Estimation of Anonymous Email Network Characteristics through Statistical Disclosure Attacks.

Social network analysis aims to obtain relational data from social systems to identify leaders, roles, and communities in order to model profiles or predict a specific behavior in users' network. Preserving anonymity in social networks is a subject of major concern. Anonymity can be compromised by disclosing senders' or receivers' identity, message content, or sender-receiver relationships. Under strongly incomplete information, a statistical disclosure attack is used to estimate the network and node characteristics such as centrality and clustering measures, degree distribution, and small-world-ness. A database of email networks in 29 university faculties is used to study the method. A research on the small-world-ness and Power law characteristics of these email networks is also developed, helping to understand the behavior of small email networks.

Extracting association patterns in network communications.

In network communications, mixes provide protection against observers hiding the appearance of messages, patterns, length and links between senders and receivers. Statistical disclosure attacks aim to reveal the identity of senders and receivers in a communication network setting when it is protected by standard techniques based on mixes. This work aims to develop a global statistical disclosure attack to detect relationships between users. The only information used by the attacker is the number of messages sent and received by each user for each round, the batch of messages grouped by the anonymity system. A new modeling framework based on contingency tables is used. The assumptions are more flexible than those used in the literature, allowing to apply the method to multiple situations automatically, such as email data or social networks data. A classification scheme based on combinatoric solutions of the space of rounds retrieved is developed. Solutions about relationships between users are provided for all pairs of users simultaneously, since the dependence of the data retrieved needs to be addressed in a global sense.

Impact of interactive computerised decision support for hospital antibiotic use (COMPASS): an open-label, cluster-randomised trial in three Swiss hospitals.

BACKGROUND: Computerised decision-support systems (CDSSs) for antibiotic stewardship could help to assist physicians in the appropriate prescribing of antibiotics. However, high-quality evidence for their effect on the quantity and quality of antibiotic use remains scarce. The aim of our study was to assess whether a computerised decision support for antimicrobial stewardship combined with feedback on prescribing indicators can reduce antimicrobial prescriptions for adults admitted to hospital. METHODS: The Computerised Antibiotic Stewardship Study (COMPASS) was a multicentre, cluster-randomised, parallel-group, open-label superiority trial that aimed to assess whether a multimodal computerised antibiotic-stewardship intervention is effective in reducing antibiotic use for adults admitted to hospital. After pairwise matching, 24 wards in three Swiss tertiary-care and secondary-care hospitals were randomised (1:1) to the CDSS intervention or to standard antibiotic stewardship measures using an online random sequence generator. The multimodal intervention consisted of a CDSS providing support for choice, duration, and re-evaluation of antimicrobial therapy, and feedback on antimicrobial prescribing quality. The primary outcome was overall systemic antibiotic use measured in days of therapy per admission, using adjusted-hurdle negative-binomial mixed-effects models. The analysis was done by intention to treat and per protocol. The study was registered with ClinicalTrials.gov (identifier NCT03120975). FINDINGS: 24 clusters (16 at Geneva University Hospitals and eight at Ticino Regional Hospitals) were eligible and randomly assigned to control or intervention between Oct 1, 2018, and Dec 31, 2019. Overall, 4578 (40·2%) of 11 384 admissions received antibiotic therapy in the intervention group and 4142 (42·8%) of 9673 in the control group. The unadjusted overall mean days of therapy per admission was slightly lower in the intervention group than in the control group (3·2 days of therapy per admission, SD 6·2, vs 3·5 days of therapy per admission, SD 6·8; p<0·0001), and was similar among patients receiving antibiotics (7·9 days of therapy per admission, SD 7·6, vs 8·1 days of therapy per admission, SD 8·4; p=0·50). After adjusting for confounders, there was no statistically significant difference between groups for the odds of an admission receiving antibiotics (odds ratio [OR] for intervention vs control 1·12, 95% CI 0·94-1·33). For admissions with antibiotic exposure, days of therapy per admission were also similar (incidence rate ratio 0·98, 95% CI 0·90-1·07). Overall, the CDSS was used at least once in 3466 (75·7%) of 4578 admissions with any antibiotic prescription, but from the first day of antibiotic treatment for only 1602 (58·9%) of 2721 admissions in Geneva. For those for whom the CDSS was not used from the first day, mean time to use of CDSS was 8·9 days. Based on the manual review of 1195 randomly selected charts, transition from intravenous to oral therapy was significantly more frequent in the intervention group after adjusting for confounders (154 [76·6%] of 201 vs 187 [87%] of 215, +10·4%; OR 1·9, 95% CI 1·1-3·3). Consultations by infectious disease specialists were less frequent in the intervention group (388 [13·4%] of 2889) versus the control group (405 [16·9%] of 2390; OR 0·84, 95% CI 0·59-1·25). INTERPRETATION: An integrated multimodal computerised antibiotic stewardship intervention did not significantly reduce overall antibiotic use, the primary outcome of the study. Contributing factors were probably insufficient uptake, a setting with relatively low antibiotic use at baseline, and delays between ward admission and first CDSS use. FUNDING: Swiss National Science Foundation. TRANSLATIONS: For the French and Italian translations of the abstract see Supplementary Materials section.

How to Develop and Implement a Computerized Decision Support System Integrated for Antimicrobial Stewardship? Experiences From Two Swiss Hospital Systems.

Background: Computerized decision support systems (CDSS) provide new opportunities for automating antimicrobial stewardship (AMS) interventions and integrating them in routine healthcare. CDSS are recommended as part of AMS programs by international guidelines but few have been implemented so far. In the context of the publicly funded COMPuterized Antibiotic Stewardship Study (COMPASS), we developed and implemented two CDSSs for antimicrobial prescriptions integrated into the in-house electronic health records of two public hospitals in Switzerland. Developing and implementing such systems was a unique opportunity for learning during which we faced several challenges. In this narrative review we describe key lessons learned. Recommendations: (1) During the initial planning and development stage, start by drafting the CDSS as an algorithm and use a standardized format to communicate clearly the desired functionalities of the tool to all stakeholders. (2) Set up a multidisciplinary team bringing together Information Technologies (IT) specialists with development expertise, clinicians familiar with "real-life" processes in the wards and if possible, involve collaborators having knowledge in both areas. (3) When designing the CDSS, make the underlying decision-making process transparent for physicians and start simple and make sure to find the right balance between force and persuasion to ensure adoption by end-users. (4) Correctly assess the clinical and economic impact of your tool, therefore try to use standardized terminologies and limit the use of free text for analysis purpose. (5) At the implementation stage, plan usability testing early, develop an appropriate training plan suitable to end users' skills and time-constraints and think ahead of additional challenges related to the study design that may occur (such as a cluster randomized trial). Stay also tuned to react quickly during the intervention phase. (6) Finally, during the assessment stage plan ahead maintenance, adaptation and related financial challenges and stay connected with institutional partners to leverage potential synergies with other informatics projects.

Prevalence of primary open-angle glaucoma in a Spanish population: the Segovia study.

PURPOSE: To determine the prevalence of primary open-angle glaucoma (POAG) in Segovia, Spain. METHODS: We conducted a cross-sectional, population-based epidemiologic study, the target population of which was residents of Segovia, Spain, aged 40 to 79 years. A sample of 569 subjects was randomly selected in a stratified manner according to gender and age groups. All participants underwent a complete ophthalmic examination that included measurement of visual acuity and refraction, tonometry, anterior segment biomicroscopy, funduscopy, stereoscopic photographs of the optic nerve head, and automated white-on-white visual field testing. Two independent observers evaluated the optic nerve photographs and visual fields. The diagnosis of POAG was established when any eye had an open angle and a glaucomatous optic nerve and glaucomatous visual field. The prevalence of POAG in the population was estimated from the prevalence in the complete sample and the patients already diagnosed at the only glaucoma service in the city. RESULTS: The estimated prevalences (99% confidence interval) in the population were, respectively, 2.1% (1.9-2.3%), and 1.7% (1.6-1.8%) for POAG and ocular hypertension. The prevalence of POAG increased with age (P < 0.005) and tended to be greater (P = 0.054) in men (2.4%) than women (1.7%). CONCLUSION: The prevalence of POAG in this Segovia population is 2.1%, similar to that estimated in previous studies performed in predominantly Caucasian populations.

Epidemiology of refractive errors in an adult European population: the Segovia study.

PURPOSE: To determine the prevalence of refractive errors in Segovia, Spain. METHODS: A cohort of 569 subjects was randomly selected in a stratified manner according to gender and age in a cross-sectional, population-based epidemiologic study, the target population of which was urban residents aged 40 to 79 years. All participants underwent an ophthalmic examination that included measurement of visual acuity (VA) and refraction, tonometry, anterior segment biomicroscopy, funduscopy, optic nerve head photography, and visual field testing. Of those, 417 subjects were enrolled who met the inclusion criteria of a phakic right eye and VA over 20/40. The prevalence of spherical errors was assessed after calculating the spherical equivalent and defining myopia as -0.5 diopters (D) or less and hyperopia as +0.50 D or more. The prevalence of astigmatism over 0.50 D was evaluated in minus cylinder form. RESULTS: The estimated prevalences (95% confidence interval) of myopia, hyperopia, and astigmatism, in the population were 25.4% (21.5-29.8%) 43.6% (39-48.4%), and 53.5% (48.7-58.2%), respectively. No significant gender difference was found in the prevalence of any refractive errors. The prevalence of myopia or the mean value did not change significantly with age. The mean hyperopia and the mean astigmatism (p < 0.01 for both) and the prevalence increased with increasing age (p < 0.01 for both). Anisometropia of 1 D or more was present in 12.3% (49/396 subjects). CONCLUSION: More than 60% of the Segovia population over 40 years of age has a refractive error, with 25.4% myopic and 43.6% hyperopic. Astigmatism is present in over half of the population and the types change with age.