Katarzyna Bień-Barkowska

Prognostic factors of long-term survival in geriatric inpatients. Should we change the recommendations for the oldest people?

ObjectivesIdentification of optimal predictors of the 5.5-year survival in former geriatric inpatients.Investigation of the direction and shape of the relationship between mortality risk and its predictors.DesignRetrospective survival analysis with the application of the Cox proportional hazards model.SettingTeaching geriatric unit.Participants478 inpatients (mean age 77.9; +6.8) discharged from geriatric ward during year 2008, without any exclusion criteria.MeasurementsComprehensive geriatric assessment of numerous health variables, body mass index (BMI), clinical and biochemical findings, and outcomes of the final diagnosis. Records on the dates of deaths were obtained from the Provincial Office of Population Register.ResultsDuring the 5.5-year follow-up 209 (43.7%) patients died. In the multivariate setup, six risk factors with an independent impact on mortality were identified: age (p=0.036), cognitive functioning on the Blessed test (p=0.005), score on instrumental ADL (p<0.0001), score on Charlson comorbidity index (p<0.0001), cholesterol level (p<0.0001), BMI (p<0.0001), and hemoglobin level (p=0.02). The latter two predictors exhibited a significant inverted J-shaped association with mortality, i.e., considerably higher risk of death corresponds to the lower values of these variables in comparison to their higher levels.ConclusionOlder age, worse IADL and cognitive functioning, and higher comorbidity were recognized as endangering one’s long-term survival. On the other hand, moderate obesity (BMI 36), higher cholesterol and the absence of anemia (hemoglobin 13.6 g/dL) are associated with longer survival. Therefore, irrespective of the individualized treatment and physical exercise, nutrient-dense food seems to be a key recommendation to prevent frailty or malnutrition in the oldest and comorbid population.

Capturing Order Book Dynamics in the Interbank EUR/PLN Spot Market

In this paper, I examine order submissions and cancellations in the Reuters Dealing 3000 Spot Matching System, the main order-driven market for interbank trading of the euro/złoty (EUR/PLN) currency pair. I generalize the asymmetric autoregressive conditional duration (AACD) model of Bauwens and Giot (2003) with respect to more than two competing risks. With the new multistate AACD model, I examine the timing of different order submissions and cancellations that take place on different sides of the market and vary according to their level of aggressiveness. I investigate different liquidity or information-oriented factors that exert an influence on the dynamics of the limit order book.

Distribution Choice for the Asymmetric ACD Models

In the paper, I generalize the Asymmetric Autoregressive Conditional Duration (AACD) model proposed by Bauwens and Giot (2003) with respect to the generalized gamma and the Burr distribution for an error term. I derive the log likelihood functions for the augmented models and show how to check the goodness-of-fit of the distributional assumptions with the application of the probability integral transforms proposed by Diebold, Gunther and Tay (1998). Moreover, I present an exemplary empirical application of the Asymmetric ACD model for the durations between submissions of market or best limit orders on the interbank trading platform for the Polish zloty. I test the impact of selected market microstructure factors (i.e. the bid-ask spread, volatility) on the time of order submissions.

Informed and uninformed trading in the EUR/PLN spot market

This article seeks to examine the intraday functioning of the interbank foreign exchange spot market of the Polish zloty using a unique set of very detailed data from the Reuters Dealing 3000 Spot Matching System for the year of 2007. Using the sequential trade model of Easley et al. (2008), we can differentiate between the time-varying patterns of strategic behaviour carried out by informed and uninformed (liquidity) traders. These conditional arrival rates for both trade categories can be used to forecast a time-varying probability of informed trading (PIN). We show that the predictions for PIN, as measures of information heterogeneity, influence the scale of impact that the order flow exerts on FX rate changes.

Silent strain of caregiving: exploring the best predictors of distress in family carers of geriatric patients

Objectives The aim of this article was to identify the best predictors of distress suffered by family carers (FCs) of geriatric patients. Methods A cross-sectional study of 100 FC-geriatric patient dyads was conducted. The negative impact of care (NIoC) subscale of the COPE index was dichotomized to identify lower stress (score of ≤15 on the scale) and higher stress (score of ≥16 on the scale) exerted on FCs by the process of providing care. The set of explanatory variables comprised a wide range of sociodemographic and care-related attributes, including patient-related results from comprehensive geriatric assessments and disease profiles. The best combination of explanatory variables that provided the highest predictive power for distress among FCs in the multiple logistic regression (LR) model was determined according to statistical information criteria. The statistical robustness of the observed relationships and the discriminative power of the model were verified with the cross-validation method. Results The mean age of FCs was 57.2 (±10.6) years, whereas that of geriatric patients was 81.7 (±6.4) years. Despite the broad initial set of potential explanatory variables, only five predictors were jointly selected for the best statistical model. A higher level of distress was independently predicted by lower self-evaluation of health; worse self-appraisal of coping well as a caregiver; lower sense of general support; more hours of care per week; and the motor retardation of the cared-for person measured with the speed of the Timed Up and Go (TUG) test. Conclusion Worse performance on the TUG test was only the patient-related predictor of distress among the variables examined as contributors to the higher NIoC. Enhancing the mobility of geriatric patients through suitably tailored kinesitherapeutic methods during their hospital stay may mitigate the burden endured by FCs.

Cognitive Functioning of Geriatric Patients: Is Hypovitaminosis D the Next Marker of Cognitive Dysfunction and Dementia?

The study objective is to investigate whether vitamin D is associated with the cognitive function of geriatric patients. This cross-sectional study involved 357 patients hospitalized in the geriatric ward who complained of memory problems (mean age: 82.3 years). The level of cognitive function was measured with the Mini-Mental State Examination (MMSE) and the clinical diagnosis of dementia was established according to the International Classification of Diseases (ICD-10) criteria. The serum 25-hydroxy vitamin D was measured with liquid chromatography-tandem mass spectrometry. The iterative Bayesian model averaging (BMA) procedure was applied to linear and logistic regression models in order to identify the best set of factors describing cognitive dysfunction and dementia, respectively. According to BMA, there is strong evidence that higher vitamin D levels, higher body mass index (BMI), and higher mobility function measured with the Timed Up and Go (TUG) test are independently associated with better cognitive performance and lower risk of dementia. Additionally, there is strong evidence that fewer years of education and lower vitamin B12 plasma levels independently describe worse cognitive performance. However, vitamin B12 levels higher than 800 pg/mL is negatively associated with the MMSE performance. Hypovitaminosis D in geriatric patients is an underrated marker of cognitive dysfunction and dementia.

Extension and verification of the asymmetric autoregressive conditional duration models

ABSTRACT We extend the asymmetric autoregressive conditional duration (AACD) model of Bauwens and Giot [Asymmetric ACD models: Introducing price information in ACD models, Empir. Econ. 28 (2003), pp. 709–731] which allows describing the joint dynamics of financial durations, i.e. times between selected micro-events (trades, price, or volume changes) and the corresponding event categories. The generalized beta distribution of the second kind (GB2) is proposed as the distribution for the error terms in the model. The GB2 distribution allows for flexible non-monotonic shapes of baseline hazard functions, which facilitates a plethora of temporal dependence patterns for event arrival times. We propose the procedures for checking the adequacy of the parametric specification with the help of simulation methods that allow computing the model residuals. Moreover, we show how to assess the goodness of fit of the AACD model using probability integral transforms. The model is used to investigate striking regularities in the manner currency dealers execute their market orders in the interbank foreign exchange spot market.

Does It Take Volume to Move the EUR/PLN FX Rates? Evidence from Quantile Regressions

This study investigates the impact of trading volume on selected quantiles of the EUR/PLN return distribution. Empirical results obtained with the quantile regression approach confirm that an increase in the turnover is associated with a significant increase in the dispersion of the corresponding return distribution. We divided the trading volume into its expected (antici-pated) and unexpected (unanticipated) component and found that the unexpected volume shocks have a significantly larger impact on the dispersion of the return distribution. We also observed that the volume-return relationship is nonlinear; the dependence is stronger with more extreme quantiles. Moreover, after accounting for a conditional volatility measure as a controlling explan-atory factor for the quantile dynamics, the impact of the expected volume declines yet remains significant especially for the most extreme quantiles.