Means-Inference as a Source of Variability in Early Helping

Humans, as compared to their primate relatives, readily act on behalf of others: we help, inform, share resources with, and provide emotional comfort for others. Although these prosocial behaviors emerge early in life, some types of prosocial behaviors seem to emerge earlier than others, and some tasks elicit more reliable helping than others. Here we discuss existing perspectives on the sources of variability in early prosocial behaviors with a particular focus on the variability within the domain of instrumental helping. We suggest that successful helping behavior not only requires an understanding of others' goals (goal-inference), but also the ability to figure out how to help (means-inference). We review recent work that highlights two key factors that support means-inference: causal reasoning and sensitivity to the expected costs and rewards of actions. Once we begin to look closely at the process of deciding how to help someone, even a seemingly simple helping behavior is, in fact, a consequence of a sophisticated decision-making process; it involves reasoning about others (e.g., goals, actions, and beliefs), about the causal structure of the physical world, and about one's own ability to provide effective help. A finer-grained understanding of the role of these inferences may help explain the developmental trajectory of prosocial behaviors in early childhood. We discuss the promise of computational models that formalize this decision process and how this approach can provide additional insights into why humans show unparalleled propensity and flexibility in their ability to help others.

CT coronary angiography vs. invasive coronary angiography in CHD

Scientific background

Various diagnostic tests including conventional invasive coronary angiography and non-invasive computed tomography (CT) coronary angiography are used in the diagnosis of coronary heart disease (CHD).

Research questions

The present report aims to evaluate the clinical efficacy, diagnostic accuracy, prognostic value cost-effectiveness as well as the ethical, social and legal implications of CT coronary angiography versus invasive coronary angiography in the diagnosis of CHD.

Methods

A systematic literature search was conducted in electronic data bases (MEDLINE, EMBASE etc.) in October 2010 and was completed with a manual search. The literature search was restricted to articles published from 2006 in German or English. Two independent reviewers were involved in the selection of the relevant publications.

The medical evaluation was based on systematic reviews of diagnostic studies with invasive coronary angiography as the reference standard and on diagnostic studies with intracoronary pressure measurement as the reference standard. Study results were combined in a meta-analysis with 95 % confidence intervals (CI). Additionally, data on radiation doses from current non-systematic reviews were taken into account.

A health economic evaluation was performed by modelling from the social perspective with clinical assumptions derived from the meta-analysis and economic assumptions derived from contemporary German sources.

Data on special indications (bypass or in-stent-restenosis) were not included in the evaluation. Only data obtained using CT scanners with at least 64 slices were considered.

Results

No studies were found regarding the clinical efficacy or prognostic value of CT coronary angiography versus conventional invasive coronary angiography in the diagnosis of CHD.

Overall, 15 systematic reviews with data from 44 diagnostic studies using invasive coronary angiography as the reference standard (identification of obstructive stenoses) and two diagnostic studies using intracoronary pressure measurement as the reference standard (identification of functionally relevant stenoses) were included in the medical evaluation.

Meta-analysis of the nine studies of higher methodological quality showed that, CT coronary angiography with invasive coronary angiography as the reference standard, had a sensitivity of 96 % (95 % CI: 93 % to 98 %), specificity of 86 % (95 % CI: 83 % to 89 %), positive likelihood ratio of 6.38 (95 % CI: 5.18 to 7.87) and negative likelihood ratio of 0.06 (95 % CI: 0.03 to 0.10). However, due to non-diagnostic CT images approximately 3.6 % of the examined patients required a subsequent invasive coronary angiography.

Using intracoronary pressure measurement as the reference standard, CT coronary angiography compared to invasive coronary angiography had a sensitivity of 80 % (95 % CI: 61 % to 92 %) versus 67 % (95 % CI: 51 % to 78 %), a specificity of 67 % (95 % CI: 47 % to 83 %) versus 75 % (95 % CI: 60 % to 86 %), an average positive likelihood ratio of 2.3 versus 2.6, and an average negative likelihood ratio 0.3 versus 0.4, respectively.

Compared to invasive coronary angiography, the average effective radiation dose of CT coronary angiography was higher with retrospective electrocardiogram (ECG) gating and relatively similar with prospective ECG gating.

The health economic model using invasive coronary angiography as the reference standard showed that at a pretest probability of CHD of 50 % or lower, CT coronary angiography resulted in lower cost per patient with true positive diagnosis. At a pretest probability of CHD of 70 % or higher, invasive coronary angiography was associated with lower cost per patient with true positive diagnosis. Using intracoronary pressure measurement as the reference standard, both types of coronary angiographies resulted in substantially higher cost per patient with true positive diagnosis.

Two publications dealing explicitly with ethical aspects were identified. The first addressed ethical aspects regarding the principles of beneficence, autonomy and justice, and the second addressed those regarding radiation exposition, especially when used within studies.

Discussion

The discriminatory power of CT coronary angiography to identify patients with obstructive (above 50 %) coronary stenoses should be regarded as “high diagnostic evidence”, to identify patients without coronary stenoses as “persuasive diagnostic evidence”. The discriminatory power of both types of coronary angiography to identify patients with or without functionally relevant coronary stenoses should be regarded as “weak diagnostic evidence”.

It can be assumed that patients with a high pretest probability of CHD will need invasive coronary angiography and patients with a low pretest probability of CHD will not need subsequent revascularisation. Therefore, CT coronary angiography may be used before performing invasive coronary angiography in patients with an intermediate pretest probability of CHD.

For identifying or excluding of obstructive coronary stenosis, CT coronary angiography was shown to be more cost-saving at a pretest probability of CHD of 50 % or lower, and invasive coronary angiography at a pretest probability of CHD of 70 % or higher. The use of both types of coronary angiography to identify or to exclude functionally relevant coronary stenoses should be regarded as highly cost-consuming.

With regard to ethical, social or legal aspects, the following possible implications were identified: under-provision or over-provision of health care, unnecessary complications, anxiety, social stigmatisation, restriction of self-determination, unequal access to health care, unfair resource distribution and legal disputes.

Conclusion

From a medical point of view, CT coronary angiography using scanners with at least 64 slices should be recommended as a test to rule out obstructive coronary stenoses in order to avoid inappropriate invasive coronary angiography in patients with an intermediate pretest probability of CHD. From a health economic point of view, this recommendation should be limited to patients with a pretest probability of CHD of 50 % or lower.

From a medical and health economic point of view, neither CT coronary angiography using scanners with at least 64 slices nor invasive coronary angiography may be recommended as a single diagnostic test for identifying or ruling out functionally relevant coronary stenoses.

To minimise any potential negative ethical, social and legal implications, the general ethical and moral principles of benefit, autonomy and justice should be considered.

Medical and health economic evaluation of prevention- and control measures related to MRSA infections or -colonisations at hospitals

Introduction

Methicillin-resistant Staphylococcus aureus (MRSA) are dangerous agents of nosocomial infections. In 2007 the prevalence of MRSA is 20.3% in Germany (Oxacilline-resistance according to EUCAST-criteria [EUCAST = European Committee on Antimicrobial Susceptibility Testing]).

Objectives

Which measurements are effective in the prevention and control of MRSA-infections in the hospital?

How effective are contact precautions, screening, decolonisation, education and surveillance?

Which recommendations can be given to health care politics on the basis of cost-effectiveness studies?

Have there been any adverse effects on patients and clinical staff?

What kind of liability problems exist?

Methods

Based on a systematic review of the literature studies are included which have been published in German or English language since 2004.

Results

1,508 articles have been found. After having surveyed the full text, 33 medical, eight economic and four ethical/juridical studies are included for the Health Technology Assessment (HTA) report.

The key result of the HTA report is that different measurements are effective in the prevention and control of MRSA-infections in hospitals, though the majority of the studies has a low quality. Effective are the conduction of differentiated screening measurements if they take into account the specific endemic situation, the use of antibiotic-control programs and the introduction and control of hygienic measurements. The break even point of preventive and control measurements cannot be defined because the study results differ too much. In the future it has to be more considered that MRSA-infections and contact precautions lead to a psycho-social strain for patients.

Discussion

It is hardly possible to describe causal efficacies because in the majority of the studies confounders are not sufficiently considered. In many cases bundles of measurements have been established but not analyzed individually. The internal and external validity of the studies is too weak to evaluate single interventions. Hygienic measurements prove to be effective in combination with other measurements. But it cannot be said which of the single measurements (gloves, washing hands, wearing gowns or masks) has the strongest effect on the reduction of MRSA. It is irritating that there are high differences in the compliance concerning hand hygiene between different studies. A general decolonisation is questionable for different reasons: first because of the side-effects for patients, second because of the high rate of spontaneous remissions in the untreated control group, third because of the differentiated process from colonisation to infection. Severalfold Hawthorne effects have been reported. One of them is that the competition between hospitals to reduce MRSA-rates leads already to a reduction.

Conclusions

It is evident that selective screening programs of risk patients considering the particular MRSA-prevalence are of use. The application of rapid tests seems to be only recommendable for risk patients and a high MRSA-prevalence. The improvement of the compliance of hand hygiene should be the basis of any prevention strategy. Training of staff members (with feedback mechanisms) is effective to improve compliance and to optimise the use of antibiotics. Antibiotic management programs are effective as well. Obviously multimodal approaches can lead to overadditive effects. Therefore the catalogue of preventive and control measurements has to be further evaluated. Good cost-efficacy studies are missing in Germany. The psychosocial effects of MRSA-infections are not researched in Germany. There is only punctual information on the risk management of hospitals.