/7/18</p><p>BMC Pulmonary Medicine 2007;7():18-18.</p><p>Published online 19 Dec 2007</p><p>PMCID:PMC2235885.</p><p></p> The alveolar volume does not show any remarkable change when related to the expired volume in healthy individuals (only 300 ml), at variance with those of COPD patients. In addition, DLCO decreases by 1.5 mmol/min/mmHg with respect to the slight changes of the alveolar volume in healthy individuals, whereas it increases by less than 1 mmol/min/mmHg for a total increase of 2.5 litres of alveolar volume in COPD patients from TLC to RV

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

CASI DI BPCO PREVALENTI, VALIDATI, E PRESENZA DI SCOMPENSO CARDIACO, PISA, 2002-2006.

;La stima di occorrenza della bronco-pneumopatia cronico ostruttiva (BPCO) ? un problema di interesse crescente; l\u27OMS ha previsto l\u27aumento della mortalit? ed il peggioramento della qualit? della vita per i pazienti BPCO. D\u27altra parte, la stima ? resa difficile da un esordio subdolo e dalla difficolt? di una diagnosi validata e differenziale rispetto ad altre patologie, come asma e scompenso cardiaco. Abbiamo stimato i casi di BPCO dai registri dei dati sanitari correnti (schede di dimissione ospedaliera e registro delle cause di morte, utilizzando i codici ICD9 = 190-192, 194,196) e da fonti cliniche (cartelle di dimissione della UO di malattie Respiratorie e UO di malattie Cardiovascolari, prestazioni ambulatoriali, e test spirometrici) dell\u27Istituto di Fisiologia Clinica del CNR, a Pisa, dal 2002 al 2006. Abbiamo studiato la funzionalit? respiratoria nel 25% dei pazienti con BPCO (definita in base ai parametri spirometrici FEV1/FVC e FEV1 predetto), la coesistenza di asma e la relazione temporale tra le diagnosi di BPCO e di scompenso cardiaco, nel periodo 2004-2006. Lo scompenso cardiaco ? definito secondo i criteri della New York Heart Association oltre alla documentazione di disfunzione ventricolare sinistra con ecocardiografia. I casi di BPCO nei pazienti di oltre 34 anni, variano poco tra il 2002 (n.1088) ed il 2006 (n.1252), con tassi di prevalenza (stima longitudinale a 3 aa) standardizzati per et?, pari a 1.67% e 1.85%,rispettivamente. La proporzione di pazienti sottoposti a spirometria (25%) rimane stabile negli anni 2004-2006, come stabile rimane la proporzione dei pazienti con BPCO confermata (89%),FEV1/FVC medio = 0.58. La distribuzione per gravit? della BPCO varia di poco nel periodo 2004-2006, con una lieve riduzione delle forme lievi (dal 34% al 29%), e una sostanziale stabilit? delle forme moderate, gravi e molto gravi. Le forme moderate sono le pi? frequenti (41%); le forme gravi e quelle molto gravi rappresentano il 12% e il 2%, rispettivamente. Nel 10% - 20% dei casi non ? stato possibile attribuire la gravit? della BPCO. L\u2711% di pazienti con BPCO (165/1516) ha avuto anche una diagnosi di scompenso cardiaco nel periodo 2004-2006. ? in corso l\u27analisi della relazione temporale tra la BPCO e patologie concomitanti (asma e scompenso cardiaco). Emerge una sottostima dei casi di BPCO stimati dai dati correnti (approccio longitudinale a 3 aa.) rispetto a quelli stimati dalle fonti cliniche. L\u2789% dei casi prevalenti di BPCO sono confermati dall\u27esame spirometrico. Lo scompenso cardiaco e la BPCO sono coesistenti nell\u2711% dei casi

Non-proportional Venn diagram describing the absolute and the exclusive contributions in cases to COPD prevalence in 5-year longitudinal 2004–2006 period, by sources.

<p><b>1634</b> subjects hospitalized (listed in HDR) in the longitudinal period, still alive at the beginning of the prevalence period, without clinical records at the NRC Institute: enrolled as <b>HDR exclusive contribution. 488 and 17</b> hospitalized subjects and outpatients respectively during 4 years preceding 2004, and deceased by the beginning of prevalence period: not included in the absolute contribution of CMR, HDR or clinical records since they had not been enrolled as prevalent cases. <b>186</b> subjects hospitalized (listed in HDR) in the longitudinal period, still alive at the beginning of the prevalence period, with clinical records also at the NRC Institute: enrolled as prevalent cases from HDR. <b>71</b> subjects deceased in the prevalence period, during or after hospitalization (HDR): enrolled as prevalent cases from HDR. <b>6</b> subjects deceased in the prevalence period, during or after hospitalizations (HDR), with clinical records as well: enrolled as prevalent cases from HDR. <b>292</b> subjects with COPD diagnosis in clinical charts or spirometry in the longitudinal period, not listed in HDR, still alive at the beginning of the prevalence period: enrolled as <b>clinical exclusive contribution. 1</b> subject deceased in the prevalence period, without hospitalization (HDR) but with spirometry: enrolled as prevalent case from clinical (spirometry) records. <b>33</b> subjects deceased in the prevalence period with COPD as underlying cause, without hospitalization (not listed in HDR) or clinical records during the longitudinal period: enrolled as <b>CMR exclusive contribution. Note: Clinical absolute contribution as reported here excludes those cases registered in common with other clinical sources.</b></p

Prevalent COPD cases with spirometry tests in two prevalence periods (3-year long longitudinal period), by sex, age group and COPD definitions, in 40+ year-old residents.

<p>Prevalent COPD cases with spirometry tests in two prevalence periods (3-year long longitudinal period), by sex, age group and COPD definitions, in 40+ year-old residents.</p

COPD confirmed cases and prevalence by periods and sex.

<p>COPD confirmed cases and prevalence by periods and sex.</p