Increase in exhaled nitric oxide is associated with bronchial hyperresponsiveness among apprentices.

RATIONALE: Airway inflammation is a hallmark of asthma. Several studies have validated the use of the fractional concentration of exhaled nitric oxide (Fe(NO)) as a surrogate marker of airway inflammation in asthma. OBJECTIVES: We examined how the change in Fe(NO) levels, since the beginning of occupational exposure, could be associated with the incidence of bronchial hyperresponsiveness (BHR) among baker, pastry maker, and hairdresser apprentices during their 2-year training. METHODS: A standardized questionnaire was administered; skin prick tests for common and specific occupational allergens were done; methacholine challenge and measurement of Fe(NO) were performed 6, 12, and 15 months after the first examination. MEASUREMENTS AND MAIN RESULTS: Of 441 apprentices initially included, 351 completed the study. The increase in Fe(NO), since the beginning of exposure, was associated with the incidence of BHR (odds ratio, 2.00 [95% confidence interval, 1.21-3.32] per unit increase in log parts per billion) both in atopic and nonatopic subjects. The average increase in Fe(NO) was similar in atopic and nonatopic subjects and was unrelated to past or current smoking habits, sex, or training track. Atopy in bakers/pastry makers and sensitization to alkaline persulfates in hairdressers were also independently associated with the incidence of BHR. BHR occurred sooner among bakers/pastry makers than among hairdressers, but its incidence leveled off later. CONCLUSIONS: Our results suggest that measurement of Fe(NO), a simple and reproducible test, could be useful in the screening of BHR in workers newly exposed to agents known to cause occupational asthma.

Early markers of airways inflammation and occupational asthma: rationale, study design and follow-up rates among bakery, pastry and hairdressing apprentices.

BACKGROUND: Occupational asthma is a common type of asthma caused by a specific agent in the workplace. The basic alteration of occupational asthma is airways inflammation. Although most patients with occupational asthma are mature adults, there is evidence that airways inflammation starts soon after inception of exposure, including during apprenticeship. Airways hyper responsiveness to methacholine is a valid surrogate marker of airways inflammation, which has proved useful in occupational epidemiology. But it is time-consuming, requires active subject's cooperation and is not readily feasible. Other non-invasive and potentially more useful tests include the forced oscillation technique, measurement of fraction exhaled nitric oxide, and eosinophils count in nasal lavage fluid. METHODS AND DESIGN: This study aims to investigate early development of airways inflammation and asthma-like symptoms in apprentice bakers, pastry-makers and hairdressers, three populations at risk of occupational asthma whose work-related exposures involve agents of different nature. The objectives are to (i) examine the performance of the non-invasive tests cited above in detecting early airways inflammation that might eventually develop into occupational asthma; and (ii) evaluate whether, and how, constitutional (e.g. atopy) and behavioural (e.g. smoking) risk factors for occupational asthma modulate the effects of allergenic and/or irritative substances involved in these occupations. This paper presents the study rationale and detailed protocol. DISCUSSION: Among 441 volunteers included at the first visit, 354 attended the fourth one. Drop outs were investigated and showed unrelated to the study outcome. Sample size and follow-up participation rates suggest that the data collected in this study will allow it to meet its objectives.

Reproducibility of exhaled nitric oxide in smokers and non-smokers: relevance for longitudinal studies.

BACKGROUND: Currently, there is much interest in measuring fractional exhaled nitric oxide (FENO) in populations. We evaluated the reproducibility of FENO in healthy subjects and determined the number of subjects necessary to carry out a longitudinal survey of FENO in a population containing smokers and non-smokers, based on the assessed reproducibility. METHODS: The reproducibility of FENO was examined in 18 healthy smokers and 21 non-smokers. FENO was assessed once at 9 AM on five consecutive days; in the last day this measurement was repeated at 2 PM. Respiratory symptoms and medical history were assessed by questionnaire. The within- and between-session repeatability of FENO and log-transformed FENO was described. The power of a longitudinal study based on a relative increase in FENO was estimated using a bilateral t-test of the log-transformed FENO using the between-session variance of the assay. RESULTS: FENO measurements were highly reproducible throughout the study. FENO was significantly higher in males than females regardless of smoking status. FENO was positively associated with height (p < 0.001), gender (p < 0.034), smoking (p < 0.0001) and percent FEV1/FVC (p < 0.001) but not with age (p = 0.987). The between-session standard deviation was roughly constant on the log scale. Assuming the between-session standard deviation is equal to its longitudinal equivalent, either 111 or 29 subjects would be necessary to achieve an 80% power in detecting a 3% or a 10% increase in FENO respectively. CONCLUSION: The good reproducibility of FENO is not influenced by gender or smoking habits. In a well controlled, longitudinal study it should allow detecting even small increases in FENO with a reasonable population size.

Relationships of physical job tasks and living conditions with occupational injuries in coal miners.

This study assessed the relationships of job tasks and living conditions with occupational injuries among coal miners. The sample included randomly selected 516 underground workers. They completed a standardized self-administred questionnaire. The data were analyzed via logistic regression method. The rate of injuries in the past two years was 29.8%. The job tasks with significant crude relative risks were: power hammer, vibrating hand tools, pneumatic tools, bent trunk, awkward work posture, heat, standing about and walking, job tasks for trunk and upper/lower limbs, pain caused by work, and muscular tiredness. Logistic model shows a strong relationship between the number of job tasks (JT) and injuries (adjusted ORs vs. JT 0-1: 2.21, 95%CI 1.27-3.86 for JT 2-6 and 3.82, 2.14-6.82 for JT>or=7), and significant ORs>or=1.71 for face work, not-good-health-status, and psychotropic drug use. Musculoskeletal disorders and certain personality traits were also significant in univariate analysis. Therefore job tasks and living conditions strongly increase the injuries, and occupational physicians could help workers to find remedial measures.

Habitual loud snoring. A study of prevalence and associations in 850 middle-aged French males.

BACKGROUND: Most studies on habitual snoring have focused on its prevalence. However, from the clinical point of view, the intensity of snoring is of upmost importance, as it suggests the existence of sleep apnoeas. OBJECTIVES: The aim of the study was to assess the prevalence of loud snoring using a standard questionnaire and to evaluate the anthropometric and sleep characteristic differences between loud and light snorers in a sample of middle-aged males. METHODS: The subjects were middle-aged active male employees. They completed a structured sleep questionnaire and had standard anthropometric measurements. Subjects reporting habitual snoring (> or =3 nights/week) were further classified as loud or light snorers. RESULTS: Of the 850 male subjects volunteering, 149 (17.5%) were habitual loud snorers. Loud snorers were older and had a greater waist-to-hip ratio as compared with light snorers. In univariate analysis, loud snoring was associated with gasping/snorting during sleep, breathing stops during sleep, waking up too early, excessive daytime sleepiness and falling asleep while watching TV. Logistic regression identified four independent associates of loud snoring: gasping during sleep, excessive daytime sleepiness, falling asleep watching TV and age. CONCLUSIONS: Loud snoring is present in a significant proportion of middle-aged men and is associated with central obesity and age. It disturbs sleep and elicits significant daytime sleepiness. Its association with breathing pauses (univariate) and its independent association with gasping during sleep suggests that loud snoring could be considered a clinical correlate of obstructive sleep apnoeas.

Relationships of job and some individual characteristics to occupational injuries in employed people: a community-based study.

This study assessed the associations of job and some individual factors with occupational injuries among employed people from a general population in north-eastern France; 2,562 workers were randomly selected from the working population. A mailed auto-questionnaire was filled in by each subject. Statistical analysis was performed with loglinear models. The annual incidence rate of at least one occupational injury was 4.45%. Significant contributing factors for occupational injuries were job category (60.8%), sex (16.2%), regular psychotropic drug use (8.5%), age groups (7.5%), and presence of a disease (7.0%). The men had higher risk than the women (adjusted odds-ratio 1.99, 95% CI 1.43-2.78). Compared to executives, intellectual professionals and teachers, labourers had the highest risk (6.40, 3.55-11.52). They were followed by farmers, craftsmen and tradesmen (6.18, 2.86-13.08), technicians (3.14, 1.41-6.70), employees (2.94, 1.59-5.48) and other subjects (3.87, 1.90-7.88). The young (< or = 29 yr) showed an increased risk. Similar odds-ratios were observed for regular psychotropic drug use (1.54, 1.16-2.05) and the presence of a disease (1.50, 1.11-2.02). Univariate analysis showed that smoking habit, overweight and excess alcohol use were also associated with injuries. The loglinear model results showed that there were associations between some of these independent factors. It was concluded that job, sex, young age, smoking habit, excess alcohol use, overweight, psychotropic drug use, and disease influenced the occupational injuries. Preventive measures concerning work conditions, risk assessment and job knowledge should be conducted in overall active population, especially in men, young workers, smokers, alcohol users, overweight workers and in individuals with a disease or psychosomatic disorders.

Reliability of the Wisconsin Sleep Questionnaire: a French contribution to international validation.

We evaluated the reliability of a French version of the Wisconsin Sleep Questionnaire designed to investigate snoring, obstructive apnoeas, and sleeping problems. The assessment of reliability included the study of internal consistency and the 3 months repeatability of the questionnaire. The questionnaire was first completed at a Center of Preventive Medicine by a random sample of 122 subjects from the community. Three months later the same form was mailed and 82 questionnaires were returned (67.2%). No significant differences existed between responders and nonresponders for anthropometric data or life habits. The internal consistency in each domain was good or satisfactory (Cronbach's alpha=0.67 to 0.81). The concordance between the answers at a 3-month interval was excellent for questions on ever snoring, frequency of snoring, gasping/choking during sleep, and breathing stops during sleep (Cohen kappa>0.60). The questions on snoring loudness, a history of sleep apnoea, and excessive daytime sleepiness were fairly reproducible (kappa 0.28 to 0.60). We found no difference in reproducibility by gender or age. In conclusion, this reliability assessment in a sample of middle-aged subjects from the community in northeastern France showed satisfactory internal consistency and 3-months reproducibility of the main questions of a French translation of the Wisconsin Sleep Questionnaire.

Who are the "occasional" snorers?

STUDY OBJECTIVES: To assess the prevalence of occasional snoring in a group of middle-aged men, and to compare anthropometric variables and prevalence of sleep-related symptoms of subjects who occasionally snore with those of other snoring categories. DESIGN: A field survey of a sample of middle-aged men in France. PARTICIPANTS: Male employees of a local university and subjects from the community attending a preventive medicine center. Participation rate was 93.5%. MEASUREMENTS: Anthropometric variables were recorded in 499 subjects aged 23 to 66 years (mean, 44.3 years). The subjects completed a standard sleep questionnaire and were classified according to the snoring frequency as never, rarely, sometimes, occasional, several nights per week, and every night. The subjects who snore occasionally represented 8.6% of the total. RESULTS: The anthropometric data of subjects who snore occasionally were similar to those of subjects who habitually snore. When compared with subjects who do not snore, older age and a larger neck girth were significant. Subjects who snore occasionally were also significantly more often subjects who snore loudly, and tended more frequently to have breathing stops during sleep. CONCLUSIONS: Our epidemiologic study shows that approximately 9% of a sample of middle-aged men snore occasionally. Subjects who snore occasionally have anthropometric characteristics close to those of subjects who snore habitually. The prevalence of the main sleep-related symptoms is between that of subjects who do not snore and of subjects who snore habitually. In an epidemiologic setting, inclusion of subjects who snore occasionally as subjects who do not snore or subjects who snore habitually will lead to bias. The present results suggest they should be identified and considered as a separate category.

Bronchial challenge testing in occupational epidemiology: is the diluent step really necessary?

BACKGROUND: There is no unanimous agreement on the use of a diluent step to preface methacholine challenge testing. The "pros" for this step are that it allows a better training of the patient; the "cons" are that it requires additional time and effort. OBJECTIVE: We examined if there were any systematic effects when either the baseline or postdiluent (saline) forced expiratory volume in 1 second (FEV1) was used to define the reactivity status. METHODS: All methacholine challenge tests performed during a 1-year period by a group of occupationally exposed workers (n = 183) were examined. RESULTS: The mean percentage change in FEV1 from baseline to postsaline was -1.44 (+/- 3.47)% and the mean absolute change was -0.043 (+/- 0.11) L (P < 0.0001 for both comparisons). The maximum decrease and increase in FEV1 from baseline were -12.7% and +10.9%, respectively. Three subjects had a fall in FEV1 after saline of 10% or more and were not given methacholine. From the remaining 180 subjects, 172 were equally classified as reactors (n = 67) or nonreactors (n = 105), both by baseline FEV1 and postsaline FEV1. Eight subjects were classified as reactors by baseline FEV1 but as nonreactors by saline FEV1. In these subjects, the average FEV1 dropped 4.9% from baseline to saline and 17.3% from saline to end-test; thus, the total FEV1 drop (22.5%) exceeded the 20% required for the test to be positive. Among reactors, no relationship was found between the response to saline and the subsequent response to methacholine (r = 0.13). CONCLUSIONS: Our data did not provide evidence to support the compulsory use of a diluent step when measuring bronchial responsiveness in populations. In general, the diluent step added time and expense to the test and, on occasion, forced a greater absolute drop in FEV1 than is needed to demonstrate bronchial hyperresponsiveness.

Not only training but also exposure to chlorinated compounds generates a response to oxidative stimuli in swimmers.

Relations between exposure to chlorinated compounds and biological markers of response to oxidative stimuli were investigated in swimmers, taking into account the effect of training. Twenty-two male swimmers aged 15-25 years were surveyed twice. Prevalence of irritant symptoms and asthma and number of hours of training were reported. Exposure to nitrogen trichloride (NCl3) and blood response to oxidative stimuli [catalase, superoxide dismutase (Cu2+/Zn2+ SOD), glutathione peroxidase (GSH-Px) activities and ceruloplasmin, ferritin and total antioxidant concentrations] were measured. Univariate analyses were completed by multivariate analyses. High prevalences of irritant symptoms and asthma were found. Multivariate analysis confirmed the results of the univariate analyses and showed that Cu2+/Zn2+ SOD activity was increased by exposure and by training (P = 0.01, P = 0.0001, respectively). Erythrocyte GSH-Px was decreased, whereas plasma GSH-Px was increased by exposure (P = 0.002, P = 0.002). No other association was found. Higher irritant symptoms and increases in the activities of erythrocyte Cu2+/Zn2+ SOD and of plasma GSH-Px with exposure support the hypothesis that the production of reactive oxygen species is not only related to training but also to exposure to chlorinated compounds. Other athletes tend to have respiratory problems such as asthma, but the exposure to chlorinated compounds may increase the respiratory disease among swimmers.