Retrospective studies of operating problems in air transport

An epidemiological model for the study of human errors in aviation is presented. In this approach, retrospective data are used as the basis for formulation of hypotheses as to system factors which may have contributed to such errors. Prospective experimental studies of aviation operations are also required in order to prove or disprove the hypotheses, and to evaluate the effectiveness of intervention techniques designed to solve operational problems in the aviation system

Prospective genetic screening decreases the incidence of Abacavir hypersensitivity reactions in the Western Australian HIV cohort study

Abacavir therapy is associated with significant drug hypersensitivity in ∼8% of recipients, with retrospective studies indicating a strong genetic association with the HLA-B*5701 allelle. In this prospective study, involving 260 abacavir-naive individuals (7.7% of whom were positive for HLA-B*5701), we confirm the usefulness of genetic risk stratification, with no cases of abacavir hypersensitivity among 148 HLA-B*5701–negative recipients

Small effects of selective migration and selective survival in retrospective studies of fertility

In this paper, we assess the accuracy of fertility estimates that are based on the retrospective information that can be derived from an existing cross-sectional population. Swedish population registers contain the information on childbearing of all people ever living in Sweden and thus allow us to avoid any problems of selectivity by virtue of survival or of out-migration when we estimate fertility measures for previous calendar periods. We calculate two types of fertility rates for each year in 1961-1999: (i) rates that are based on the population that were living in Sweden at the end of 1999 and (ii) rates that also include the information on people who had died or emigrated before the turn of the century. We find that the omission of information on emigrated and deceased individuals, as the situation would be in any demographic survey, most often have negligible effects on our fertility measures. However, first-birth rates of immigrants gradually become more biased as we move back in time from 1999 so that they increasingly tend to over-estimate the actual fertility of that population.Sweden, bias, fertility measurements, retrospective analysis

The GOAL study: a prospective examination of the impact of factor V Leiden and ABO(H) blood groups on haemorrhagic and thrombotic pregnancy outcomes

Factor V Leiden (FVL) and ABO(H) blood groups are the common influences on haemostasis and retrospective studies have linked FVL with pregnancy complications. However, only one sizeable prospective examination has taken place. As a result, neither the impact of FVL in unselected subjects, any interaction with ABO(H) in pregnancy, nor the utility of screening for FVL is defined. A prospective study of 4250 unselected pregnancies was carried out. A venous thromboembolism (VTE) rate of 1·23/1000 was observed, but no significant association between FVL and pre-eclampsia, intra-uterine growth restriction or pregnancy loss was seen. No influence of FVL and/or ABO(H) on ante-natal bleeding or intra-partum or postpartum haemorrhage was observed. However, FVL was associated with birth-weights >90th centile [odds ratio (OR) 1·81; 95% confidence interval (CI<sub>95</sub>) 1·04–3·31] and neonatal death (OR 14·79; CI<sub>95</sub> 2·71–80·74). No association with ABO(H) alone, or any interaction between ABO(H) and FVL was observed. We neither confirmed the protective effect of FVL on pregnancy-related blood loss reported in previous smaller studies, nor did we find the increased risk of some vascular complications reported in retrospective studies

Biased Estimation of Adjusted Odds Ratios From Incomplete Covariate Data Due to Violation of the Missing at Random Assumption

We investigate the possible bias due to an erroneous missing at random assumption if adjusted odds ratios are estimated from incomplete covariate data using the maximum likelihood principle. A relation between complete case estimates and maximum likelihood estimates allows us to identify situations where the bias vanishes. Numerical computations demonstrate that the bias is most serious if the degree of the violation of the missing at random assumption depends on the value of the outcome variable or of the observed covariate. Implications for the analysis of prospective and retrospective studies are given

Interdisciplinary communication for environmental effectiveness: Forward-looking lessons from leadership, followership and strategic entrepreneurship

This article contends that interdisciplinary interactions, and temporal factors, influence communications between environment and organisations in ways that are understudied. It tracks the evolution of one recent interface between strategy and entrepreneurship to illustrate the process in action and to suggest how that hybrid can, in turn, interface with new leadership research to improve organisational responses at a time of fast-moving change. In addition, it makes a case for integrating action learning, action research, and action inquiry, as a method for generating more relevant and forward-looking case material than retrospective studies of past practice

Hydrologic models for land-atmosphere retrospective studies of the use of LANDSAT and AVHRR data

The use of a Geographic Information System (GIS) and LANDSAT analysis in conjunction with the Simulator for Water Resources on a Rural Basin (SWRRB) hydrologic model to examine the water balance on the Little Washita River basin is discussed. LANDSAT analysis was used to divide the basin into eight non-contiguous land covers or subareas: rangeland, grazed range, winter wheat, alfalfa/pasture, bare soil, water, woodland, and impervious land (roads, quarry). The use of a geographic information system allowed for the calculation of SWRRB model parameters in each subarea. Four data sets were constructed in order to compare SWRRB estimates of hydrologic processes using two methods of maximum LAI and two methods of watershed subdivision. Maximum LAI was determined from a continental scale map, which provided a value of 4.5 for the entire basin, and from its association with the type of land-cover (eight values). The two methods of watershed subdivision were determined according to drainage subbasin (four) and the eight land-covers. These data sets were used with the SWRRB model to obtain daily hydrologic estimates for 1985. The results of the one year analysis lead to the conclusion that the greater homogeneity of a land-cover subdivision provides better water yield estimates than those based on a drainage properties subdivision

Periprocedural prognostic factors in coronary interventions – retrospective studies

Background: Approximately 11,000 revascularization procedures, either percutaneous coronary interventions (PCI) or coronary artery bypass grafting surgery (CABG), are performed yearly in Finland for coronary artery disease. Periprocedural risk factors for mortality and morbidity as well as long-term outcome have been extensively studied in general populations undergoing revascularization. Treatment choice between PCI and CABG in many high risk groups and risk-stratification, however, needs clarification and there is still room for improvement in periprocedural outcomes. Materials and methods: Cohorts of patients from Finnish hospitals revascularized between 2001 and 2011 were retrospectively analyzed. Patient records were reviewed for baseline variables and postprocedural outcomes (stroke, myocardial infarction, quality of life measured by the EQ-5D –questionnaire, repeat revascularization, bleeding episodes). Data on date and mode of death was acquired from Statistics Finland. Statistical analysis was performed to identify predictors of adverse events and compare procedures. Results: Postoperative administration of blood products (red blood cells, fresh frozen plasma, platelets) after isolated CABG independently and dose-dependently increases the risk of stroke. Patients 80 years or older who underwent CABG had better survival at 5 years compared to those who underwent PCI. After adjusting for baseline differences survival was similar. Patients on oral anticoagulation (OAC) for atrial fibrillation (AF) treated with CABG had better survival and overall outcome at 3 years compared to PCI patients. There was no difference in incidence of stroke or bleeding episodes. Differences in outcome remained significant after adjusting for propensity score. Lower health-related quality of life (HRQOL) scores as measured by the visual analogue scale (VAS) of the EQ-5D questionnaire at 6 months after CABG predicted later major adverse cardiac and cerebrovascular events (MACCE). Deteriorating function and VAS scores between 0 and 6 months on the EQ-5D also independently predicted later MACCE. Conclusions: Administration of blood products can increase the risk of stroke after CABG and liberal use of transfusions should be avoided. In the frail subpopulations of patients on OAC and octogenarians CABG appears to offer superior long-term outcome as compared to PCI. Deteriorating HRQOL scores predict later adverse events after CABG. Keywords: percutaneous coronary intervention, coronary artery bypass grafting, age over 80, transfusion, anticoagulants, coronary artery disease, health-related quality of life, outcome.Sepelvaltimotoimenpiteiden ennusteelliset tekijät – retrospektiivisiä tutkimuksia Tausta: Suomessa tehdään vuosittain yli 10 000 sepelvaltimoiden pallolaajennusta (PCI) ja ohitusleikkausta (CABG). Toimenpiteeseen liittyviä riskitekijöitä ja pitkäaikaisennustetta on tutkittu laajalti tavanomaisissa potilasaineistoissa. Toimenpidevalintaa ohjaavaa tietoa riskiryhmistä sekä riskinarviointikeinoja kuitenkin tarvitaan yhä ja välittömiä toimenpiteen jälkeisiä tuloksia voi edelleenkin parantaa. Aineisto ja menetelmät: Vuosien 2001 ja 2011 välillä suomalaisissa sairaaloissa sepelvaltimoihin kohdistuvin toimenpitein hoidettuja potilaskohortteja tutkittiin taannehtivasti. Potilasasiakirjoista etsittiin toimenpidettä edeltävät sairastavuustiedot, toimenpidejakson tiedot sekä toimenpiteen jälkeisen ajan tiedot (aivo- ja sydäninfarktit, uusintatoimenpiteet, verenvuodot ja EQ-5D –lomakkeella mitattu elämänlaatu). Kuolintiedot haettiin Tilastokeskuksen rekistereistä. Tilastomatemaattisin keinoin selvitettiin myöhäissairastavuutta ja -kuolleisuutta ennakoivat tekijät ja toimenpideryhmien väliset erot. Tulokset: Leikkauksen jälkeinen verituotteiden (punasolut, jääplasma, verihiutaleet) annostelu lisää annosriippuvaisesti ja itsenäisesti toimenpiteen jälkeisen aivoinfarktin riskiä. Yli 80-vuotiaat sepelvaltimotoimenpitein hoidetut potilaat ovat todennäköisemmin elossa ohitusleikkauksen kuin pallolaajennuksen jälkeen 5 vuoden seuranta-aikana. Lähtötilanteen muuttujien samankaltaistamisen jälkeen ei tullut esille eroa ryhmien välillä. Eteisvärinän vuoksi antikoaguloitujen potilaiden elossaolo ja haittatapahtuman todennäköisyys ovat paremmat ohitusleikkauksen jälkeen. Aivoinfarkteissa tai verenvuodoissa ei ollut eroa ryhmien välillä. Tulos säilyy propensity score -korjauksen jälkeen. Huonompi visual analogue scale (VAS) -arvo EQ-5D -lomakkeella mitattuna 6 kk CABG:n jälkeen ennakoi haittatapahtumia. Huononeva VAS ja toimintakyky EQ-5D -lomakkeella mitattuna ennakoivat myöhempiä haittatapahtumia. Johtopäätökset: Verituotteiden anto ohitusleikkauksen jälkeen lisää aivoinfarktin riskiä ja sitä tulisi pyrkiä välttämään. Tutkituissa suuren riskin potilasryhmissä (yli 80-vuotiaat ja eteisvärinän vuoksi antikoaguloidut) ennuste vaikutti paremmalta sepelvaltimoiden ohitusleikkauksen kuin pallolaajennuksen jälkeen. Huononeva elämänlaatu EQ-5D -mittarilla arvioituna ennustaa ohitusleikkauksen jälkeisiä haittatapahtumia.Siirretty Doriast