Effect of smoking on FEV decline in a cross-sectional and longitudinal study of a large cohort of Japanese males

OBJECTIVE: The effects of cigarette smoking and smoking cessation on age-related pulmonary function decline was assessed in both cross-sectional and longitudinal studies. METHODOLOGY: In the cross-sectional study, pulmonary function data from 11,875 healthy asymptomatic males, aged between 35 and 74, were analysed and correlated with their smoking history and age. In the longitudinal study, changes in pulmonary function were monitored over a 5-year period in 1888 healthy males. RESULTS: The cross-sectional study showed that the difference in FEV(1) between male never smokers and current smokers was small at a younger age but increased with age. A beneficial effect on FEV(1) decline was observed in those who ceased smoking, even within the previous 12 months. Longitudinally, current smokers showed a more rapid decline in FEV(1) over the 5-year period than non-smokers. Those who ceased smoking had lower rates of decline in FEV(1) than those who continued to smoke. CONCLUSION: These results indicate that cigarette smoking is associated with a reduction in pulmonary function, and that smoking cessation has a beneficial effect on FEV(1) decline. Provision of a smoking cessation program for all smokers, especially those showing a rapid decline of FEV(1), should be considered as an important strategy to prevent progression of COPD.     

Lower respiratory illnesses promote FEV(1) decline in current smokers but not ex-smokers with mild chronic obstructive pulmonary disease: results from the lung health study

We analyzed Lung Health Study (LHS) data to assess the effect of self-reported lower respiratory illnesses resulting in physician visits (LRI) on lung function. Participants were 5,887 smokers aged 35-60 yr, FEV(1)/FVC < 0.70 and FEV(1) of 55-90% predicted. Two-thirds were randomized into an intensive smoking cessation program (SI); one-third were advised only to stop smoking (UC). For 5 yr participants had annual spirometry and questioning regarding LRI. SI had greater rates of smoking cessation than usual care (UC) with fewer LRI (p = 0.0008). Sustained quitters had fewer LRI than continuing smokers (p = 0.0003). In the year LRI occurred, FEV(1) did not change in sustained quitters, but decreased significantly in smokers (p = 0.0001) with some recovery the following year if no LRI occurred. Over 5 yr, LRI had a significant effect on rate of decline of FEV(1) only in smokers. In smokers averaging one LRI/yr over 5 yr there were additional declines in FEV(1) of 7 ml /yr (p = 0.001). Smokers with more than one LRI/yr had greater declines. Chronic bronchitis was associated with increased frequencies of LRI, but did not affect their influence on lung function. Smoking and LRI had an interactive effect on FEV(1) in people with mild COPD, and in smokers frequent LRI may influence the long-term course of the disease.     

Smoking and lung function of Lung Health Study participants after 11 years

Eleven years after Lung Health Study (LHS) entry, we performed spirometry in 77.4% of surviving participants who enrolled in a long-term follow-up study. Those not enrolling tended to be younger male heavy smokers who continued to smoke during the LHS. Their initial LHS lung function, after adjustment for these factors, did not differ from that of enrollees. Smoking habits by original LHS treatment groups (smoking intervention vs. usual care) tended to converge, but 93% of participants who were abstinent throughout the LHS were still abstinent at 11 years. Differences in lung function between treatment groups persisted; smoking intervention participants had less decline in FEV(1) than usual care participants. Men who quit at the beginning of the LHS had an FEV(1) rate of decline of 30.2 ml/year, whereas women who quit declined at 21.5 ml/year. Men continuing to smoke throughout the 11 years declined by 66.1 ml/year, and women continuing to smoke declined by 54.2 ml/year. When decline in FEV(1) was expressed as a percentage of predicted normal value, no significant sex-based difference was apparent among continuing smokers. At 11 years, 38% of continuing smokers had an FEV(1) less than 60% of the predicted normal value compared with 10% of sustained quitters.     

Effects of randomized assignment to a smoking cessation intervention and changes in smoking habits on respiratory symptoms in smokers with early chronic obstructive pulmonary disease: the Lung Health Study

PURPOSE: To evaluate the effects of randomly assigning smokers who have early chronic obstructive pulmonary disease (COPD) to a smoking-cessation intervention on the symptoms of chronic cough, chronic phlegm production, wheezing and shortness of breath, and to determine the effects of quitting smoking on these symptoms. SUBJECTS AND METHODS: A total of 5,887 male and female smokers 35 to 60 years of age with early COPD [defined as a forced expiratory volume in the first second (FEV1) of 55% to 90% of predicted and FEV1/forced vital capacity (FVC) <0.70] were enrolled in a 5-year clinical trial. Two-thirds of participants were randomly assigned to smoking-intervention groups and one-third to a usual-care group. The intervention groups attended 12 intensive smoking-cessation sessions that included behavior modification techniques and the use of nicotine chewing gum. One intervention group was treated with ipratropium bromide by inhaler; the other intervention group received placebo inhalers. The usual-care group was advised to stop smoking. All participants were followed annually. Smoking status was biochemically validated by salivary cotinine measurements or exhaled carbon monoxide values. RESULTS: Validated 5-year sustained smoking cessation occurred in 22% of participants in the intervention compared with only 5% of participants in the usual-care group. At the end of the study, the prevalence of each of the four symptoms in the two intervention groups was significantly less than in the usual-care group (P <0.0001). For example, among participants who did not report cough at baseline, 15% of those in the intervention groups had cough at least 3 months during the year, compared with 23% of those in usual care. Sustained quitters had the lowest prevalence of all four symptoms, whereas continuous smokers had the greatest prevalence of these symptoms. Changes in symptoms occurred primarily in the first year after smoking cessation. Respiratory symptoms were associated with greater declines in FEV1 during the study (P <0.001). Ipratropium bromide had no long-term effects on respiratory symptoms. CONCLUSIONS: In this prospective randomized trial using an intention-to-treat analysis, smokers with early COPD who were assigned to a smoking-cessation intervention had fewer respiratory symptoms after 5 years of follow-up.     

Smoking cessation--but not smoking reduction--improves the annual decline in FEV1 in occupationally exposed workers

INTRODUCTION: Individuals exposed both to cigarette smoke and respiratory pollutants at work incur a greater risk of development of airway hyperresponsiveness (AHR) and accelerated decline in forced expiratory volume in 1 s (FEV1) than that incurred by subjects undergoing each exposure separately. We examined whether smoking cessation or smoking reduction improves AHR and thereby slows down the decline in FEV1 in occupationally exposed workers. METHODS: We examined 165 workers (137 males and 28 females) participating in a smoking cessation programme. Nicotine tablets were used for smoking cessation or smoking reduction. Respiratory symptoms were assessed by questionnaire, FEV1 by spirometry and AHR by methacholine challenge test. At 1 year, subjects were classified into quitters, reducers, or continuing smokers. RESULTS: Sixty-seven subjects completed the study (32 quitters; 17 reducers; 18 continuing smokers). Respiratory symptoms improved markedly in quitters (P<0.001 for all comparisons) and less so in reducers (P values between 0.163 and 0.027). At 1 year, FEV1 had slightly but significantly improved in quitters (P=0.006 vs. smokers; P=0.038 vs. reducers) and markedly deteriorated in reducers and continuing smokers. Concurrent, 1-year change in AHR did not differ significantly among the groups. CONCLUSION: In occupationally exposed workers, stopping smoking markedly improved respiratory symptoms and, in males, slowed the annual decline in FEV1. Smoking reduction resulted in smaller improvements in symptoms but deterioration in FEV1. These findings were independent of AHR. While smoking cessation should remain the ultimate goal in workplace cessation programmes more studies are necessary to better ascertain the benefits of smoking reduction.     

Effects of smoking habits on pulmonary function. Cross-sectional and longitudinal studies in male subjects on medical check-up]

Cross-sectional and longitudinal studies were done to evaluate effects of cigarette smoking and smoking cessation on age-related pulmonary function decline. Data on pulmonary function from 11,875 healthy asymptomatic men between the ages of 35 and 74 years were analyzed on the basis of smoking habits in each age group. Longitudinal changes in pulmonary function during a 5-yr period were also assessed in relation to smoking habits in 1888 healthy men. Cross-sectional studies showed that the difference of FEV1 between man current smokers and men who had never smoked is small at younger ages but increases with increases in age. A beneficial effect on FEV1 decline was observed in former smokers, even in less than 1 year after smoking cessation. Longitudinally, current smokers showed a more rapid decline in FEV1 in 5 years than nonsmokers. The men who quitted smoking had lower rates of decline in FEV1 than those who continued to smoke. These results indicate that cigarette smoking is associated with reduced pulmonary function and that smoking cessation may have a beneficial effect on FEV1 decline. Provision of a smoking cessation program for all smokers, especially those with a rapid decline of FEV1, should be considered a very important strategy to prevent progression of COPD.     

Smoking reduction and the rate of decline in FEV(1): results from the Lung Health Study.

Previous findings from the Lung Health Study have shown that smoking cessation and sustained abstinence substantially reduce the rate of decline in forced expiratory volume (FEV(1)) among smokers with early chronic obstructive pulmonary disease (COPD) when compared with continuing smoking. Intermittent quitters demonstrated rates of FEV(1) decline intermediate between those of sustained quitters and continuing smokers. In this study, data from 1,980 participants were analysed from 10 centres of the Lung Health Study in the USA and Canada. All participants were smokers with mild-to-moderate COPD who were unable to quit smoking at any time during the 1st yr of the study. No linear relationship was found between reduction in cigarettes per day and changes in FEV(1) during the 1st yr of the study. However, examination of the data revealed that this relationship was nonlinear. Further analysis found that smokers who reduced their cigarettes per day to very low amounts had smaller declines in FEV(1) than those who did not. Reduction in cigarettes per day was associated with only minimal changes in the presence of chronic respiratory symptoms. In conclusion, compensatory changes in smoking behaviour may account for the limited and unpredictable impact of smoking reduction on lung function decline and symptom prevalence when compared with smoking cessation.     

Success of smoking cessation in patients with chronic obstructive pulmonary disease

Smoking causes chronic obstructive pulmonary disease (COPD) in 15 to 20% of smokers. Smoking accelerates the annual rate of FEV(1) decline, whereas it was demonstrated that smoking cessation is the major factor that reduces this decline. The aims of this prospective study were to assess the success rate and factors affecting smoking cessation, besides, to evaluate the effect of cessation on annual FEV(1) decline. Sixty-five consecutive patients with COPD and as a control group 50 ageand sex-matched healthy smokers who were admitted to our smoking cessation clinic were enrolled in the study. Intensive behavioral therapy alone or with nicotine replacement therapy or bupropion HCL was given to both groups and success rate of smoking cessation after one year was assessed. It was shown that demographic features of the subjects and the history of COPD had no effect on success of smoking cessation. At the end of one year the rate of smoking cessation was 29% in patients with COPD and 49% in the control group (p< 0.05). All different therapy interventions had similar effects on smoking cessation. The annual FEV(1) values increased 29 mL in quitters and decreased 25 mL in patients continuing smoking (p> 0.05). In this study, we concluded that the success of smoking cessation in COPD patients admitted to the smoking cessation clinic was significantly lower than healthy smokers and annual FEV(1) decline was decreased in quitters.     

Bronchodilator response in the lung health study over 11 yrs.

Long-term changes in bronchodilator response in people with mild chronic obstructive pulmonary disease were assessed in this study. Changes in forced expiratory volume in one second (FEV1) in response to isoproterenol was measured in 4,194 participants in the Lung Health Study annually for 5 yrs, and again 11 yrs after study entry. Responses were quantitated in terms of mL (absolute), as per cent of the pre-bronchodilator value (relative), and as a per cent of the predicted normal value (% predicted). At baseline, the mean pre-bronchodilator FEV1 was 75.4% predicted, and responses were small. Relative and percentage predicted responses were similar in males and females; and correlated positively with methacholine reactivity, and negatively with smoking intensity and age. Baseline bronchodilator responses did not correlate with subsequent decline in FEV1. There was a substantial increase in response over the first year of the study, largely due to smoking cessation, with larger increases in those who stopped smoking. After the first year absolute responses changed little in those who maintained smoking cessation, but increased in those who did not. Mean relative and percentage predicted responses increased in all participants throughout the study. There was substantial annual variability of absolute response, and it was poorly reproducible in individual participants. In conclusion, smoking cessation increased bronchodilator response, and response did not predict the rate of decline of forced expiratory volume in one second.     

Clinical course and prognosis of patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a basically benign disease, but the prognosis is so poor that the mortality rate is similar to some malignant diseases. Depending on the disease severity, the 5-year mortality rate of patients with COPD varies from 40 to 70%. The three major causes of death have been identified as COPD itself, lung cancer, and cardiovascular disease. The following factors have been reported to be related to survival: FEV1 (especially the maximal attainable lung function), age, gender, PaO2, PaCO2, body weight, and comorbidity. There have been several large-scale randomized clinical trials to examine the prophylactic effects of inhaled anti-cholinergics and inhaled corticosteroids on the annual decline in FEV1. However, unfortunately, in all of the published studies, these drugs had no effect on the annual decline in FEV1.     

Longitudinal changes in forced expiratory volume in one second in adults. Effects of smoking and smoking cessation

Longitudinal changes in FEV1 (delta FEV1) in relationship to smoking habits were examined in 1,705 adults enrolled in a prospective study of a general population sample. In both men and women, there were excessive rates of decline in FEV1 in smokers, at least in those smoking more than 10 cigarettes per day. The excess decline of smokers was age dependent, particularly in men, with much of the excess loss of function occurring between 50 and 70 yr of age. Effects of smoking on delta FEV1, observed minus expected delta FEV1 and observed minus expected percent delta FEV1, were greater in men than in women even when controlled for current cigarette dose. Ex-smokers show delta FEV1 values similar to those of nonsmokers. In subjects younger than 35 yr of age, quitting smoking during follow-up was associated with an actual increase in FEV1. In men 50 to 70 yr of age, smoking cessation early in the study appeared to lead to a relatively prompt return to normal rates of functional decline. Thus, the findings suggest relatively prompt beneficial effect of smoking cessation even in late middle age.     

Short- and long-term efficacy of fluticasone propionate in subjects with early signs and symptoms of chronic obstructive pulmonary disease. Results of the DIMCA study

BACKGROUND: Early treatment with inhaled corticosteroids may prevent progression of irreversible obstruction in COPD, especially in patients with bronchial hyperresponsiveness. We investigated the clinical effects of early introduction of inhaled steroids in subjects showing early signs and symptoms of COPD without a prior clinical diagnosis. METHODS: Study subjects were detected in a general population screening and monitoring program. Those with a moderately accelerated annual FEV1 decline and persistent respiratory symptoms were invited to participate in a 2-year randomized controlled trial comparing fluticasone propionate DPI 250 microg b.i.d. with placebo. Pre- and post-bronchodilator (BD) FEV1, PC20 histamine, functional status (COOP/WONCA charts) and occurrence of exacerbations were periodically assessed. Subjects recorded respiratory symptoms. Post-BD FEV1 decline served as the main outcome. Multivariable repeated measurements analysis techniques were applied. RESULTS: 48 subjects were randomized (24 fluticasone, 24 placebo). After 3 months, the post-BD FEV1 had increased with 125 ml (SE = 68, P = 0.075) and the pre-BD FEV1 with 174 ml (SE 90, P = 0.059) in the fluticasone relative to the placebo group. The subsequent post-BD and pre-BD FEV1 decline were not beneficially modified by fluticasone treatment. There were no statistically significant differences in respiratory symptoms, functional status, or exacerbations favoring fluticasone. Subgroup analysis indicated that the presence of bronchial hyperresponsiveness modified the initial FEV1 response on fluticasone, but not the subsequent annual FEV1 decline. CONCLUSION: Early initiation of inhaled steroid treatment does not seem to affect the progressive deterioration of lung function or other respiratory health outcomes in subjects with early signs and symptoms of COPD. In subjects at risk for, or in an early stage of COPD, long-term inhaled steroid treatment should not be based on a single spirometric evaluation after 3 months.     

A pooled analysis of FEV1 decline in COPD patients randomized to inhaled corticosteroids or placebo

BACKGROUND: There is controversy about whether therapy with inhaled corticosteroids (ICSs) modifies the natural history of COPD, characterized by an accelerated decline in FEV(1). METHODS: The Inhaled Steroids Effect Evaluation in COPD (ISEEC) study is a pooled study of patient-level data from seven long-term randomized controlled trials of ICS vs placebo lasting >/= 12 months in patients with moderate-to-severe COPD. We have previously reported a survival benefit for ICS therapy in COPD patients using ISEEC data. We aimed to determine whether the regular use of ICSs vs placebo improves FEV(1) decline in COPD patients, and whether this relationship is modified by gender and smoking. RESULTS: There were 3,911 randomized participants (29.2% female) in this analysis. In the first 6 months after randomization, ICS use was associated with a significant mean (+/- SE) relative increase in FEV(1) of 2.42 +/- 0.19% compared with placebo (p < 0.01), which is quantifiable in absolute terms as 42 mL in men and 29 mL in women over 6 months. From 6 to 36 months, there was no significant difference between placebo and ICS therapy in terms of FEV(1) decline (-0.01 +/- 0.09%; p = 0.86). The initial treatment effect was dependent on smoking status and gender. Smokers who continued to smoke had a smaller increase in FEV(1) during the first 6 months than did ex-smokers. Female ex-smokers had a larger increase in FEV(1) with ICS therapy than did male ex-smokers. CONCLUSIONS: We conclude that in COPD in the first 6 months of treatment, ICS therapy is more effective in ex-smokers than in current smokers with COPD in improving lung function, and women may have a bigger response to ICSs than men. However, it seems that after 6 months, ICS therapy does not modify the decline in FEV(1) among those who completed these randomized clinical trials.     

Predictors of lung function and its decline in mild to moderate COPD in association with gender: results from the Euroscop study

BACKGROUND: There is increasing appreciation of gender differences in COPD but scant data whether risk factors for low lung function differ in men and women. We analysed data from 3 years follow-up in 178 women and 464 men with COPD, participants in the Euroscop Study who were smokers unexposed to inhaled corticosteroids. METHODS: Explanatory variables of gender, age, starting age and pack-years smoking, respiratory symptoms, FEV(1)%FVC and FEV(1)%IVC (clinically important measures of airway obstruction), body mass index (BMI), and change in smoking were included in multiple linear regression models with baseline and change in post-bronchodilator FEV(1) as dependent variables. RESULTS: Reduced baseline FEV(1) was associated with respiratory symptoms in men only. Annual decline in FEV(1) was not associated with respiratory symptoms in either men or women, and was 55 ml less in obese men (BMI 30 kg/m(2)) than men having normal BMI, an effect not seen in women. It was 32 ml faster in women with FEV(1)%FVC相似文献   

Decline of FEV1 in scuba divers

STUDY OBJECTIVES: Obstructive changes in lung function have been reported with cumulative scuba diving exposure. The aim of this study was to investigate the decline in FEV1 in scuba divers over time. DESIGN: Prospective controlled cohort study. SETTING: German Naval Medical Institute. PATIENTS: Four hundred sixty-eight healthy, male, military scuba divers and 122 submariners (control subjects) were entered. MEASUREMENTS AND RESULTS: Pulmonary function tests were performed in all subjects on at least three occasions with a minimum interval of 1 year between first and last measurement. The decline in FEV1 was investigated fitting a general linear model to FEV1 across time with a factorial main-effects model for slopes and intercepts with respect to the factors group, smoking status, and baseline FEV1. Mean baseline age of all subjects was 32 years (SD, 9.1), and mean body mass index was 24.7 kg/m2 (SD, 2.4). Subjects were followed up for 5 years (range, 1 to 9 years) on average. Baseline FEV1 exceeded the predicted values in both divers and nondiving control subjects. There was no significant difference in the decline of FEV1 between divers and control subjects. Over time, FEV1 declined more rapidly in smokers than in nonsmokers (p = 0.0064) and declined more rapidly also in subjects with a baseline FEV1 above average compared to subjects below average (p < 0.0001). The annual decline of FEV1 peaked in smoking divers who had a high FEV1 at baseline. CONCLUSIONS: The data indicate that scuba diving is not associated with an accelerated decline in FEV1. Combined exposure to diving and smoking contributes to the fall of FEV1; therefore, smoking cessation is advised for divers.     

The US Lung Health Study

Abstract The US Lung Health Study was a randomized clinical trial carried out in 10 clinical centres in the United States of America and Canada that enrolled 5887 male and female smokers age 35–60 years with early chronic obstructive pulmonary disease (COPD). Its purpose was to determine whether a programme incorporating smoking intervention and use of an inhaled bronchodilator (ipratropium bromide) can slow the rate of declinein the forced expiratory volume in one second (FEV₁) in middle aged smokers with early COPD. Participants were randomized with equal probability into three groups: (i) smoking intervention plus bronchodilator; (ii) smoking intervention plus placebo; or (iii) no intervention. The primary outcome was rate of change and cumulative change in FEV₁ over a 5 year period. The primary finding was that the use of the bronchodilator did not influence the long-term decline in FEV₁. However, the aggressive smoking intervention programme significantly reduced the age-related decline in FEV₁.     

Smoking cessation during alcohol treatment: a randomized trial of combination nicotine patch plus nicotine gum

Aims   The primary aim was to compare the efficacy of smoking cessation treatment using a combination of active nicotine patch plus active nicotine gum versus therapy consisting of active nicotine patch plus placebo gum in a sample of alcohol-dependent tobacco smokers in an early phase of out-patient alcohol treatment. A secondary aim was to determine whether or not there were any carry-over effects of combination nicotine replacement on drinking outcomes.
Design   Small-scale randomized double-blind placebo-controlled clinical trial with 1-year smoking and drinking outcome assessment.
Setting   Two out-patient substance abuse clinics provided a treatment platform of behavioral alcohol and smoking treatment delivered in 3 months of weekly sessions followed by three monthly booster sessions.
Participants   Participants were 96 men and women with a diagnosis of alcohol abuse or dependence and smoking 15 or more cigarettes per day.
Intervention   All participants received open-label transdermal nicotine patches and were randomized to receive either 2 mg nicotine gum or placebo gum under double-blind conditions.
Findings   Analysis of 1-year follow-up data revealed that patients receiving nicotine patch plus active gum had better smoking outcomes than those receiving patch plus placebo gum on measures of time to smoking relapse and prolonged abstinence at 12 months. Alcohol outcomes were not significantly different across medication conditions.
Conclusions   Results of this study were consistent with results of larger trials of smokers without alcohol problems, showing that combination therapy (nicotine patch plus gum) is more effective than monotherapy (nicotine patch) for smoking cessation.     

Hospitalizations and mortality in the Lung Health Study

This report deals with deaths and hospitalizations during the 5-year Lung Health Study, as documented by examination of appropriate records. There were 149 deaths (2.5%) during the study, caused largely by lung cancer and cardiovascular disease, particularly coronary heart disease. A total of 12.8% of participants were hospitalized, with cancer, cardiovascular disease, and nonmalignant respiratory disease accounting for 75% of hospitalizations. There were no significant differences among the original treatment groups for all-cause mortality, lung cancer, or hospitalizations for respiratory disease. Deaths and hospitalizations for cardiovascular disease and coronary artery disease were more common in the smoking intervention plus Atrovent inhaler (SI-A) group, which received ipratropium bromide, than in the smoking intervention plus placebo inhaler (SI-P) group, which received placebo, and the differences approached statistical significance. However, we were unable to find a dose effect, in that differences were not related to self-reported inhaler compliance. In the SI-A group, nine participants were hospitalized for supraventricular tachycardia as compared with two in the SI-P group, and SI-A participants with this condition were unusually compliant with their inhaled medication. When all participants were considered and smoking status considered as a time-dependent covariate, smoking cessation was associated with significant reductions in fatal or nonfatal cardiovascular disease and coronary artery disease.     

Variability of spirometry in chronic obstructive pulmonary disease: results from two clinical trials

Objective: Our goal is to determine short-term intraindividual biologic and measurement variability in spirometry of patients with a wide range of stable chronic obstructive pulmonary disease severity, using datasets from the National Emphysema Treatment Trial (NETT) and the Lung Health Study (LHS). This may be applied to determine criteria that can be used to assess a clinically meaningful change in spirometry. Methods: A total of 5,886 participants from the LHS and 1,215 participants from the NETT performed prebronchodilator spirometry during two baseline sessions. We analyzed varying criteria for absolute and percent change of FEV(1) and FVC to determine which criterion was met by 90% of the participants. Results: The mean +/- SD FEV(1) for the initial session was 2.64 +/- 0.60 L (75.1 +/- 8.8% predicted) for the LHS and 0.68 +/- 0.22 L (23.7 +/- 6.5% predicted) for the NETT. The mean +/- SD number of days between test sessions was 24.9 +/- 17.1 for the LHS and 85.7 +/- 21.7 for the NETT. As the degree of obstruction increased, the intersession percent difference of FEV(1) increased. However, the absolute difference between tests remained relatively constant despite the severity of obstruction (0.106 +/- 0.10 L). Over 90% of participants had an intersession FEV(1) difference of less than 225 ml irrespective of the severity of obstruction. Conclusions: Absolute changes in FEV(1) rather than percent change should be used to determine whether patients with chronic obstructive pulmonary disease have improved or worsened between test sessions.     

Exacerbations and lung function decline in COPD: new insights in current and ex-smokers

AIM: To investigate whether there is a significant relationship between an increased frequency of exacerbations and the rate of forced expiratory volume in 1s (FEV(1)) decline in COPD patients. METHODS-MEASUREMENTS: About 102 COPD patients (44 smokers, 58 ex-smokers) participated in a 3-year prospective study. Exacerbations were identified as worsening of patient's respiratory symptoms as recorded on diary cards. Spirometry was performed every 6 months. The effect of frequent exacerbations on lung function was investigated using random effects models. RESULTS: The median (mean(95% CI)) annual exacerbation rate was 2.85 (3.1 (2.7-3.6)). Patients with an annual exacerbation rate over the median rate had significantly lower baseline post-bronchodilation FEV(1)(%pred), higher MRC dyspnoea score and chronic cough compared to patients who had an annual exacerbation rate less than the median. The average annual rate of FEV(1)(%pred), adjusted for smoking decline (DeltaFEV(1)), was found significantly increased in frequent compared to infrequent exacerbators (P=0.017). The highest DeltaFEV(1) was observed in smokers frequent exacerbators and a significant interaction between exacerbation frequency and DeltaFEV(1) was also observed in ex-smokers. CONCLUSIONS: Our findings suggest that an increased frequency of exacerbations is significantly associated with FEV(1) decline even in ex-smokers. Thus, smoking and frequent exacerbations may have both negative impact on lung function. Smoking cessation and prevention of exacerbations should be a major target in COPD.