title: Frequency and causes of combined obstruction and restriction identified in pulmonary function tests in adults.
abstract: BACKGROUND
  The frequency of combined obstruction and restriction identified in pulmonary function tests has not been well described. Moreover, although the causes of combined-obstruction-and-restriction patterns are known, the frequency of the various etiologies has received little attention.
  
  
  METHODS
  We retrospectively reviewed medical records and surveyed pulmonologists.
  
  
  RESULTS
  43,212 PFT sessions were evaluated, which yielded 130 patients who satisfied our criteria for spirometry evidence of combined obstruction and restriction. Their demographic features were: mean +/- SD age 54 +/- 14 y, 51% male, mean +/- SD body mass index 28.8 +/- 6.7 kg/m(2), mean +/- SD height 174 +/- 9 cm (men) and 162 +/- 7 cm (women). The causes of combined obstruction and restriction were classified as either a pulmonary parenchymal disorder (Group A, n = 49, 38%) or a combination of pulmonary parenchymal and non-pulmonary diseases (Group B, n = 63, 48%). In 18 patients (14%) no clear etiology of combined obstruction and restriction could be determined. The most common pulmonary disease was chronic obstructive pulmonary disease (45/130, 35%), and the most common non-parenchymal disease was congestive heart failure (27/130, 21%). We electronically sent a survey to 55 pulmonary physicians, of whom 30 (55%) responded. The respondents estimated that combined obstruction and restriction occurs in approximately 20% of all the pulmonary function tests performed in their practices and that pulmonary parenchymal diseases were responsible for 35% of all instances of combined obstruction and restriction.
  
  
  CONCLUSIONS
  Combined obstruction and restriction occurs infrequently and is more commonly caused by a combination of pulmonary parenchymal and non-pulmonary disorders. Pulmonologists' impressions regarding the frequency and causes are generally discordant with the observed frequencies.
authors.affiliation: Department of Pulmonary and Critical Care Medicine, Respiratory Institute, The Cleveland Clinic, Cleveland, Ohio 44195, USA.
authors.forename: Enrique
authors.initials: E
authors.lastname: Diaz-Guzman
authors.forename: Kevin
authors.initials: K
authors.lastname: McCarthy
authors.forename: Alan
authors.initials: A
authors.lastname: Siu
authors.forename: James K
authors.initials: JK
authors.lastname: Stoller
mesh_terms: D000402:Airway Obstruction; D001291:Attitude of Health Personnel; D005260:Female; D006801:Humans; D017563:Lung Diseases, Interstitial / Q000150:complications* / Q000209:etiology; D008173:Lung Diseases, Obstructive / Q000150:complications* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D010991:Plethysmography; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D011795:Surveys and Questionnaires