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Jonathan Shapiro

Publications and source records attributed to Jonathan Shapiro.

9 recordsLinked to original sources
PubMed2006

The association between psoriasis, diabetes mellitus, and atherosclerosis in Israel: a case-control study.

BACKGROUND: Previous reports demonstrated an association between psoriasis and other diseases including heart failure and diabetes mellitus. OBJECTIVES: Our aim was to describe the association between psoriasis, diabetes mellitus, and atherosclerosis in Israel. METHODS: A cross-sectional study was performed utilizing the database of Maccabi Healthcare Services (MHS), a large health provider organization in Israel. Case patients were defined as subjects who were diagnosed with psoriasis. Patients with diabetes and atherosclerosis were identified by using the MHS diabetes and cardiovascular registries, respectively. The control group included MHS enrollees without psoriasis. The proportion of diabetes and atherosclerosis among case and control groups was compared. Chi-square tests were used to compare categorical parameters. Logistic regression models were used for multivariate analyses. RESULTS: The study included 46,095 patients with psoriasis (case patients) and 1,579,037 subjects without psoriasis (control patients). The age-adjusted proportion of diabetes was significantly higher in psoriasis patients as compared with the control group (odds ratio [OR] 1.27, 95% confidence interval [CI] 1.1-1.48). The age-adjusted proportion of atherosclerosis was significantly higher in psoriasis patients as compared with the control group (OR 1.28, 95% CI 1.04-1.59). In patients with psoriasis, a multivariate logistic regression model demonstrated an association between diabetes and the multiple use of very potent topical steroids (P < .05) or use of systemic medication for psoriasis (methotrexate, cyclosporine or acitretin) (P < .001). A similar model demonstrated an association between atherosclerosis and the use of phototherapy (P < .001). LIMITATIONS: Our study was based on a computerized database. The diagnosis of psoriasis was based on digitally transmitted data. Therefore overestimation (false-positive cases) and underestimation (false-negative cases) of psoriasis patients may exist, thereby being a source for information bias. A second limitation is selection bias that may occur due to the possibility that reporting of both psoriasis and associated illnesses is higher in individuals who are seeking medical care. A third limitation concerns the causal effect between occurrence of psoriasis and atherosclerosis or diabetes. The dataset of MHS records diagnoses only from 1997 and does not record the date of disease onset. CONCLUSIONS: Our study supports previous reports for an association between psoriasis and atherosclerosis and psoriasis and diabetes. Further study is needed to support this observation.

Adolescent↗
PubMed2005

Health provider determinants of nonattendance in pediatric otolaryngology patients.

INTRODUCTION: Nonattendance for otolaryngology appointments disrupts the management of medical care and leads to ineffective use of resources. The determinants of nonattendance in pediatric otolaryngology patients have not been well documented. OBJECTIVES: To investigate health provider determinants of nonattendance in pediatric otolaryngology patients. STUDY DESIGN: We assessed the effects of waiting time for an appointment and the timing of the appointment (during the day, week, and year) on nonattendance proportions during a 1 year period. Chi square tests were used to analyze statistically significant differences of categorical variables. Logistic regression was used for multivariate analyses. RESULTS: A total of 2,628 pediatric visits were included in the study. The overall proportion of nonattendance at the pediatric otolaryngology clinic was 33.0%. Nonattendance proportions were 32.7% between 7 AM and 9 AM; 28.3% between 9 AM and 2 PM, and 36.5% between 2 PM and 8 PM (P < .001). The proportion of nonattendance was 24.1% when there was a short waiting time for an appointment (0-7 days), and 36.3% when there was an intermediate waiting time (7-15 days), and 36.6% when there was a long waiting time (15 days and above)(P < .001, P < .012, respectively). CONCLUSIVE: Health provider determinants of nonattendance in pediatric otolaryngology clinic appointments include the waiting time for an appointment and the hour of the appointment within the day.

Adolescent↗
PubMed2003

Increased warfarin doses and decreased international normalized ratio response after nationwide generic switching.

OBJECTIVE: Our objective was to examine possible changes in the effectiveness of warfarin after a nationwide generic substitution of formulations in 1998. METHODS: In the computerized records of a health maintenance organization database, we identified 975 patients who took warfarin continuously over two 6-month periods, before (period 1) and after (period 2) the generic switch. In this sample we performed a retrospective, between-period paired comparison of warfarin doses dispensed and international normalized ratio (INR) levels maintained, as well as of the apparent warfarin sensitivity index (calculated as INR/Warfarin dose [in milligrams per day]). RESULTS: Overall, for period 2, doses were 26.5% higher and INR 4.2% lower, with a 14.7% reduction in warfarin sensitivity index (P <.001). The findings were strongest in the 61 of 975 patients (6.3%) dispensed the lowest maintenance doses (<1.0 mg/d), with minimal change at greater than 3 mg/d. In 94 other patients (9.6%) in whom doses were unchanged, INR (median with 5th and 95th percentiles) dropped to subtherapeutic levels, from 2.2 (1.8, 3.0) to 1.7 (1.3, 1.8) (P <.001). There were no adverse events, expressed as no change in hospital admissions. Apparent warfarin sensitivity was reduced in period 2 by 15% to 20% (P <.001) across all period 1 INR levels. CONCLUSION: Because a general unidirectional change in INR response per unit warfarin dose cannot be explained by biologic mechanisms or confounding, we conclude that slightly reduced bioavailability (within the acceptable bioequivalence range) of the new formulation led to overestimated period 2 doses and reduced apparent warfarin sensitivity in all patient subgroups (by period 1 dose or INR), which was most prominent in those individuals with the lowest maintenance dose requirements.

Anticoagulants↗
PubMedDate not supplied

A self-organising network that grows when required.

The ability to grow extra nodes is a potentially useful facility for a self-organising neural network. A network that can add nodes into its map space can approximate the input space more accurately, and often more parsimoniously, than a network with predefined structure and size, such as the Self-Organising Map. In addition, a growing network can deal with dynamic input distributions. Most of the growing networks that have been proposed in the literature add new nodes to support the node that has accumulated the highest error during previous iterations or to support topological structures. This usually means that new nodes are added only when the number of iterations is an integer multiple of some pre-defined constant, A. This paper suggests a way in which the learning algorithm can add nodes whenever the network in its current state does not sufficiently match the input. In this way the network grows very quickly when new data is presented, but stops growing once the network has matched the data. This is particularly important when we consider dynamic data sets, where the distribution of inputs can change to a new regime after some time. We also demonstrate the preservation of neighbourhood relations in the data by the network. The new network is compared to an existing growing network, the Growing Neural Gas (GNG), on a artificial dataset, showing how the network deals with a change in input distribution after some time. Finally, the new network is applied to several novelty detection tasks and is compared with both the GNG and an unsupervised form of the Reduced Coulomb Energy network on a robotic inspection task and with a Support Vector Machine on two benchmark novelty detection tasks.

Algorithms↗