Biomedical subjects

R Pistelli

Publications and source records attributed to R Pistelli.

At least 55 records · Page 3Linked to original sources

PubMed1996

Postural variations of pulmonary diffusing capacity in insulin-dependent diabetes mellitus.

STUDY OBJECTIVE: To assess whether posture-related changes of diffusing capacity could be considered as an early sensitive marker of pulmonary abnormalities in patients with insulin-dependent diabetes mellitus (IDDM) and whether the postural variations of pulmonary capillary blood volume (Vc) could reflect the lung capillary damage that characterizes the diabetic microangiopathy. DESIGN: Carbon monoxide diffusing capacity (DCO) was measured by the single-breath method. Four DCO measurements, two in sitting and two in supine position, were performed in each subject using gas mixtures containing different oxygen concentrations. Membrane and capillary volume components of the diffusion capacity were calculated and both were expressed as absolute value and corrected by alveolar volume (VA). PATIENTS: Twenty IDDM patients and 20 normal subjects matched for age and sex were studied. MEASUREMENTS AND RESULTS: The IDDM patients showed normal pulmonary volumes and flows. No significant differences between the two groups were found for DCO, coefficient of diffusion, Vc, and pulmonary capillary blood volume corrected by alveolar volume in sitting position. All these indexes significantly increased in normal subjects but not in diabetics, by changing the posture of the subject from sitting to supine position. In a multivariate analysis, the presence of diabetes mellitus and the age of the subjects were the only significant predictors of Vc postural changes. CONCLUSIONS: This postural test, adjusted for age, could be included in a screening diagnostic procedure for an early assessment of pulmonary abnormalities in diabetic patients. The lack of Vc postural increase in diabetics could reflect the presence of a microangiopathy involving the pulmonary small vessels.

Adult↗

PubMed1996

Maximal inspiratory pressure in elite soccer players.

The respiratory muscle strength of elite athletes has been assessed only for some competitive sports and different conclusions have been reported. The aim of this study was to evaluate the inspiratory muscle strength in a group of professional soccer players in comparison with a group of sedentary subjects. Maximal Inspiratory Pressure (PImax) was measured both at Functional Residual Capacity (FRC) and at Residual Volume (RV) in 130 subjects: 27 of these were elite soccer players (all males, aged 22 +/- 3 years) and 103 were normal sedentary subjects (77 males and 26 females, aged 44 +/- 19 years). Predictive linear models were produced by a stepwise regression analysis in the whole sample of subjects. Both PImaxFRC and PImaxRV models included female gender and ageing as negative predictors, and Body Mass Index (BMI) as positive predictor of the inspiratory pressures. The model predicting PImaxFRC was slightly more accurate than the model predicting PImaxRV (r-squared: 0.38 vs 0.36, respectively). After adjustment for the variables entered in these models, PImaxFRC and PImaxRV were respectively 1.54 KPa and 1.08 KPa higher in soccer players than in sedentary subjects but this result was statistically significant (p < 0.02) only for PImaxFRC. We conclude that the inspiratory muscle strength is increased in soccer players and PImax measured at FRC seems more sensitive in order to discriminate between subjects with different level of physical activity.

Adolescent↗

PubMed1996

Equivalence of pharmacokinetic characteristics and bronchodilating effect between two combined formulations of nedocromil sodium and salbutamol: MDI and nebulizer solution.

The aim of this study was to determine the equivalence of single doses of two nedocromil sodium/salbutamol combined formulations, namely (a) metered dose inhaler (MDI) (nedocromil sodium 4 mg + salbutamol 0.2 mg) and (b) nebulizer solution (nedocromil sodium 10 mg + salbutamol 1.5 mg), in a group of healthy volunteers. The plasma pharmacokinetic profiles of nedocromil sodium and the pharmacodynamic effect (bronchodilation) of salbutamol were evaluated. Twelve healthy volunteers entered this randomized, cross-over study. All subjects completed the pharmacokinetic section of the study. Nine of them completed also the pharmacodynamic part of the study. After preliminary controls, treatments were administered on separate days and in random order. Blood samples were collected 5, 10, 20, 30, 45 min, 1, 1.5, 2, 3 and 4h after test medication. Specific airways resistance (sRaw) was measured 5, 10, 20, 30, 40, 50 and 60 min following test treatment administration. The pharmacokinetic profiles of nedocromil sodium were evaluated using the maximum plasma concentration (Cmax), the time to peak plasma concentration (tmax) and the area under the curve from 0 to infinity (AUCzero-->infinity), derived from the plasma concentration/time curves. The bronchodilating effect of the two test treatments were evaluated as sRaw percentage change at each time point, maximum sRaw percentage change (sRawMAX) and area under the curve (AUC) of sRaw percentage change plotted against the time of recording. The mean pharmacokinetic results for MDI and nebulizer solution were, respectively: Cmax = 7.59 ng.ml-1 +/- 4.99 and 9.64 ng.ml-1 +/- 5.22 (p = 0.36), tmax = 0.21 hour +/- 0.08 and 0.28 hour +/- 0.14 (p = 0.19), AUCzero-->infinity = 6.28 ng.ml-1.h +/- 2.91 and 12.91 ng.ml-1.h +/- 4.12 (p = 0.008), while the mean pharmacodynamic results were: sRawMAX = -37.91% +/- 13.77 and -39.69% +/- 9.69 (p = 0.69), AUC = -1465.5 delta %.h +/- 799.3 and -1683.4 delta %.h +/- 496.3 (p = 0.45). No statistically significant differences between treatments were found also for sRaw percentage change at each time point. The absorption of nedocromil sodium was proportional to the two administered nominal doses and similar to values obtained after administration of nedocromil sodium alone. The two combined formulations of nedocromil sodium and salbutamol produce an equivalent bronchodilating effect. These results confirm the pharmacological equivalence of the two products, whichever may be used according to specific therapeutic needs.

Administration, Intranasal↗

PubMed1995

Household and community determinants of exposure to involuntary smoking: a study of urinary cotinine in children and adolescents.

The study examines the role of several potential predictors of urinary cotinine levels in a cross-sectional sample of 1,072 nonsmoking children and adolescents in Latium, Italy, during 1990-1991. As expected, there was a strong relation between passive exposure to smoking and the amount of maternal and paternal self-reported smoking. The urinary cotinine level increased with a decreasing level of paternal education and with an increasing index of household crowding; self-report of recent exposure to smoking outside the home was a strong predictor of the biologic marker. The analysis was then restricted to 346 subjects whose parents claimed that they were nonsmokers and that there were no smokers at home. In this group, however, 57 children reported some active smoking at home by their parents. Those with parents suspected to be "deceivers" had higher level of urinary cotinine than did those truly not exposed. In addition, urinary cotinine in this group was clearly associated with duration of exposure to smoking outside home. The study indicates that both factors related to family circumstances and exposure outside the household setting are strong determinants of urinary cotinine levels. The finding may be considered a direct confirmation that passive smoking among children should be viewed as a specific community responsibility.

Adolescent↗

PubMed1995

Is maternal asthma a risk factor for low birth weight? Results of an epidemiologic survey.

The association between history of asthma in the mother and low birth weight (< 2,500 g) was studied in 2,929 primary schoolchildren, randomly selected from three areas of the Lazio Region, Italy, and enrolled in a cross-sectional survey to assess their health status in relation to environmental factors. A history of asthma in the mother was associated with a higher prevalence of low birth weight, with a crude OR of 2.95 (95% CI 1.10-6.72). After stratification for other variables, an association was still present only for males (OR 4.13; 95% CI 1.01-12.53), when mothers had smoked in pregnancy (OR 8.02; 95% CI 1.63-32.28) and were resident in an industrial town (OR 10.21; 95% CI 2.69-32.27). An OR of 6.43 was also found when mothers belonged to low social class, but the 95% CI included the unity. These results suggest that a history of asthma in the mother is a risk factor for low birth weight, but only when other adverse factors are concurrently present.

Adult↗

PubMed1995

Predicting mortality of patients hospitalized for acutely exacerbated chronic obstructive pulmonary disease.

PURPOSE: To identify factors affecting the short-term prognosis of patients with acutely exacerbated chronic obstructive pulmonary disease (COPD). PATIENTS AND METHODS: The 590 patients having COPD as primary disease who were hospitalized in the pneumology unit of a university hospital from 1981 to 1990 were studied. A standardized protocol for the treatment of acutely exacerbated COPD was adopted for all the patients. The patient records were retrospectively analyzed by two observers, and 23 clinical and laboratory variables defining the patient status on admission were collected. Age and arterial gas data were also taken into account, and the outcome mortality was recorded. Interobserver reproducibility was tested by computing the kappa coefficient and Spearman's rho for dichotomous and continuous variables, respectively. The relationship of clinical and laboratory factors to the outcome was assessed first by univariate analysis and then by a logistic regression analysis assessing the independent predictive role of variables previously shown to be univariately correlated with mortality. RESULTS: The mortality rate was 14.4%. The logistic regression analysis identified four independent predictors of death: age (odds ratio [OR] 1.07; 95% confidence interval [CI] 1.04 to 1.11), alveolar-arterial oxygen gradient greater than 41 mm Hg (OR 2.33; 95% CI 1.39 to 3.90), ventricular arrhythmias (OR 1.91; 95% CI 1.10 to 3.31), and atrial fibrillation (OR 2.27; 95% CI 1.14 to 4.51). CONCLUSIONS: Patients with acutely exacerbated COPD having a high risk of death can be identified at the time of admission. Variables reflecting heart dysfunction are important determinants of this risk. Among pulmonary function data, only alveolar-arterial oxygen gradient contributes to the predictive model.

Acute Disease↗

PubMed1995

Effects of a filter at the mouth on pulmonary function tests.

The aim of this study was to verify whether the increase of resistance to airflow using a filter at the mouth could determine significant systematic errors of measurement or change the diagnostic performance in a respiratory physiology laboratory. The effect of the new filter Spirobac (DAR Spa, Italy) was assessed on out-patients referred to our laboratory for routine functional evaluation. The following tests were performed: maximal expiratory flow-volume curve, plethysmographic lung volume and airway resistance, bronchodilator test, and methacholine challenge test. Each test was performed randomly, twice with the filter and twice without. Significant differences between measurements with and without filter were found for forced vital capacity, forced expiratory volume in one second, airway resistance, and specific airway conductance (sGaw). These differences were unrelated to the average values of the measurements, except for sGaw. The limits of agreement were within the range of intraindividual short-term repeatability for almost all of the function indices. The overall concordance between tests performed with and without filter was 78% for bronchodilator test and 53% for methacholine test. However, in all the cases but one, the concordance of the methacholine test was inside the short-term repeatability. We conclude that the filter Spirobac has a statistically significant effect on the results of some pulmonary function tests. However, this is not considered to be clinically significant, since the changes due to the filter were within the intraindividual variability of repeated measurements for almost all the function indices and no appreciable classification error was found in diagnostic tests.

Adult↗

PubMed1995

Use of metaiodobenzylguanidine (MIBG) in pneumology.

Norepinephrine (NE) is one of the many biologically active substances that are metabolized by the lung. The norepinephrine uptake in the lung has been widely investigated in animal studies in order to detect abnormalities of the endothelial cells. 131I- or 123I-labelled metaiodobenzylguanidine (MIBG) is a radioactive tracer that shares several metabolic pathways with NE; it has been used instead NE or both in animal and in human studies for the same purposes. It has been definitely demonstrated that MIBG lung uptake following intravenous administration is a reliable marker of minimal endothelial cell lesions and it allows one to investigate several conditions involving damage to the lung vasculature such as adult respiratory distress syndrome, post-actinic lung fibrosis or chemotherapic lung toxicity. MIBG could also potentially be used as a tracer of the neuroadrenergic system of the airways, once it has been deposited in the whole branches of the bronchial tree. With this in mind we evaluated the feasibility of the administration of MIBG in radioaerosol form. We first performed a chromatographic study on [123I]MIBG aliquots aerosolized for variable lengths of time (2-30 minutes). Radiochemical purity was always over 96%, thus demonstrating that aerosolization does not significantly modify the stability of the tracer. We then compared both the lung clearance curves and the scintigraphic images in two groups of normal subjects who respectively underwent [123I]MIBG and 99mTc-DTPA radioaerosol dynamic scintigraphy. We found that MIBG clearance to be significantly lower than that of DTPA (135 +/- 32 minutes versus 69 +/- 27 minutes, p < 0.01), probably due to its being trapped in the adrenergic nerve endings of the airways. The pulmonary distribution of both tracers was homogeneous, as demonstrated by the correspondence of the values for the aerosol penetration index in both groups of subjects. Such results warrant further research and pharmacologic tests.

3-Iodobenzylguanidine↗

PubMed1994

The cardiopulmonary response to incremental exercise test: the effect of aging.

The aims of the present study were to define the respective roles of the cardiac and respiratory response to exercise as determinants of the age-related physiological decrease in exercise performance, and to assess the relationship between aging and interindividual variability in the response to effort. We studied 91 normal subjects recruited in three age-groups: Group A (42 children, aged 10 +/- 2 years); Group B (29 young adults, aged 27 +/- 5 years); Group C (20 elderly, aged 74 +/- 9 years). All the subjects underwent an incremental cycle ergometer exercise test with a work load increase of 15 W every 2 minutes in groups A and C, and 25 W every 2 minutes in group B, until they achieved 80% of the predicted maximal heart rate. Ventilatory equivalent changes during exercise were significantly lower in group A than in the other two groups, and in group B compared to group C. Exercise-induced changes in oxygen pulse were significantly higher in group A, but no difference was found between groups B and C. Thus, gas-exchange function and overall exercise performance decrease with advancing age, whereas cardiovascular performance is well maintained in normal elderly subjects. Discriminant analysis showed that the exercise response conformed to the group-specific model in 74% and 79% of subjects in groups A and B, but only in 50% of the group C subjects; 5% and 45% of the elderly subjects were functionally classified in groups A and B, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗

PubMed1994

Passive smoking as a determinant of bronchial responsiveness in children.

The effect of passive smoking on the degree of nonspecific bronchial responsiveness (BR) in children was evaluated. In a cross-sectional survey of primary school children (7 to 11 yr) in Latium (Italy), a total of 1,215 methacholine challenge tests was performed. The children were divided into nonresponders (PC20 FEV1 > 64 mg/ml) and responders (PC20 FEV1 < or = 64 mg/ml), the latter including a subgroup of strong responders (PC20 FEV1 < or = 4.0 mg/ml). The role of passive smoking exposure was analyzed through logistic regression models. Higher odds ratios were found among girls (for strong responders: maternal smoking, OR 2.92; paternal smoking, OR 2.59); moreover, among girls there was a dose-response relationship with the number of cigarettes smoked by the mother. An effect modification was also detected for father's education and household crowding: maternal and paternal smoking were strong predictors of bronchial hyperresponsiveness in families in which the head was less educated and in overcrowded houses. The results were confirmed using a continuous index of BR (slope) and after adjustment for baseline airway caliber. We suggest that the effect of parental smoking on children's bronchial responsiveness is detectable when the conditions for a higher exposure level at home are met; females seem to be more susceptible.

Bronchial Hyperreactivity↗

PubMed1994

Bronchial asthma: still an inadequately assessed and improperly treated disease.

In this paper we present data on the assessment and treatment of asthma in a large sample (13,899 subjects) representative of the population of young males living in four districts of the Tuscany region (Italy). In this group, 404 asthmatics (2.9%) were identified and 365 of the eligible patients were included in the study. A total of 323 asthmatics (88.5%) reported respiratory symptoms during the preceding year. A total of 162 asthmatics (44%) had previously had lung function tests to assess asthma, whereas in 89% of the patients the atopic component of asthma had been previously evaluated by prick tests. Fifty-seven percent of the patients in whom bronchial obstruction was observed and 38% of the asthmatics with severe bronchial hyperresponsiveness (BH) were receiving either no medication or treatment with only one drug. The drugs prescribed most frequently during the preceding year were beta agonists (56%) as opposed to sodium cromoglycate (22%) and inhaled steroids (17%); the latter two drugs were included in the therapy of 143 asthmatics (39%) and represented the treatment of choice in 16% of the subjects with bronchial obstruction and in 38% of the subjects with severe BH. We conclude that in our sample of young asthmatics the pulmonary function tests and the inhaled anti-inflammatory drugs were insufficiently utilized.

Asthma↗

PubMed1993

Effects of environment on atopic status and respiratory disorders in children.

BACKGROUND: We investigated whether living in areas with higher air pollution levels increases the prevalence of positive skin reactivity in children and the possible synergic effect of air pollution exposure and atopy on respiratory disorders. METHODS: This cross-sectional study was conducted in an urban area, in an industrialized area, and in a rural control area in the Latium region of Italy. A total of 2226 subjects, aged 7 to 11 years, were studied. RESULTS: The prevalence of children with positive skin test results did not vary significantly over the areas (urban area = 21.0%, industrialized area = 22.0%, rural area = 20.2%). Children living in polluted areas experienced significantly more cough and phlegm (odds ratio [OR] = 1.5), rhinitis (OR = 1.7), pneumonia (OR = 1.7), and early respiratory infections (OR = 1.4) than control subjects. The pattern of the odds ratios for atopy and air pollution suggested that the two factors were probably additive in affecting asthma and early respiratory infections (synergy index [SI] = 1.04 and 1.27, respectively), whereas they seemed to act synergically in regard to cough and phlegm (SI = 1.59), rhinitis (SI = 3.01), and pneumonia (SI = 2.75). CONCLUSION: Environmental air pollution seems not to increase the prevalence of atopic status; it seems, however, to enhance the development of clinical symptoms among already sensitized subjects.

Air Pollutants↗

PubMed1993

The relationship between sporting activity and smoking habits in young adults.

The authors investigated the relationship between sporting activity and smoking habits in young Italian men. One thousand, one hundred fifty-three men, age 20 years, completed a self-administered questionnaire on their smoking habits and sporting activity patterns. Five hundred sixty subjects (53%) were found to be smokers, with a high prevalence of heavy smokers (33.6%). Four hundred sixty-four (44%) of the examined subjects were sportsmen. In the group of young men not engaged in sports, the rate of smokers was significantly higher. Non-sportsmen started smoking earlier than sportsmen, and the prevalence of heavy smokers was significantly higher in the non-sportsmen group than in the sportsmen group. Finally, the young men not engaged in sports were more likely to be habitual smoke inhalers than sportsmen. These results suggest that sporting activity may indirectly influence smoking habits.

Adult↗

PubMed1993

Respiratory symptoms and bronchial responsiveness are related to dietary salt intake and urinary potassium excretion in male children.

To investigate whether dietary salt intake and urinary sodium and potassium levels are related to respiratory symptoms and bronchial responsiveness, a cross-sectional study among 2593 subjects aged 9 to 16 was conducted in four communities of the Latium region (Italy). Questionnaires were administered to the parents, urine samples were collected, lung function, methacholine challenge tests and prick tests were performed. Information about familial and personal dietary salt use and respiratory health was collected from the parents of 2439 (94%) subjects. A total of 2020 methacholine challenge tests and 916 urinary sodium and potassium levels were available for analysis. Personal table salt use was strongly related to cough and phlegm apart from colds (adjusted odds ratios, OR, 1.87, 95% confidence intervals, CI, 1.20-2.90), wheezing apart from colds (OR, 2.19, 95% CI, 1.27-3.77), wheezing with dyspnoea (OR, 1.45, 95% CI, 0.98-2.12) and wheezing after exercise (OR, 2.16, 95% CI, 1.35-3.44). These associations were mainly found in boys. Use of familial table salt and canned food showed no relation to respiratory symptoms. Increased bronchial responsiveness was associated with a higher urinary potassium excretion in boys, but not with urinary sodium. In conclusion, personal table salt use is related to an increased prevalence of bronchial symptoms; an increase in bronchial responsiveness among those with higher potassium excretion also seems to be implied. Although it is difficult to interpret the results of this study in causal terms, the findings might be relevant to the distribution of bronchial symptoms and diseases in the population.

Adolescent↗

PubMed1992

Effects of environment and passive smoking on the respiratory health of children.

A cross-sectional survey was conducted to evaluate the possible effects of outdoor air pollution and of parental smoking on the respiratory health of children. A total of 3092 primary schoolchildren living in two polluted areas (an industrial town, Civitavecchia, and the city of Rome) and in a rural area, were chosen. A self-administered questionnaire was filled in by the parents of 2929 children (94.2%). A broad spectrum of respiratory symptoms and illnesses were taken as outcome variables. The frequency of most outcome variables was higher among children from the polluted areas than among those growing up in the non-polluted area (e.g. asthma: odds ratio (OR) = 1.4 for Civitavecchia, OR = 1.3 for Rome). Exposure to any passive smoking increased OR of having night cough (OR = 1.8), snoring (OR = 1.4), and respiratory infections during the first 2 years of life (OR = 1.3). A further increase in risk was observed in children whose mothers smoked or if both parents were smokers (asthma, OR = 1.5). When the separate and joint effects of the two exposures were studied, the patterns of OR did not suggest synergism between the two factors. The study indicates that both air pollution and passive smoking cause an increase in respiratory symptoms in children, although there would seem to be no additional effects of the two exposures together.

Child↗

PubMed1992

Population values of lung volumes and flows in children: effect of sex, body mass and respiratory conditions.

The functional relationship of gender, anthropometric measures and respiratory condition in predicting respiratory function in children was explored, using data collected in a random sample survey in Central Italy (2,176 subjects). Regression equations for the logarithmic transformation of the functional data were obtained, using sex, ln(height), ln(body mass index) (BMI) and ln(age) as predicting variables. The fit of the model was better for forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and peak expiratory flow (PEF) (R2 = 0.655, 0.603 and 0.312, respectively) than for maximal expiratory flows. Variables indicating the presence of respiratory conditions (recent respiratory infections, asthma, cough and/or phlegm) were forced in the models; only a marginal change in the predictions was observed. Data analysis while controlling for FVC, as a proxy for total lung capacity, revealed no substantial sex difference in airways; furthermore, airways size relative to lung size falls with increasing FVC in both sexes. In overweight subjects (BMI greater than 90th percentile) the relationship between height and lung volume was modified by sex, the coefficient for ln(height) being higher in girls and lower in boys. A comparison between equations from the present study and available reference data revealed that our population differs from standards derived from laboratory data and is more similar to those derived from population studies.

Asthma↗

PubMed1991

Factors affecting variations in pulmonary diffusing capacity resulting from postural changes.

The relation of postural changes to the diffusing capacity of the lung for carbon monoxide (DLCO) was investigated in 12 normal nonsmokers in order to evaluate the influence of body position on several components of lung resistance to gas diffusion. The well-known increase in CO diffusing capacity in the supine position was obtained only for data corrected for alveolar volume (KCO: 6.18 +/- 0.75 vs. 5.45 +/- 0.67 ml/min/mm Hg/l; p less than 0.005). Moreover, only the membrane component (Dm) increased significantly in supine subjects (KDm = 2.81 +/- 1.32 vs. 1.82 +/- 0.54 ml/min/mm Hg/l; p less than 0.05), the increase in capillary blood volume (Vc) being not significant (KVc = 12.54 +/- 4.22 vs. 11.17 +/- 3.79 ml/l; NS). These data could be interpreted as a demonstration of a more homogeneously distributed ventilation with respect to diffusion surface in healthy young people in a supine position. The amount of surface available for diffusion seems therefore to be a limiting factor to gas flow across the lungs in these subjects. Thus a straightforward attribution of posturally influenced changes in CO diffusing capacity exclusively to factors affecting Vc is not recommended, particularly in pathological conditions, if information about variation in distribution of ventilation is unavailable.

Adult↗

PubMed1991

Indices of nonspecific bronchial responsiveness in a pediatric population.

A cross-sectional survey of the prevalence of asthma and bronchial hyperreactivity among schoolchildren (7 to 11 years old) was carried out in three areas of the Latium region (Central Italy). Out of 1,777 children tested with methacholine challenge (MCT), 15.1 percent had a 20 percent fall in FEV1 after a provocative concentration (PC20FEV1) of 4 mg/ml of methacholine or less; 69.7 percent had a PC20FEV1 less than 64.0 mg/ml, whereas 50.3 percent were nonresponders. Two continuous measures of bronchial responsiveness, the slope (percentage of change in FEV1 per mg/ml of methacholine) and the area under the dose response curve, were calculated in order to avoid the loss of information in nonresponders. Applying a receiver operating characteristic (ROC) curve analysis, the three estimators did not show any statistically significant difference in their overall performance in detecting asthma (ROC areas: PC20FEV1 = 0.683, slope = 0.681, area = 0.702 or asthma-like symptoms. The log transformation of slope, having a unimodal and slightly skewed shape, is an appealing continuous measure of bronchial responsiveness useful for epidemiologic studies. The final choice of an appropriate estimator of the concentration-response curve to methacholine, however, depends upon both the statistical tests or the modelling procedures to be used and clarification of the prognostic value of different indices of bronchial responsiveness.

Asthma↗