Showing papers by "University of Saskatchewan published in 1995"

Disclosure Policy, Information Asymmetry, and Liquidity in Equity Markets*

Abstract: . This study investigates the relation between disclosure policy and liquidity in equity markets. Disclosure policy influences market liquidity because uninformed investors “price protect” against adverse selection, and this price protection is manifested in market liquidity. Bid-ask spreads, the empirical measure of market liquidity used in this study, are predicted to be inversely related to disclosure policy. In addition, increased trading by informed traders and higher probability of information event occurrence are predicted to both increase spreads and intensify the relation between spreads and disclosure policy. These predictions apply during periods in which no news about the firm is disclosed or pending. The results show that relative bid-ask spreads for firms with disclosure rankings in the bottom third of the empirical distribution are approximately 50 percent higher than spreads for firms with disclosure rankings in the top third of the empirical distribution. Tests that assume endogenous disclosure policy reveal a significant negative relation between disclosure policy and spreads, even after controlling for the effects of return volatility, trading volume, and share price. Tests for cross-sectional variation in spreads and for the sensitivity of spreads to disclosure policy based on informed trade activity and probability of information event occurrence are generally consistent with the predictions, though these results are not statistically significant. The findings of this study are consistent with the notion that a well-regarded disclosure policy reduces information asymmetry and hence increases liquidity in equity markets. Resume. L'auteur analyse la relation entre la politique d'information et la liquidite des marches d'actions. La politique d'information influe sur la liquidite du marche, etant donne que les investisseurs non informes se protegent contre les choix prejudiciables en ce qui a trait aux cours, comportement de protection qui se manifeste dans la liquidite du marche. Les ecarts entre les cours acheteur et vendeur, la mesure empirique de la liquidite du marche utilisee dans la presente etude, devraient presenter, selon les previsions, une relation inverse avec la politique d'information. De plus, l'intensification de l'activite des negociateurs informes et la probabilite accrue de l'occurrence d'un evenement d'information devraient, selon les previsions, augmenter tous les deux les ecarts et consolider la relation entre les ecarts et la politique d'information. Ces previsions s'appliquent aux cours des periodes dans lesquelles aucune information nouvelle au sujet de l'entreprise n'est publiee ou n'est sur le point de l'etre. Les resultats demontrent que les ecarts relatifs entre cours acheteur et vendeur des entreprises dont la publication d'information les place dans le tiers inferieur de la distribution empirique sont d'environ 50 pour cent superieurs aux ecarts des entreprises dont la publication d'information les place dans le tiers superieur de la distribution empirique. Les tests qui supposent une politique d'information endogene revelent une relation negative significative entre la politique d'information et les ecarts, meme apres avoir controle les consequences de la volatilite du rendement, le volume des operations et le cours de l'action. Les tests relatifs a la variation transversale des ecarts et de la sensibilite des ecarts a la politique d'information, basee sur l'activite de negociation informee et la probabilite d'occurrence d'un evenement d'information, sont generalement conformes aux previsions, bien que les resultats n'en soient pas statistiquement significatifs. Les conclusions de l'etude confirment le principe selon lequel une politique d'information bien pensee reduit l'asymetrie de l'information et, par consequent, augmente la liquidite des marches d'actions.

Differential influence of nerve growth factor on neuropeptide expression in vivo: a novel role in peptide suppression in adult sensory neurons

Abstract: In this study the actions of NGF in regulating peptide expression were examined in vivo in adult rat primary sensory neurons. The hypothesis that NGF might tonically inhibit expression of some peptides was tested specifically. In situ hybridization and immunohistochemistry were used to detect presence or absence of alpha-CGRP, beta-CGRP, SP, SOM, VIP, CCK, NPY, and GAL as well as their mRNAs. In neurons in normal lumbar DRG alpha-CGRP, beta-CGRP, SP, and SOM are abundantly and heterogeneously expressed whereas few neurons have detectable VIP, CCK, NPY, or GAL. Two weeks following sciatic nerve transection, concentrations of alpha-CGRP, beta-CGRP, SP, and SOM plus their mRNAs have decreased to background in all but a few neurons. In contrast, VIP, CCK, NPY, and GAL are now synthesized in many neurons. Delayed intrathecal infusion of NGF (125 ng/microliter/hr) for 7 d, starting 2 weeks after injury counteracted the decrease in expression of alpha-CGRP, beta-CGRP and SP expression, but not SOM. This lack of influence of NGF on SOM is consistent with the absence of high-affinity NGF receptors and trk mRNA in SOM-positive neurons. Delayed infusion of NGF also reduced the number of neurons expressing VIP, CCK, NPY, and GAL after injury by approximately one-half in each subpopulation. Therefore, we suggest that NGF suppresses expression of these four peptides but only if the neurons also have NGF receptors. The results show that NGF can regulate peptide expression differentially and may also be part of the signal that allows reversion to normal of responses to injury as axons regenerate.

Lipid peroxidation and activity of antioxidant enzymes in diabetic rats

Abstract: We hypothesized that oxygen free radicals (OFRs) may be involved in pathogenesis of diabetic complications. We therefore investigated the levels of lipid peroxidation by measuring thiobarbituric acid reactive substances (TBARS) and activity of antioxidant enzymes [superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT)] in tissues and blood of streptozotocin (STZ)-induced diabetic rats. The animals were divided into two groups: control and diabetic. After 10 weeks (wks) of diabetes the animals were sacrificed and liver, heart, pancreas, kidney and blood were collected for measurement of various biochemical parameters. Diabetes was associated with a significant increase in TBARS in pancreas, heart and blood. The activity of CAT increased in liver, heart and blood but decreased in kidney. GSH-Px activity increased in pancreas and kidney while SOD activity increased in liver, heart and pancreas. Our findings suggest that oxidative stress occurs in diabetic state and that oxidative damage to tissues may be a contributory factor in complications associated with diabetes.

Bovine Herpesvirus 1 (Bhv-1(: Biology, Pathogenesis, and Control

Abstract: Publisher Summary The past decade has seen very significant progress in the identification and characterization of the proteins of vovine herpesvirus 1 (BHV-1), and in understanding their role in the initiation of infection at the receptor level and in virus replication. Furthermore, advances in immunology have allowed dissection of the host immune response and identification of the specific protein/glycoproteins and epitopes on these glycoproteins involved in the modulation of the infection. This progress has provided an opportunity to better understand the events involved in the pathogenesis of BHV-1 as well as to develop more effective methods of controlling this disease through vaccine development. The ability to study these virus-cell interactions in the natural host not only aids in controlling BHV-1, but lays the foundation for a better understanding of herpesvirus infection in general. This chapter summarizes the recent advances regarding the proteins/glycoproteins present in the virus, their characterization, and function in infection and virus replication, as well as their interaction with various cells of the immune system.

Sequential Monte Carlo simulation for composite power system reliability analysis with time varying loads

Abstract: The paper illustrates the development and utilization of an annual chronological load curve for each load bus in a composite generation and transmission system and a sequential Monte Carlo simulation approach for composite system reliability assessment. Antithetic variates as a variance reduction technique has been applied to the simulation model to increase the efficiency of the simulation. An approximate method using a load duration curve of the system load and an enumeration process have been applied to the developed load model and the results are compared in this paper. >

Catalytic conversion of a biomass-derived oil to fuels and chemicals I: Model compound studies and reaction pathways

Abstract: The reactions over HZSM-5 catalyst of a number of model compounds were studied in a fixed-bed micro-reactor operating at 3.6 WHSV, atmospheric pressure and temperature range 330–410°C. The compounds were propanoic acid, methyl ester of acetic acid, 4-methylcyclohexanol, cyclopentanone, 2-methylcyclopentanone, methoxybenzene, ethoxybenzene, phenol and 2-methoxy-4-(2-propenyl)phenol. These compounds represented the acid, ester, alcohol, aldehyde and ketone, ether and phenol chemical groups, which were identified as the main components of a bio-oil obtained by the high pressure liquefaction (HPL) of aspen poplar wood. Also, the reactions of a synthetically prepared volatile feed and bio-oil volatiles over HZSM-5 catalyst were investigated. The objective was to understand and identify the reaction steps involved in the HZSM-5 conversion of the bio-oil. The intent was to obtain a reaction pathway which could be used for modeling the conversion of the bio-oil. Based on the results, two reaction pathways were proposed. It was observed that the conversion of the bio-oil was complex and involved a number of reactions. These reactions could be categorized as: 1. 1. Primary reactions. These include cracking and deoxygenation. 2. 2. Intermediate or secondary reactions. These include secondary cracking, oligomerization, olefin formation and cyclization. 3. 3. Terminal or terminating reactions. These include alkylation, isomerization, disproportionation, polymerization and condensation reactions.

Reconstructing avian diets using stable-carbon and nitrogen isotope analysis of egg components: patterns of isotopic fractionation and turnover

Abstract: Because eggs are composed of nutrients that are ultimately derived from the diet of adult females, the relative abundance of naturally-occurring stable isotopes of carbon and nitrogen in eggs should be related to those in their diet and this may form the basis of a method for tracing diets. Before such dietary reconstructions can be established, however, it is necessary to know how isotopic signatures change (or fractionate) from the diet during the synthesis of various egg components. In this study, stable-carbon and nitrogen isotopic fractionation factors between diet and whole yolk, lipid-removed yolk, albumen, and shell membranes of eggs of captively-raised Mallards (Anas platyrhynchos), Japanese Quail (Coturnix japonica), Prairie Falcons (Falco mexicanus), Peregrine Falcons (Falco peregrinus), and Gyrfalcons (Falco rusticolis) were established. In addition, carbon isotope fractionation patterns between diet and eggshell carbonate and yolk lipid were determined for quail, Mallards and falcons. On average, yolk, albumen and membranes were enriched in 15 N relative to diet for all birds by 3.4‰, a value typical of processes associated with protein synthesis. For quail and Mallards, albumen, membranes, and shell carbonate were enriched in 13 C relative to diet by 1.5, 3.6, and 14.9‰, respectively, and whole yolk was depleted in 13 C by 2.6‰ due to the presence of yolk lipids. Falcons showed lower carbon diet-tissue fractionation for all tissues (albumen: +0.9, whole yolk: -1.9, membranes: +2.7, carbonate: +11.2‰) and this may be due to a greater reliance on dietary lipids vs. carbohydrates for the synthesis of egg components or on fractionation differences associated with fermentation of carbohydrates. Patterns of isotopic fractionation between diet and Mallard eggs were not influenced by clutch order. A diet-switch experiment using quail indicated that albumen, shell membrane and shell carbonate values reflect diet integrated over 3-5 days and yolk over eight days prior to laying. Because birds were fed ad libitum, these data provide baseline data on fractionation patterns for birds optimally mobilizing nutrients from diet to egg components. These values may differ for those wild birds that rely more heavily on endogenous reserves.

Antioxidant activity of allicin, an active principle in garlic

Abstract: Garlic has been claimed to be effective against diseases, in the pathophysiology of which oxygen free radicals (OFRs) have been implicated. Effectiveness of garlic could be due to its ability to scavenge OFRs. However, its antioxidant activity is not known. We investigated the ability of allicin (active ingredient of garlic) contained in the commercial preparation Garlicin to scavenge hydroxyl radicals (·OH) using high pressure liquid chromatographic (HPLC) method. ·OH was generated by photolysis of H2O2 (1.25–10 μmoles/ml) with ultraviolet light and was trapped with salicylic acid which is hydroxylated to produce ·OH adduct products 2,3- and 2,5-dihydroxybenzoic acid (DHBA). H2O2 produced a concentration-dependent ·OH as estimated by ·OH adduct products 2,3-DHBA and 2,5-DHBA. Allicin equivalent in Garlicin (1.8, 3.6, 7.2, 14.4, 21.6, 28.8 and 36 μg) produced concentration-dependent decreases in the formation of 2,3-DHBA and 2,5-DHBA. The inhibition of formation of 2,3-DHBA and 2,5-DHBA with 1.8 μg/ml was 32.36% and 43.2% respectively while with 36.0 μg/ml the inhibition was approximately 94.0% and 90.0% respectively. The decrease in ·OH adduct products was due to scavenging of ·OH and not by scavenging of formed ·OH adduct products. Allicin prevented the lipid peroxidation of liver homogenate in a concentration-dependent manner. These results suggest that allicin scavenges ·OH and Garlicin has antioxidant activity.

First Sight: A human body outline labeling system

Abstract: First Sight, a vision system in labeling the outline of a moving human body, is proposed in this paper. The emphasis of First Sight is on the analysis of motion information gathered solely from the outline of a moving human object. Two main processes are implemented in First Sight. The first process uses a novel technique to extract the outline of a moving human body from an image sequence. The second process, which employs a new human body model, interprets the outline and produces a labeled two-dimensional human body stick figure for each frame of the image sequence. Extensive knowledge of the structure, shape, and posture of the human body is used in the model. The experimental results of applying the technique on unedited image sequences with self-occlusions and missing boundary lines are encouraging. >

Design, implementation and testing of an artificial neural network based fault direction discriminator for protecting transmission lines

Abstract: This paper describes a fault direction discriminator that uses an artificial neural network (ANN) for protecting transmission lines. The discriminator uses various attributes to reach a decision and tends to emulate the conventional pattern classification problem. An equation of the boundary describing the classification is embedded in the multilayer feedforward neural network (MFNN) by training through the use of an appropriate learning algorithm and suitable training data. The discriminator uses instantaneous values of the line voltages and line currents to make decisions. Results showing the performance of the ANN-based discriminator are presented in the paper and indicate that it is fast, robust and accurate. It is suitable for realizing an ultrafast directional comparison protection of transmission lines. >

The Future of Canadian Agricultural Cooperatives: A Property Rights Approach

Abstract: prise seems to be in jeopardy. Substitutes for farm-produced products and inputs are, to an increasing extent, coming from nonfarm sectors. Vertically integrating relationships shift control to the industrial sectors serving agriculture, and make entrepreneurship of the family-farm obsolete. The rise of farm-product factories, as in eggs and feeder cattle, suggests the feasibility of giant-sized firms organized along the lines of industrial corporations. If traditional agriculture is in the process of eroding away, the whole conception of the farmer cooperative and its role in society will need to be reexamined. If I am not mistaken, a compelling argument can be made for farmer cooperatives in an atomistic setting. Disappearance of atomism will cause that rationale to vanish with it

Sector-specific patterns of organizational design change*

Abstract: Recent approaches to understanding change in organizations have moved beyond just looking at structure and have focused on the role of values in defining the manner in which organizations change. This article integrates the concepts of design archetypes, tracks and high impact systems in an effort to understand the patterns of change for an institutionally specific set of organizations. the sample used for the study was a set of Canadian national sport organizations undergoing institutional change. Three design archetypes (Kitchen Table, Boardroom and Executive Office) that represent institutionally specific coherent value-structure relationships were used to show that patterns of change are determined by the extent to which the coherence of organizational design elements shift over time. Using these design archetypes as a model for change, tracks were identified that provided an indication of the degree and direction of change and the extent to which design coherence was maintained. This paper shows that there is variety in organizational design coherence and that this is related to patterns of change. In addition, reorientations to a new design are signalled by changes in structures or systems that are central to the organization's purpose and as such can have a high impact on moving the organization to a new design.

Habitat selection as a hierarchy: the spatial scales of winter foraging by muskoxen

Abstract: We studied the winter resource selection of muskoxen Ovibos moschatus in the High Arctic using a nested hierarchy of spatial scales : 1) population range, 2) travel routes, 3) feeding sites (i.e. clusters of feeding craters), 4) feeding craters, and 5) diet (i.e. plant species). We found that, generally, patterns of selection remained consistent across all levels. At successively smaller scales, muskoxen selected for higher graminoid abundance and particularly for thinner, softer snow cover, although we did not reject the hypothesis of random travel route selection. Muskoxen uncovered forages from beneath the snow cover, by cratering, near the floristic and nival extremes of availability. Selection was consistently biased toward use of water sedge, Carex aquatilis. As scale changed, however, muskoxen showed reversals of preference for some other forage species. Diet was dominated by C. aquatilis and cotton sedge, Eriophorum angustifolium, species characteristic of lowland meadows. During spring melt, muskoxen moved to snow-free uplands to feed. Dietary quality, as revealed by fecal nitrogen, increased at this time. The consistency of the results across scales implied that these local levels of habitat selection occurred within one scaling domain.

Catalytic conversion of canola oil to fuels and chemicals over various cracking catalysts

Abstract: The catalytic conversion of canola oil to fuels and chemicals was studied over HZSM-5, H-mordenite, H-Y, silicalite, aluminum-pillared clay (AL-PILC) and silica-alumina catalysts in a fixed bed micro-reactor. The reactor was operated at atmospheric pressure, a temperature range of 375−500°C and weight hourly space velocity (WHSV) of 1.8 and 3.6 h−1. An organic liquid product (OLP), light hydrocarbon gases and water were the major products. The objective was to maximize the amount of OLP and its hydrocarbon content as well as optimize the selectivity for gas phase olefinic hydrocarbons. In addition, the performance of each catalyst in terms of minimizing the coke formation was examined. Among the six catalysts, HZSM-5 gave the highest amount of OLP of 63 mass% at 1.8 WHSV and 400°C. The hydrocarbon content of this OLP product was 83.8 mass%. With the exception of silica-alumina and aluminum-pillared clay catalysts, the other catalysts gave high concentrations of aromatic hydrocarbons which ranged between 23.1–95.6 mass% of OLP. The gas products consisted mostly C3 and C4 hydrocarbons. Ethylene, propylene and butanes were some of the valuable hydrocarbon gases. The olefin/paraffin ratio of the gas products was highest for AL-PILC catalysts but it never exceeded unity. The results showed that it was possible to significantly alter the yield and selectivity for the different hydrocarbon products by using different catalysts or changing the catalyst functionality such as acidity, pore size and crystallinity. Reaction pathways based on these results are proposed for the conversion of canola oil La conversion catalytique d'huile de canola en combustibles et produits chimiques a ete etudiee sur des catalyseurs HZSM-5, H-mordenite, H-Y, silicalite, argile renforce d'aluminium (AL-PILC) et silice-alumine dans un micro-reacteur a lit fixe. Le reacteur a fonctionne a la pression atmospherique, dans une gamme de temperatures entre 375 et 500°C et a un volume par volume par heure (VVH) de 1,8 et 3,6 h−1. Les principaux produits sont un produit organique liquide (POL), des gaz d'hydrocarbures legers et de l'eau. L'objectif etait de maximiser la quantite de POL et sa teneur en hydrocarbures et egalement d'optimiser la selectivite pour les hydrocarbures olefiniques de la phase gazeuse. Par ailleurs, la performance de chaque catalyseur a ete examinee par rapport a la capacite de minimiser la formation de coke. Parmi les six catalyseurs, le HZSM-5 a donne la plus forte quantite de POL (63% en masse a un VVH de 1,8 et a 400°C). La teneur en hydrocarbures de ce produit organique liquide est de 83,8% en masse. A l'exception des catalyseurs de silice-alumine et d'argile renforce d'aluminium, les catalyseurs ont donne de fortes concentrations d'hydrocarbures aromatiques dont le pourcentage en masse du POL est compris entre 23,1 et 95,6. Les produits gazeux sont essentiellement des hydrocarbures C3 et C4. L'ethylene, le propylene et les butanes sont quelques-uns des gaz d'hydrocarbures interessants. Le rapport olefine/parafine des produits gazeux est plus grand pour les catalyseurs AL-PILC mais n'a jamais excede l'unite. Les resultats montrent qu'il est possible d'alterer considerablement le rendement et la selectivite pour les differents produits d'hydrocarbures en utilisant differents catalyseurs ou en modifiant la fonctionnalite des catalyseurs, telles l'acidite, la taille des pores et la cristalinite. Des voies reactives basees sur ces resultats sont proposees pour la conversion de l'huile de canola.

Clonal dispersal and spatial mixing in populations of the plant pathogenic fungus, Sclerotinia sclerotiorum

Abstract: Two thousand seven hundred and forty‐seven isolates of Sclerotinia sclerotiorum were sampled from four field populations of canola in western Canada. Each field was sampled in a grid of 128 50‐m 50‐m quadrats plus four intensive quadrats each sampled in a diagonal transect. Sampling was done at two phases of the disease cycle: (1) from ascospore inoculum on petals and (2) from disease lesions in stems. A total of 594 unique genotypes was identified by DNA fingerprinting. In each field, a small group of clones represented the majority of the sample, with a large group of clones or genotypes sampled once or twice. Clone frequencies were compared by χ2 tests. The difference in profiles of clone frequencies for the two fields sampled in 1991 was not significant, but in 1992 the difference in profiles was marginally significant, indicating some local population substructure. The difference in profiles of clone frequencies for petals and lesions was not significant in each of the two fields sampled in 1991. In each of the two fields sampled in 1992, however, the difference was highly significant, consistent either with selection for some clones or with waves of immigration during the disease cycle. Nine of the 30 most frequently sampled clones from this study were previously recovered in a macrogeographical sample from western Canada in 1990. For spatial analyses, randomization tests indicated no significant spatial aggregation of either clones on petals or clones from lesions. Also, isolates of a clone on petals were not closer to isolates of the same clone from lesions than could be predicted by chance. Both observations suggest spatial mixing of ascospore inoculum from resident or immigrant sources.

Recent Advances in Methods of Assessing Dietary Amino Acid Requirements for Adult Humans

Abstract: The requirements for the indispensable amino acids have been determined by a number of different methods. Historically, descriptive or gross measures like growth and nitrogen balance have been used. However, technological advancements in recent years have resulted in the use of more precise and mechanistic metabolic approaches (i.e., plasma amino acid concentrations, amino acid oxidation, indicator amino acid oxidation) to examine requirement. Nevertheless, the current recommendations are still based on nitrogen balance studies. Requirement estimates based on other methodologies, such as plasma amino acid concentrations and direct amino acid oxidation, suggest that the requirement estimates derived from nitrogen balance experiments are too low. However, these higher estimates have also been criticized on conceptual and methodological grounds, resulting in considerable controversy in the area of indispensable amino acid requirements. A new technique, indicator amino acid oxidation, addresses many of the criticisms directed toward the alternative methods and the proposed higher requirement estimates. This paper reviews the current knowledge of amino acid requirements and makes recommendations in light of new information that has been provided from recent indicator amino acid oxidation research. It is concluded that the nitrogen balance-based estimates of amino acid requirement are too low.

Site preference of rare earth elements in fluorapatite

Abstract: Crystals ofLa-, Gd-, and Dy-bearing fluorapatite [La-FAp, Gd-FAp, Dy-FAp; CalO-X-2YNayREEx+y (P1_xSixO.)6A2, with x = 0.24-0.29, Y = 0,32-0.36; P6/m] have been synthesized hydrothermally, and their structures refined at room temperature with single-crystal X-ray intensities to R = 0.015-0.018. Na is essentially restricted to the Cal position in La-FAp, Gd-FAp, and Dy-FAp, in contrast to Nd-FAp, which was synthesized under slightly different conditions and has appreciable Na in Ca2 as well. Site occupancies for REE in Cal and Ca2, respectively, are 0.023(1) and 0.093(1) in LaFAp, 0.038(1) and 0.111(1) in Nd-FAp, 0.038(0) and 0.077(0) in Gd-FAp, and 0.039(1) and 0.060(1) in DyFAp. The REE site occupancy ratio (REE-Ca2 to REE-Cal) appears to decrease monotonically for REE3+cations through the 4f transition-metal series. With this assumption, site occupancy ratios (REE-Ca2 to REE-Cal) for some other REE in natural apatite are estimated to be: La 4.04, Ce 3.67, Pr 3.30, Nd 2.92, Sm 2.47, Eu 2.25, Gd 2.03, Dy 1.54, Y 1.29, Er 1.05. These single-REEsite occupancyratios may not be transferrable to natural apatite, The Cal and Ca2 site occupancies are generallyconsistent with site preferences deduced from bond-valence calculations, which show that the substitutions for Ca lead to equalization of Cal and Ca2 bond valences. Also, the REE site occupancy ratio correlates inversely with F bond valence.

The Group Size-Cohesion Relationship in Minimal Groups

Abstract: Four studies were undertaken to investigate the relationship between cohesion and group size in exercise groups. Study 1 compared the perceptions of cohesiveness of members of small and large exercise classes assessed in the eighth week of group development in a 13-week session. Study 2 compared the perceptions of cohesiveness of members of small and large exercise classes assessed in the third week of group development in a 13-week session. Study 3 used a longitudinal design to assess the possible changes in perceptions of cohesiveness of members of small and large groups over time. The purpose of Study 4 was to determine how an intervention program focusing on team-building principles would influence perceptions of cohesiveness in small and large exercise classes. It was concluded that perceptions of task and social cohesion are greater in smaller groups, and that a team-building program can offset the negative impact of increased group size.

Validity of the recording of ischaemic heart disease and chronic obstructive pulmonary disease in the Saskatchewan health care datafiles

Abstract: The internal validity of the recording of information about ischaemic heart disease (IHD) and chronic obstructive pulmonary disease (COPD) in the administrative health care datafiles of the Canadian province of Saskatchewan is investigated. Comparisons between hospital data and medical charts for acute myocardial infarction and chronic airways obstruction patients showed excellent diagnostic agreement: 97 per cent and 94 per cent, respectively. Appropriate physician service claims were identified for 89 per cent of hospitalizations for IHD and COPD and exact concordance between diagnoses in the two datafiles varied between 15 per cent for acute/sub-acute IHD and 80 per cent for asthma; including any physician diagnosis within the same broad category (IHD or COPD) increased concordance to 79-94 per cent for IHD and 64-88 per cent for COPD. Contextual information related to the hospitalizations was clinically and epidemiologically realistic.