Background: The Global initiative for chronic Obstructive Lung Disease (GOLD) defines COPD as a fixed postbronchodilator\r\nratio of forced expiratory volume in 1 second and forced vital capacity (FEV1/FVC) below 0.7. Agedependent\r\ncut-off values below the lower fifth percentile (LLN) of this ratio derived from the general population\r\nhave been proposed as an alternative. We wanted to assess the diagnostic accuracy and prognostic capability of\r\nthe GOLD and LLN definition when compared to an expert-based diagnosis.\r\nMethods: In a prospective cohort study, 405 patients aged = 65 years with a general practitionerââ?¬â?¢s diagnosis of\r\nCOPD were recruited and followed up for 4.5 (median; quartiles 3.9; 5.1) years. Prevalence rates of COPD according\r\nto GOLD and three LLN definitions and diagnostic performance measurements were calculated. The reference\r\nstandard was the diagnosis of COPD of an expert panel that used all available diagnostic information, including\r\nspirometry and bodyplethysmography.\r\nResults: Compared to the expert panel diagnosis, ââ?¬Ë?GOLD-COPDââ?¬â?¢ misclassified 69 (28%) patients, and the three LLNs\r\nmisclassified 114 (46%), 96 (39%), and 98 (40%) patients, respectively. The GOLD classification led to more false\r\npositives, the LLNs to more false negative diagnoses. The main predictors beyond the FEV1/FVC ratio for an expert\r\ndiagnosis of COPD were the FEV1 % predicted, and the residual volume/total lung capacity ratio (RV/TLC). Adding\r\nFEV1 and RV/TLC to GOLD or LLN improved the diagnostic accuracy, resulting in a significant reduction of up to\r\n50% of the number of misdiagnoses. The expert diagnosis of COPD better predicts exacerbations, hospitalizations\r\nand mortality than GOLD or LLN.\r\nConclusions: GOLD criteria over-diagnose COPD, while LLN definitions under-diagnose COPD in elderly patients as\r\ncompared to an expert panel diagnosis. Incorporating FEV1 and RV/TLC into the GOLD-COPD or LLN-based\r\ndefinition brings both definitions closer to expert panel diagnosis of COPD, and to daily clinical practice.
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