The Validity and Applicability of Using a Generic Exposure Assessment Model for Occupational Exposure to Nano-Objects and Their Aggregates and Agglomerates.

BACKGROUND: Control banding can be used as a first-tier assessment to control worker exposure to nano-objects and their aggregates and agglomerates (NOAA). In a second tier, more advanced modelling approaches are needed to produce quantitative exposure estimates. As currently no general quantitative nano-specific exposure models are available, this study evaluated the validity and applicability of using a generic exposure assessment model (the Advanced REACH Tool-ART) for occupational exposure to NOAA. METHOD: The predictive capability of ART for occupational exposure to NOAA was tested by calculating the relative bias and correlations (Pearson) between the model estimates and measured concentrations using a dataset of 102 NOAA exposure measurements collected during experimental and workplace exposure studies. RESULTS: Moderate to (very) strong correlations between the ART estimates and measured concentrations were found. Estimates correlated better to measured concentration levels of dust (r = 0.76, P < 0.01) than liquid aerosols (r = 0.51, P = 0.19). However, ART overestimated the measured NOAA concentrations for both the experimental and field measurements (factor 2-127). Overestimation was highest at low concentrations and decreased with increasing concentration. Correlations seemed to be better when looking at the nanomaterials individually compared to combined scenarios, indicating that nanomaterial-specific characteristics are not well captured within the mechanistic model of the ART. DISCUSSION: Although ART in its current state is not capable to estimate occupational exposure to NOAA, the strong correlations for the individual nanomaterials indicate that the ART (and potentially other generic exposure models) have the potential to be extended or adapted for exposure to NOAA. In the future, studies investigating the potential to estimate exposure to NOAA should incorporate more explicitly nanomaterial-specific characteristics in their models.

Time trends of period prevalence rates of patients with inhaled long-acting beta-2-agonists-containing prescriptions: a European comparative database study.

BACKGROUND: Inhaled, long-acting beta-2-adrenoceptor agonists (LABA) have well-established roles in asthma and/or COPD treatment. Drug utilisation patterns for LABA have been described, but few studies have directly compared LABA use in different countries. We aimed to compare the prevalence of LABA-containing prescriptions in five European countries using a standardised methodology. METHODS: A common study protocol was applied to seven European healthcare record databases (Denmark, Germany, Spain, the Netherlands (2), and the UK (2)) to calculate crude and age- and sex-standardised annual period prevalence rates (PPRs) of LABA-containing prescriptions from 2002-2009. Annual PPRs were stratified by sex, age, and indication (asthma, COPD, asthma and COPD). RESULTS: From 2002-2009, age- and sex-standardised PPRs of patients with LABA-containing medications increased in all databases (58.2%-185.1%). Highest PPRs were found in men ≥ 80 years old and women 70-79 years old. Regarding the three indications, the highest age- and sex-standardised PPRs in all databases were found in patients with "asthma and COPD" but with large inter-country variation. In those with asthma or COPD, lower PPRs and smaller inter-country variations were found. For all three indications, PPRs for LABA-containing prescriptions increased with age. CONCLUSIONS: Using a standardised protocol that allowed direct inter-country comparisons, we found highest rates of LABA-containing prescriptions in elderly patients and distinct differences in the increased utilisation of LABA-containing prescriptions within the study period throughout the five European countries.

Suboptimal prescribing of proton-pump inhibitors in low-dose aspirin users: a cohort study in primary care.

OBJECTIVE: Determine the adherence to recommendations of concomitant proton-pump inhibitor (PPI) treatment in regular low-dose of aspirin (LDASA) users, taking factors associated with the probability of receiving a PPI into account. DESIGN: Cohort study. SETTING: Data were obtained from 120 Dutch primary care centres participating in the Netherlands Information Network of Primary Care (LINH). PARTICIPANTS: Patients 18 years and older who were regularly prescribed LDASA (30-325 mg) in 2008-2010 were included. MAIN OUTCOME MEASURES: Regular medication use was defined as receiving each consecutive prescription within 6 months after the previous one. Based on national guidelines, we categorised LDASA users into low and high gastrointestinal (GI) risk. A multilevel multivariable logistic regression analysis was applied to identify patient characteristics that influenced on the probability of regular PPI prescriptions. RESULTS: We identified 12 343 patients who started LDASA treatment, of whom 3213 (26%) were at increased risk of GI complications. In this group, concomitant regular use of PPI was 46%, 36% did not receive PPI prescriptions and 18% obtained prescriptions irregularly (p<0.0001). The chance to obtain regularly PPI prescriptions versus no PPI was significantly influenced by, among others, previous GI complications (OR 13.9 (95% CI 11.8 to 16.4)), use of non-steroidal anti-inflammatory drugs (OR 5.2 (4.3 to 6.3)), glucocorticosteroids (6.1 (4.6 to 8.0)), selective serotonin reuptake inhibitors (9.1 (6.7 to 12.2)), drugs for functional GI disorders (2.4 (1.9 to 3.0)) and increased age. CONCLUSIONS: Primary care physicians do not fully adhere to the current recommendations to prescribe PPIs regularly to LDASA users with an increased GI risk. More than 50% of the patients with an increased GI risk are not treated sufficiently with a concomitant PPI, increasing the risk of GI side effects. This finding underlines the necessity to consider merging recommendations into one common, standard and frequently used recommendation by primary care physicians.

Advanced REACH Tool (ART): calibration of the mechanistic model.

The mechanistic model of the Advanced Reach Tool (ART) provides a relative ranking of exposure levels from different scenarios. The objectives of the calibration described in this paper are threefold: to study whether the mechanistic model scores are accurately ranked in relation to exposure measurements; to enable the mechanistic model to estimate actual exposure levels rather than relative scores; and to provide a method of quantifying model uncertainty. Stringent data quality guidelines were applied to the collated data. Linear mixed effects models were used to evaluate the association between relative ART model scores and measurements. A random scenario and company component of variance were introduced to reflect the model uncertainty. Stratified analyses were conducted for different forms of exposure (abrasive dust, dust, vapours and mists). In total more than 2000 good quality measurements were available for the calibration of the mechanistic model. The calibration showed that after calibration the mechanistic model of ART was able to estimate geometric mean (GM) exposure levels with 90% confidence for a given scenario to lie within a factor between two and six of the measured GM depending upon the form of exposure.