Biomedical subjects

L R Arends

Publications and source records attributed to L R Arends.

6 recordsLinked to original sources

PubMed2002

Accuracy of eosinophils and eosinophil cationic protein to predict steroid improvement in asthma.

BACKGROUND: There is a large variability in clinical response to corticosteroid treatment in patients with asthma. Several markers of inflammation like eosinophils and eosinophil cationic protein (ECP), as well as exhaled nitric oxide (NO), are good candidates to predict clinical response. AIM: We wanted to determine whether we could actually predict a favourable response to inhaled corticosteroids in individual patients. METHODS: One hundred and twenty patients with unstable asthma were treated with either prednisolone 30 mg/day, fluticasone propionate 1000 microg/day b.i.d. or fluticasone propionate 250 microg/day b.i.d., both via Diskhaler. They were treated during 2 weeks, in a double-blind, parallel group, double dummy design. We measured eosinophils and ECP in blood and sputum, and exhaled nitric oxide as inflammatory parameters before and after 2 weeks in order to predict the changes in forced expiratory volume in 1 s (FEV1), provocative concentration of methacholine causing a 20% fall in FEV1 (PC20 Mch), and asthma quality of life (QOL). Secondly, to test whether these results were applicable in clinical practice we determined the individual prediction of corticosteroid response. RESULTS: We found that changes in FEV1, PC20 Mch and QOL with corticosteroids were predominantly predicted by their respective baseline value and to a smaller extent by eosinophils in blood or sputum. ECP, measured in blood or sputum, was certainly not better than eosinophils in predicting clinical response to corticosteroids. Smoking status was an additional predictor for change in FEV1, but not for change in PC20 Mch or QOL. Prediction of a good clinical response was poor. For instance, high sputum eosinophils (> or = 3%) correctly predicted an improvement in PC20 Mch in only 65% of the patients. CONCLUSION: Our findings show that baseline values of the clinical parameters used as outcome parameters are the major predictors of clinical response to corticosteroids. Eosinophil percentage in blood or sputum adds to this, whereas ECP provides no additional information. Correct prediction of clinical response in an individual patient, however, remains poor with our currently used clinical and inflammatory parameters.

Adolescent↗

PubMed2001

One-year treatment with different dosing schedules of fluticasone propionate in childhood asthma. Effects on hyperresponsiveness, lung function, and height.

Dose-dependent effects of inhaled corticosteroids have been described. Although it has been advised to start treatment with inhaled corticosteroids with a high dose tapering off subsequently (stepdown approach), no clinical studies have assessed this strategy. We compared two different dosage schedules of inhaled fluticasone propionate (FP) in chronic persistent childhood asthma with respect to efficacy (airways hyperresponsiveness [PD(20)], lung function, exhaled nitric oxide [eNO]) and safety (height). During this double-blind study, children with asthma (aged 6-10 yr) were randomized to receive either FP 200 microg/d (constant dose approach) or to start with 1000 microg/d with two monthly reductions to 500, 200, and 100 microg/d (stepdown approach). PD(20) improved in both approaches during treatment with FP, with a significantly better PD(20) after 2 mo of 1000 microg/d followed by 500 microg/d in the stepdown approach versus 200 microg/d in the constant dose approach. No significant differences in PD(20) or other efficacy parameters were found after 1 yr. Changes in standing height were similar in both treatment approaches. This study showed no superior clinical effect of a stepdown approach compared with a constant dose strategy of FP for 1 yr in children with chronic persistent asthma.

Administration, Inhalation↗

PubMed2001

Peri-marketing surveillance of lamotrigine in The Netherlands: doctors' and patients' viewpoints.

PURPOSE: Evaluation of daily clinical practice in prescribing lamotrigine in refractory epilepsy patients. METHODS: A collaborative, retrospective, peri-marketing study was performed in in- and out-patients attending one of the three Dutch epilepsy centres. Analysis of both patients' and doctors' information was performed in 520 patients using questionnaires and medical files. RESULTS: After one year of treatment 76% of patients maintained LTG treatment, an intention-to-treat analysis showed > = 50% seizure reduction in 23% of patients; 20-50% seizure reduction in 23% of patients. Six percent of patients became at least three months seizure free. In about 20% of patients seizures became less severe and shorter of duration, while in 6% an increase was found. After three months a significant decrease in number of concomitant antiepileptic drugs was found (change from mean 1.8 to 1.5 AEDs) (p = < 0.01). After twelve months the mean number of AEDs was 1.4 per patient. Overall percentage of side effects appeared to be significantly higher if patients' questionnaire data were used. Epilepsy patients considered side effects as an important factor in the choice of medication and in withdrawal of medication. Future developments of new AEDs should take this into account. CONCLUSION: This perimarketing study gives insight information about long-term daily use of lamotrigine, with emphasis on effectiveness. Patients complained in the questionnaires much more about side-effects, than was known according to the medical file. Therefore, it seems necessary to perform perimarketing studies more systematically.

Adolescent↗

PubMed2000

Baseline risk as predictor of treatment benefit: three clinical meta-re-analyses.

A relationship between baseline risk and treatment effect is increasingly investigated as a possible explanation of between-study heterogeneity in clinical trial meta-analysis. An approach that is still often applied in the medical literature is to plot the estimated treatment effects against the estimated measures of risk in the control groups (as a measure of baseline risk), and to compute the ordinary weighted least squares regression line. However, it has been pointed out by several authors that this approach can be seriously flawed. The main problem is that the observed treatment effect and baseline risk measures should be viewed as estimates rather than the true values. In recent years several methods have been proposed in the statistical literature to potentially deal with the measurement errors in the estimates. In this article we propose a vague priors Bayesian solution to the problem which can be carried out using the 'Bayesian inference using Gibbs sampling' (BUGS) implementation of Markov chain Monte Carlo numerical integration techniques. Different from other proposed methods, it uses the exact rather than an approximate likelihood, while it can handle many different treatment effect measures and baseline risk measures. The method differs from a recently proposed Bayesian method in that it explicitly models the distribution of the underlying baseline risks. We apply the method to three meta-analyses published in the medical literature and compare the results with the outcomes of the other recently proposed methods. In particular we compare our approach to McIntosh's method, for which we show how it can be carried out using standard statistical software. We conclude that our proposed method offers a very general and flexible solution to the problem, which can be carried out relatively easily with existing Bayesian analysis software. A confidence band for the underlying relationship between true effect measure and baseline risk and a confidence interval for the value of the baseline risk measure for which there is no treatment effect are easily obtained by-products of our approach.

Bayes Theorem↗

PubMed1999

[Roaming through methodology. XVI. What to do about missing data].

Medical scientific research involving multiple measurements in patients is usually complicated by missing values. In case of missing values the choice is to limit the analysis to the complete cases or to analyse all available data. Both methods may suffer from substantial bias and may only be applied in a valid way if the rather strong assumption of 'missing completely at random' holds for the missing values, i.e. the missing value is not related to the other measured data nor to unmeasured data. Two other statistical methods may be applied to deal with missing values: the likelihood approach and the multiple imputation method. These methods make efficient use of all available data and take into account information implied by the available data. These methods are valid under the less stringent assumption of 'missing at random', i.e. the missing value is related to the other measured data, but not to unmeasured data. The best approach is to ensure that no data are missing.

Clinical Trials as Topic↗

PubMed1999

Effects of inhaled fluticasone and oral prednisolone on clinical and inflammatory parameters in patients with asthma.

BACKGROUND: Guidelines state that oral and inhaled corticosteroids are the cornerstone of asthma treatment. The effect of both types of treatment can be assessed by measuring lung and systemic parameters. Treatment for two weeks with either oral prednisolone (30 mg/day), high dose fluticasone propionate (2000 microg/day, FP2000), or lower dose FP (500 microg/day, FP500), both given by a dry powder inhaler, were compared. METHODS: One hundred and twenty patients with asthma were treated for two weeks in a double blind parallel group design. Lung function, asthma symptoms, airway hyperresponsiveness (PC(20) methacholine and adenosine-5'-monophosphate), sputum eosinophil and eosinophilic cationic protein (ECP) levels were measured as lung parameters. In addition, morning serum blood cortisol, blood eosinophil, and serum ECP levels were measured as systemic parameters. RESULTS: PC(20) methacholine and adenosine-5'-monophosphate showed significantly greater improvement with FP2000 (1.99 and 4.04 doubling concentrations (DC), respectively) than prednisolone (0.90 DC, p = 0.02; 2.15 DC, p = 0. 05) and marginally more than with FP500 (1.69 and 3.54 DC). Changes in sputum eosinophil and ECP concentrations showed similar trends; the decrease in ECP was significantly greater with FP2000 than with FP500. In contrast, the systemic parameters of steroid activity (cortisol, peripheral blood eosinophils, and serum ECP) decreased to a similar extent with FP2000 and prednisolone but significantly less with FP500. CONCLUSIONS: Oral prednisolone (30 mg/day) was inferior to FP2000 in improving airway hyperresponsiveness to both methacholine and AMP, with similar trends in forced expiratory volume in one second (FEV(1)), sputum eosinophil and ECP concentrations. Systemic effects were similar with prednisolone and FP2000 and less with FP500.

Administration, Inhalation↗