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Biomedical subjects

B Rijcken

Publications and source records attributed to B Rijcken.

54 records · Page 3Linked to original sources
PubMed1994

Airway hyperresponsiveness, prevalence of chronic respiratory symptoms, and lung function in workers exposed to irritants.

The association between occupational exposure to airway irritants and the prevalence of chronic respiratory symptoms and level of lung function, and whether these associations were modified by airway hyperresponsiveness, smoking, and a history of allergy were studied in 668 workers from synthetic fibre plants. Respiratory symptoms were recorded with a self administered Dutch version of the British Medical Research Council questionnaire, with additional questions on allergy. Airway responsiveness was measured by a 30 second tidal breathing histamine challenge test. On the basis of job titles and working department, the current state of exposure of all workers was characterised as (1) no exposure, reference group; (2) white collar workers; (3) SO2 HCl, SO4(2); (4) polyester vapour; (5) oil mist and vapour; (6) polyamide and polyester vapour; (7) multiple exposure. Workers exposed to airway irritants were not simultaneously exposed to airborne dust. Airway hyperresponsiveness (AHR), defined as a 20% fall in forced expiratory volume in one second (FEV1) at < or = 32 mg/ml histamine, was present in 23% of the subjects. The association between exposure groups and prevalence of symptoms was estimated by means of multiple logistic regression; the association with level of lung function (forced vital capacity (FVC), FEV1, maximum mid-expiratory flow rate (MMEF)) was estimated by means of multiple linear regression. Both methods allow simultaneous adjustment for potential confounding factors. The exposure groups were associated with a higher prevalence of chronic respiratory symptoms. Lower prevalence of symptoms was found for workers exposed to SO2, HCl, and SO4(2-), most likely due to pre-employment selection procedures. Current smoking, AHR, and a history of allergy were significantly associated with a higher prevalence of chronic respiratory symptoms, independent of each other, and independent of irritant exposure. The association between exposure and prevalence of symptoms was greater in smokers than in ex-smokers and non-smokers. This difference was most clearly seen in the polyester vapour and polyamide and polyester vapour group. No modification of the association between exposure groups and prevalence of symptoms by airway hyperresponsiveness could be shown. The exposure groups were not significantly associated with a lower level of lung function. Adjustment for chronic respiratory symptoms did not change the results. There were no indications of a possible interaction between exposure and AHR, current smoking, or a history of allergy on lung function. Workers of the polyester vapour and the oil mist and vapour group with >10 years of exposure had a lower FEV1 (beta = -295 and -358 ml) and significantly lower MMEF (beta = -1080 and -1247 ml/s; p < 0.05) than the reference group. The number of workers of both group were, however, small (n = 10 and n = 13 respectively). More investigations between low level exposure to irritant and respiratory health.

Adult↗
PubMed1994

Discrepancies between longitudinal and cross-sectional change in ventilatory function in 12 years of follow-up.

We compared the age dependence of cross-sectional and longitudinal changes in ventilatory function. FEV1, FVC, and data on chronic respiratory symptoms were obtained from 4,395 adults in a longitudinal survey of normal populations in two different areas in the Netherlands. They participated in up to five surveys at 3-yr intervals between 1972 to 1973 and 1984 to 1985. The ventilatory function in the oldest cohorts is substantially lower than might have been expected from the longitudinal change in the youngest cohorts. This holds for males and females, smokers and nonsmokers, subjects with or without symptoms, and for both survey populations. The robustness of the findings is demonstrated by various data-analytic strategies or omitting one or two of the five surveys from the analysis. Selective loss to follow-up cannot explain the discrepancy. It is concluded that the main differences between our longitudinal and cross-sectional findings may be due to a cohort effect. The implication is that in longitudinal studies of populations at risk, reference equations based on cross-sectional surveys may overestimate longitudinal change and hence lead to underestimating effects of exposure. Similarly, in clinical studies, accelerated decline in ventilatory function may be underrated if it is compared with cross-sectional standards. In older people at any one age the ventilatory function seems to improve in successive birth cohorts.

Adult↗
PubMed1994

Distribution of peak expiratory flow variability by age, gender and smoking habits in a random population sample aged 20-70 yrs.

Peak expiratory flow (PEF) variability can be considered as an index of bronchial lability. Population studies on PEF variability are few. The purpose of the current paper is to describe the distribution of PEF variability in a random population sample of adults with a wide age range (20-70 yrs), and to assess relationships to age, gender and smoking habits. PEF data were collected in 511 participants of the Dutch part of the European Community Respiratory Health Survey. A training effect was found, absolute PEF values on the first measurement day being significantly lower. Females had greater PEF variability (adjusted for age, height and pack-years) and lower absolute PEFs than males. The mean within-day variation (amplitude % mean) was 3.66% (SD 2.03%), whereas the mean day-to-day variation was relatively small: 0.08% (SD 1.53%). Absolute PEFs were lower and amplitude % mean were significantly higher in older age groups. Smoking was significantly associated with lower mean PEFs and greater amplitude % mean. We observed lower mean values of the amplitude % mean than other investigators, possibly related to lower frequency of PEF recording (twice daily). We conclude that PEF and PEF variability have a normal or log-normal distribution. When studying PEF variability, age, gender and smoking habits should be taken into account.

Adult↗
PubMed1994

Smoking, changes in smoking habits, and rate of decline in FEV1: new insight into gender differences.

We wanted to test the hypothesis that gender differences in effects of smoking on the rate of decline in pulmonary function may be related to gender differences in the frequency of smoking. Data from the Vlagtwedde-Vlaardingen study in The Netherlands were analysed, to investigate the rate of decline in forced expiratory volume in one second (delta FEV1) in relation to smoking status and gender. 4,554 participants, initially aged 15-54 yrs, provided 16,900 pairs of observations at 3 yr intervals over 24 yrs of follow-up. Lifetime nonsmokers accounted for 11% of male participants and 45% of female participants. Compared with lifetime nonsmokers, estimated excess delta FEV1 for light, moderate, and heavy continued smokers was 4.4, 9.5 and 13.5 ml.yr-1 for men and 6.1, 10.8 and 18.8 ml.yr-1 for women, respectively. Female former smokers had a significantly more rapid delta FEV1 (beta = 4.4, SE = 1.6 ml.yr-1) than lifetime nonsmokers; but male former smokers had a slower rate of decline (beta = 4.1, SE = 2.3 ml.yr-1) than lifetime nonsmokers. Overall gender difference in smoking effects on delta FEV1 was statistically significant. Among subjects who smoked an identical amount at the beginning of the study period those who quit smoking during the period had a significantly slower delta FEV1 than those who continued smoking, for both men (beta = 20.6, SE = 3.9 ml.yr-1) and women (beta = 15.7, SE = 3.4 ml.yr-1). Younger quitters (< 45 yrs) benefited significantly more from smoking cessation than older quitters (> or = 45 yrs).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Factors associated with bronchial responsiveness to histamine in a population sample of adults.

The association of age, gender, number of eosinophils, area of residence, cigarette smoking, respiratory symptom prevalence, and FEV1 with the level of bronchial responsiveness was studied in a random sample of 2,216 subjects aged 15 to 72 yr. Subjects participated in the Dutch longitudinal study on chronic obstructive pulmonary disease. In 18 yr of follow-up, 5,012 observations were collected. Interviewers used a standardized questionnaire to assess the presence of respiratory symptoms. Bronchial responsiveness was measured by a histamine challenge test. Because multiple measurements within a subject are correlated, multivariate regression methods for correlated outcome were used. A greater number of eosinophils, skin test positivity, and living in a rural area (Vlagtwedde) were associated with increased responsiveness, independently of the level of FEV1 and the presence of respiratory symptoms. Older age was associated with increased responsiveness, and this was even more so in subjects with symptoms. Cigarette smokers were more responsive than nonsmokers, but this association was not significant if the level of FEV1 was taken into account. Hyperresponsiveness was more likely to be present if the amount of cigarettes smoked per day was greater. The level of responsiveness did not differ significantly between males and females. For the same degree of obstruction, however, expressed as the FEV1/VC ratio, males tended to be less responsive than females. The analyses were repeated using the dose-response slope as a continuous measure of responsiveness and by applying a method to adjust for censoring the responsiveness data. These analyses yielded identical results.

Adult↗
PubMed1993

Long-term variability of bronchial responsiveness to histamine in a random population sample of adults.

Long-term variability of bronchial responsiveness has been studied in a random population sample of adults. During a follow-up period of 18 yr, 2,216 subjects contributed 5,012 observations to the analyses. Each subject could have as many as seven observations. Bronchial responsiveness was assessed with a histamine challenge test. The threshold value was defined as the concentration of histamine that caused a decrease in FEV1 of 10% of more (PC10). After a 3-yr interval, a change of the threshold value with two or more doubling concentrations occurred in 21% of the subjects. This proportion increased to 43% if the time between two measurements increased to 18 yr. Of all subjects with multiple observations, 41% were always nonresponders (PC10 > or = 32 mg/ml), 11% were always responders (PC10 < or = 16 mg/ml), and 48% changed responder status. Of the subjects with greater than three observations, 65% changed responder status. Regression analyses, stratified by symptom status, sex, and smoking habit, were used to estimate intraclass correlation coefficients (ICC) as a measure of variability of responsiveness. On average, ICC values were low (0.40), also indicating considerable variability. With adjustment for FEV1, age, area of residence, and eosinophil count, the ICC values decreased slightly. This indicated that with adjustment, the total variability decreased more than the within-subject variability. ICC values did not differ significantly between asymptomatic and symptomatic subjects. Analyses of responsiveness as a binary variable revealed similar results.

Adolescent↗
PubMed1992

Perception of airway obstruction in a random population sample. Relationship to airway hyperresponsiveness in the absence of respiratory symptoms.

Subjects with asymptomatic airway hyperresponsiveness in epidemiologic studies may have variable airway obstruction that is not perceived as dyspnea. We tested the hypothesis that such subjects are less likely to report an increase in dyspnea during histamine-induced bronchoconstriction than symptomatic hyperresponders. A random population sample of 412 middle-aged subjects was studied. Before and after a standardized histamine challenge test, subjects recorded Borg scores for dyspnea: any increase in Borg score was considered significant. More than 80% of hyperresponsive subjects (PC10 histamine < or = 16 mg/ml) had no symptoms. The presence of prechallenge dyspnea was related to increased airways responsiveness and current smoking. An increase in Borg score was associated with younger age, more severe airway responsiveness, atopy, and female sex. The level of and increase in the Borg score were not significantly related to level and change in airway caliber (FEV1). In hyperresponsive subjects (PC10 < or = 16 mg/ml), subjects who reported dyspnea, wheeze, or asthma were more likely to show an increase in Borg score during histamine provocation than asymptomatic subjects (adjusted odds ratio 4.01, 95% confidence interval 1.01 to 16.00, p = 0.049), after adjustment for age, sex, smoking habits, FEV1, and atopy. This suggests that asymptomatic hyperresponders may have variable airway obstruction that is not recognized as breathlessness.

Adult↗
PubMed1992

Reproducibility of childhood respiratory symptom questions.

The reproducibility of answers to childhood respiratory symptom questions was investigated by administering two childhood respiratory symptom questionnaires twice, with a one month interval, to the same population of Dutch school children. The questionnaires were completed by the parents of 410 children from 6-12 yrs old. One questionnaire was developed by the World Health Organization (WHO). The other questionnaire was developed for use by school health services and was based mainly on the American Thoracic Society (ATS) questionnaire for respiratory symptoms in childhood. It was called the Child Health Care (CHC) Questionnaire. Half of the parents received a questionnaire in which the WHO questions came first on both occasions, the other half a questionnaire in which the CHC questionnaire came first on both occasions. The reproducibility of the answers was assessed by calculating Cohen's Kappa, a chance-corrected measure of association. Questions about "wheeze", "asthma", "bronchitis", "cough and phlegm", and "pneumonia" were found to give good to excellent reproducibility, with Kappa values ranging from 0.60-0.96. Questions about "phlegm", "cough", "chest congestion" and "runny/congested nose" were less satisfactory in this respect, with Kappa values generally well below 0.60. The reproducibility of the answers did not depend on the order in which the questionnaires were administered, on the gender or age of the child, or on the smoking habits or educational level of the parents.

Child↗
PubMed1991

Is it useful to distinguish between asthma and chronic obstructive pulmonary disease in respiratory epidemiology.

Disagreement exists on how to define asthma in population studies. Features characteristic of asthma also have been demonstrated in nonasthmatic subjects. For example, although in a random sample of 339 subjects investigated in the Netherlands, subjects with a history of asthmatic attacks, wheeze and/or dyspnea, or chronic dry cough on average were the most responsive (mean PD20 values for histamine of 11.5, 17.0, and 15.0 mg/ml) and asymptomatic subjects were the least responsive (mean PD20, 45.4 mg/ml), the distributions of PD20 values in all groups overlapped considerably. The best way to investigate the association between exposure and disease is in a cohort study. It is argued that follow-up studies in patients may have limited meaning because of a high risk for selection bias. Furthermore, in general, diagnostic disease entities will not represent homogeneous exposure groups. It is concluded that end points of disease should be defined as objectively as possible, for instance, as the level of FEV1, or as simple respiratory symptoms such as dyspnea, wheeze, or chronic cough. Terms such as "asthma," "COPD," or "CNSLD" will not be helpful in defining end points because there is a risk that they could introduce bias, misclassification, and hence confusion.

Asthma↗
PubMed1990

The relationship of eosinophilia and positive skin test reactivity to respiratory symptom prevalence in a community-based population study.

We studied the relationship of the prevalence of a variety of respiratory symptoms to positive skin test reactivity (skin test index greater than or equal to 3) and/or eosinophilia (greater than or equal to 275 eosinophilic cells per cubic millimeter of blood) in a community-based population sample (N = 2805), adjusting for age, gender, area of residence, and cigarette smoking. We considered subjects with neither positive skin test reactivity nor eosinophilia to be the reference group. Positive skin test reactivity without eosinophilia (N = 487; 17.3%) was significantly associated with persistent wheeze (odds ratio value (OR) = 1.6; 95% confidence interval of the odds ratio value (CI) = 1.0 to 2.6) and with asthmatic attacks (OR = 3.2; CI = 2.0 to 5.3). Positive skin test reactivity in combination with eosinophilia (N = 92; 3.3%) was also significantly associated with persistent wheeze (OR = 2.7; CI = 1.2 to 6.0) and with asthmatic attacks (OR = 10.4; CI = 5.3 to 20.2), however, with a stronger association than in subjects with positive skin test reactivity alone. Finally, eosinophilia without positive skin test reactivity (N = 170; 6.1%) was significantly associated with chronic cough (OR = 1.8; CI = 1.2 to 2.7), bronchitis episodes (OR = 2.1; CI = 1.4 to 3.2), dyspnea grade greater than or equal to III (OR = 1.7; CI = 1.0 to 2.8), and asthmatic attacks (OR = 3.0; CI = 1.5 to 6.6).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Incidence of diseases of the lower respiratory tract in family practice and low level air pollution.

A simple contact registration in family practices in an urban area in the Netherlands was shown to be a suitable instrument for measuring and analysing the incidence of diseases of the lower respiratory tract. This incidence showed a topographical and a temporal variation. The topographical component was related to the sulphur dioxide (SO2) air pollution in the different districts. The temporal component consisted partly of seasonal variations and partly of short-term variations. A moderate effect of the SO2 air pollution on the temporal variation was observed, but it was weak, possibly owing to the relatively low levels of SO2 in Amsterdam. The present study shows that contact registration in family practices may yield useful data for epidemiological analysis.

Adolescent↗
PubMed1989

The distribution of bronchial responsiveness to histamine in symptomatic and in asymptomatic subjects. A population-based analysis of various indices of responsiveness.

The distribution of bronchial responsiveness (BR) and the place of symptomatic subjects in this distribution was investigated in a random population sample of 339 subjects who participated in the 1984 survey of the Vlagtwedde/Vlaardingen Study. BR was assessed by a histamine provocation test. The following indices of BR were used: (1) a histamine threshold both at 10 and at 20% decreases in FEV1 (PC10 and PC20); (2) the concentration causing a 10 or a 20% decrease estimated by linear interpolation (IPC10 and IPC20), and by linear regression of all data points (PD10 and PD20); (3) the slope of the linear regression line through all data points (SAP) and the slope of the line through the origin and the last data point (SOL). Disease was defined as the self-reported presence of respiratory symptoms from a respiratory symptom questionnaire. Bronchial challenge was considered as a test to predict symptom prevalence. Receiver-operator characteristic curves were applied to define optimal cutoff points for each of the indices used to define a positive and a negative test. For each index, sensitivity, specificity, predictive value of a positive and negative test, and efficiency rate of the test were calculated. The overall distribution of BR in this population appeared to be log normal for the different continuous indices. Subjects with symptoms were on the more responsive tail of the distribution. After adjusting for age, sex, smoking habit, and level of pulmonary function, the mean log-transformed values of PD10, PD20, SAP, and SOL for the various symptom groups differed significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

The relationship between airway responsiveness to histamine and pulmonary function level in a random population sample.

The association of nonspecific bronchial responsiveness (BR) with pulmonary function level has been studied in a random population sample of 2,156 male and female subjects 15 to 64 yr of age participating in the Vlagtwedde-Vlaardingen field survey on chronic obstructive pulmonary disease (COPD) being conducted in the Netherlands. About 25% of the subjects responded with a decrease in baseline FEV1 of 10% or more after challenge with histamine in a concentration of 16 mg/ml or less inhaled over 30 s (PC10). In a stratified analysis, pulmonary function level appeared to be associated with BR in a dose-response relationship. The mean %FEV1 was consistently lower in the more responsive subjects. This relationship was confirmed in linear regression analyses, adjusting for age, sex, area of residence, and smoking habits. Exclusion of subjects with %FEV1 less than 80% diminished but did not change the association between FEV1 and BR. The magnitude of the effect of responsiveness on level of pulmonary function was considerable and statistically significant. In the subjects older than 21 yr of age, male responders (PC10 at less than or equal to 16 mg/ml) on average had an adjusted FEV1 of 32.5 centiliters less than nonresponders, and female responders had an adjusted FEV1 of 30.5 centiliters less (p less than 0.001). BR appeared to be an independent predictor of pulmonary function level after adjustment for age, sex, area of residence, respiratory symptom prevalence, and cigarette smoking. The effect of cigarette smoking on pulmonary function level in this population sample was significant only in men older than 21 yr of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

The relationship of nonspecific bronchial responsiveness to respiratory symptoms in a random population sample.

The relationship of airway responsiveness to respiratory symptom prevalence has been studied in a cross-sectional analysis of a random subpopulation from a large-scale population study on chronic obstructive pulmonary disease (COPD) being conducted in the Netherlands. In 1,905 subjects with complete data on age, sex, area of residence, smoking habits, and respiratory symptom prevalence, airway responsiveness was assessed by a histamine challenge test. Subjects with a decrease in FEV1 of greater than or equal to 10% at a histamine concentration of less than or equal to 16 mg/ml were considered to be responders. Bronchial hyperresponsiveness appeared to be age dependent, with the proportion of responders increasing from 13% in those 14 to 24 yr of age to 40% in those 55 to 64 yr of age (p less than 0.001). Respiratory symptom outcomes included chronic cough, chronic phlegm, dyspnea, bronchitic episodes, persistent wheeze, and asthmatic attacks. Respiratory symptom prevalence rates were significantly higher in responders (p less than 0.001 for all symptoms). Cigarette smoking is known to be related to respiratory symptom prevalence and possibly to bronchial responsiveness. Because of these associations, we examined the relationship of bronchial responsiveness to respiratory symptoms within cigarette smoking categories. For all respiratory symptoms, it was found that, regardless of smoking category, responders were more likely to be symptomatic than were nonresponders. Odds ratios ranged from 1.7 for chronic cough to 4.4 for asthmatic attacks.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Epidemiology of chronic obstructive pulmonary disease (COPD).

Epidemiology can contribute in the fight against COPD by: providing information necessary for planning and management of health care; contributing to the knowledge of natural history and etiology, which is important for treatment and prevention; providing information for early detection and for clinical decision making.

Adolescent↗
PubMedDate not supplied

The association of airways responsiveness to respiratory symptom prevalence and to pulmonary function in a random population sample.

In a random population sample of 1905 subjects we studied the occurrence of respiratory symptoms in relation to airways responsiveness. Responders (PC10 FEV1 to histamine at 16 mg.ml-1 or less) had crude prevalence rates two to three times higher than nonresponders. In logistic regression analysis, odds ratios were estimated for each threshold value, compared to the reference value (greater than 32 mg.ml-1), controlling for age, sex, area of residence, and smoking habit. Odds ratios increased with decreasing threshold values in a dose-response relationship for all symptoms, except for bronchitis periods. We analysed the association of airways responsiveness to pulmonary function level by multiple linear regression, controlling for age, sex, height, area of residence, and smoking habit. There was an inverse relationship of FEV1 level to threshold value. Male subjects within a threshold value of 1 mg.ml-1 had a mean adjusted FEV1 of 1170 ml less than males with a threshold value of greater than 32 mg.ml-1. The relationship of responsiveness to decline of FEV1 with time was studied in 186 male subjects who took part in five consecutive surveys from 1967 to 1981. The greatest mean adjusted yearly decline was noted in responding smokers: 35.3 ml per yr, compared to nonreactive nonsmokers: 10.9 ml per yr. Regression analysis of the yearly decline in 169 subjects with at least two pairs of two consecutive threshold tests revealed that the more positive tests subjects had, the greater was their mean adjusted yearly decline. It is concluded that airways responsiveness may be an important factor in the development of chronic obstructive pulmonary disease.

Adult↗