Category Archives: Pulmonary Function : Part 22

Comparison of Tucson and Cracow Longitudinal Studies: Discussion (Part 2)

The differences in lung function between subjects with persistent and remitting dyspnea were not apparent but the former tended to have either lower initial and final FEV, levels or faster FEV, decline. Further analysis has shown that more than four fifths of subjects with the remission of symptom (as defined herein) reported still milder dyspnea symptoms in the final examination and ended with markedly diminished FEV,. The interactions of smoking and dyspnea, seen only in analysis of final FEV,, suggest that people who smoke despite the symptoms have pulmonary function levels on average expected for smokers, while those with the symptoms and reduced ventilatory function never smoked or gave up the habit before the study. Such patterns of associations could occur if a number of other than respiratory conditions are associated with breathlessness. Continue reading

Comparison of Tucson and Cracow Longitudinal Studies: Discussion (Part 1)

Comparison of Tucson and Cracow Longitudinal Studies: Discussion (Part 1)This analysis shows that a number of associations between pulmonary function and symptoms are similar in different populations. These consistencies indicate that the relationships found in both studies are not due to chance and represent part of natural history of airflow obstruction. buy asthma inhalers
The results of analysis of FEV, levels and slopes were the most consistent for the symptoms of the “asthmatic” type, ie, for wheeze, attacks of breathlessness, and diagnosed asthma. In general, subjects with such persistent symptoms had relatively poor lung function throughout the study and experienced an accelerated decline. Those with remission of these symptoms had better lung function than those with persistent symptoms, and they had FEV, declines similar to those in the nonsymptomatic group. New subjects had an initial FEV, similar to those seen in subjects without the symptoms, but they experienced much faster decline and ended with an FEV, worse than those with no symptoms at the final examination. Continue reading

Comparison of Tucson and Cracow Longitudinal Studies: Results (Part 5)

Symptoms and FEV1 Slope
The most consistent association of the symptoms with FEV1 slope was seen for new dyspnea. This relationship with this symptom was significant in male subjects of both cities and in Tucson female subjects even after adjustment for other symptoms (Table 5). In Cracow women, the associations were rather weak. In men of both cities, steeper FEV, slopes were also correlated with new attacks of breathlessness, and in women, with persistent asthma syndrome. Association between FE Vt slope and chronic phlegm and/or cough was found only in Cracow men and Tucson women. Continue reading

Comparison of Tucson and Cracow Longitudinal Studies: Results (Part 4)

Symptoms and Final FEV1
Although the final FEV1 was related to most of the symptoms when they were considered separately, not all associations remained significant when analyzed simultaneously with other symptoms (Table 4). The most consistent effects were seen for the different status variables related to dyspnea and attacks of breathlessness, as were found in the analysis of initial FEV, level. In Tucson women, the latter symptom was not significant; rather, wheeze and the asthma syndrome were — ventolin inhalers. Besides dyspnea and “asthmatic-type” symptoms (attacks of breathlessness, wheeze, and asthma syndrome), final FEVX was significantly related to persistent or new chronic phlegm in Tucson men and women and to new chronic bronchitis in Cracow men. The pattern of the associations was not very consistent but, in most cases, the negative effects of persistent symptoms exceeded those of new symptoms, and both were greater than the effects, of remitting symptoms. Continue reading

Comparison of Tucson and Cracow Longitudinal Studies: Results (Part 3)

In the equations for FEV, slope and FEV, final level, the initial FEV,/FVC ratio was included as one of the covariables. Steeper FEV, slopes were observed in women from both cities and in Cracow men with higher initial FEV,/FVC ratios. This is likely due to regression to the mean. In Tucson men, the relation was not significant and corresponds to accelerated FEV, decline in male smokers with low (below 70 percent) FEV/FVC ratio found previously. In the equations for the final FEV,, the initial ratio summarized (to some extent) the condition of respiratory function at the beginning of the studies. (That is, those with lower initial ratios had lower final FEV, levels). ventolin inhaler
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Comparison of Tucson and Cracow Longitudinal Studies: Results (Part 2)

Comparison of Tucson and Cracow Longitudinal Studies: Results (Part 2)The proportions of subjects with persistent, new, or remitting symptoms differed markedly between both populations (Table 2). Chronic cough and/or phlegm (“bronchitis” symptoms), both persistent and new symptoms, tended to be more frequent in Cracow than in Tucson, with the most marked differences in men. Also, dyspnea was more frequent in Cracow than in Tucson, but mainly in women. In contrast, higher in Tucson were the rates of persistent wheeze, attacks of breathlessness, and the asthmatic syndrome (“asthmatic” symptoms) in both sexes. The incidence rates of new symptoms were not so different. Continue reading

Comparison of Tucson and Cracow Longitudinal Studies: Results (Part 1)

Characteristics of the Analyzed Groups
The Tucson and Cracow analyzed groups differed markedly with respect to age and smoking habits (Table 1). The Tucson sample was stratified according to age, while the age structure of the Cracow sample was representative for the Cracow population. As a result, the proportion of subjects aged 51 to 70 years was much greater in Tucson (31.7 percent of men analyzed here and 50.2 percent women) than in the Cracow group (21.0 percent and 21.8 percent, respectively). Continue reading

Comparison of Tucson and Cracow Longitudinal Studies (Part 6)

The basic models (with the covariables only) were supplemented by the variables representing symptoms or syndromes when predicting FEV, change or final FEV,. Each symptom was represented by the set of three dummy, 0-1, variables with the “Never” category as the reference one. Therefore, the regression coefficients shown in the tables are the estimates of differences between the values of the dependent variable in people with given category of the symptom and people without the symptom (adjusted for possible confounding of all remaining factors included into the regression model). First, the relation of pulmonary function to each of the symptoms separately was evaluated, and the next stage was the selection of the “final” parsimonious regression models. These models contained maximal sets of the symptoms significant simultaneously in one model, had the greatest adjusted determination coefficients, and had the smallest standard errors of estimate. The models were selected separately for each dependent variable, city, and sex from among the models with all possible subsets of symptoms. In the result, the estimated effects of each symptom included in the model were adjusted for the effects of other symptoms included, and not only for such covariables as age or smoking. In the final stage, the interactions between the significant symptom categories and age, smoking, or education were estimated. Continue reading

Comparison of Tucson and Cracow Longitudinal Studies (Part 5)

Comparison of Tucson and Cracow Longitudinal Studies (Part 5)The principal analytic methodology used in this article was linear regression with dummy variables. Software (SPSS/PC +) was used to perform the calculations. The dependent variables were the initial and final FEV, levels as well as the FEV, slope (ml/y), derived by linear regression for each individual using his/her FEV, values from all three surveys. The use of regression methods is equivalent to covariance analysis herein, so the independent variables in the models of initial FEV, should not be interpreted as predictors, but as factors in the unbalanced covariance analysis. The analysis was performed separately for male and female subjects in each city and consisted of four stages. Buy Asthma Inhalers Online
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Comparison of Tucson and Cracow Longitudinal Studies (Part 4)

To describe dynamics of the symptoms, the following rates were calculated, with denominators reflecting differences in populations at risk: the persistence rate (percent) = Persistent/Total (x 100) (equivalent to period prevalence rate or prevalence rate of persistent symptoms); the incidence rate (percent) = New/(Never+New) (X 100); the remission rate (percent) = Remissions/(Persist-ent + Remissions). The validity of the above classification of the symptom dynamics or status, based on three selected surveys, was evaluated using the data from all surveys (one to eight) of the Tucson study. Nearly 90 percent of subjects classified as “never symptomatic” using data from three surveys were asymptomatic in any other survey. For wheeze and dyspnea it exceeded 98 percent when the symptom was reported in one survey or less. For chronic bronchitis this fraction was 92 percent. For wheeze and dyspnea, new onsets and remissions were quite consistent as well: 65 percent to 80 percent of subjects would be classified identically if data from all surveys were used. The persistence of chronic cough and/or phlegm (“bronchitis” symptoms) was less consistent: almost 35 percent of subjects classified as persistent in our analysis denied having the symptoms in all surveys other than those used herein (compared with 3 percent and 9 percent for wheeze and dyspnea). Continue reading

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