Testing the construct validity of hospital care quality indicators: a case study on hip replacement.

BACKGROUND: Quality indicators are increasingly used to measure the quality of care and compare quality across hospitals. In the Netherlands over the past few years numerous hospital quality indicators have been developed and reported. Dutch indicators are mainly based on expert consensus and face validity and little is known about their construct validity. Therefore, we aim to study the construct validity of a set of national hospital quality indicators for hip replacements. METHODS: We used the scores of 100 Dutch hospitals on national hospital quality indicators looking at care delivered over a two year period. We assessed construct validity by relating structure, process and outcome indicators using chi-square statistics, bootstrapped Spearman correlations, and independent sample t-tests. We studied indicators that are expected to associate as they measure the same clinical construct. RESULT: Among the 28 hypothesized correlations, three associations were significant in the direction hypothesized. Hospitals with low scores on wound infections had high scores on scheduling postoperative appointments (p-value = 0.001) and high scores on not transfusing homologous blood (correlation coefficient = -0.28; p-value = 0.05). Hospitals with high scores on scheduling complication meetings, also had high scores on providing thrombosis prophylaxis (correlation coefficient = 0.21; p-value = 0.04). CONCLUSION: Despite the face validity of hospital quality indicators for hip replacement, construct validity seems to be limited. Although the individual indicators might be valid and actionable, drawing overall conclusions based on the whole indicator set should be done carefully, as construct validity could not be established. The factors that may explain the lack of construct validity are poor data quality, no adjustment for case-mix and statistical uncertainty.

Influences of definition ambiguity on hospital performance indicator scores: examples from The Netherlands.

RESEARCH OBJECTIVE: Reliable and unambiguously defined performance indicators are fundamental to objective and comparable measurements of hospitals' quality of care. In two separate case studies (intensive care and breast cancer care), we investigated if differences in definition interpretation of performance indicators affected the indicator scores. DESIGN: Information about possible definition interpretations was obtained by a short telephone survey and a Web survey. We quantified the interpretation differences using a patient-level dataset from a national clinical registry (Case I) and a hospital's local database (Case II). In Case II, there was additional textual information available about the patients' status, which was reviewed to get more insight into the origin of the differences. PARTICIPANTS: For Case I, we investigated 15 596 admissions of 33 intensive care units in 2009. Case II consisted of 144 admitted patients with a breast tumour surgically treated in one hospital in 2009. RESULTS: In both cases, hospitals reported different interpretations of the indicators, which lead to significant differences in the indicator values. Case II revealed that these differences could be explained by patient-related factors such as severe comorbidity and patients' individual preference in surgery date. CONCLUSIONS: With this article, we hope to increase the awareness on pitfalls regarding the indicator definitions and the quality of the underlying data. To enable objective and comparable measurements of hospitals' quality of care, organizations that request performance information should formalize the indicators they use, including standardization of all data elements of which the indicator is composed (procedures, diagnoses).

Frostbite of both first digits of the foot treated with delayed hyperbaric oxygen:a case report and review of literature.

BACKGROUND: Frostbite is an uncommon event that can occur from exposure to temperatures below -4 degrees C and can lead to potential serious tissue damage and necrosis. This in turn can result in debilitating amputations in otherwise healthy people. The pathophysiological mechanisms of frostbite have marked similarities to those seen in thermal burns, ischemia/reperfusion injuries and crush injuries--i.e., non-healing wounds and inflammatory processes. These injuries are commonly treated with hyperbaric oxygen therapy. OBJECTIVES: Evidence for treating frostbite with hyperbaric oxygen (HBO2) is scarce, and to date HBO2 is not a standard addition in the multidisciplinary care of freezing injuries. We aim to contribute to the available evidence with a case report and review the literature to reassess the multidisciplinary treatment of frostbite injuries. CASE REPORT AND REVIEW OF LITERATURE: We present a case report of a woman with deep frostbite of the toes treated with hyperbaric oxygen therapy, after a delay of 21 days, with good results. No surgical intervention was needed. A literature search revealed 17 human case reports on frostbite and four animal studies in which hyperbaric oxygen was applied. All case reports showed positive effects, and in none of the cases was amputation necessary. In the animal studies, two showed significant positive results regarding tissue loss and reduction of inflammatory markers, whereas two did not. CONCLUSIONS: Based on our case report as well as the literature and the mechanisms of hyperbaric oxygen, we make the recommendation that this therapy be considered as an addition to the multidisciplinary treatment of frostbite, even after significant delay of treatment.

Influences of hospital information systems, indicator data collection and computation on reported Dutch hospital performance indicator scores.

BACKGROUND: For health care performance indicators (PIs) to be reliable, data underlying the PIs are required to be complete, accurate, consistent and reproducible. Given the lack of regulation of the data-systems used in the Netherlands, and the self-report based indicator scores, one would expect heterogeneity with respect to the data collection and the ways indicators are computed. This might affect the reliability and plausibility of the nationally reported scores. METHODS: We aimed to investigate the extent to which local hospital data collection and indicator computation strategies differ and how this affects the plausibility of self-reported indicator scores, using survey results of 42 hospitals and data of the Dutch national quality database. RESULTS: The data collection and indicator computation strategies of the hospitals were substantially heterogenic. Moreover, the Hip and Knee replacement PI scores can be regarded as largely implausible, which was, to a great extent, related to a limited (computerized) data registry. In contrast, Breast Cancer PI scores were more plausible, despite the incomplete data registry and limited data access. This might be explained by the role of the regional cancer centers that collect most of the indicator data for the national cancer registry, in a standardized manner. Hospitals can use cancer registry indicator scores to report to the government, instead of their own locally collected indicator scores. CONCLUSIONS: Indicator developers, users and the scientific field need to focus more on the underlying (heterogenic) ways of data collection and conditional data infrastructures. Countries that have a liberal software market and are aiming to implement a self-report based performance indicator system to obtain health care transparency, should secure the accuracy and precision of the heath care data from which the PIs are calculated. Moreover, ongoing research and development of PIs and profound insight in the clinical practice of data registration is warranted.

Thinking about touch facilitates tactile but not auditory processing.

Mental imagery is considered to be important for normal conscious experience. It is most frequently investigated in the visual, auditory and motor domain (imagination of movement), while the studies on tactile imagery (imagination of touch) are scarce. The current study investigated the effect of tactile and auditory imagery on the left/right discriminations of tactile and auditory stimuli. In line with our hypothesis, we observed that after tactile imagery, tactile stimuli were responded to faster as compared to auditory stimuli and vice versa. On average, tactile stimuli were responded to faster as compared to auditory stimuli, and stimuli in the imagery condition were on average responded to slower as compared to baseline performance (left/right discrimination without imagery assignment). The former is probably due to the spatial and somatotopic proximity of the fingers receiving the taps and the thumbs performing the response (button press), the latter to a dual task cost. Together, these results provide the first evidence of a behavioural effect of a tactile imagery assignment on the perception of real tactile stimuli.

The validity of indicators for assessing quality of care: a review of the European literature on hospital readmission rate.

BACKGROUND: Quality indicators are increasingly being implemented in Europe for policy and management purposes. Many of these indicators were initially developed and implemented in the USA. However, the suitability of directly adopting indicators that have been developed in a different health care system can be questioned. Therefore, we investigate the validity behind the readmission rate indicator in the European setting. METHODS: A systematic literature study was conducted to identify the status of scientific research on the validity of this indicator (January 1999 and April 2010). Descriptive information as well as information on the data source, indicator definition, risk adjustment factors, and conclusions was assessed. RESULTS: The majority of the 486 included studies focused on the actual use of the indicator as an outcome measure in European countries. Only 21 studies specifically addressed its validity, or important prerequisites of validity. There is little consensus over the time-frame used to calculate the indicator, the type of readmission that is included, and the case-mix adjustment applied. CONCLUSIONS: Despite the increase in Europe of the use of the readmission rate as a measure of quality of care, the amount of research performed on its validity is scarce. Those studies that report on validity replicate earlier, mainly US findings (<1999) of methodological problems and express reservations on its large-scale use. The readmission rate as an indicator should be used with care. Users should address issues related to definition, time-frame and case-mix adjustment as part of the process to enhance validity in the European settings.

Grasping Weber's illusion: The effect of receptor density differences on grasping and matching.

Weber found that distances between tactile stimuli on a high-receptor-density area are perceived as being larger than identical distances on a low-receptor-density area (Weber's illusion). Previous studies of visual illusions suggest that illusion effects vary with the type of response given. Here we tested a modified version of Weber's illusion in which a solid object was placed on the forearm or hand. Blindfolded participants were required either to give a size estimation or to grasp the object. The results showed that size estimation of solid objects was consistent with Weber's illusion, whereas grasping responses showed an opposite pattern (e.g., larger hand opening for objects on the forearm). A second experiment showed that this pattern is not due to biomechanical differences induced by the difference in spatial position of the target objects on the hand and arm. We suggest that the larger grip aperture when grasping objects on the arm were due to an increase in safety margin as a response to greater uncertainty about the object dimensions due to reduced receptor density.

Fingers crossed! An investigation of somatotopic representations using spatial directional judgements.

Processing of tactile stimuli requires both localising the stimuli on the body surface and combining this information with a representation of the current posture. When tactile stimuli are applied to crossed hands, the system first assumes a prototypical (e.g. uncrossed) positioning of the limbs. Remapping to include the crossed posture occurs within about 300 ms. Since fingers have been suggested to be represented in a mainly somatotopic reference frame we were interested in how the processing of tactile stimuli applied to the fingers would be affected by an unusual posture of the fingers. We asked participants to report the direction of movement of two tactile stimuli, applied successively to the crossed or uncrossed index and middle fingers of one hand at different inter-stimulus intervals (15 to 700 ms). Participants almost consistently reported perceiving the stimulus direction as opposite to what it was in the fingers crossed condition, even with SOAs of 700 ms, suggesting that on average they did not incorporate the unusual relative finger positions. Therefore our results are in agreement with the idea that, by default, the processing of tactile stimuli assumes a prototypical positioning of body parts. However, in contrast to what is generally found with tactile perception with crossed hands, performance did not improve with SOAs as long as 700 ms. This suggests that the localization of stimuli in a somatotopic reference and the integration of this representation with postural information are two separate processes that apply differently to the hands and fingers.

[Treating frostbite injuries]. / Behandeling van bevriezingsletsels.

Frostbite injuries rarely occur in healthy Dutch persons. However, as the number of people engaging in winter and outdoor activities and travelling to high altitudes increases, the risk of frostbite also increases. Frostbite is a cold-induced injury which results from two processes: freezing and microvascular occlusion. Adequate first aid, which focuses on the prevention of refreezing and mechanical injury, and rapid rewarming together with the administration of ibuprofen, are of the greatest importance for limiting eventual tissue damage. Iloprost infusion and possibly (r)tPA are indicated if a patient presents within 24 hours after the tissue has thawed and the injury is such that severe morbidity can be expected. If the patient presents after this time period, hyperbaric oxygen therapy may be considered; however, the evidence available on this type of treatment is limited.

Integration of tactile input across fingers in a patient with finger agnosia.

Finger agnosia has been described as an inability to explicitly individuate between the fingers, which is possibly due to fused neural representations of these fingers. Hence, are patients with finger agnosia unable to keep tactile information perceived over several fingers separate? Here, we tested a finger agnosic patient (GO) on two tasks that measured the ability to keep tactile information simultaneously perceived by individual fingers separate. In experiment 1 GO performed a haptic search task, in which a target (the absence of a protruded line) needed to be identified among distracters (protruded lines). The lines were presented simultaneously to the fingertips of both hands. Similarly to the controls, her reaction time decreased when her fingers were aligned as compared to when her fingers were stretched and in an unaligned position. This suggests that she can keep tactile input from different fingers separate. In experiment two, GO was required to judge the position of a target tactile stimulus to the index finger, relatively to a reference tactile stimulus to the middle finger, both in fingers uncrossed and crossed position. GO was able to indicate the relative position of the target stimulus as well as healthy controls, which indicates that she was able to keep tactile information perceived by two neighbouring fingers separate. Interestingly, GO performed better as compared to the healthy controls in the finger crossed condition. Together, these results suggest the GO is able to implicitly distinguish between tactile information perceived by multiple fingers. We therefore conclude that finger agnosia is not caused by minor disruptions of low-level somatosensory processing. These findings further underpin the idea of a selective impaired higher order body representation restricted to the fingers as underlying cause of finger agnosia.

Mental body distance comparison: a tool for assessing clinical disturbances in visual body image.

Despite numerous body size estimation studies, it cannot be concluded that the disturbance of body image in anorexia nervosa (AN) is specifically one of the visual body images. We adopted a visual imagery method, the Distance Comparison task, to enable across-population testing of differences in visual body image with respect to shape. Participants were asked to mentally scan across two body widths (e.g. hips and shoulders) and to decide as quickly as possible which one was longer or shorter. If the mental representation accessed to make such comparisons is visual, an inverse relation would be expected between RT and distance difference on the body to be judged (i.e. actual difference in size between the two body widths), with accuracy increasing with increasing distance difference. Females with high body shape concern (scoring high on the Body Shape Questionnaire: BSQ, n=23) were compared to females with low body shape concern (scoring low on the BSQ, n=19). RT and distance differences on the body demonstrated standard distance differences effects: RT increased and accuracy decreased with decreasing distance differences on the body. Groups differed with respect to accuracy, in that females high on body shape concern were significantly less accurate than females low on body shape concern when making evaluations involving small (9cm) differences, which implies a less appropriate visual image of the own body in the former group. With respect to the relation between RT and body distance difference, on the other hand, there were no differences between groups. We concluded that evaluations of own body size employ visual imagery and that the distance comparison task holds promise for the assessment of visual disturbances in body image in clinical populations.

A double dissociation between somatosensory processing for perception and action.

Human neuropsychology suggests that there are two distinct body representations. Body image and body schema are, respectively, thought to be involved in conscious perceptual judgments and unconscious sensorimotor guidance. The evidence is based on the double dissociation between disorders of perceptual detection and sensorimotor guidance. Until now, research focused on cases that had impaired tactile pressure sensitivity and comparisons of performance were of cases suffering from different types of lesions (peripheral and central). Here, we report a unique double dissociation in two stroke patients with intact basic somatosensory processing (tactile detection). One patient was poor at identifying the position of where she had been touched on a line drawing of a hand, but was able to point accurately towards the actual position on her/his hand itself. The reverse pattern was observed in the other patient. This finding provides further support for separate processing for body image and body scheme.

Grasping Weber's illusion: the effect of receptor density differences on grasping and matching.

Weber found that distances between tactile stimuli on a high-receptor-density area are perceived as being larger than identical distances on a low-receptor-density area (Weber's illusion). Previous studies of visual illusions suggest that illusion effects vary with the type of response given. Here we tested a modified version of Weber's illusion in which a solid object was placed on the forearm or hand. Blindfolded participants were required either to give a size estimation or to grasp the object. The results showed that size estimation of solid objects was consistent with Weber's illusion, whereas grasping responses showed an opposite pattern (e.g., larger hand opening for objects on the forearm). A second experiment showed that this pattern is not due to biomechanical differences induced by the difference in spatial position of the target objects on the hand and arm. We suggest that the larger grip aperture when grasping objects on the arm were due to an increase in safety margin as a response to greater uncertainty about the object dimensions due to reduced receptor density.

Differences in finger localisation performance of patients with finger agnosia.

Several neuropsychological studies have suggested parallel processing of somatosensory input when localising a tactile stimulus on one's own by pointing towards it (body schema) and when localising this touched location by pointing to it on a map of a hand (body image). Usually these reports describe patients with impaired detection, but intact sensorimotor localisation. This study examined three patients with a lesion of the angular gyrus with intact somatosensory processing, but with selectively disturbed finger identification (finger agnosia). These patients performed normally when pointing towards the touched finger on their own hand but failed to indicate this finger on a drawing of a hand or to name it. Similar defects in the perception of other body parts were not observed. The findings provide converging evidence for the dissociation between body image and body schema and, more importantly, reveal for the first time that this distinction is also present in higher-order cognitive processes selectively for the fingers.