Single breath nitrogen test in an epidemiologic survey in North Italy. Reliability, reference values and relationships with symptoms

The usefulness of single breath nitrogen test (SBN2) was evaluated in a cross-sectional epidemiologic survey on a general population sample (n = 3,289) of North Italy. Each subject was submitted to CNR standardized questionnaire and to lung function testing using automated equipment (Hewlett-Packard 47804S). Acceptable closing volume (CV) and slope of alveolar plateau (DN2%/L) tracings were performed by only 1,370 and 1,982 subjects respectively, in comparison with the 2,638 diffusing capacity and the 3,079 forced vital capacity acceptable maneuvers. Prediction equations were computed on normal subjects for CV indices, with the exception of DN2%L: they were similar to those found in other studies. Significant differences among smoking categories were found for all the SBN2 parameters in males, but only for DN2%/L in females. The latter was also able to distinguish either subjects with airway obstruction from those without it or symptomatic from asymptomatic individuals, but DN2%/L did not give more information than V̇max75, a sensitive index of flow volume curve. Our results suggest that the place of SBN2 in large scale epidemiologic testing has not been justified

Reference values for vital capacity and flow-volume curves from a general population study

A longitudinal epidemiological respiratory study has been started in the North of Italy to investigate the natural history of obstructive airways disease and the long-term effect of SO2 exposure. The first cross-sectional study was completed in this unpolluted area before the activation of a thermoelectric power plant (500 tons of SO2 produced daily). Follow-up surveys are planned after pollution emission starts for a period of ten years. A sample (n = 3289) representative of the general population was drawn from the villages of the area according to the different risks of pollution exposure. Subjects completed questionnaires and performed lung function tests, including forced expiratory (FVC) manoeuvres. For 801 'normal' subjects, prediction equations have been derived in age/sex groups for slow vital capacity (VC) and variables from the FVC manoeuvre. Comparison with predictions of other studies are reported. Differences among FVC predictions were found, indicating that the use of different criteria for determination of the FVC manoeuvre end-point can affect results. In 'normals' VC was higher than FVC in older subjects. The difference between VC and FVC may be hypothesized as an epidemiological indication of the ageing effect on the mechanical properties of the ventilatory system

Reference values for vital capacity and flow-volume curves from a general population study.

Abstract A longitudinal epidemiological respiratory study has been started in the North of Italy to investigate the natural history of obstructive airways disease and the long-term effect of SO2 exposure. The first cross-sectional study was completed in this unpolluted area before the activation of a thermoelectric power plant (500 tons of SO2 produced daily). Follow-up surveys are planned after pollution emission starts for a period of ten years. A sample (n = 3289) representative of the general population was drawn from the villages of the area according to the different risks of pollution exposure. Subjects completed questionnaires and performed lung function tests, including forced expiratory (FVC) manoeuvres. For 801 'normal' subjects, prediction equations have been derived in age/sex groups for slow vital capacity (VC) and variables from the FVC manoeuvre. Comparisons with predictions of other studies are reported. Differences among FVC predictions were found, indicating that the use of different criteria for determination of the FVC manoeuvre end-point can affect results. In 'normals' VC was higher than FVC in older subjects. The difference between VC and FVC may be hypothesized as an epidemiological indication of the ageing effect on the mechanical properties of the ventilatory system

Respiratory effects of occupational exposure in a general population sample in North Italy

We assessed the effects of occupational exposure in a general population sample living in an unpolluted rural area of North Italy. In the age range of 18 to 64 yr, there were 417 participants who reported any exposure to dusts, chemicals, or gases and 1,218 who reported no exposure. Each subject completed a standardized interviewer-administered questionnaire (CNR-questionnaire). A variable proportion of participants succeeded in performing flow-volume curves, diffusing capacity of carbon monoxide, and slope of alveolar plateau of nitrogen. There was no significant difference for symptom prevalence rates between exposed and nonexposed in men and women who smoke. In nonsmoking women, those exposed showed significantly higher prevalence rates for exertional dyspnea and asthma. Regarding lung function, in exposed male smokers there was a significantly higher slope of the alveolar plateau. In exposed female nonsmokers, FEV1 and forced expiratory flows were significantly lower. Multiple logistic models in the overall group, accounting for age, smoking, and pack-years, showed that work exposure was associated significantly with higher risks for all symptoms in men (e.g., odds ratio: 2.76 for dyspnea, 2.31 for asthma, 1.69 for cough, and 1.64 for phlegm); in females, the association was significant for dyspnea (OR = 3.74) and asthma (OR = 3.29). Exposed men also had a significantly higher risk for þV1 or FEV1/FVC% below 70 (OR = 1.45). Our findings confirm those of the other few epidemiologic surveys in general population samples and contribute to the suggestion of a causal association between occupational exposure and chronic obstructive pulmonary disease