Do differences in the administrative structure of populations confound comparisons of geographic health inequalities?

<p>Background: Geographical health inequalities are naturally described by the variation in health outcomes between areas (e.g. mortality rates). However, comparisons made between countries are hampered by our lack of understanding of the effect of the size of administrative units, and in particular the modifiable areal unit problem. Our objective was to assess how differences in geographic and administrative units used for disseminating data affect the description of health inequalities.</p> <p>Methods: Retrospective study of standard populations and deaths aggregated by administrative regions within 20 European countries, 1990-1991. Estimated populations and deaths in males aged 0-64 were in 5 year age bands. Poisson multilevel modelling was conducted of deaths as standardised mortality ratios. The variation between regions within countries was tested for relationships with the mean region population size and the unequal distribution of populations within each country measured using Gini coefficients.</p> <p>Results: There is evidence that countries whose regions vary more in population size show greater variation and hence greater apparent inequalities in mortality counts. The Gini coefficient, measuring inequalities in population size, ranged from 0.1 to 0.5 between countries; an increase of 0.1 was accompanied by a 12-14% increase in the standard deviation of the mortality rates between regions within a country.</p> <p>Conclusions: Apparently differing health inequalities between two countries may be due to differences in geographical structure per se, rather than having any underlying epidemiological cause. Inequalities may be inherently greater in countries whose regions are more unequally populated.</p&gt

Carotid plaque morphology: A review

The recent North American Symptomatic Carotid Endarterectomy Trial has answered fairly conclusively the questions concerning the optimal management of patients with symptoms who have a > 70% stenosis of the internal carotid artery. It has also had the effect of refocusing attention on carotid pathology. The main question still to be answered is whether surgical management is the optimum treatment for other groups of patients with carotid disease. From various studies done on the natural history of carotid plaques it is apparent that there are subgroups who may benefit from surgery, namely those who will progress to stroke if not treated. The problem comes in identifying these subgroups by the factors which cause them to progress. This paper aims to review the role that plaque morphology has in the development of symptoms and whether it should be included with degree of stenosis in assessing the risk of a carotid plaque. The non-invasive assessment of plaque morphology is also reviewed. The evidence from this review does not support the use of plaque morphology as a discriminating factor for carotid endarterectomy at present

Outcome of selective patching following carotid endarterectomy

Objectives:Routine patch angioplasty has been advocated following carotid endarterectomy but patching can be associated with complications. This study assesses the effect of a selective patching policy based on distal internal carotid diameter on the rate of restenosis and outcome following carotid endarterectomy.Design, material and methods:A consecutive series of 213 patients underwent carotid endarterectomy performed by one surgeon. Preoperative carotid dimensions were measured intraoperatively using calipers. Following endarterectomy a 5mm Dacron patch was selectively employed if the distal internal carotid was 5mm or less (group 1, 95 patients) or 6mm or less (group 2, 118 patients). Patients underwent colour-coded Duplex scanning at 24 h, 1 week, 3, 6, 9, and 12 months, and yearly following this.Results:Overall 27 restenoses (5 residual) of 50% or greater and two occlusions developed. Patching was performed in 47% of group 1 and 61% of group 2 arteries. In group 1 14% of patched compared with 24% of non-patched arteries developed restenosis at 24 months (p = 0.4). In group 2 13% of patched compared to 11% of non-patched arteries developed restenosis at 12 months (p > 0.5). Stroke rate at 24 months were similar for patched and non-patched patients in groups 1 (p > 0.5) and 2 (p = 0.4).Conclusions:This study suggests that patch angioplasty of larger carotid arteries may be unnecessary. Randomisation of larger arteries between patch and primary closure would be required to confirm this

Late reoperation in vascular surgery

Objectives:Assessment of late reoperation (after 30 days) following vascular surgery.Design:Analysis of a prospectively collected database of consecutive patients undergoing vascular surgery.Setting:A single teaching unit's experience between 1986–1993.Materials:Patients undergoing 2501 primary arterial reconstructions.Chief outcome measures:Reoperation after 30 days.Main results:One hundred and fifty eight patients (6%) underwent further operations, at more than 1 month after the primary procedure. Primary procedures at highest risk for reoperations were axillobifemoral bypasses and femorodistal bypasses with respective late reoperation rates of 20% and 16%. The majority of patients required late reoperation because of graft occlusion or stenosis. Overall, of the 158 late reoperations performed, 114 were related to the same arterial segment with the same presenting symptoms as the primary operation, and 44 for a different indication. A second or subsequent reoperation was required in 54 patients and the overall operative mortality was 11%.Conclusion:Patients undergoing certain vascular procedures, should be informed of the high risk of a subsequent procedure when consent is obtained

Immediate Hemodynamic Effect of the Additional Use of the SCD EXPRESS™ Compression System in Patients with Venous Ulcers Treated with the Four-layer Compression Bandaging System

ObjectivesTo test the hypothesis that the SCD EXPRESS™ intermittent pneumatic compression applied in combination with a four-layer bandage in patients with venous ulcers increases popliteal vein volume flow and velocity.DesignTwenty limbs of 18 patients with venous leg ulcers were studied, median age 76 years. The Total Volume Flow (TVF) and the Peak Systolic Velocity (PSV) were recorded in the popliteal vein using duplex ultrasonography. Measurements were made (i) without bandage, (ii) with four layer bandage and (iii) following the application of the SCD Compression System on top of a four-layer bandage for at least 15 minutes.ResultsThe median VCSS was 17 (range, 12–22) while the median VSDS for reflux was 4.5 (range, 1–7.5). The median TVF was 71mL/min (inter-quartile range 57–101) without bandage, 112 (IQR 89–148) with four-layer bandage and 291 (IQR 241–392) with the addition of the SCD System (P<.001, Wilcoxon signed ranks test). The median PSV was 8.4cm/sec (IQR 6.8–14) without bandage, 13 (9.0–19) with four-layer bandage and 27 (21–31) with the addition of the SCD System (P<.001, Wilcoxon signed ranks test). Both TVF and PSV increased slightly with the addition of the four-layer bandage. However, with the addition of the SCD System these parameters increased three fold.ConclusionsThe SCD EXPRESS Compression System accelerates venous flow in the legs of patients with venous ulcers already treated with a four-layer bandage. The combination of four-layer compression with the SCD System on healing venous ulcers needs to be tested by a clinical effectiveness study

Compression ultrasonography for false femoral artery aneurysms: Hypocoagulability is a cause of failure

Objectives:false femoral artery aneurysm is an occasional complication of percutaneous cardiovascular radiological procedures. Compression ultrasonography causes thrombosis non-invasively, reducing need for operative intervention. The technique fails in a proportion of cases. Analysis was undertaken to identify causes of failure.Design:prospective open study.Materials and Methods:patients presenting with false femoral artery aneurysm since 1984 were identified from a computerised database (BIPAS). Since 1993 compression ultrasonography has been performed as first line treatment according to a standard protocol. Prospectively collected ultrasonographic data and case notes were reviewed to identify causes of failed compression.Results:false femoral artery aneurysm occurred as a complication in 32/26 687 (0.12%) cardiovascular radiological procedures. Eighteen aneurysms were treated by compression. The technique was successful in 11/18 (61%) cases but primary failure occurred in seven cases. Six out of seven had bleeding abnormalities (Chi-squared analysis with Yates correction 10.55, p=0.0012), four were anticoagulated and compression was subsequently successful following reversal of warfarin therapy in three of these patients. In 4/18 cases surgical repair was necessary.Conclusions:compression ultrasonography is an effective treatment of false femoral aneurysms, however, hypocoagulability is a significant cause of failure. For patients in whom anticoagulation cannot be reversed, primary surgical repair should be considered

Inhibitory Effect of TIMP Influences the Morphology of Varicose Veins

AbstractObjectivesImbalance of matrix metalloproteinase enzymes (MMP) and their inhibitors (TIMPs) may contribute to the development of varicose veins. We hypothesised that, histological changes in varicose vein wall correlate with alterations in expression of MMP/TIMP.MethodsVaricose veins (n = 26) were compared with great saphenous vein (GSV) segments (n = 11) from arterial bypass, and with arm and neck veins from fistula and carotid operations (n = 13). Varicose vein wall thickness was measured, enabling categorisation as atrophic and hypertrophic. MMP-2, MT1-MMP, TIMP-2, and TIMP-3 expression were quantitatively analysed by immunohistochemistry.ResultsThere was significantly higher expression of TIMP-2 (immunopositive area 4.34% versus 0.26%), linked with connective tissue accumulation in the tunica media of varicose veins as compared with arm and neck vein controls. TIMP-2 and TIMP-3 expression was higher in hypertrophic than atrophic segments (3.2% versus 0.99% for TIMP-2, 1.7% versus 0.08% for TIMP-3). Similarly, TIMP-2 and TIMP-3 had elevated expression in the thicker proximal varicose vein segments compared to distal (4.3% versus 1.3% for TIMP-2 and 0.94% versus 0.41% for TIMP-3).ConclusionsThis study linked morphological changes in varicose vein walls with MMP/TIMP balance. A higher TIMP expression favours deposition of connective tissue and thus thicker vein wall, reducing matrix turnover by suppression of protease activity

The Spectral Action Principle in Noncommutative Geometry and the Superstring

A supersymmetric theory in two-dimensions has enough data to define a noncommutative space thus making it possible to use all tools of noncommutative geometry. In particular, we apply this to the N=1 supersymmetric non-linear sigma model and derive an expression for the generalized loop space Dirac operator, in presence of a general background, using canonical quantization. The spectral action principle is then used to determine a spectral action valid for the fluctuations of the string modes.Comment: Latex file, 13 pages. Correction to equation 47, which should read Tr| |^2 and not |Tr |^2. Final form to appear in Physics Letters