Undiagnosed COPD Common


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Undiagnosed COPD Common
  By Michael Smith, North American Correspondent, MedPage Today
April 06, 2010
  MedPage Today Action Points

  • Explain to interested patients that a large proportion of people found to have COPD in this study had not been previously diagnosed with the condition.
  • Consider suggesting spirometry to patients with risk factors for COPD.
  ReviewMany people with chronic obstructive pulmonary disease (COPD) aren’t aware that they have the condition, researchers said.In a population of long-term smokers, about one in five was found to have COPD after spirometric testing, according to Roger Goldstein, MBChB, of West Park Healthcare Centre in Toronto, and colleagues.But only a third of the patients were aware that they had COPD before the testing, Goldstein and colleagues reported online in CMAJ.The clinical implication, they wrote, is that screening of at-risk people should be more frequent. And the findings imply that such screening can lead to early detection of COPD in high-risk patients in the primary care setting, they added.The prevalence of COPD has been estimated to be about 10% among people 40 and older, but known risk factors — such as older age and history of smoking — can increase the risk, the researchers noted.To measure the prevalence of COPD, the researchers recruited patients 40 and older with a history of at least 20 pack-years of smoking from three primary care practices in Ontario.All told, 1,003 patients met inclusion criteria, answered a questionnaire about symptoms, and underwent successful spirometry.The researchers defined COPD as a postbronchodilator ratio of one-second forced expiratory volume (FEV1) to forced vital capacity (FVC) of less than 0.7 and an FEV1 of less than 80%.After the testing, 208 patients — or 20.7% — met the clinical criteria for COPD, Goldstein and colleagues found.But of those, only 67 (32.7%) of those who completed the pretest questionnaire had been diagnosed with the condition before the test, they said.Among the participants with COPD, 196 completed an interview after spirometry. Of those:

  • 29.6% reported a previous diagnosis of heart disease, 51% reported hypertension, 21.9% reported diabetes, and 6.1% had had a stroke
  • 1.5% reported lung cancer and the same proportion reported tuberculosis
  • Four participants were using home oxygen
  • 53.7% (110 individuals) reported cough, the most common respiratory symptom

To pin down clinical characteristics that might help primary care doctors pick out patients with COPD, the researchers analyzed medical charts of participants who had spirometric evidence of the disease during the first year of the study.Those with COPD were matched for sex, age within five years, and recruitment site with three or fewer participants who did not have spirometric evidence of COPD.All told, the chart analysis included 382 participants — 107 with COPD and 275 controls — divided into four groups: those with positive spirometry results and a previously charted diagnosis, those with positive spirometry tests, but no previous diagnosis, those with negative spirometry, but a previous diagnosis, and those for whom both spirometry and chart were negative.A regression analysis showed that few clinical characteristics distinguished among the groups, the researchers said.The exception was the number of respiratory symptoms, which distinguished between undiagnosed and correctly diagnosed COPD, with a statistically significant odds ratio of 0.62 for each additional symptom, they found.The implication is that doctors should encourage spirometry for patients with risk factors for COPD, they said.The participants were almost exclusively white, the researchers cautioned, which may limit the applicability of the findings to other ethnic groups.The study was supported by the Government of Ontario and the Ontario Lung Association.

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