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Biomedical subjects

A Dirksen

Publications and source records attributed to A Dirksen.

At least 73 records · Page 4Linked to original sources
PubMed1996

Long-term performance of a hand held spirometer.

BACKGROUND: A study was undertaken to test the long term performance of a small hand held spirometer for self-administered serial spirometric testing. METHODS: Thirty turbine pocket spirometers (MicroMedical DiaryCard) were used in a clinical trial on 22 emphysematous patients with severe alpha 1-antitrypsin deficiency. The spirometers were able to store the date, time, forced expiratory volume in one second (FEV1), forced vital capacity (FVC), peak expiratory flow (PEF), and flow-volume loop for each blow. Every four weeks when the patients came for alpha 1-antitrypsin infusions the performance of their spirometer was checked before and after retrieval of the data from the spirometer. Calibration checks were threefold and included volume calibration with a 1.0 litre and 3.0 litre syringe, and flow calibration with a decompression calibrator. RESULTS: After two years of study the mean number of spirometric recordings performed per spirometer was 693 (range 237-1178), and the mean number of calibration checks was 33 (range 2-57). The coefficient of variation of the calibration signal was 1-2% for syringes and 0.5-1% for the decompression calibrator. The bearings of one turbine exhibited excessive friction after 17 months. None of the other 29 instruments showed drift, and a general drift of all spirometers towards larger or smaller readings could not be shown. However, unforeseen problems in the stability of the calibrating devices were observed. CONCLUSIONS: The small hand held turbine spirometers are suitable for long term patient-administered serial spirometric testing. The two year durability is acceptable and the long term reproducibility excellent.

Calibration↗
PubMed1995

[Survival of patients with severe alpha 1-antitrypsin deficiency].

Previous estimates of survival of patients with alpha-1-antitrypsin deficiency (alpha 1ATD) have been based on selected patients. In this paper we have compared the survival of 397 patients with severe alpha-1-antitrypsin deficiency either ascertained because of pulmonary impairment (index cases) or ascertained through family studies (non-index cases). The patients were drawn from the nationwide Danish alpha 1ATD register. The overall median survival was 54.5 years with no significant difference between males and females. Survival for index cases was less than for the non-index cases regardless of smoking history (49.4 years and 69.3 years respectively). When we analyzed index cases and non-index cases separately there was no difference between the survival of smokers and never-smokers in the index group. In the non-index group smokers had a shorter survival than never-smokers. The survival of non-index never-smokers was similar to the survival of the normal Danish population. We conclude that the prognosis of severe alpha 1ATD is better than previously assumed, and that although smoking is a major risk factor the development of emphysema in patients with severe alpha 1ATD is multifactorial.

Adult↗
PubMed1995

Extrinsic and intrinsic asthma from childhood to adult age: a 10-yr follow-up.

BACKGROUND: Asthma constitutes one of the most common chronic diseases in childhood, yet little is known about the factors that determine the outcome in childhood asthma. The purpose of this study was to describe various factors of potential importance for the outcome in children with intrinsic and extrinsic asthma. METHODS: Of 85 consecutive children, 5-15 years of age with asthma, 70 (82%) participated in a 10-yr follow-up examination. At the time of referral, all children underwent certain tests for asthma (case history, total IgE, skin prick tests, radioallergosorbent (RAST) tests and specific bronchial provocations). On the basis of these tests, 24 children had intrinsic asthma and 46 children had extrinsic asthma. RESULTS: At the follow-up examination, 60 of the 70 adults (86%, 20 with intrinsic asthma) had current symptoms; 54 of the 60(90%; 18 with intrinsic asthma) were receiving maintenance therapy. Both FEV1 %predicted and FEV1/FVC increased significantly (from 73% +/- 19% to 92% +/- 17% and from 75% +/- 13% to 80% +/- 12% respectively) from childhood to early adulthood (P < 0.0001 and P < 0.001), respectively); a matching amelioration of symptoms was observed (P < 0.0001). Adults with current symptoms had a significantly lower FEV1 %predicted at the time of follow-up (90% +/- 2% vs. 100% +/- 4%, P < 0.02) but not in childhood (73% +/- 20% vs. 71% +/- 10%) than adults who had ceased wheezing. CONCLUSIONS: In children with intrinsic asthma, the outcome seems to be predicted by a combination of the initial frequency of symptoms (P = 0.04), initial FEV1 (P = 0.002), active smoking (P = 0.001) and age at onset of respiratory symptoms (P = 0.001), whereas the initial FEV1 (P < 0.001) seems to be a strong predictor for the outcome in children with extrinsic asthma. These findings suggest that the pathogenic mechanisms underlying intrinsic and extrinsic asthma in children may differ.

Adolescent↗
PubMed1995

Decline in FEV1 among patients with severe hereditary alpha 1-antitrypsin deficiency type PiZ.

Severe alpha 1-antitrypsin (alpha 1-AT) deficiency is characterized by a decrease in serum alpha 1-AT to values < 20% of normal. Severe airflow obstruction, most commonly due to pulmonary emphysema secondary to the destruction of pulmonary elastic tissue, may develop at an early age in persons with alpha 1-AT deficiency. The purpose of this study was to estimate the annual decline in FEV1 (delta FEV1) in alpha 1-AT-deficient patients, to compare delta FEV1 in a referral population (index cases) with subjects found through family studies (nonindex cases), and to evaluate the role of smoking cessation on delta FEV1. One hundred and sixty-one subjects from the Danish alpha 1-AT-deficiency study who were older than 25 yr and who had a recorded smoking history and at least two spirometric examinations 1 yr apart were studied. The delta FEV1 for each individual was determined by regression analysis of FEV1 on follow-up time. The overall mean delta FEV1 was 81 ml/yr. There was no significant difference in delta FEV1 between 113 index cases and 48 nonindex cases even after controlling for age, initial FEV1, sex, and lifetime tobacco consumption. One hundred of the subjects were ex-smokers, 18 had never smoked, and 43 were current smokers. The mean delta FEV1 among the current smokers was 132 ml/yr, versus 52 ml/yr among the ex-smokers (p < 0.001). For the never-smokers, the mean delta FEV1 was 86 ml/yr.

Adult↗
PubMed1994

Allergen skin test reactivity in an unselected Danish population. The Glostrup Allergy Study, Denmark.

The aim of this study was to assess the distribution of allergen skin test reactivity in an unselected Danish population. A total of 793 subjects, aged 15-69 years, were invited, and 599 (75.5%) attended. The skin prick test was performed with standardized allergen extracts of high potency. Skin reactivity occurred in 28.4% of the subjects. The frequency of skin reactivity to the specific allergens ranged from 1.5% (Cladosporium) to 12.5% (Dermatophagoides pteronyssinus), and the frequencies of skin reactivity to the allergen groups (pollen, animal dander, house-dust mites, and molds) were 17.6%, 8.7%, 14.0%, and 3.2%, respectively. Young women appeared to reflect the average skin reactivity. When compared with young women, skin reactivity to animal dander was more probable in young men (odds ratio (OR) value = 2.6; 95% confidence interval (CI) of odds ratio value = 1.1-6.1). Current smokers were less likely than nonsmokers to be skin-reactive to pollen (OR = 0.4; 95% CI = 0.3-0.7). In conclusion, allergen skin test reactivity was common, and was related to sex, age, smoking history, and probably genetic predisposition.

Adolescent↗
PubMed1994

Survival of patients with severe alpha 1-antitrypsin deficiency with special reference to non-index cases.

BACKGROUND: Previous estimates of the survival times of patients with alpha 1-antitrypsin deficiency have been based on selected patients. METHODS: The survival times of 397 patients with severe alpha 1-antitrypsin deficiency identified by pulmonary impairment (index cases) or through family studies (non-index cases) were compared. RESULTS: The overall median survival time was 54.5 years with no significant difference between men and women. Survival for index cases was less than for the non-index cases regardless of smoking history (49.4 years and 69.3 years respectively). When index and non-index cases were analysed separately there was no difference between the survival of smokers and never smokers in the index group. In the non-index group smokers had a shorter survival time than never smokers. The survival time of never smokers was similar to that of the normal Danish population. CONCLUSIONS: The prognosis of severe alpha 1-antitrypsin deficiency is better than previously assumed and, although smoking is a major risk factor, the development of emphysema in patients with severe alpha 1-antitrypsin deficiency is multifactorial.

Adult↗
PubMed1994

Airways obstruction and two year survival in patients with severe alpha 1-antitrypsin deficiency.

Because of the limited number of donor organs available, the selection of patients for lung transplantation is crucial. One important issue in setting priorities is the life expectancy without transplantation. The purpose of this study was to estimate survival based on lung function, in alpha 1-antitrypsin deficient patients. Data from the Danish alpha 1-antitrypsin deficiency registry were analysed. The basic element of the analysis was two year intervals, characterized by date of spirometry and known mortality status 2 yrs later. We found a simple exponential relationship between lung function (forced expiratory volume one second (FEV1)) and two year survival on conservative treatment. The formula implies an almost 100% two year survival until FEV1 falls below one third of predicted normal; at this level two year mortality increases and will reach 50% at a FEV1 of 15% predicted. In conclusion, the two year mortality of emphysema patients due to alpha 1-antitrypsin deficiency increases exponentially with decreasing FEV1 and the results imply that only a few patients who underwent lung transplantation would have had a better two year prognosis without this procedure.

Denmark↗
PubMed1993

[Allergy and bronchial reactivity in children and adolescents from Copenhagen].

The relationship between bronchial responsiveness and the results of a skin prick test was studied in 527 children and adolescents from Copenhagen. All participants completed a questionnaire concerning birth weight, breastfeeding, month of birth, month of examination, allergic symptoms in themselves or their parents. Furthermore, skin prick test reactivity to nine common aero-allergens, lung function, serum IgE, and bronchial responsiveness to histamine and exercise were measured. A total of 158 (30%) subjects showed signs of allergy (defined as a positive reaction to the skin prick test), of whom 53 (10%) subjects had positive skin reactivity and 105 subjects had moderate skin reactivity; 366 (70%) subjects had no signs of allergic disease as measured by the pride test. The most important marker for the degree of bronchial responsiveness was asthma (p < 0.001), month of examination (p < 0.01) and allergy (skin reactivity to one or more allergens) (p < 0.05). Furthermore, the degree of bronchial responsiveness to inhaled histamine was significantly related to a history of asthma in two first degree relatives (p < 0.01) and the skin reactivity to house-dust mites (p < 0.01), whereas the degree of bronchial responsiveness to exercise was significantly associated with the level of serum IgE (p < 0.05), month of birth (p < 0.001) and birth weight (p < 0.05). In conclusion, allergy is an important risk factor for the presence of increased degree of bronchial responsiveness to inhaled histamine and to exercise.

Adolescent↗
PubMed1993

[The course of bronchial asthma in adults. Factors of importance for the annual decline of lung function].

The purpose of this study was to describe the relation of various factors of potential importance to the rate of decline in lung function in adults with intrinsic and extrinsic asthma. Of 180 asthmatic patients, 143 (79%) participated in a 10 year follow up examination; 94 patients had intrinsic asthma and 49 extrinsic asthma. Patients with intrinsic asthma had an annual decline in FEV1 of 50 ml, whereas those with extrinsic asthma had a decline of 23 ml; the rate of decline of lung function increased with increasing age in both groups. There was no relation between rate of decline in lung function and number of cigarettes smoked. An inverse relation between initial FEV1 and decline in FEV1 was found for the patients with extrinsic asthma but not for the patients with intrinsic asthma. A high degree of airway variability--that is, reversibility in FEV1--at the time of enrollment was found to be associated with a steeper decline in lung function in patients with intrinsic asthma, whereas increasing degrees of obstruction (decreasing FEV1/VC ratio at enrollment) and need for treatment with corticosteroids were associated with a more pronounced decline in FEV1 in patients with extrinsic asthma. The rate of decline in lung function is greater in patients with intrinsic asthma than in patients with extrinsic asthma; the prognosis for intrinsic and extrinsic asthma is to some extent influenced by different factors, which suggests that the pathogenetic mechanisms underlying intrinsic and extrinsic asthma may differ.

Adult↗
PubMed1993

Can subjects with a positive allergen skin test be selected by a short questionnaire? The Glostrup Allergy Study, Denmark.

The objective was to evaluate a postal questionnaire screening procedure for selection of subjects with positive reactions to skin prick tests with common allergens. The project consisted of a screening, with subsequent skin prick test of two selected groups. The setting was the Glostrup Population Studies institute in Copenhagen, Denmark. Participants in the screening included 8000 subjects, aged 15-69 years. The subjects were randomly selected from the population of western Copenhagen County, Denmark. From the 6998 respondents (87.5%), 793 subjects were randomly selected (Random Group), and 788 subjects were chosen on the basis of their answers to the questionnaire (Symptom Group). Both groups were invited to take skin prick tests. Attendance rates were 75.5% (Random Group) and 80.6% (Symptom Group). The main outcome measures were responses (yes or no) to the specific questions and the subjects' skin reaction (positive or negative). The association between symptoms and skin reactivity, adjusted for the effects of sex and age, was summarized by odds ratios. Symptoms on exposure to allergens were highly associated with positive skin reactivity. In the Symptom Group the percentage of subjects with at least one positive skin reaction was 57.7%, which was twice as much (28.4%) as in the Random Group. The results show that it was possible to select a group with high skin reactivity on the basis of the symptoms reported in the screening. Questions about exposure to allergens were the most appropriate for selection of this group.

Adolescent↗
PubMed1992

Distribution of serum IgE in children and adolescents aged 7 to 16 years in Copenhagen, in relation to factors of importance.

The distribution of total serum-IgE and factors of importance for the level of IgE was studied in a random sample of 508 children and adolescents, aged 7-16 years, from Copenhagen. A detailed history about asthma, rhinitis, dermatitis and urticaria was obtained, and a physical examination, skin prick test with 9 common allergens, lung function test, bronchial challenge with inhaled histamine and exercise, and measurement of IgE (kU/l) were performed. The distribution of IgE among children and adolescents was found to exhibit a log normal distribution and a positive skin prick test, allergic symptoms, a family history of allergic diseases, age and smoking were found to be significantly related to an increased level of IgE. No relationship was found between increased bronchial responsiveness and IgE. The geometric mean of "normal" values of IgE (*1 SD and *2 SD) of the Danish children and adolescents was 18 kU/l (*4.7, *18.2), suggesting that normal IgE values were within 330 kU/l. Measurement of IgE as the only screening for allergic disease is unreliable, as the predictive value of an elevated IgE in population samples was found to be 50%, whereas misclassification (1-specificity) of asymptomatic subjects as allergic because of an increased IgE was low (4%). In conclusion, total IgE is highly influenced by allergen skin reactivity. Further, this study suggests that normal IgE values were within 330 kU/l, although the range was wide.

Adolescent↗
PubMed1992

A 10 year follow up of 180 adults with bronchial asthma: factors important for the decline in lung function.

BACKGROUND: Little is known about the factors that determine outcome in asthma. The purpose of this study was to describe the relation of various factors of potential importance to the rate of decline in lung function in adults with intrinsic and extrinsic asthma. METHODS: Of 180 asthmatic patients, 143 (79%) participated in a 10 year follow up examination. At the time of enrollment all patients underwent certain tests for asthma (case history, total IgE, skinprick tests, the radioallergosorbent test (RAST), histamine release from basophil leucocytes, and specific bronchial provocations). On the basis of these tests 94 patients had intrinsic asthma and 49 extrinsic asthma. RESULTS: Patients with intrinsic asthma had an annual decline in FEV1 of 50 ml, whereas those with extrinsic asthma had a decline of 22.5 ml; the rate of decline of lung function increased with increasing age in both groups. An inverse relation between initial FEV1 and decline in FEV1 (the "horse racing effect") was found for the patients with extrinsic asthma but not for the patients with intrinsic asthma. There was no relation between rate of decline in lung function and number of cigarettes smoked. A high degree of airway variability--that is, reversibility in FEV1--at the time of enrollment was found to be associated with a steeper decline in lung function in patients with intrinsic asthma, whereas increasing degrees of obstruction (decreasing FEV1/VC ratio at enrollment) and need for treatment with corticosteroids were associated with a more pronounced decline in FEV1 in patients with extrinsic asthma. CONCLUSIONS: The rate of decline in lung function is greater in patients with intrinsic asthma than in patients with extrinsic asthma; the prognosis for intrinsic and extrinsic asthma is to some extent influenced by different factors, which suggests that the pathogenetic mechanisms underlying intrinsic and extrinsic asthma may differ.

Adult↗
PubMed1992

Airway calibre as a confounder in interpreting bronchial responsiveness in asthma.

BACKGROUND: The relation between airway responsiveness to constrictor agents and forced expiratory volume in one second (FEV1) is important when interpreting change in airway responsiveness after an intervention. The aim of the study was to analyse the relation between FEV1 as a percentage of predicted values (% predicted) and airway responsiveness between and within asthmatic subjects. METHODS: Results of non-specific bronchial challenge tests were pooled from two randomised crossover studies comparing the effect of a non-sedative antihistamine with placebo in 35 patients with moderate asthma. The design of the two studies was similar: the provocative concentration of either histamine (first study) or methacholine (second study) resulting in a 20% decrease in ventilatory capacity (PC20) was repeated at two week intervals while patients were treated with the antihistamine or placebo. The dose of inhaled corticosteroid was gradually reduced during the study. Data were analysed with PC20 as the dependent variable in a general linear model so that the influence on PC20 of inhaled corticosteroid dose, antihistamine, and choice of bronchoconstricting agent could be separated from the influence of FEV1% predicted. RESULTS: The correlation coefficient between mean PC20 and mean prechallenge FEV1 for each patient was 0.45. In the general linear model two thirds (65%) of the variation in PC20 was due to variation between subjects. One third of the within subject variation in PC20 could be explained by variation in prechallenge FEV1% predicted (a change in FEV1 of 27% predicted was associated with one doubling or halving of PC20). Treatment with the antihistamine had no influence on PC20, except when histamine was used as the bronchoconstricting agent. The dose of inhaled corticosteroid had a small but significant effect. CONCLUSIONS: The variation in a patient's PC20 over time (several months) is related to changes in FEV1% predicted. Variation in FEV1% predicted explains less of the variation in bronchial responsiveness between subjects where a patient specific factor, which is probably related to the pathogenesis of bronchial asthma, seems to dominate.

Adrenal Cortex Hormones↗
PubMed1992

Mortality and decline in lung function in 213 adults with bronchial asthma: a ten-year follow up.

The purpose of this longitudinal study was to describe mortality and change in lung function in adults with bronchial asthma, and furthermore to investigate a potential difference in the prognosis for patients with intrinsic and extrinsic asthma. Out of 213 asthmatics admitted to our hospital, 170 (82%) participated in a 10-year follow-up examination; according to the tests for extrinsic asthma at the first examination, the patients were divided into 117 patients with intrinsic asthma and 53 subjects with extrinsic asthma. Twenty-seven (13%) patients, 23 with intrinsic and 4 with extrinsic asthma, died during the observation period, which was almost twice the number expected in both intrinsic and extrinsic asthmatics, but because of the small number of patients with extrinsic asthma, the findings were statistically significant for the intrinsic asthmatics only (p less than 0.05). Seventeen (8.2%) died of pulmonary diseases, of whom 9 (6 patients with intrinsic asthma) died in an acute attack of bronchial asthma. After a questionnaire concerning respiratory symptoms had been answered, a lung function test was performed in all subjects in both 1976-1979 and 1988. A histamine challenge test was performed at the examination in 1988. Of the 143 subjects who were re-examined in 1988, 96% still had respiratory symptoms. The first lung function test in 1976-1979 showed no difference in FEV1 (% predicted) between the two groups, whereas the annual mean loss of FEV1 during the observation period for the intrinsic and extrinsic asthmatics was 50 ml and 22.5 ml, respectively (p less than 0.0001). Decline in FEV1 was found to be independent of smoking habits in both patient groups. We found that the decline in lung function increased with increasing age in both intrinsic and extrinsic asthmatics (p less than 0.001 and p less than 0.05, respectively). The so-called "horse-racing effect" could be demonstrated for the patients with extrinsic asthma (p less than 0.003); whereas no significant relation was found between FEV1 at the time of enrollment and decline of FEV1 for the intrinsic asthmatics. We conclude that asthmatic subjects have an excess mortality and that the prognosis for intrinsic asthma is worse than that of extrinsic asthma with regard to rate of decline in lung function.

Adolescent↗
PubMed1992

A seven-year follow-up study of 343 adults with bronchial asthma.

A study of 343 urban adult outpatients with a history of bronchial asthma was initiated in 1981. Asthma was verified by a reversibility in airflow obstruction of at least 0.5 1 in forced expiratory volume (FEV1) (70%). The rest of the 343 patients was included because of diurnal variations of at least 100 l/min in peak expiratory flow (PEF) (22%), or because of a characteristic history of asthma (8%). In 1988, a follow-up study was performed. Two hundred-fourteen patients replied (80%), 100 women and 114 men. Fifty-four did not respond, but were known to be alive. Twenty-one had emigrated; of these, the fate of five was unknown. The mortality rate was significantly raised among the men (Standard mortality rate (SMR) = 1.55). In 19%, the cause of death was pulmonary. Seventeen percent were found dead. In these, no cause of death was obvious, and they may have died from an exacerbation of their pulmonary disease. One hundred and forty-four had non-allergic and 69 allergic asthma verified retrospectively by positive skin prick test in 1988. One was not tested and not classified. Seventy-five percent of the whole group were smokers. An annual decline of approximately 90 ml per year in FEV1 was found in both groups and was only partially explained by smoking and ageing. The remaining observed decline in lung function may be caused by asthma. Reversibility of 0.5 l in FEV1 was only maintained in the allergic group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗