OBJECTIVES: To validate the Chronic Obstructive Pulmonary Disease Severity Score (COPDSS), a severity screening tool specific to COPD patients, for use in the Spanish primary health care system. METHODS: Cross-sectional, multicenter study, which included clinically stable COPD patients, with a recent spirometry, and a diagnosis of COPD based on a FEV1(%)<80% predicted. All patients provided signed informed consent to participate. Data on current respiratory symptoms and number of COPD exacerbations in the previous 12 months were collected, and patients were classified using the Medical Research Council (MRC) dyspnea scale. The COPDSS was administered by physicians in face-to-face interviews, and patients' most recent FEV1 values were recorded. Concurrent validity of the COPDSS was evaluated by examining the association between COPDSS scores and dyspnea status, number of exacerbations in the last 12 months, and FEV1(%). Receiver Operating Characteristics (ROC) curves were used to test the score's sensitivity and specificity. RESULTS: For this preliminary analysis, data was available from a total of 292 predominantly male (86%) patients (mean age = 67 years) reporting daily cough (71%), expectoration (74%), progressive dyspnea (60%) having 2 exacerbations per year as a mean. A moderate correlation was found between FEV1(%) and COPDSS (r=-0.331, p<0.001), though COPDSS correlated more strongly with current dyspnea status (r=0.595, p<0.001) and number of exacerbations in the past 12 months (r=0.510, p<0.001). The instrument discriminated between patients with varying degrees of dyspnea (grades 0, 1 or 2 vs grades 3 or 4 on the MRC scale; area under the ROC curve=0.867), and between patients defined according to number of exacerbations in the last 12 months (0-2 vs >=3; area under ROC curve=0.787). CONCLUSIONS: This preliminary analysis indicates that the COPDSS is likely to be a useful tool in primary health care in Spain.