1,720,973 research outputs found
Optimal weighted estimation versus Cochran-Mantel-Haenszel
No full textsponsorship: Financial support from the IAP research network #P7/06 of the Belgian Government (Belgian Science Policy) is gratefully acknowledged. The research leading to these results has also received funding from the European Seventh Framework program FP7 2007-2013 under grant agreement Nr. 602552. We gratefully acknowledge support from the IWT-SBO ExaScience grant. Intego is funded on a regular basis by the Flemish Government (Ministry of Health and Welfare). (IAP research network of the Belgian Government (Belgian Science Policy)|P7/06, European Seventh Framework program FP7 2007-2013|602552, IWT-SBO ExaScience grant, Flemish Government (Ministry of Health and Welfare))status: Publishe
Pneumococcal vaccination prevented severe LRTIs in adults: a causal inference framework applied in registry data
No full textOBJECTIVES: We estimated the effect of pneumococcal vaccination (PV) on acute lower respiratory tract infections (LRTIs) in various age and risk groups using different methods within a causal inference methodological framework. STUDY DESIGN AND SETTING: We used data from a general practitioners' morbidity registry for the year 2019. Both traditional statistical methods (regression-based and propensity score methods) and machine learning techniques were deployed. Multiple imputation was used to account for missing data. Relative risks (RRs) with 95% confidence intervals were estimated. Sensitivity analyses were performed to account for the severity of LRTIs and differences in vaccination registration. RESULTS: All methods showed a standardized mean difference below 0.1 for each covariate. No method was found to be superior to another. PV (combination of conjugate and polysaccharide vaccine) had an overall protective effect for severe LRTIs. PV was protective in different age and risk groups, especially in people aged 50-84 years with an intermediate risk group. CONCLUSION: Using several techniques, PV was found to prevent severe LRTIs and confirmed the recommendations of the Belgian Superior Health Council.status: Publishe
A longitudinal transition imputation model for categorical data applied to a large registry dataset
No full textImputation of longitudinal categorical covariates with several waves and many predictors is cumbersome in terms of implausible transitions, colinearity, and overfitting. We designed a simulation study with data obtained from a general practitioners' morbidity registry in Belgium for three waves, with smoking as the longitudinal covariate of interest. We set varying proportions of data on smoking to missing completely at random and missing not at random with proportions of missingness equal to 10%, 30%, 50%, and 70%. This study proposed a 3-stage approach that allows flexibility when imputing time-dependent categorical covariates. First, multiple imputation using fully conditional specification or multiple imputation for the predictor variables was deployed using the wide format such that previous and future information of the same patient was utilized. Second, a joint Markov transition model for initial, forward, backward, and intermittent probabilities was developed for each imputed dataset. Finally, this transition model was used for imputation. We compared the performance of this methodology with an analyses of the complete data and with listwise deletion in terms of bias and root mean square error. Next, we applied this methodology in a clinical case for years 2017 to 2021, where we estimated the effect of several covariates on the pneumococcal vaccination. This methodological framework ensures that the plausibility of transitions is preserved, overfitting and colinearity issues are resolved, and confounders can be utilized. Finally, a companion R package was developed to enable the replication and easy application of this methodology.The Flemish Government (Ministry of Health and Welfare) funds Intego on a regular basis. The funding source had no involvement in the study design, collection or interpretation of data, writing of the report, or decision to submit the article for publication. The authors hereby state the independence of the researchers from the funders. The Intego project was presented to the Belgian Privacy Commission (No. SCSZG/13/079) and approved by the ethical review board of the Medical School of the Catholic University of Leuven (No. ML 1723). This permission completely covered the current investigation. In the Intego protocol, participating GP practices must inform their patients that the practice participates in a morbidity registration network
Pneumococcal vaccination coverage and adherence to recommended dosing schedules in adults: a repeated cross-sectional study of the INTEGO morbidity registry
No full textBACKGROUND: Since 2014, Belgium's Superior Health Council has recommended pneumococcal vaccination for adults aged 19-85 years at increased risk for pneumococcal diseases with a specific vaccine administration sequence and timing. Currently, Belgium has no publicly funded adult pneumococcal vaccination program. This study investigated the seasonal pneumococcal vaccination trends, evolution of vaccination coverage and adherence to the 2014 recommendations. METHODS: INTEGO is a general practice morbidity registry in Flanders (Belgium) that represents 102 general practice centres and comprised over 300.000 patients in 2021. A repeated cross-sectional study was performed for the period between 2017 and 2021. Using adjusted odds ratios computed via multiple logistic regression, the association between an individual's characteristics (gender, age, comorbidities, influenza vaccination status and socioeconomic status) and schedule-adherent pneumococcal vaccination status was assessed. RESULTS: Pneumococcal vaccination coincided with seasonal flu vaccination. The vaccination coverage in the population at risk decreased from 21% in 2017 to 18.2% in 2018 and then started to increase to 23.6% in 2021. Coverage in 2021 was highest for high-risk adults (33.8%) followed by 50- to 85-year-olds with comorbidities (25.5%) and healthy 65- to 85-year-olds (18.7%). In 2021, 56.3% of the high-risk adults, 74.6% of the 50+ with comorbidities persons, and 74% of the 65+ healthy persons had an adherent vaccination schedule. Persons with a lower socioeconomic status had an adjusted odds ratio of 0.92 (95% Confidence Interval (CI) 0.87-0.97) for primary vaccination, 0.67 (95% CI 0.60-0.75) for adherence to the recommended second vaccination if the 13-valent pneumococcal conjugate vaccine was administered first and 0.86 (95% CI 0.76-0.97) if the 23-valent pneumococcal polysaccharide vaccine was administered first. CONCLUSION: Pneumococcal vaccine coverage is slowly increasing in Flanders, displaying seasonal peaks in sync with influenza vaccination campaigns. However, with less than one-fourth of the target population vaccinated, less than 60% high-risk and approximately 74% of 50 + with comorbidities and 65+ healthy persons with an adherent schedule, there is still much room for improvement. Furthermore, adults with poor socioeconomic status had lower odds of primary vaccination and schedule adherence, demonstrating the need for a publicly funded program in Belgium to ensure equitable access.sponsorship: Research council of the Vrije Universiteit Brussel|OZR3863BOF, Internal Funds KU Leuven|3M190682, Fonds Wetenschappelijk Onderzoek|1242021N, MSD, Belgiumstatus: Publishe
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Fast and optimal algorithm for case-control matching using registry data: application on the antibiotics use of colorectal cancer patients
No full textBACKGROUND: In case-control studies most algorithms allow the controls to be sampled several times, which is not always optimal. If many controls are available and adjustment for several covariates is necessary, matching without replacement might increase statistical efficiency. Comparing similar units when having observational data is of utter importance, since confounding and selection bias is present. The aim was twofold, firstly to create a method that accommodates the option that a control is not resampled, and second, to display several scenarios that identify changes of Odds Ratios (ORs) while increasing the balance of the matched sample. METHODS: The algorithm was derived in an iterative way starting from the pre-processing steps to derive the data until its application in a study to investigate the risk of antibiotics on colorectal cancer in the INTEGO registry (Flanders, Belgium). Different scenarios were developed to investigate the fluctuation of ORs using the combination of exact and varying variables with or without replacement of controls. To achieve balance in the population, we introduced the Comorbidity Index (CI) variable, which is the sum of chronic diseases as a means to have comparable units for drawing valid associations. RESULTS: This algorithm is fast and optimal. We simulated data and demonstrated that the run-time of matching even with millions of patients is minimal. Optimal, since the closest controls is always captured (using the appropriate ordering and by creating some auxiliary variables), and in the scenario that a case has only one control, we assure that this control will be matched to this case, thus maximizing the cases to be used in the analysis. In total, 72 different scenarios were displayed indicating the fluctuation of ORs, and revealing patterns, especially a drop when balancing the population. CONCLUSIONS: We created an optimal and computationally efficient algorithm to derive a matched case-control sample with and without replacement of controls. The code and the functions are publicly available as an open source in an R package. Finally, we emphasize the importance of displaying several scenarios and assess the difference of ORs while using an index to balance population in observational data.sponsorship: The Flemish Government (Ministry of Health and Welfare) funds Intego on a regular basis. The funding source had no involvement in study design, collection or interpretation of data, writing report, and decision to submit article for publication. The authors hereby state the independence of the researchers from the funders. (Flemish Government (Ministry of Health and Welfare) funds Intego on a regular basis)status: Publishe
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Assessing testing rates for viral hepatitis B and C by general practitioners in Flanders, Belgium: a registry-based study
No full textOBJECTIVES: Chronic infections with hepatitis B virus (HBV) and hepatitis C virus (HCV) have a major impact on mortality worldwide. Although effective treatments are available for both HBV and HCV infection, <50% of the patients are even diagnosed in Belgium. This study assessed the real-life testing-and diagnosis rate by general practitioners (GPs) in Flanders, Belgium. SETTING: We assessed the testing rate for HBV and HCV in 48 primary care practices with electronic medical records linked into one central registry in Flanders, Belgium. PARTICIPANTS: The registry contains data of 440 140 patients over 20 years, which corresponds to 2.2% of the total Flemish population yearly. The primary care practices are distributed across Flanders and the patient population is representative for the distribution of age, gender and socioeconomic status at the community level. RESULTS: Of 440 140 patients included in the registry, 7892 (1.8%) patients were screened for hepatitis B surface antigen (HBsAg) and 7206 (1.6%) for hepatitis C antibody (HCV Ab) of whom 369 (4.7%) and 163 (2.3%) tested positive, respectively. Of 14 059 patients with chronic liver enzyme elevation, 1112 (7.9%) and 1395 (9.9%) were tested for HBsAg and HCV Ab, respectively. There was no improvement in testing rates over time. CONCLUSIONS: This study demonstrates that real-life testing uptake for viral hepatitis B and C is suboptimal in the general practices in Flanders, even in patients with chronically elevated liver enzymes. As GPs play a crucial role in prevention, diagnosis and linkage to care, efforts and strategies to increase the testing uptake for HBV and HCV are urgently needed.sponsorship: This work was supported by Gilead Sciences by an unrestricted grant to KULeuven. (Gilead Sciences)status: Publishe
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