title: Impact of direct substitution of arm span length for current standing height in elderly COPD.
abstract: BACKGROUND
  Arm span length is related to standing height and has been studied as a substitute for current standing height for predicting lung function parameters. However, it has never been studied in elderly COPD patients.
  
  
  OBJECTIVE
  To evaluate the accuracy of substituting arm span length for current standing height in the evaluation of pulmonary function parameters and severity classification in elderly Thai COPD patients.
  
  
  METHODS
  Current standing height and arm span length were measured in COPD patients aged >60 years. Postbronchodilator spirometric parameters, forced vital capacity (FVC), forced expiratory volume in first second (FEV1), and ratio of FEV1/FVC (FEV1%), were used to classify disease severity according to global initiative for chronic obstructive lung disease criteria. Predicted values for each parameter were also calculated separately utilizing current standing height or arm span length measurements. Student's t-tests and chi-squared tests were used to compare differences between the groups. Statistical significance was set at P<0.05.
  
  
  RESULTS
  A total of 106 COPD patients with a mean age of 72.1±7.8 years, mean body mass index of 20.6±3.8 kg/m(2), and mean standing height of 156.4±8.3 cm were enrolled. The mean arm span length exceeded mean standing height by 7.7±4.6 cm (164.0±9.0 vs 156.4±8.3 cm, P<0.001), at a ratio of 1.05±0.03. Percentages of both predicted FVC and FEV1 values based on arm span length were significantly lower than those using current standing height (76.6±25.4 vs 61.6±16.8, P<0.001 and 50.8±25.4 vs 41.1±15.3, P<0.001). Disease severity increased in 39.6% (42/106) of subjects using arm span length over current standing height for predicted lung function.
  
  
  CONCLUSIONS
  Direct substitution of arm span length for current standing height in elderly Thai COPD patients should not be recommended in cases where arm span length exceeds standing height by more than 4 cm.
authors.affiliation: Division of Pulmonary, Critical Care and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Chaicharn
authors.initials: C
authors.lastname: Pothirat
authors.affiliation: Division of Pulmonary, Critical Care and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Warawut
authors.initials: W
authors.lastname: Chaiwong
authors.affiliation: Division of Pulmonary, Critical Care and Allergy, Department of Internal Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Nittaya
authors.initials: N
authors.lastname: Phetsuk
mesh_terms: D000367:Age Factors; D000368:Aged; D000886:Anthropometry / Q000379:methods*; D001827:Body Height; D001993:Bronchodilator Agents / Q000627:therapeutic use; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D005541:Forced Expiratory Volume; D006801:Humans; D008168:Lung / Q000187:drug effects / Q000503:physiopathology*; D008875:Middle Aged; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000145:classification / Q000175:diagnosis* / Q000188:drug therapy / Q000503:physiopathology; D012720:Severity of Illness Index; D013147:Spirometry; D013785:Thailand; D034941:Upper Extremity / Q000033:anatomy & histology*; D014797:Vital Capacity
chemical_list: D001993:Bronchodilator Agents
keywords: arm span; chronic obstructive pulmonary disease; severity; spirometry; standing height