Predictors of asthma control in children from different ethnic origins living in Amsterdam

To identify factors associated with asthma control in a multi-ethnic paediatric population. We interviewed 278 children with paediatrician diagnosed asthma (aged 7-17 years) and one of their parents. Asthma control was assessed with the Asthma Control Questionnaire (ACQ). Detailed information about sociodemographic variables, asthma medication, knowledge of asthma, inhalation technique and environmental factors were collected. Turkish and Moroccan parents were interviewed in their language of choice. Logistic regression analyses were used to identify correlates of asthma control. Of the 278 children, 85 (30.6%) were Dutch, 84 (30.2%) were Moroccan, 58 (20.9%) were Turkish and 51 (18.3%) were Surinamese. Overall, almost 60% had a status of well-controlled asthma, as indicated by the ACQ. Only 51 of the 142 (35.9%) Moroccan and Turkish parents had a good comprehension of the Dutch language. In logistic regression analyses the risk of having uncontrolled asthma was significantly higher among Surinamese children (OR 2.3; 95% CI 1.06-4.83), respondents with insufficient comprehension of the Dutch language (OR 2.3; 95% CI 1.08-4.78), children using woollen blankets (OR 9.8; 95% CI 1.52-63.42), and significantly lower among male (OR 0.5; 95% CI 0.31-0.91) and non-daily users of inhaled corticosteroids (OR 0.6; 95% CI 0.38-1.07). In conclusion, ethnicity as well as insufficient comprehension of the Dutch language appeared to be independent risk factors for uncontrolled asthma. Special attention should be given to children from immigrants groups for example by calling in an interpreter by physicians when comprehension is insufficient.     

Dual antiplatelet therapy unmasks distinct platelet reactivity in patients with coronary artery disease

Summary. Background: Platelet‐induced thrombosis is a major risk factor for recurrent ischemic events, although platelet function in patients with cardiovascular disease taking aspirin and clopidogrel is very poorly characterized. The aim of this study was to assess platelet reactivity in patients with cardiovascular disease taking aspirin and clopidogrel. Methods: We developed a rapid assay to measure platelet aggregation in response to arachidonic acid, collagen, adenosine diphosphate (ADP), epinephrine and thrombin receptor activating peptide (TRAP) in 80 healthy volunteers. We then recruited 200 consecutive patients from outpatient clinics and the cardiac catheterization laboratory and tested platelet function. Platelet aggregation induced by epinephrine is a marker of global platelet reactivity. We tested platelet function in 146 patients compliant with antiplatelet therapy. Platelet aggregation to epinephrine was divided into quartiles. The platelet response to the other agonists was analysed based on the response to epinephrine. Results: Platelet reactivity increased significantly across the quartiles in response to epinephrine in healthy volunteers and patients (P < 0.0001). A significant increase in response across quartiles was seen with all agonists in healthy volunteers (P < 0.001). In contrast, a significant increase in response across quartiles was only seen with ADP in patients (P < 0.0001). Hypertension, smoking and diabetes were significantly associated with increasing platelet reactivity to epinephrine (P < 0.05). Conclusion: This study shows that platelet response differs between healthy volunteers and patients on dual antiplatelet therapy. In patients with cardiovascular disease, dual antiplatelet therapy unmasks a distinct type of platelet reactivity in response to epinephrine and ADP but not other agonists.     

Clopidogrel discontinuation and platelet reactivity following coronary stenting

See also Lordkipanidzé M, Harrison P. Beware of being caught on the rebound. This issue, pp 21–3. Summary. Aims: Antiplatelet therapy with aspirin and clopidogrel is recommended for 1 year after drug‐eluting stent (DES) implantation or myocardial infarction. However, the discontinuation of antiplatelet therapy has become an important issue as recent studies have suggested a clustering of ischemic events within 90 days of clopidogrel withdrawal. The objective of this investigation was to explore the hypothesis that there is a transient ‘rebound’ increase in platelet reactivity within 3 months of clopidogrel discontinuation. Methods and Results: In this prospective study, platelet function was assessed in patients taking aspirin and clopidogrel for at least 1 year following DES implantation. Platelet aggregation was measured using a modification of light transmission aggregometry in response to multiple concentrations of adenosine diphosphate (ADP), epinephrine, arachidonic acid, thrombin receptor activating peptide and collagen. Clopidogrel was stopped and platelet function was reassessed 1 week, 1 month and 3 months later. Thirty‐two patients on dual antiplatelet therapy were recruited. Discontinuation of clopidogrel increased platelet aggregation to all agonists, except arachidonic acid. Platelet aggregation in response to ADP (2.5, 5, 10, and 20 μm ) and epinephrine (5 and 20 μm ) was significantly increased at 1 month compared with 3 months following clopidogrel withdrawal. Thus, a transient period of increased platelet reactivity to both ADP and epinephrine was observed 1 month after clopidogrel discontinuation. Conclusions: This study demonstrates a transient increase in platelet reactivity 1 month after clopidogrel withdrawal. This phenomenon may, in part, explain the known clustering of thrombotic events observed after clopidogrel discontinuation. This observation requires confirmation in larger populations.     

Determining the optimal dosage regimen for H2-receptor antagonist therapy—a dose validation approach

A large number of clinical studies have been performed to establish the safety and efficacy of H2-receptor antagonist therapy. Few if any of these studies have attempted to address the rationale for the dosage and/or dosage regimens being studied. This study is the first large-scale clinical trial, the purpose of which is to validate the chosen regimen and to address the issue of an optimal therapy for a specific patient population. A regimen of a single nightly dosage is generally acknowledged to offer the potential for improved patient compliance. Furthermore, recent research had suggested that suppression of nocturnal acid secretion is all that is required to heal duodenal ulcers. Hence such a regimen offered the potential for an effective lowered dosage of cimetidine with minimal interference with gastric physiology, increased safety and substantial efficacy. This multicentre, double-blind, placebo-controlled trial therefore evaluated a 4-week course of single night-time dosage of cimetidine. After 4 weeks of treatment the cumulative, endoscopically proven, ulcer healing rate with an 800 mg regimen was 73%, which was statistically higher and significantly superior to the 41% healing seen with placebo (P less than 0.001). The 400 mg nocte dosage regimen of cimetidine normally used as maintenance therapy was significantly inferior to the 800 mg nocte regimen (P = 0.01), and increasing the dosage to 1600 mg nocte for 4 weeks failed to provide a significant improvement in healing over the 800 mg nocte regimen. This 800 mg nocte regimen provided rapid pain relief, with 75% of the patients being free of night-time pain and 65% free of day-time pain, by the end of the first week. The 400 mg 'maintenance dosage' was unable to provide this degree of rapid, complete and early relief to patients with a duodenal ulcer. Furthermore, increasing the dosage to 1600 mg nocte failed to increase the level of early pain relief significantly, perhaps because the extensive response of duodenal ulcer patients to the 800 mg nocte regimen leaves little room for improvement. Based both on the early symptom relief and the ulcer healing rate during 4 weeks of treatment, it is concluded that an 800 mg night-time dosage of cimetidine may be an optimal regimen for many duodenal ulcer patients, particularly those who in the physician's opinion will benefit from a once-daily regimen.     

Adherence to inhaled corticosteroids in children with asthma and their parents

Poor adherence to inhaled corticosteroids (ICSs) may contribute to the recent rise in asthma morbidity. In general, appropriate adherence to ICSs is a complex process that is influenced by various determinants. The purpose of this study was to identify factors that were associated with adherence to ICSs in children with asthma and their parents in a multi-ethnic population in Amsterdam, the Netherlands. Two hundred and thirty-two children, aged 7-17 years, with paediatrician diagnosed asthma and their parents completed questionnaires examining socio-demographics, asthma control, knowledge of asthma and other determinants of adherence. Adherence to ICSs was assessed by self-report and pharmacy record data. We used logistic regression analyses to identify factors associated with adherence to ICSs in children and parents separately. We found no differences in adherence between the different ethnic groups. In the multivariate analysis for children, well-controlled asthma (OR: 4.12; CI: 1.50-11.3) was associated with poorer adherence, whereas positive subjective view of parents (OR: 0.45; CI:0.25-0.81) and self-efficacy (OR:0.51; CI: 0.35-0.75) were inversely associated with poorer adherence. A consistent result with the multivariate models for parents was the inversely significant association between poorer adherence and positive subjective view of parents to use ICSs (OR: 0.39; CI:0.19-0.77). Regardless of ethnic background, children positively stimulated by their parents to use ICSs showed a better adherence than children who experienced less positive influences. These results emphasise the importance of involving parents in the treatment of their child's asthma in order to enhance adherence to ICSs.