Conflict of Interest. Actelion, Bohringer-Ingelheim, Bayer (Congress support and study). LFT parameters used in COPD diagnosis and their role in clinical practice: Lower Limit of Normal. Esen KIYAN, MD İ.Ü. İstanbul Medical Faculty Department of Respiratory Diseases.
Actelion, Bohringer-Ingelheim, Bayer (Congress support and study)
Esen KIYAN, MD
İ.Ü. İstanbul Medical Faculty
Department of Respiratory Diseases
Below 5th percentile of reference population (false negative rate %5)
Hankinson JL, AJRCCM 1999
In healty people, decrease in FEV1 with age is bigger than decrease in FVC. This causes decrease in FEV1/FVC ratio by age.
Age>45, LLN for FEV1/FVC<0.70
(Falaschetti E, ERJ 2004; Stanojevic S, AJRCCM;2008; Stanojevic S, ERJ 2010)
LLN=predicted value – (1.645*SD)
Usin the lower limit of normal for the FEV1/FVC ratio reduces the misclassification of airway obstruction. Swanney Thorax 2008
40 646 adult/13 136 asymptomatic and never smoker
American (4630)-Dutch (1204)-British (7302) populations’s pirometry data
COPD prevalence in asymptomaticandneversmokeradults.HSE: HealthSurveyforEngland 1995-96, NL: Hollanda verisi, NHANES: NationalHelathandNutritionExaminationSurvey (beyaz ırk için Amerika verisi)
LLN for FEV1/FVC decreases in healthy population with age (in man 57, in women 55 prediction equations)
False COPD diagnosis in healthy adults over 60 years: %17-45 in men, %7-26 in women
Swanney Thorax 2008
Hardie JA, ERJ 2002; Celli BR, ERJ 2003; Roberts SD, Chest 2006; Vollmer WM, ERJ 2009; Swanney MP, Thorax 2008; Ko FWS, ERJ 2008; Schermer TR, ERJ 2008; Miller MR, Chesy 2010; Vaz Fragoso CA, AJRCCM 2010
1995-1996 Health Surveys for England
Nonsmoker men without asthma,
At 47 age, LLN for FEV1/FVC<0.7 line (false positive)
47-49 ages LLN for FEV1>%80 pred (GOLD stage 1/milfd obst.)
Over 50, LLN for<%80 pred (GOLD stage 2/moderate obst.)
GOLD0 criteria misses COPD cases in young adults and therefore causes delay in treatment to prevent disease progression
Cerveri 2009: Age<52, true COPD diagnosis with fixed ratio is 77% in women and 57% in men.
Hansen 2007: false negative diagnosis is 50% with fixed ratio
Hoesein M, et al. Lower limit of normal or FEV1/FVC<0.70 in diagnosing COPD: An evidence-based review. Respir Med 2011.
MEDLINE, EMBASE, Cochrane data
Studies between 1966-2010
Total 1954 studies……………18 evaluated
Level of evidence (1a/b---expert opinion:5)
COPD prevalence according to diagnostic criteria
>LLN but <0.70 (in-between obstruction) group had higher comorbidity-especially cardiac.
Mortality (HR 1.3) andhospitalisation (HR 2.6) higherthancaseswith normal spirometry
Fixedratiomayidentify at-risk patients. Using LLN toclassifylungdisease in olderpeoplemaymiss a part of thepopulationmorelikelytohavecomplications.
FEV1/FVC LLN, FEV1<%80
LLN and FEV1<%80
Ratio and FEV1 <LLN
GOLD 2-4 prevalence
Local pred equations
COPD prevalence in never smoker healthy people
Underdiagnosis in young adults
Delay in treatment
Problems of LLN
White people have at least 30 reference equations for FEV1/FVC LLN
They must be specific for countries
LLN is an statistical definition and decreases misclassifications.
Is it true to use GOLD COPD diagnosis criteri?