Using FEV1/FVC

Part 1 Establish the lower limit of normal for the FEVl/FVC ratio in ShanghaiObjective To establish the lower limit of normal for the FEV1/FVC ratio in Shanghai.Methods Carrying out epidemic study in health examination and presurgical patients who received pulmonary function test in PFT laboratory of Zhongshan hospital between Jun,2009-Feb,2010.360 patients were selected and the criteria as followed:without chronic respiratory symptom; normal result with pulmonary imaging examination;without endocrine or metabolic disease;pulmonary function test result is abnormal or roughly abnormal. Based on the statistical requirement,the new PFT index predicted equations were calculated. And the new predicted values calculated by the new equations were compared to the predicted values which calculated by the Zhongshan hospital equations with respect to correlation analysis and diversity. Accordingly,study the qualification of the subjects.On these grounds,calculate the equation of the lower limit of the normal for the FEV1/FVC and the normal range for the percentage of predicted value of FEV1/FVC.Results①predicted equations from the subjects:the equation for VC=-2.725+0.679 X gender-0.019×age+0.039×height+0.008×weight;predicted equation for TLC=-5.222+0.878×gender-0.005×age+0.061×height;predicted equation for FRC=-2.477+0.537×gender+0.037×height-0.017×weight;predicted equation for RV=-2.806+0.194×sex+0.011×age+0.027×height-0.011×weight;predicted equation for RV=14.891-1.883×sex+0.748×age+0.101×height-0.171×weight; predicted equation for FVC=-3.091+0.702×gender-0.02×age+0.044×height; predicted equation for FEV1=-1.653+0.564×gender-0.022×age+0.033×height; predicted equation for FEV1/FVC=99.121-0.138×age-0.147×weight.②for two sets of VC predicted values,correlation coefficient is 0.985,diversity is-0.3%;for two sets of TLC predicted values,correlation coefficient is 0.981,diversity is-3.9%; for two sets of FRC predicted values,correlation coefficient is 0.980,diversity is-2.2%;for two sets of RV predicted values,correlation coefficient is 0.963,diversity is -5.0%;for two sets of RV predicted values,correlation coefficient is 0.989, diversity is-2.0%;for two sets of FVC predicted values,correlation coefficient is0.981,diversity is 0.7%;for two sets of FEV1 predicted values,correlation coefficent is 0.989,diversity is 4.7%;for two sets of FEV1/FVC predicted values,correlation coefficent is0.968,diversity is 2.4%③Actual values for LLN of FEV1/FVC in terms of every age group as followed:Age18-30:80%;Age 31-40: 77%;Age 41-50:74%;Age 51-60:74%;Age 61-70:75%;above 70 age:73%.The equation of LLN for FEV1/FVC=101.9235-0.1436949×age-0.117508×height.The lower limit of normal for FEV1/FVC%pred is 92%.Conclusion The subjects could represent the normal population in Shanghai; According to the subjects,the equation of LLN for FEV1/FVC=101.9235-0.1436949 X age-0.117508 X height;and the lower limit of normal for FEV1/FVC%pred is 92%.Part 2 Using FEV1/FVC18 years old;no obvious evidence of cardiac disease;without endocrine or metabolic disease;complete the pulmonary test successfully.The whole subjects were sorted into 6 groups by the age.And in each age group,they are sorted into 3 exposed groups.With the golden standard of LLN for FEV1/FVC,using the following standards diagnose airway obstruction and COPD respectively:①GOLD: FEV1/FVC<70%;②1995 ERS guildlines:FEV1/FVC<88% predicted value(male), 89% predicted value(female);③FEV1/FVC<80% predicted value;④FEV1/FVC<92% predicted value;⑥FEV1/FVC<95% predicted value.Compare the sensitivity and specificity of different standards which diagnose airway obstruction and COPD.Results①119 subjects(28.7%)were diagnosed airway obstrction by the golden standard.Among them,16 subjects(3.77%)were diagnosed asthma refer to the medical history,imaging examination and bronchodilatation test,and 103 subjects were diagnosed COPD(24.29%).Airway obstuction detection rate for each age group as followed:Age 18-30:16.67%;Age 31-40:13.73%;Age 41-50:21.86%;Age 51-60: 24.49%;Age61-70岁:36.79%;Age above 70:37.80%. prevalence rate of COPD for each age group as followed:Age18-30岁:0%;Age31-40岁:5.8%;Age41-50岁:21.86%;Age51-60岁:21.43%;Age 61-70岁:33.96%;Age above 70:35.36%。Airway obstuction detection rate for each exposed group as followed:Group A: 22.22%;Group B:23.17%;Group C:41%.prevalence rate of COPD for each exposed group as followed:Group A:16.46%;Group B:23.17%;Group C:39%.②Diagnosing airway obstruction:GOLD standard sensitivity is 68.91%,spcecifity is 100%(Kappa value 0.76, P<0.05);ERS guideline(1995) sensitivity is 57.98%,specifity is 100% (Kappa value 0.66, P<0.05);FEV1/FVC<80% pred standard sensitivity is 27.73%, specifity is 100%(Kappa value 0.36,P<0.05);FEV1/FVC%pred<92% standard sensitivity is 87.39%,specifity is 99.67%(Kappa value 0.90,P<0.05)。FEV1/FVC%pred<95% standard sensitivity is 96.64%,specifity is 92.46%(Kappa value 0.85,P<0.05)。③Diagnosing COPD:GOLD standard sensitivity is 70.87%, spcecifity is 100%(Kappa value 0.78,P<0.05);ERS guideline(1995) sensitivity is 53.4%,specifity is 100%(Kappa值0.63,P<0.05);FEV1/FVC<80% pred standard sensitivity is 27.73%,specifity is 100%(Kappa value 0.36,P<0.05); FEV1/FVC%pred<92% standard sensitivity is 86.41%,specifity is 99.67%(Kappa value 0.86,P<0.05);FEV1/FVC%pred<92% standard sensitivity is 96.12%,specifity is 92.46%(Kappa value 0.83,P<0.05)。④All the specificity of the GOLD standards ERS guideline(1995) and FEV1/FVC<80% pred standard are 100% both for airway obstruction and COPD diagnosis.The sensitivity of GOLD standard are up to 82%-90% for subjects over 60.But for subjects below 50,its rate of missed diagnosis is as high as 71%-100%;Except for the 18-30 year old group,ERS guideline(1995) sensitivity are low as 21%-66%;FEV1/FVC%pred<80% standard sensitivity are the worst,only 0%-50%;Both FEV1/FVC%pred<92% standard and FEV1/FVC%pred<95% standard sensitivity are well,especially for subjects below 40,their sensitivity are as high as 100% but missing part of specificity contemporary.Among them,FEV1/FVC%pred<92% standard specificity almost 100% for each age group.The other get the high sensitivity as high as 92%-100% but only have specificity as 86%-98%。Conclusion Using FEV1/FVC<70% likely leads to missed diagnosis for airway obstruction and COPD,especially in youth. FEV1/FVC%pred<92% standard is realiable standard for qualitative diagnosis for airway obstruction and COPD. FEV1/FVC%pred<95% standard could try to diagnose airway obstruction and COPD early.Strongly recommend using LLN for FEV1/FVC or the FEV1/FVC%pred<92% standard as the qualitative diagnosis for airway obstruction and COPD in clinic.