A predictive Bayesian approach to risk analysis in health care

Background  

The Bayesian approach is now widely recognised as a proper framework for analysing risk in health care. However, the traditional text-book Bayesian approach is in many cases difficult to implement, as it is based on abstract concepts and modelling.     

Abductor pollicis longus tendon interposition for arthrosis in the first carpometacarpal joint: 55 thumbs reviewed after 3 (1-5) years

We have performed an interposition arthroplasty using the abductor pollicis longus (APL) tendon for arthrosis in the basal joint of the thumb in our department since 1995. Before this, we had been using an interposition with the flexor carpi radialis (FCR) tendon. We re-examined 47 patients (55 thumbs) after a median follow-up of 41 (16-60) months. The pain relief was excellent in 32 thumbs, and 25 patients improved their ability to perform daily tasks. Mobility was well preserved. Key pinch and grip strengths averaged 78% and 89%, respectively, of those in unaffected hands. An excellent general result was reported by 34 patients, while 4 patients would not have consented to the operation if they had known the outcome in advance.     

Impact of changes in heart rate and stroke volume on the cross sectional flow velocity distribution of diastolic mitral blood flow

The effect of changes in stroke volume on the cross sectional velocity distribution in the mitral orifice during passive mitral inflow was studied in six patients with total atrioventricular block, atrial fibrillation and VVI pacemakers during periods with different heart rates. The time velocity integrals recorded both in the left ventricular outflow tract and at the mitral orifice decreased significantly as the heart rate was increased from 60 to 80 and from 80 to 100 beats per minute. Instantaneous cross sectional flow velocity profiles were constructed by time interpolation of the velocity data from each point in sequentially delayed two dimensional digital ultrasound maps. Each patient had a characteristic cross sectional flow velocity profile in the mitral orifice recorded at the level of the leaflet tips in a four chamber view. The velocity profiles varied between the patients. With increase in heart rate only minimal changes in the flow profiles from individual patients were seen. The maximum velocity through the mitral orifice overestimated the cross sectional mean velocity at the same time by a factor of 1.4–1.9. The maximum time velocity integral overestimated the cross sectional mean by a factor of 1.4–1.8. The observed cross sectional skew varied between patients but did not change significantly with increasing heart rate and decrease in stroke volume.     

Experimental application of thermosensitive paramagnetic liposomes for monitoring magnetic resonance imaging guided thermal ablation.

The use of a liposomal paramagnetic agent with a T(1)-relaxivity that increases markedly at temperatures above the phase transition temperature (T(m)) of the liposomal membrane was evaluated during magnetic resonance imaging (MRI) guided hyperthermia ablation. A neodymium-yttrium aluminum garnet (Nd-YAG) laser unit and a radiofrequency ablation system were used for tissue ablation in eight rabbit livers in vivo. One ablation was made in each animal prior to administration of the liposomal agent. Liposomes with a T(m) of 57 degrees C containing gadodiamide (GdDTPA-BMA) were injected iv, and two additional ablations were performed. T(1)-weighted scans were performed in heated tissue, after tissue temperature had normalized, and 15-20 min after normalization of tissue temperature. Increase in signal intensity (DeltaSI) for ablations prior to injection of the agent was 13.0% (SD = 5.7) for the laser group and 9.1% (SD = 7.9) for the radiofrequency group. Signal intensity after administration of the agent unrelated to heating was not statistically significant (DeltaSI = 1.4%, P = 0.35). For ablations made after injection of the agent, a significant increase was found in the laser (DeltaSI = 34.5%, SD = 11.9) and radiofrequency group (DeltaSI = 21.6%, SD = 22.7). The persistent signal enhancement found in areas exposed to a temperature above the threshold temperature above T(m) allows thermal monitoring of MRI guided thermal ablation.     

Ligand-induced conformational changes allosterically activate Toll-like receptor 9

Microbial and synthetic DNA rich in CpG dinucleotides stimulates Toll-like receptor 9 (TLR9), whereas DNA lacking CpG either is inert or can inhibit TLR9 activation. The molecular mechanisms by which TLR9 becomes activated or is inhibited are not well understood. Here we show that TLR9 bound to stimulatory and inhibitory DNA; however, only stimulatory DNA led to substantial conformational changes in the TLR9 ectodomain. In the steady state, 'inactive' TLR9 homodimers formed in an inactivated conformation. Binding of DNA containing CpG, but not of DNA lacking CpG, to TLR9 dimers resulted in allosteric changes in the TLR9 cytoplasmic signaling domains. In endosomes, conformational changes induced by DNA containing CpG resulted in close apposition of the cytoplasmic signaling domains, a change that is probably required for the recruitment of signaling adaptor molecules. Our results indicate that the formation of TLR9 dimers is not sufficient for its activation but instead that TLR9 activation is regulated by conformational changes induced by DNA containing CpG.     

Pig herds free from human pathogenic Yersinia enterocolitica

Pork products are a substantial source of human yersiniosis, a foodborne disease caused by Yersinia enterocolitica. Thus, the ability to eliminate this agent from pig herds would be an important step in producing human pathogen-free pork. Pig herds free from Y. enterocolitica O:3/biovar 4 have been established and maintained. According to serologic and cultural testing results, 15 of 16 specific pathogen-free herds were free from Y. enterocolitica O:3/biovar 4; this closed breeding pyramid has remained free from this organism since 1996. Pig herds free from human pathogenic Y. enterocolitica suggest that human pathogen-free herds could be attained to provide pork free from zoonotic agents.     

Modelling seasonal and weather dependency of cardiac arrests using the covariate order method

A data set concerning cardiac arrests treated by the Emergency Medical Service in Trondheim during a nine year period is analysed. The relationship between the occurrence of cardiac arrest and covariates related to weather and season is examined. The covariate order method is used in the analysis of the data. It is explained how this method can be extended to recurrent event data, and the practical usefulness and flexibility of the method is demonstrated in these analyses. In the analyses a significant relationship between outdoor air temperature, or factors closely related to outdoor air temperature, and the occurrence of cardiac arrest is found. The incidence of cardiac arrest decreases with increasing temperature. Further a significant effect of snowfall is also found, with increased intensity of cardiac arrest on days with snowfall. A more borderline significant effect of precipitation is also identified.     

Myocardial performance index (Tei index) does not reflect long-term changes in left ventricular function after acute myocardial infarction

AIMS: To evaluate whether changes in myocardial performance index (MPI or Tei index) were related to changes in other Doppler echocardiographic parameters after acute myocardial infarction, or had any independent prognostic impact in a 2-year observational study. METHODS AND RESULTS: Seventy-one patients with acute myocardial infarction without heart failure were examined at baseline, 3 months, and 2 years. MPI was significantly related to end-diastolic and end-systolic volume indexes, ejection fraction, maximal velocity, and time velocity integral of early mitral filling wave at 3 months and 2 years. MPI did not contribute significantly to the prediction of any changes in the measures of diastolic or systolic function at 3 months or 2 years. Baseline MPI was significantly higher in patients who later developed heart failure(0.55 +/- 0.16)than in other patients(0.43 +/- 0.13, P = 0.006), but had no independent predictive power for the development of heart failure or death relative to end-systolic volume index and deceleration time of early mitral filling wave. CONCLUSION: MPI did not accurately reflect changes in Doppler and two-dimensional echocardiographic measures of diastolic or systolic function during a 2-year follow-up after acute myocardial infarction, and did not have any independent prognostic impact.