Female fertility and longevity

Does bearing children shorten a woman’s life expectancy? Pleiotropic theories of aging predict that it should, and in particular, the Disposable Soma theory predicts unequivocally that this effect should be inescapable. But many demographic studies, historic and current, have found no such effect. In this context, the Caerphilly cohort study stands apart as the sole test that corroborates the theory. Why has this study found an effect that others fail to see? Their analysis is based on Poisson regression, a statistical technique that is accurate only if the underlying data are Poisson-distributed. But the distribution of the number of children born to women in the Caerphilly database departs strongly from Poisson at the high end. This makes the result overly sensitive to a handful of women with 15 children or more who lived before 1700. When these five women are removed from a database of more than 2,900, the Poisson regression no longer shows a significant result. Bilinear regression relating life span to fertility and date of birth results in a small positive coefficient for fertility, in agreement with the main trend of reported results.     

Practical Assessment of the Tradeoff between Fatal Bleeding and Coronary Thrombotic Risks using the Academic Research Consortium for High Bleeding Risk Criteria

Aims: We aimed to establish a practical method for the assessment of tradeoff between thrombotic and bleeding risks. Methods: We aimed to investigate the balance between bleeding risk and coronary thrombotic risk according to the number of the Academic Research Consortium for high bleeding risk (ARC-HBR) criteria in the multicenter prospective ST/non-ST elevation myocardial infarction (STEMI/NSTEMI) registry (N=12,093). Patients were divided as follows by the number of ARC-HBR criteria fulfilled: group 0, 0 major with ≤ 1 minor (N=6,792); group 1, 1 major with 0 minor (N=1,705); group 2, 0 major with ≥ 2 minors (N=790); group 3, 1 major with ≥ 1 minor (N=1,709); group 4, 2 majors with ≥ 0 minors (N=861); and group 5, ≥ 3 majors with ≥ 0 minor (N=236). We assessed the acute-phase absolute risk differences between bleeding and coronary thrombotic events in each group. Results: At 7-day follow-up, all patients (groups 0–5) had a higher risk of major bleeding than that of any myocardial infarction (MI). Patients at ARC-HBR (groups 1–5) had a balanced risk between fatal MI and fatal bleeding, whereas patients at non-ARC-HBR (group 0) had a higher risk of fatal MI than that of fatal bleeding. Conclusions: All STEMI/NSTEMI patients have a relatively high risk of major bleeding as compared with the risk of any MI in the acute phase. The ARC-HBR criteria would be a practical tool for assessing the tradeoff between fatal bleeding and fatal MI risks. This practical assessment would be helpful for the optimal decision-making of appropriate treatment strategy considering the balance between bleeding and coronary thrombotic risks.     

Dynamic resolution selection in ultrasonic strain imaging

Ultrasonic strain imaging promises to be a valuable tool in medical diagnostics. Reliability and ease-of-use have become important considerations. These depend on selection of appropriate imaging parameters. Two tasks are undertaken here. The tradeoff between resolution and estimation precision is examined closely to establish models for the relationships with imaging parameters and data properties. These models are then applied in a system that automatically sets the imaging parameters responsive to the data quality and the required estimation precision, so as to produce more meaningful images under varying scan conditions. The new system is applied to simulation, in vitro and in vivo data for validation. It reduces the complexity of the sonographer's role in strain imaging, and produces images of reliable quality even when the level of signal decorrelation varies throughout the ultrasound data. (E-mail: jel35@eng.cam.ac.uk)     

Myoelectric changes in the triceps surae muscles under sustained contractions

Summary Synergistic behaviour of triceps surae muscles (medial gastrocnemius-MG, lateral gastrocnemius-LG, soleus-SOL) during sustained submaximal plantarflexions was investigated in this study. Six male subjects were asked to sustain an isometric plantar flexor effort to exhaustion at two different knee angles. Exhaustion was defined as the point when they could no longer maintain the required tension. The loads sustained at 0 and 120 degrees of knee flexion represented 50% and 36% of their maximum voluntary contraction (MVC) respectively. MVC was measured at 0 degree knee flexion. During the contractions, electromyograms (EMG) from the surface of the triceps surae muscles were recorded. Changes in the synergistic behaviour of the triceps surae were assessed via partial correlations of the average EMG (AEMG) between three muscle combinations; MG/LG, MG/SOL, LG/SOL, and correlation between SOL/MG+LG and MG/SOL+LG. The latter combinations were based on either common fibre type or innervation properties. Two types of synergisms were identified: trade-off and coactivation. Trade-off and coactivation synergies were defined by significant (p<0.05) positive and negative correlations respectively. Coactivation synergism was found to occur predominantly under conditions of high load or reduced length of the triceps surae, and increased with the duration of the contraction. Trade-off synergism was evident when the muscles were at their optimum length and the loads sustained were submaximum. Complete shutdown of one muscle activity was ruled out. It is postulated that, in the absence of voluntary strategies on the part of the subjects, changes in the syznergistic behaviour of the triceps surae muscles, manifested through trade-off and coactivation, is dependent on the load placed on the muscle and the muscle effectiveness as characterized by the force/length curve.     

A development framework for semantically interoperable health information systems

Background

Semantic interoperability is a basic challenge to be met for new generations of distributed, communicating and co-operating health information systems (HIS) enabling shared care and e-Health. Analysis, design, implementation and maintenance of such systems and intrinsic architectures have to follow a unified development methodology.

Methods

The Generic Component Model (GCM) is used as a framework for modeling any system to evaluate and harmonize state of the art architecture development approaches and standards for health information systems as well as to derive a coherent architecture development framework for sustainable, semantically interoperable HIS and their components. The proposed methodology is based on the Rational Unified Process (RUP), taking advantage of its flexibility to be configured for integrating other architectural approaches such as Service-Oriented Architecture (SOA), Model-Driven Architecture (MDA), ISO 10746, and HL7 Development Framework (HDF).

Results

Existing architectural approaches have been analyzed, compared and finally harmonized towards an architecture development framework for advanced health information systems.

Conclusion

Starting with the requirements for semantic interoperability derived from paradigm changes for health information systems, and supported in formal software process engineering methods, an appropriate development framework for semantically interoperable HIS has been provided. The usability of the framework has been exemplified in a public health scenario.     

Compensating wage differentials and the impact of health insurance in the public sector on wages and hours

This paper examines the trade-off between wages and employer spending on health insurance for public sector workers, and the relationship between coverage and hours worked. Our primary approach compares trends in wages and hours for public employees with and without state/local government provided health insurance using individual-level micro-data from the 1992–2011 CPS. To adjust for differences between insured and uninsured public sector employees, we create a matched sample based on an employee's propensity to receive health insurance. We assess the relationship between state contribution to the health plan premium, state-level healthcare spending, and the wages and hours of state and local government employees. We find modest reductions in wages are associated with having employer-sponsored health insurance (ESHI), although this effect is not precisely measured. The reduction in wages associated with having ESHI is larger among non-unionized workers. Further, we find little evidence that provision of health insurance increases hours worked.