Suzanne J. Wilson

Prospective Outcomes of Injury Study: recruitment, and participant characteristics, health and disability status

The Prospective Outcomes of Injury Study aims to identify predictors of disability following injury. Participants were selected from the entitlement claims register of New Zealands no-fault compensation insurer, the Accident Compensation Corporation, and followed up by interview for 2 years. This report describes changes to intended Prospective Outcomes of Injury Study methods and key characteristics of the cohort, with an emphasis on general health and disability before injury and soon afterwards. There were 2856 injured participants in the first interview, which occurred 3.2 months (median) after injury. The recruitment period was extended to enable inclusion of sufficient Māori participants. At the first interview, most participants were experiencing worse health status and increased disability compared to before injury, despite less than one-third reporting admission to hospital because of their injury. Analysis of outcome predictors related to post-injury function, disability and return-to-work soon after injury and 1 year later is now under way.

Prevalence and predictors of sub-acute phase disability after injury among hospitalised and non-hospitalised groups: a longitudinal cohort study

Introduction To reduce the burden on injury survivors and their supporters, factors associated with poor outcomes need to be identified so that timely post-injury interventions can be implemented. To date, few studies have investigated outcomes for both those who were hospitalised and those who were not. Aim To describe the prevalence and to identify pre-injury and injury-related predictors of disability among hospitalised and non-hospitalised people, three months after injury. Methods Participants in the Prospective Outcomes of Injury Study were aged 18–64 years and on an injury entitlement claims register with New Zealands no-fault injury compensation insurer, following referral by healthcare professionals. A wide range of pre-injury demographic, health and injury-related characteristics were collected at interview. Participants were categorised as ‘hospitalised’ if they were placed on New Zealands National Minimum Data Set within seven days of the injury event. Injury severity scores (NISS) and 12 injury categories were derived from ICD-10 codes. WHODAS assessed disability. Multivariable analyses examined relationships between explanatory variables and disability. Results Of 2856 participants, 2752 (96%) had WHODAS scores available for multivariable analysis; 673 were hospitalised; 2079 were not. Disability was highly prevalent among hospitalised (53.6%) and non-hospitalised (39.4%) participants, three-months after injury. In both groups, pre-injury disability, obesity and higher injury severity were associated with increased odds of post-injury disability. A range of other factors were associated with disability in only one group: e.g. female, ≥2 chronic conditions and leg fracture among hospitalised; aged 35–54 years, trouble accessing healthcare, spine or lower extremity sprains/dislocations and assault among non-hospitalised. Significance Disability was highly prevalent among both groups yet, with a few exceptions, factors associated with disability were not common to both groups. Where possible, including a range of injured people in studies, hospitalised and not, will increase understanding of the burden of disability in the sub-acute phase.

Slow axonal transport of the cytosolic chaperonin CCT with Hsc73 and actin in motor neurons

Molecular chaperones are well known for their role in facilitating the folding of nascent and newly synthesized proteins, but have other roles, including the assembly, translocation and renaturation of intracellular proteins. Axons are convenient tissues for the study of some of these other roles because they lack the capacity for significant protein synthesis. We examine the axonal transport of the cytosolic chaperonin containing T‐ complex polypeptide 1 (CCT) by labeling lumbar motor neurons with [35S]methionine and examining sciatic nerve proteins by 2‐D gel electrophoresis and immunoblotting. All CCT subunits identifiable with specific antibodies, namely CCTα, CCTβ, CCTγ and CCTϵ/CCTθ (the latter two subunits colocalized in analyses of rat nerve samples), appeared to be labeled in “slow component b” of axonal transport along with the molecular chaperone Hsc73 and actin, a major folding substrate for CCT. Our results are consistent with molecular chaperones having a post‐translational role in maintaining the native form of actin during its slow transport to the axon terminal and ensuring its correct assembly into microfilaments.

Estimating subject-specific body segment parameters using a 3-dimensional modeller program

The estimation of body segment properties is important in the biomechanical analysis of movement. Current subject-specific estimation methods however can be expensive and time-consuming, while other methods do not adequately take into account individual or group variability. We describe a simple procedure for estimating subject-specific geometric properties, independent of joint centres. The method requires only a small number of anthropometric measurements and digital images of the segment or subject, a 3-dimensional modeller program and simple mathematical calculations to estimate segment volumes and centroids. Assuming that the segment is of uniform density, its mass and moment of inertia can also be derived. Future work should include generating segment density profiles for particular populations, to increase the accuracy of the method, and comparing the accuracy of the results obtained with those produced by other techniques.

Validity of using linked hospital and police traffic crash records to analyse motorcycle injury crash characteristics

Linking hospital discharge and police traffic crash records has been used to provide information on causes and outcomes for hospitalised traffic crash cases. Motorcyclists are particularly vulnerable to injury in a traffic crash, but no published linkage studies have reported in detail on this road user group. The present study examined motorcycle traffic crash injury cases in New Zealand in 2000-2004 by probabilistically linking national hospital discharge records with police traffic crash reports. Injury cases had to have spent at least one night in hospital before being discharged and were defined as serious or moderate based on their International Classification of Disease Injury Severity Scores (ICISS). Despite a robust linkage process, only 46% of cases could be linked to a police record; 60% of the serious injuries and 41% of the moderate. The low linkage was most likely due to under-reporting of crashes to or by the police. While moderate injury cases were expected to be under-reported, the level of under-reporting of cases with serious threat-to-life injuries is concerning. To assess whether the linked dataset could provide valid information on the crash circumstances and injury outcomes of hospitalised motorcycle crash cases, the characteristics of the linked and unlinked hospital discharge cases were compared using chi-square tests and multivariate logistic regression. Serious injury cases were less likely to be linked if only one vehicle was involved, or the injured riders and passengers were younger than 20 years or spent less than one week in hospital. For moderate injury cases, there were also differences in linkage by injured body region and crash month. While these discrepancies need to taken into consideration when interpreting results, the linked hospital-police dataset has the potential to provide insights into motorcycle crash circumstances and outcomes not otherwise obtainable.

Prevalence and predictors of disability 24-months after injury for hospitalised and non-hospitalised participants: results from a longitudinal cohort study in New Zealand.

Introduction Most studies investigating disability outcomes following injury have examined hospitalised patients. It is not known whether variables associated with disability outcomes are similar for injured people who are not hospitalised. Aims This paper compares the prevalence of disability 24 months after injury for participants in the Prospective Outcomes of Injury Study who were hospitalised and those non-hospitalised, and also seeks to identify pre-injury and injury-related predictors of disability among hospitalised and non-hospitalised participants. Methods Participants, aged 18–64 years, were recruited from an injury claims register managed by New Zealand’s no-fault injury compensation insurer after referral by health care professionals. A wide range of pre-injury socio-demographic, health and psychosocial characteristics were collected, as well as injury-related characteristics; outcome is assessed using the WHODAS. Multivariable models estimating relative risks of disability for hospitalised and non-hospitalised participants were developed using Poisson regression methods. Results Of 2856 participants, analyses were restricted to 2184 (76%) participants for whom both pre-injury and 24 month WHODAS data were available. Of these, 25% were hospitalised. In both hospitalised and non-hospitalised groups, 13% experience disability (WHODAS≥10) 24 months after injury; higher than pre-injury (5%). Of 28 predictor variables, seven independently placed injured participants in the hospitalised group at increased risk of disability 24 months after injury; eight in the non-hospitalised. Only four predictors (pre-injury disability, two or more pre-injury chronic conditions, pre-injury BMI≥30 and trouble accessing healthcare services) were common to both the hospitalised and non-hospitalised groups. There is some evidence to suggest that among the hospitalised group, Māori have higher risk of disability relative to non-Māori. Conclusions At 24 months considerable disability is borne, equally, by hospitalised and non-hospitalised groups. However, predictors of disability are not necessarily consistent between the hospitalised and non-hospitalised groups, suggesting caution in generalising results from one group to the other.

Difficulties in functioning 1 year after injury: the role of preinjury sociodemographic and health characteristics, health care and injury-related factors.

OBJECTIVE To identify the role of preinjury sociodemographic and health characteristics, injury and injury-related health care characteristics in determining functional outcomes 12 months after injury. DESIGN Prospective cohort study involving 1-year follow-up. SETTING Community. PARTICIPANTS Study participants (N=2282; age range, 18-64y inclusive) were those in the Prospective Outcomes of Injury Study who completed the 12-month interview. The original cohort of 2856 were injured and registered with New Zealands national no-fault injury insurance agency. With the exception of injury and hospitalization, information on predictors and outcomes was obtained directly from the participants, primarily by telephone interviews, approximately 3 and 12 months after their injury. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES The functional outcomes of interest were the 5 dimensions of the EQ-5D plus a cognitive dimension. Our multivariate analyses included adjustment for preinjury EQ-5D status and time between injury and the 12-month interview. RESULTS Substantial portions of participants continued to have adverse outcomes, especially pain/discomfort, 12 months after their injury. The significance of factors varied by outcome. Factors adversely associated with at least 3 of the 6 outcomes were preinjury EQ-5D status, being female, aged 45 to 64 years, inadequate household income, preinjury disability, 2 or more prior chronic illnesses, smoking regularly, dislocation or sprains to the spine or upper extremities, and having a relatively severe injury. CONCLUSIONS A range of preinjury sociodemographic and health characteristics are associated with several adverse functional outcomes 1 year after injury, independent of the nature and severity of injury. The latter, however, also have independent effects on the outcomes.

Influence of right atrial pressure on the cardiac pacemaker response to vagal stimulation

We have recently shown that the intrinsic rate response to an increase in right atrial pressure is augmented when cardiac muscarinic receptors are activated. This present study examines the cardiac pacemaker response to vagal stimulation at different values of right atrial pressure in isolated rat right atrium and in the rabbit heart in situ. In the rat atrium, when pressure was raised in steps from 2 to 10 mmHg, there was a progressive reduction in the response to vagal stimulation [40.5 +/- 7.2% reduction (mean +/- SE) at 8 mmHg, P < 0.01], which was independent of the level of vagal bradycardia, that persisted in the presence of the beta-adrenergic agonist isoproterenol. In barbiturate-anesthetized rabbits with cervical vagi cut and beta-adrenergic blockade, raising right atrial pressure approximately 2.5 mmHg by blood volume expansion reduced the bradycardia elicited by electrical stimulation of the peripheral end of the right vagus nerve (9.1 +/- 1.1% reduction, P < 0.0001). These results demonstrate that vagal bradycardia is modulated by the level of right atrial pressure and suggest that normally right atrial pressure may interact with cardiac vagal activity in the control of heart rate.

Prevalence of poor outcomes soon after injury and their association with the severity of the injury.

Little is known of injury outcomes among non-hospitalised injured populations. This study examined the occurrence of poor outcomes 3 months after injury among the 2856 participants in the Prospective Outcomes of Injury Study, most of whom had sustained injuries considered of minor severity (by injury severity scoring) and had not received treatment at a hospital facility. The prevalence of poor outcomes was high across all health, physical functioning and social functioning domains and expectation characteristics examined, including for those participants with the ‘least severe’ injuries. Approximately half of the cohort reported experiencing moderate to high pain or psychological distress and reduced social participation, and three-quarters did not consider themselves recovered. Our findings demonstrate that, to obtain an accurate understanding of injury burden, injury outcome research should not focus only on those injured persons who are hospitalised.

Physical Components of Soft-Tissue Ballistic Wounding and Their Involvement in the Generation of Blood Backspatter*

Abstract:  Gunshot backspatter comprises biological material expelled backward through bullet entry holes. Crime scene investigators analyze backspatter patterns to infer wounding circumstances. An understanding of the mechanism of backspatter generation, and the relationship between spatter patterns and bullet and tissue characteristics, would enhance the predictive value of such analysis. We examined soft‐tissue ballistic wounding responses to determine the underlying components and how these might be relevant to the generation of backspatter. We identified five mechanistic components to ballistic wounding (elastic, viscous, crushing, cutting, and thermal), each related to mechanical disciplines (respectively, solid mechanics, fluid mechanics, fracture mechanics, rheology, and thermodynamics). We identified potential roles for these five components in backspatter formation and provide a scenario whereby a sequence of events incorporating these components could lead to backspatter generation and expulsion. This research provides a framework for the mathematical representation, and subsequent computational predictive modeling, of backspatter generation and pattern formation.