Creatine Kinase Is Decreased in Childhood Asthma

Rationale: The identification of novel molecules associated with asthma may provide insights into the mechanisms of disease and their potential clinical implications. Objectives: To conduct a screening of circulating proteins in childhood asthma and to study proteins that emerged from human studies in a mouse model of asthma. Methods: We included 2,264 children from eight birth cohorts from the Mechanisms of the Development of ALLergy project and the Tucson Children's Respiratory Study. In cross-sectional analyses, we tested 46 circulating proteins for association with asthma in the selection stage and carried significant signals forward to a validation and replication stage. As CK (creatine kinase) was the only protein consistently associated with asthma, we also compared whole blood CK gene expression between subjects with and without asthma (n = 249) and used a house dust mite (HDM)-challenged mouse model to gain insights into CK lung expression and its role in the resolution of asthma phenotypes. Measurements and Main Results: As compared with the lowest CK tertile, children in the highest tertile had significantly lower odds for asthma in selection (adjusted odds ratio, 95% confidence interval: 0.31; 0.15-0.65; P = 0.002), validation (0.63; 0.42-0.95; P = 0.03), and replication (0.40; 0.16-0.97; P = 0.04) stages. Both cytosolic CK forms (CKM and CKB) were underexpressed in blood from asthmatics compared with control subjects (P = 0.01 and 0.006, respectively). In the lungs of HDM-challenged mice, Ckb expression was reduced, and after the HDM challenge, a CKB inhibitor blocked the resolution of airway hyperresponsiveness and reduction of airway mucin. Conclusions: Circulating concentrations and gene expression of CK are inversely associated with childhood asthma. Mouse models support a possible direct involvement of CK in asthma protection via inhibition of airway hyperresponsiveness and reduction of airway mucin.

Overview of the EU PAS register post-authorization studies performed in Europe from September 2010 to December 2018

BACKGROUND

The European post-authorisation study (EU PAS) register is a repository launched in 2010 by the European Medicines Agency (EMA). All EMA-requested PAS, commonly observational studies, must be recorded in this register. Multi-database studies (MDS) leveraging secondary data have become an important strategy to conduct PAS in recent years, as reflected by the type of studies registered in the EU PAS register.

OBJECTIVES

To analyse and describe PAS in the EU PAS register, with focus on MDS.

METHODS

Studies in the EU PAS register from inception to 31^st December 2018 were described concerning transparency, regulatory obligations, scope, study type (e.g. observational study, clinical trial, survey, systematic review/meta-analysis), study design, type of data collection and target population. MDS were defined as studies conducted through secondary use of >1 data source not linked at patient-level. Data extraction was carried out independently by 14 centres with expertise in pharmacoepidemiology, using publicly available information in the EU PAS register including study protocol, whenever available, using a standardised data collection form. For validation purposes, a second revision of key fields for a 15% random sample of studies was carried out by a different centre. The inter-rater reliability (IRR) was then calculated. Finally, to identify predictors of primary data collection-based studies /vs those based on secondary use of healthcare databases) or MDS (vs. non-MDS), odds ratios (OR) and 95% confidence intervals (CI) were calculated fitting univariate logistic regression models.

RESULTS

Overall, 1,426 studies were identified. Clinical trials (N=30; 2%), systematic reviews/meta-analyses (N=16; 1%) and miscellaneous study designs (N=46; 3%) were much less common than observational studies (N=1,227; 86%). The protocol was available for 63% (N=360) of 572 observational studies requested by a competent authority. Overall, 36% (N=446) of observational studies were based fully or partially on primary data collection. Of 757 observational studies based on secondary use of data alone, 282 (37%) were MDS. Drug utilisation was significantly more common as a study scope in MDS compared to non-MDS studies. The overall percentage agreement among collaborating centres that collected the data concerning study variables was highest for study type (93.5%) and lowest for type of secondary data (67.8%).

CONCLUSIONS

Observational studies were the most common type of studies in the EU PAS register, but 30% used primary data, which is more resource-intensive. Almost half of observational studies using secondary data were MDS. Data recording in the EU PAS register may be improved further, including more widespread availability of study protocols to improve transparency.

Modification of systemic anti-cancer therapies and weight loss, a population-level real-world evidence study

Background:

Involuntary weight loss may occur during systemic anti-cancer therapy (SACT), causing treatment disruption and poorer prognoses. There remain gaps in clinical awareness as to which patients may benefit from nutritional interventions that aim to prevent unintended weight loss during SACT.

We utilised England’s population-level cancer registry data, conducting a pan-cancer assessment of patient weight loss during SACT. We aimed to identify cancers with weight loss-associated treatment modifications, potential beneficiaries of nutritional intervention.

Methods:

This cross-sectional study used England’s Cancer Analysis System database, including SACT-treated adults with one tumour and ⩾2 weight recordings between 2014 and 2018. Binary weight loss (threshold: 2.5%) was derived from patients’ most negative weight change from first SACT weight recording. The Martin et al. body mass index-adjusted weight loss grading system (BMI-WLG) was assigned. We describe binary weight loss, BMI-WLG and treatment modification status by cancer. Multivariate logistic regression models of weight loss (binary and BMI-WLG) and a composite outcome of patient treatment-modification status by cancer were produced.

Results:

Our study population contained 200,536 patients across 18 cancers; 28% experienced binary weight loss during SACT. Weight loss patients were more likely to have multiple types of treatment modifications recorded across all cancers. Regression analyses included 86,991 patients. Binary weight loss was associated (p < 0.05) with higher likelihood of treatment modification in; colon [Odds Ratio (OR) = 1.72, 95% confidence interval (CI): 1.42, 2.07]; gynaecologic (excl. ovarian) (OR = 1.48, 95% CI: 1.08, 2.01); stomach (OR = 1.6, 95% CI: 1.04, 2.06); lung (OR = 1.38, 95% CI: 1.21, 1.58); leukaemia (OR = 1.30, 95% CI: 1.09, 1.55); head and neck (OR = 1.30, 95% CI: 1.02, 1.65) and oesophageal (OR = 1.29, 95% CI: 1.01, 1.64) cancers. In lung, colon, and grouped gastro-intestinal cancers, association between BMI-WLG and treatment modification increased by WLG.

Discussion:

Our study is a wide assessment of weight loss during SACT using England’s cancer registry data. Across different cancers we found patients have weight loss-associated treatment modifications during SACT, a precursor to poorer prognoses. Our findings highlight cancers that may benefit from improved nutritional intervention during SACT.

Predictors of Beta-Hexachlorocyclohexane blood levels among people living close to a chemical plant and an illegal dumping site

BACKGROUND

Hexachlorocyclohexane is a synthetic chemical with several isomers, including β-Hexachlorocyclohexane (β-HCH). In 2005, a large contamination of crude milk from some bovine farms along the Sacco River (Central Italy) was detected; it was related to the illegal disposal of large quantities of processing waste by a chemical industry of the area. A biomonitoring study, conducted in 2007 on a sample of the residing population, found high values of β-HCH in people living close to the river. These results led to the establishment of a clinical and epidemiological surveillance program on all the exposed population. The aim of the study was to evaluate the determinants of β-HCH blood levels in people living within 1 Km of the Sacco River, focusing on the role of specific foods, body mass index and risk factors not yet identified.

METHODS

The program involved all people living within 1 km of the river. A descriptive analysis of β-HCH blood levels was done in relation to the potential determinants including specific foods. Regression analysis was used to study the association between potential determinants and (natural log) β-HCH haematic concentration. The results were expressed as geometric mean ratios (GMR). To take into account similarities within the families we adjusted for family clustering.

RESULTS

A total of 602 subjects (87.2%) agreed to participate in the surveillance. The β-HCH geometric mean serum concentration was 72 ng/g lipid. The regression analysis showed that being female (GMR: 1.32, 95%CI: 1.14-1.53), elderly (GMR_{> 70yy}: 10.04, 95%CI: 6.65-15.15), obese (GMR: 1.63, 95%CI: 1.28-2.08), eating food of local/own production (GMR 1.47, 95%CI: 1.15-1.88) and using water from private wells (GMR_drink:1.47, 95%CI: 1.00-2.14 and GMR_wash: 1.48, 95%CI: 1.17-1.87) were associated with higher β-HCH values. There was inverse association with breastfeeding (GMR: 0.64, 95%CI: 0.47-0.86). The focus on specific foods showed that the most important factors were eggs and beef.

CONCLUSIONS

The study indicated a greater contamination for older people, and those drinking and washing with water from private wells and consuming locally produced food, especially eggs and beef.

Safety and effectiveness of direct oral anticoagulants versus vitamin K antagonists: results from 3 Italian regions

Background

In Italy, direct oral anticoagulant drugs (DOACs) were authorized for stroke prevention in patients with non-valvular atrial fibrillation (NVAF) in 2013. There is conflicting evidence on their benefit-risk profile under real world conditions.

Methods

The Italian Medicines Agency funded this study to investigate effectiveness and safety of DOACs compared to vitamin K antagonists (VKAs) in three Italian regions. An observational study was conducted with a sequential propensity-score-matched new user parallel-cohort design in the period July 2013-December 2015 using administrative health data. DOAC users with NVAF diagnosis were 1:1 matched to VKA users based on a PS which accounted for over 90 potential confounders at baseline. Applying an as-treated approach with a 90-day renewal grace time, patients were followed from the day after the first prescription of the study drug until occurrence of the outcome, death, discontinuation, switch, end of health plan enrolment, or study end. Outcomes were total and cardiovascular mortality, acute myocardial infarction, ischemic and haemorrhagic stroke, and gastrointestinal bleeding. Analyses were performed, using Cox proportional hazard models stratified by matched set. The results of the regional analyses were combined through a random-effects meta-analysis.

Results

During the first 30 months of authorisation for NVAF, DOACs were increasingly prescribed. Overall, 72,434 new anticoagulant users were enrolled, 34% of whom received a DOAC. After PS matching, 37,266 patients contributed to the analysis. No differences between the study groups were found for total and cardiovascular mortality, myocardial infarction and ischemic stroke. DOAC users were at higher risk of gastrointestinal bleeding (HR 1.41, 95%CI 1.07-1.86) and at a not significant lower risk of haemorrhagic stroke (HR 0.36, 95%CI 0.10-1.33).

Conclusions

The present study confirms findings from previous research regarding bleeding events, whereas we did not find a reduced risk of mortality in DOAC users. Further research on single active agents and specific populations is warranted.

Integrating Clinical and Epidemiologic Data on Allergic Diseases Across Birth Cohorts: A Harmonization Study in the Mechanisms of the Development of Allergy Project

The numbers of international collaborations among birth cohort studies designed to better understand asthma and allergies have increased in the last several years. However, differences in definitions and methods preclude direct pooling of original data on individual participants. As part of the Mechanisms of the Development of Allergy (MeDALL) Project, we harmonized data from 14 birth cohort studies (each with 3-20 follow-up periods) carried out in 9 European countries during 1990-1998 or 2003-2009. The harmonization process followed 6 steps: 1) organization of the harmonization panel; 2) identification of variables relevant to MeDALL objectives (candidate variables); 3) proposal of a definition for each candidate variable (reference definition); 4) assessment of the compatibility of each cohort variable with its reference definition (inferential equivalence) and classification of this inferential equivalence as complete, partial, or impossible; 5) convocation of a workshop to agree on the reference definitions and classifications of inferential equivalence; and 6) preparation and delivery of data through a knowledge management portal. We agreed on 137 reference definitions. The inferential equivalence of 3,551 cohort variables to their corresponding reference definitions was classified as complete, partial, and impossible for 70%, 15%, and 15% of the variables, respectively. A harmonized database was delivered to MeDALL investigators. In asthma and allergy birth cohorts, the harmonization of data for pooled analyses is feasible, and high inferential comparability may be achieved. The MeDALL harmonization approach can be used in other collaborative projects.

[Validation of algorithms for the identification of subjects with chronic disease using health information systems]

OBJECTIVES

to test the validity of algorithms to identify diabetes, chronic obstructive pulmonary disease (COPD), hypertension, and hypothyroidism from routinely collected health data using information from self-reported diagnosis and laboratory or functional test.

SETTING AND PARTICIPANTS

clinical or self-reported diagnosis from three surveys conducted in Lazio Region (Central Italy) between year 2010 and 2014 were assumed as gold standard and compared to the results of the algorithms application to administrative data.

MAIN OUTCOME MEASURES

prevalence resulted from administrative data and from information available in the surveys were compared. Sensitivity, specificity, positive predictive value, and positive likelihood ratio of algorithms with respect to self-reported diagnosis, laboratory or functional test, assumed as gold standards, were calculated.

RESULTS

we analyzed data of 7,318 subjects (1,545 for diabetes, 1,783 for COPD, 2,448 for hypertension, and 1,542 for hypothyroidism). For hypertension and hypothyroidism, we observed a higher prevalence from laboratory or functional test compared to self-reported diagnosis (54.5% vs. 44.9% and 7.5% vs. 1.5%). Sensitivity of administrative data with respect to self-reported diagnosis resulted 90.9%, 38.5%, 88.3%, and 47.8%, respectively, for diabetes, COPD, hypertension, and hypothyroidism. Respectively, specificity was 97.4%, 91.7%, 84.8% and 91.8%; positive predictive value was 70,9%, 38.1%, 82.6% and 8.1%. All values of positive likelihood ratio resulted moderate (about 5), with exception of the diabetes algorithm and the disease-specific payment exemptions register for hypertension (respectively 35.5 and 17.4).

CONCLUSION

hypertension and hypothyroidism resulted markedly underdiagnosed from self-reported data. Case identification algorithms are highly specific, allowing their utilization for selection of cohort of subject affected by chronic diseases. The sub-optimal sensitivity observed for COPD and hypothyroidism could limit the utilization of the algorithms for prevalence estimation.

Variations in the prevalence of childhood asthma and wheeze in MeDALL cohorts in Europe

While there is evidence for variations in prevalence rates of childhood wheeze and asthma between countries, longitudinal, individual-level data are needed to understand these differences. The aim of this study was to examine variations in prevalence rates of childhood asthma, wheeze and wheeze with asthma in Europe.

We analysed datasets from 10 MeDALL (Mechanisms of the Development of ALLergy) cohorts in eight countries, representing 26 663 children, to calculate prevalence rates of wheeze and asthma by child age and wheeze with asthma at age 4 years. Harmonised variables included outcomes parent-reported wheeze and parent-reported doctor-diagnosed asthma, and covariates maternal education, parental smoking, pets, parental asthma, doctor-diagnosed allergic rhinitis, doctor-diagnosed eczema and wheeze severity.

At age 4 years, asthma prevalence varied from 1.72% in Germany to 13.48% in England and the prevalence of wheeze varied from 9.82% in Greece to 55.37% in Spain. Adjusted estimates of the proportion of 4-year-old children with wheeze diagnosed with asthma remained highest in England (38.14%, 95% CI 31.38–44.90%) and lowest in Spain (15.94%, 95% CI 6.16–25.71%).

The large differences in prevalence rates of asthma, wheeze and wheeze with asthma at age 4 years between European cohorts may indicate that childhood asthma is more readily diagnosed in some countries while going unrecognised elsewhere.

Large variations in childhood wheeze across Europe do not match large variations in diagnosed childhood asthmahttp://ow.ly/eJQk30aPInr

[Inverse probability weighting (IPW) for evaluating and "correcting" selection bias]

INTRODUCTION

the Inverse probability weighting (IPW) is a methodology developed to account for missingness and selection bias caused by non-randomselection of observations, or non-random lack of some information in a subgroup of the population.

OBJECTIVES

to provide an overview of IPW methodology and an application in a cohort study of the association between exposure to traffic air pollution (nitrogen dioxide, NO₂) and 7-year children IQ.

METHOD

this methodology allows to correct the analysis by weighting the observations with the probability of being selected. The IPW is based on the assumption that individual information that can predict the probability of inclusion (non-missingness) are available for the entire study population, so that, after taking account of them, we can make inferences about the entire target population starting from the nonmissing observations alone.The procedure for the calculation is the following: firstly, we consider the entire population at study and calculate the probability of non-missing information using a logistic regression model, where the response is the nonmissingness and the covariates are its possible predictors.The weight of each subject is given by the inverse of the predicted probability. Then the analysis is performed only on the non-missing observations using a weighted model.

CONCLUSIONS

IPW is a technique that allows to embed the selection process in the analysis of the estimates, but its effectiveness in "correcting" the selection bias depends on the availability of enough information, for the entire population, to predict the non-missingness probability. In the example proposed, the IPW application showed that the effect of exposure to NO2 on the area of verbal intelligence quotient of children is stronger than the effect showed from the analysis performed without regard to the selection processes.

[Residential cohort approach in industrial contaminated sites: the ERAS Lazio project]

The population-based cohort study is the best design for assessing the possible health effects resulting fromliving in contaminated sites. The ERAS (Epidemiology,Waste disposal, Environment and Health) Project was established to study the health of people living in close proximity to urban solid waste treatment (RU) plants in Lazio. It was conducted using an integrated approach, which consisted in studying mortality and hospital discharges of residential cohorts surrounding urban waste treatment plants. The level of exposure of each address was assigned using pollution dispersion models and studying the effects on mortality and hospital discharges. Further studies were conducted on residents of areas adjacent to waste disposal sites (includingMalagrotta in Rome), incinerators andmechanical biological treatment plants. The final version of the ERAS Report is available at www.eraslazio.it. The residential cohort approach and the combination of environmental and health-related information proved invaluable in the assessment of the health impact of solid waste treatment in Lazio.

Piccolipiù, a multicenter birth cohort in Italy: protocol of the study

Background

The fetal and infant life are periods of rapid development, characterized by high susceptibility to exposures. Birth cohorts provide unique opportunities to study early-life exposures in association with child development and health, as well as, with longer follow-up, the early life origin of adult diseases. Piccolipiù is an Italian birth cohort recently set up to investigate the effects of environmental exposures, parental conditions and social factors acting during pre-natal and early post-natal life on infant and child health and development. We describe here its main characteristics.

Methods/design

Piccolipiù is a prospective cohort of expected 3000 newborns, who will be recruiting in six maternity units of five Italian cities (Florence, Rome, Trieste, Turin and Viareggio) since October 2011. Mothers are contacted during pregnancy or at delivery and are offered to participate in the study. Upon acceptance, their newborns are recruited at birth and followed up until at least 18 years of age. At recruitment, the mothers donate a blood sample and complete a baseline questionnaire. Umbilical cord blood, pieces of umbilical cord and heel blood spots are also collected. Postnatal follow-up currently occurs at 6, 12, and 24 months of age using on-line or postal self administered questionnaire; further questionnaires and medical examinations are envisaged. Questionnaires collect information on several factors, including mother’s and/or child’s environmental exposures, anthropometric measures, reproductive factors, diet, supplements, medical history, cognitive development, mental health and socioeconomic factors. Health promotion materials are also offered to parents.

Discussion

Piccolipiù will broaden our understanding of the contribution of early-life factors to infant and child health and development. Several hypotheses on the developmental origins of health can be tested or piloted using the data collected from the Piccolipiù cohort. By pooling these data with those collected by other existing birth cohorts it will be possible to validate previous findings and to study rare exposures and outcomes.

A biomonitoring study on blood levels of beta-hexachlorocyclohexane among people living close to an industrial area

BACKGROUND

A chemical plant manufacturing pesticides has been operating since the 1950's in the Sacco River Valley (Central Italy). In 2005, high beta-hexachlorocyclohexane (Beta-HCH) concentrations were found in milk of cows raised and fed near the river. We report the results of a biomonitoring study conducted in this region to evaluate the body burden of Beta-HCH and to identify the determinants of the human contamination.

METHODS

We defined four residential areas by their distance from the chemical plant and the river, and selected a stratified random sample of 626 people aged 25-64 years. We evaluated the association, in terms of the geometric mean ratio (GMR), between several potential determinants and Beta-HCH serum concentrations using multivariate linear regression analysis.

RESULTS

Two hundred forty-six serum samples were analysed to assess Beta-HCH levels (mean concentration: 99 ng/g lipid; Standard Deviation: 121; Geometric Mean: 60.6; Geometric Standard Deviation: 2.65). We found a strong association between Beta-HCH and living in the area close to the river (GMR: 2.00; 95%CI: 1.36-2.94). Beta-HCH levels were also associated with age, level of education, use of private wells and consumption of local food.

CONCLUSIONS

The results suggest that people living close to the river may have been contaminated by Beta-HCH, most likely through water from private wells and privately grown food. A programme of epidemiological and clinical surveillance is on-going on this population.

[Mortality and morbidity among municipal waste workers in Rome: a cohort study]

INTRODUCTION

The adverse health effects associated with waste treatment processes are of great concern as large population groups and workers may be exposed to refuse-derived toxic substances. The main effects are respiratory and gastrointestinal infections, reduced lung function, irritations, allergic reactions, and injuries.

OBJECTIVE

To evaluate morbidity and mortality among a cohort of municipal waste workers in Rome.

METHODS

All 6839 workers (18.6% women) involved in waste collection, transportation and landfill disposal employed since 01/01/1994, with a minimum period of employment of five years were enrolled and with follow-up until 31/12/2009. The assessment of vital status was carried out through linkages with information systems (municipality records, mortality and hospital information systems), and through contacts with municipalities of residence. Gender specific standardized mortality (SMR) and hospitalization (SHR) ratios were calculated, using regional population mortality (and hospitalization) rates.

RESULTS

Overall, in this cohort workers had the same mortality as the population of the Region. Hospitalizations for natural causes were significantly higher than expected among workers involved in transportation (SHR = 1.25, 95% CI = 1.13-1.38) and in waste collection (SHR(men) = 1.14, 95% CI = 1.07-1.22; SHR(women) = 1.65, 95% CI = 1.47-1.84). Among women there was an excess of hospitalizations for respiratory diseases (SHR = 1.95, 95% CI = 1.33-2.77), for digestive system disorders (SHR = 1.37, 95% CI = 1.03-1.79) and for injuries and intoxications (SHR = 2.28, 95% CI = 1.69-2. 99).

CONCLUSIONS

The study did not find any increased mortality among the workers of either sexes. Female workers deserve further surveillance mainly due to an increased risk of trauma and respiratory and gastrointestinal disorders.

[Epidemiologic studies on the health status of the population living in the Sacco River Valley]

OBIETTIVO: to analyze the health status of the population living in an area close to the Colleferro industrial plant.

SETTING AND PARTICIPANTS

the area of the Sacco River Valley, Central Italy nearby Rome, has been heavily polluted over the years by industrial wastes deriving from the chemical industrial plant in Colleferro. In 2006, it was discovered that the herds of livestock were contaminated by beta-hexachlorocycloexane (β-HCH, an industrial waste belonging, as well as lindane, to the group of hexachlorocycloexane isomers).

MAIN OUTCOME MEASURES

the analyses of mortality and morbidity were carried out for the 1998-2007 period (calculation of standardized mortality ratios, SMR), and for the period 2003-2007 (calculation of standardized hospitalization ratios, SHR), respectively. The general population in the Lazio Region has been considered as reference. In addition, a biomonitoring study was conducted on a sample of the population living in 4 areas of the Sacco River Valley with different levels of exposure and the following persistent organic pollutants were measured in the blood (α, β and γ-HCH, HCB p,p'-DDT and p,p'- DDE, 6 NDL-PCB congeners and 12 DL-PCBs, PCDDs and PCDFs), and heavy metals (Cd, Hg, Pb).

RESULTS

cancer mortality in men was increased in the area (SMR=1.20), especially for specific cancer sites (stomach, larynx, lungs, pleura, myeloma); in women an excess of mortality from diabetes was detected (SMR=1.44). The analysis of morbidity indicated an excess of hospitalization for various cancers (larynx, myeloma) in men, for respiratory illness and asthma in both genders and for thyroid disease in women. The biomonitoring study found high mean concentration of β-HCH (mean: 99.05 ng/g fat, SD=121.3), with higher levels in the population living along the river (mean=150 ng/g fat; SD=153.5), likely occurred through water and local food.

CONCLUSION

the area of Colleferro has been polluted by multiple sources and the human population has been exposed to industrial chemicals, toxic substances in the workplace, and to the cumulative accumulation of organic pesticides especially through water and food.

Definition of patients treated with evidence based drugs in absence of prescribed daily doses: the example of acute myocardial infarction

PURPOSE

Define patients treated with evidence-based drugs in a cohort discharged after acute myocardial infarction (AMI) in absence of prescribed daily doses (PDD). To compare different drug use measures and analyze their impact on the effect estimate of risk factors related to drug use.

METHODS

AMI patients discharged in Rome during 2006-2007 were selected from the Hospital Information System. Drugs claimed during the 12 months after discharge were retrieved. Measures of drug use were defined as: 'continuity' (one prescription each follow-up quarter-year) and the 'proportion of days covered' calculated by defined daily doses (DDDs) or pill counts (PCs) (≥ 80% of individual follow-up). Poly-therapy was defined through the same drug use measure for all drug groups. Kappa index was calculated to analyze the concordance between measures. For each measure we estimated the effect of age, gender and Percutaneous Transluminal Coronary Angioplasty (PTCA) on poly-therapy.

RESULTS

Poly-therapy rates varied between 11.5 and 37.8% in the cohort and between 17.3 and 56.9% in patients with at least one prescription for all drugs. Concordance between all measures was high for antiplatelets (k=0.74) and very low for beta-blockers (k=0.22). According to measures used, gender and older age effects slightly varied, while PTCA remained a strong determinant of drug use.

CONCLUSIONS

Different measures of exposure to drug treatment may affect the estimate of the proportion of treated patients and the effect estimates of risk factors. Drug dispense registries are useful, but it is necessary to develop and validate methodologies in absence of PDD.