Effect of ethnic background on Danish hospital utilisation patterns

The aim of the study is to examine possible ethnic differences in the utilisation patterns of hospitalised immigrants versus patients born in Denmark. Data were obtained from the Register of Prevention at Statistics Denmark. This register includes both clinical and socio-demographic data. All patients discharged as inpatients during 1997 at Bispebjerg Hospital (a major hospital in Copenhagen) were identified through the Register of Prevention and linked to data concerning diagnosis, place of birth, age and gender. To compare immigrants with patients born in Denmark, a study group and a reference group were formed. The final study group consisted of all patients characterised by 22 major diagnostic categories and born outside the five Nordic countries (altogether 858 persons accounting for 976 inpatient contacts). The reference group consisted of 2004 patients accounting for 2432 inpatient contacts characterised by the same diagnostic categories among a random sample of 10,000 patients born in Denmark. The measure of utilisation employed was length of inpatient stay determined by the total number of days that each admission lasted. Data were analysed by a multiple regression analysis controlling for age, gender, diagnosis and place of birth. The results show that for some diagnostic groups, native Danes have longer inpatient stay compared to immigrants, whereas for other diagnostic groups immigrants have longer inpatient stay than native Danes. There was no overall effect of ethnicity on duration of hospital stay and consequently the utilisation patterns of inpatient care seem to reflect equal care for equal needs.     

Multisensory contributions to the shelter-seeking behavior of a mormyrid fish,Gnathonemus petersii Günther (Mormyridae,Teleostei): the role of vision,and the passive and active electrosenses

This study examined how weakly electric fish, Gnathonemus petersii, integrate multiple sensory modalities (passive and active electrosenses, and vision) to maintain proximity to tubular structures, serving as the fish's hiding place or shelter during the daytime. By moving the shelter along a linear 2-meter path, causing a mechanical disturbance, we challenged the fish's shelter-seeking behavior and used the length of travel that shelter proximity was maintained (contact distance) as an indicator of how well the animal maintained its shelter. In order to determine the contribution of vision and electrosense to this behavior, four groups of fish were tested in which: (1) all three modalities were intact; (2) vision alone was eliminated by optic nerve transection; (3) the active electrosense was silenced by spinal cord transection rendering the electric organ inoperative; and (4) both vision and active electrosense were deactivated. Further elimination or minimization of various sensory cues was achieved by testing the fish with optically transparent, acrylic shelters (Plexiglas) that stimulate active, but not passive, electrosense, and aluminum shelters that theoretically stimulate all three modalities. As expected, performance was optimal when all three modalities were operating, but better than expected from quantitative models based on additive processes alone. Although the absence of one sense (vision or active electrosense) caused initial deficits, these were fully compensated for over repeated daily exposure to the task, suggesting that learning might generate sensory substitution and/or the formation of sensory expectation. Finally, environmental conditions, such as shelter opacity, also affected shelter-seeking performance, sometimes in a negative direction. These results demonstrate that: (1) the integration of multiple sensory inputs in G. petersii can be synergistic, additive, redundant, or even inhibitory, and (2) multisensory processes also take into account the respective sensory cues; i.e. (a) the prevailing ambient light intensity and optical qualities of the object; (b) the geometry and strength of the DC potential emanating from the object ('battery effect'); and (c) the complex perceived impedance differential with the surrounding medium.     

Biochemical markers for brain damage after cardiac surgery -- time profile and correlation with cognitive dysfunction

BACKGROUND: Cerebral dysfunction is common after cardiac surgery and may be reflected in increasing blood concentrations of neuron specific enolase (NSE) and S-100 beta protein. The aim of the study was to determine the optimal timing of blood sampling. METHODS: We studied 15 patients undergoing coronary artery bypass grafting. Serum concentrations of NSE and S-100 beta protein were measured before surgery and after 12, 18, 24, 30, and 36 h. Neuropsychological testing was performed before surgery, at discharge from hospital and after 3 months. RESULTS: Serum concentrations of both NSE and S-100 beta protein increased significantly. At the first postoperative test, seven patients had cognitive dysfunction and a significant correlation was found between the composite z-score and the increase in the NSE level after 36 h (R = 0.76, P=0.001). The median increase in NSE after 36 h was 4.1 microg/l in patients having cognitive dysfunction and 0.9 microg/l in the remaining patients (P<0.05). No significant correlation was found between cognitive dysfunction and the increase in S-100 beta protein. After 3 months, no statistically significant correlation was found between either NSE or S-100 beta protein and cognitive dysfunction. CONCLUSION: NSE seems to be a useful blood marker for early cognitive dysfunction after coronary artery bypass grafting, optimal timing of blood sampling being at approximately 36 h postoperatively.     

The assessment of postoperative cognitive function

Postoperative cognitive function (POCD) has been subject to extensive research. In the literature, large differences are apparent in methodology such as the test batteries, the interval between sessions, the endpoints to be analysed, statistical methods, and how neuropsychological deficits are defined. Traditionally, intelligence tests or tests developed for clinical neuropsychology have been used. The tests for detecting POCD should be based on well-described sensitivity and suitability in relation to surgical patients. In tests using scores, floor/ceiling effects may compromise the evaluation if the tests are either too easy or to difficult. Uncontrolled testing facilities and change of test personnel may affect the test performance. Practice effects are pronounced in neuropsychological tests but have generally been ignored. The use of a suitable normative population is essential to allow correction for practice effects and variability between sessions. Missing follow-up may severely compromise valid conclusions since subjects unable or unwilling to be examined are particularly prone to suffer from POCD. In the statistical analysis of the test results, the evaluation should be based on differences between pre- and postoperative performance. Parametric statistical tests are not relevant unless the appropriate Gaussian distributions are present, perhaps after transformation of data. The definition of cognitive dysfunction should be restrictive and the criteria should be fulfilled in only a small proportion of volunteers. In the literature, these requirements often have not been fulfilled. This precludes a reasonable estimation of the incidence of POCD and the conclusions of comparative studies should be interpreted with great caution. In this review article, we present a number of recommendations for the design and execution of studies within this area. In addition, the critical reader may use these recommendations in the evaluation of the literature.