Use of alcohol intoxication codes for serious non-fatal hospitalised injury.

AIM: To determine the extent to which ICD-10 alcohol intoxication codes are used for serious hospitalised injury and the distribution of these codes according to gender, age, injury mechanism and intent, severity of injury, and whether the patient was treated in an Intensive Care Unit. DESIGN: Cross-sectional study. SETTING: New Zealand. PARTICIPANTS: All injury hospital discharges in 2010 that met specified severity criteria. MEASUREMENTS: Cases which had a measurement of BAC (Y90) coded, or only a subjective assessment of alcohol intoxication (F10.0). FINDINGS: 2.5% had a blood alcohol recorded (Y90) and a further 3% were coded as being intoxicated but there was no blood alcohol code. All factors investigated were shown to be independently associated with the assignation of codes. Notable findings were the elevated odds of an alcohol code for males, assault and the more severe injuries. CONCLUSIONS: Assessment of alcohol intoxication among seriously injured persons appears to be very uncommon. The development of a standardised instrument for clinical judgement of intoxication would be highly desirable.

HLA-A, -B, -DR allele group frequencies in 7007 kidney transplant list patients in 27 UK centres.

This observational study aims to determine the HLA specificity frequencies of patients on the UK renal transplant list, which can be used as a resource for those laboratories that support the UK renal transplant programme. Whilst the HLA specificity frequencies may differ from that of the general population, it is the individuals on the transplant list who are in need of a new kidney, which has to be provided from the general population. Any differences in protein allele frequencies between this patient population and the general population are likely to be minimal because of the very large number of patients included. The HLA-A, -B and -DR allele group frequencies from 7007 patients on the UK kidney transplant list (August, 2009) were analysed. HLA types had been submitted to NHSBT to register patients on the UK deceased donor kidney waiting list. The data were submitted from 27 different registering centres throughout the UK. Within this data set, 25 different HLA-A, 50 HLA-B and 18 HLA-DR allele groups were present. The most common allele groups at each locus were -A2 (phenotype frequency 42.6%), -B44 (phenotype frequency 23.3%) and -DR4 (phenotype frequency 29.8%). The least common allele groups at each locus were -A19, - A43, -B16, -B21, -B22, -B83 and -DR5. Reports of HLA frequency (protein allotype) data from populations as large as this are not readily available adding value to this observational study.

Is length of stay in hospital a stable proxy for injury severity?

RESEARCH QUESTION: Is length of stay (LoS) in hospital a stable proxy for severity of injury when monitoring time trends in serious injury incidence? OBJECTIVE: To investigate whether LoS metrics (mean, median and proportion exceeding several LoS thresholds) have changed over time for injury diagnoses with known severity. DESIGN: Time series investigation. SUBJECTS AND SETTING: New Zealand population admitted to hospital for injury and discharged during the period 1989 to 1998. MAIN OUTCOME MEASURES: Interpolated median and geometric mean lengths of stay, as well as the proportion of cases that have an LoS greater than or equal to 3, 4, 7 and 14 days in hospital. METHODS: ICD-9-CM diagnoses that are approximately homogeneous in regard to severity of injury (ICD-HS diagnoses) were identified. Trends were investigated in the LoS statistics for: injury and non-injury diagnoses combined; all injury diagnoses; major body sites of injury; severity strata; and ICD-HS diagnoses. RESULTS: Almost without exception, there was a decline in the LoS statistics over time for all diagnoses, all injury diagnoses, each body site of injury investigated, severity strata, and the ICD-HS diagnoses. CONCLUSIONS: Reductions in median and geometric mean LoS over time, as well as reductions in the proportion exceeding selected LoS thresholds, were due to factors other than reductions in the incidence of serious injury; for example, changes in service delivery over time. An LoS threshold should not be used as a proxy for severity of injury if the goal is to monitor time trends in injury incidence.

Improving the predictive ability of the ICD-based Injury Severity Score.

OBJECTIVE: To assess whether the use of integrated hospitalization and mortality data sources and/or the inclusion of comorbidity improve the predictive ability of the International Classification of Disease (ICD)-based Injury Severity Score (ICISS). DESIGN: Models using either the ICISS based solely on hospital discharge data or one of nine modified ICISSs as the predictor variable were assessed on their ability to predict survival using logistic regression modeling. SETTING: New Zealand. Patients or SUBJECTS: Inpatients, with an S00-T89 ICD-10-AM principal diagnosis, and fatalities, with any S00-T89 ICD-10-AM diagnosis, occurring in 2000-2003. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Models were compared in terms of their discrimination (concordance), calibration, and goodness-of-fit. RESULTS: 186 835 cases including 9968 deaths met the inclusion criterion. The modified ICISS that included both mortality data and Charlson comorbid conditions at the ICD-10-AM level had the best concordance and high calibration. Calibration curves indicated that scores using hospital discharge data only to calculate survival risk ratios underestimated mortality, whereas scores using hospital discharge and mortality data overestimated mortality. CONCLUSIONS: Valid measurement of injury severity is important for both meaningful research and surveillance and to assist in classifying information to meet specific injury policy, prevention, and control needs. This study suggests that the predictive ability of ICISS would be improved if both mortality and comorbidity data were included in its calculation.

Factors associated with hip protector adherence among older people in residential care.

BACKGROUND: There is evidence to suggest that hip protectors (HPs) prevent fractures among older people living in nursing homes. Studies have found HP wearing rates (adherence) to be low. OBJECTIVES: To investigate factors that are associated with adherence and whether those factors account for the variation in adherence between residential care homes (RCHs). DESIGN: Six-month prospective study. SUBJECTS AND SETTING: 299 people aged 65 years and over (80% female, mean age 86 years) living in 17 RCHs. 128 of these wore HPs at least once. METHODS: All residents in the homes were offered three pairs of SAFEHIP HPs, and adherence was measured using diaries completed daily. A mixed model regression analysis was used to investigate predictive factors for wearing HPs and the effects of these factors on the between-home variability in adherence. RESULTS: Increased HP adherence was associated with hypertension, incontinence, a previous history of falls and fractures, and hip fracture history in the RCH. Decreased adherence was associated with arthritis of the lower limbs and dizziness on first rising. The large variation in adherence between RCHs was almost completely explained by these factors. DISCUSSION: The evidence for the efficacy of HPs is weakening. Low adherence compromises the power of trials to detect a real effect. The literature is inconsistent regarding what factors are associated with adherence. Nevertheless, it suggests that some people who are at increased risk of fracture are more likely to wear HPs. Variations in staff or resident knowledge and attitude towards HPs may explain some variation between homes.

Developing valid indicators of injury incidence for "all injury".

BACKGROUND/AIMS: This paper focuses on the methods used to develop indicators for "all injury" incidence for the New Zealand Injury Prevention Strategy (NZIPS), launched in June 2003. Existing and previously proposed New Zealand national non-fatal injury indicators exhibited threats to validity. Population/ SETTING: The total population of New Zealand. METHODS: The authors proposed fatal and new non-fatal injury indicators for "all injury" based on national mortality and hospitalizations data. All of the candidate indicators were subjected to a systematic assessment of validity, using the International Collaborative Effort on Injury Statistics (ICE) criteria. Based on the results of that validation, the authors identified four proposed NZIPS indicators. RESULTS: The proposed "all injury" indicators were as follows: age standardized injury mortality rate per 100 000 person-years at risk; number of injury deaths; age standardized serious non-fatal injury rate per 100 000 person-years at risk; and number of cases of serious non-fatal injury. The authors identified no threat-to-validity when assessed against the ICE criteria. The estimated numbers and rates of serious non-fatal injury increased over the period, in contrast to the numbers and rates of fatal injury. CONCLUSION: The authors have proposed serious non-fatal injury indicators that they judge suffer substantially less bias than traditional non-fatal injury indicators. This approach to indicator development is consistent with the view that before newly proposed indicators are promulgated, they should be subjected to formal validation. The authors are encouraged that the New Zealand Government has accepted these arguments and proposed indicators, and are starting to act on some of their recommendations, including the development of complementary indicators.

Injury outcome indicators: the development of a validation tool.

BACKGROUND: Researchers have previously expressed concern about some national indicators of injury incidence and have argued that indicators should be validated before their introduction. AIMS: To develop a tool to assess the validity of indicators of injury incidence and to carry out initial testing of the tool to explore consistency on application. METHODS: Previously proposed criteria were shared for comment with members of the International Collaborative Effort on Injury Statistics (ICE) Injury Indicators Group over a period of six months. Immediately after, at a meeting of Injury ICE in Washington, DC in April 2001, revised criteria were agreed over two days of meetings. The criteria were applied, by three raters, to six non-fatal indicators that underpin the national road safety targets for Canada, New Zealand, and the United Kingdom. Consistency of ratings were judged. CONSENSUS OUTCOME: The development process resulted in a validation tool that comprised criteria relating to: (1) case definition, (2) a focus on serious injury, (3) unbiased case ascertainment, (4) source data for the indicator being representative of the target population, (5) availability of data to generate the indicator, and (6) the existence of a full written specification for the indicator. On application of these criteria to the six road safety indicators, some problems of agreement between raters were identified. CONCLUSION: This paper has presented an early step in the development of a tool for validating injury indicators, as well as some directions that can be taken in its further development.

On the significance of fiber branching in the human myocardium.

Myocardial tissue exhibits a high degree of organization in that the cardiac muscle fibers are both systematically aligned and highly branched. In this study, the influence and significance of fiber branching is analyzed mathematically. In order to allow for analytic solutions, a regular geometry and simplified constitutive relations are considered. It is found that branching is necessary to stabilize the ventricular wall.

The forces generated within the musculature of the left ventricular wall.

OBJECTIVES: To test the hypothesis that two populations of myocardial fibres-fibres aligned parallel to the surfaces of the wall and an additional population of fibres that extend obliquely through the wall-when working in concert produce a dualistic, self stabilising arrangement. METHODS: Assessment of tensile forces in the walls of seven porcine hearts by using needle probes. Ventricular diameter was measured with microsonometry and the intracavitary pressure through a fluid filled catheter. Positive inotropism was induced by dopamine, and negative inotropism by thiopental. The preload was raised by volume load and lowered by withdrawal of blood. Afterload was increased by inflation of a balloon in the aortic root. The anatomical orientation of the fibres was established subsequently in histological sections. RESULTS: The forces in the fibres parallel to the surface decreased 20-35% during systolic shrinkage of the ventricle, during negative inotropism, and during ventricular unloading. They increased 10-30% on positive inotropic stimulation and with augmentation in preload and afterload. The forces in the oblique transmural fibres increased 8-65% during systole, on positive inotropic medication, with an increase in afterload and during ventricular shrinkage, and decreased 36% on negative inotropic medication. There was a delay of up to 147 ms in the drop in activity during relaxation in the oblique transmural fibres. CONCLUSION: Although the two populations of myocardial fibres are densely interwoven, it is possible to distinguish their functions with force probes. The delayed drop in force during relaxation in obliquely oriented fibres indicates that they are hindered in their shortening to an extent that parallels any increase in mural thickness. The transmural fibres, therefore, contribute to stiffening of the ventricular wall and hence to confining ventricular compliance.

A critical evaluation of results of partial left ventriculectomy.

BACKGROUND: Because of the variation in the surgical procedures designed to reduce ventricular radius, along with differences in hospital care, it is difficult to disentangle the factors that may contribute to the success or failure of the partial left ventriculectomy. METHODS AND RESULTS: We undertook partial left ventriculectomy in 18 patients, 10 suffering from idiopathic dilated cardiomyopathy and 8 from ischemic heart disease. We assessed the amount of reduction in wall stress, the systolic thickening of the ventricular wall, and the extent of connective tissue in the excised segment of the wall. Of the overall group, six patients died, three from infarction, one of stroke, one with asystole, and one with ventricular fibrillation. The mean decrease in measured mesh tension was 40% (p < 0.001). Most patients exhibited improvements postoperatively in terms of the systolic thickening of the posterior and superior free walls of the left ventricle. In those in whom the events could be monitored, life-threatening arrhythmias posed complications in three of four patients with ischemic heart disease, and in two of six patients suffering from idiopathic dilated cardiomyopathy. In one patient, death was associated with a transmural alignment of fibrous tissue. CONCLUSIONS: Our measured reductions in myocardial mesh tension were in keeping with the anticipated theoretical reduction in wall stress expected from partial ventriculectomy. The basic concept underscoring surgical maneuvers to reduce ventricular radius, therefore, is sound. A potential trap is the resection of the marginal artery. Critical myofibrosis was a rare complication. Arrhythmias, which are common, can successfully be treated by implantation of antitachycardic and defibrillatory devices.

Traps for the unwary in estimating person based injury incidence using hospital discharge data.

BACKGROUND: Injuries resulting in admission to hospital provide an important basis for determining priorities, emerging issues, and trends in injury. There are, however, a number of important issues to be considered in estimating person based injury incidence using such data. Failure to consider these could result in significant overestimates of incidence and incorrect conclusions about trends. AIM: To demonstrate the degree to which estimates of the incidence of person based injury requiring hospital inpatient treatment vary depending on how one operationally defines an injury, and whether or not day patients, readmissions, and injury due to medical procedures are included. METHOD: The source of data for this study was New Zealand's National Minimum Dataset. The primary analyses were of a dataset of all 1989-98 discharges from public hospital who had an external cause of injury and poisoning code assigned to them. RESULTS: The results show that estimates of the incidence of person based injury vary significantly depending on how one operationally defines an injury, and whether day patients, readmissions, and injury due to medical procedures are included. Moreover the effects vary significantly by pathology and over time. CONCLUSIONS: (1) Those using New Zealand hospital discharge data for determining the incidence of injury should: (a) select cases which meet the following criteria: principal diagnosis injury only cases, patients with day stay of one day or more, and first admissions only, (b) note in their reporting that the measure is an estimate and could be as high as a 3% overestimate. (2) Other countries with similar data should investigate the merit of adopting a similar approach. (3) That the International Collaborative Effort on Injury Statistics review all diagnoses within International Classification of Diseases 9th and 10th revisions with a view to reaching consensus on an operational definition of an injury.

Measure for measure: the quest for valid indicators of non-fatal injury incidence.

In this edition of Public Health, McClure and colleagues report on research that considered the criterion validity of indicators based on serious long bone fracture and length of stay in hospital. They found that neither were sensitive or specific indicators for serious injury as defined by an Injury Severity Score (ISS) of 16 or more. They contend that their study findings ' em leader strongly support a return to a measure similar in intent to that encapsulated in the original UK Green Paper em leader '. We contend that their analysis does not provide any empirical evidence to support their view that there should be a return to the Green Paper: Our Healthier Nation indicator. Furthermore, we consider the analyses that they carry out to validate both the Saving Lives: Our Healthier Nation and the serious long bone fracture indicators are flawed. We agree that national (or state) indicators are very influential. They encourage preventive action and resource use aimed at producing favourable changes to these indicators. However, each of the four non-fatal indicators considered in their analysis have problems. Formal validation of existing indicators is necessary and the following aspects of validity should be addressed: face; criterion; consistency; and completeness and accuracy of the source date. Taking into account the current national data systems in England, possible options for one or more national non-fatal unintentional injury indicators have been proposed in our paper. Furthermore, the International Collaborative Effort on Injury Statistics (ICE) Injury Indicators Group is about to embark on the development of a strategic framework for the development of valid indicators of non-fatal injury occurrence.

Hip protector compliance among older people living in residential care homes.

OBJECTIVES: To estimate the compliance rates for the use of hip protectors among people living in residential care homes. Population/setting: People aged 65 years and over living in residential care homes with 20 or more beds in East Kent, south east England. METHODS: Seventeen homes with the highest historical frequency of hip fractures were selected. All residents were offered SAFEHIP hip protectors. Care staff recorded daily hip protector compliance on diary cards over six months. Compliance rates were estimated from the number of sessions (morning, afternoon, evening, night) that a person wore hip protectors. RESULTS: A total of 153 (51%) out of 299 residents agreed to wear hip protectors The 24 hour compliance rate for those who were issued with hip protectors and wore them at least once was 29%: 37% in the daytime and 3% at night. Daytime compliance rates reduced from 47% for the first month, to around 30% for months 5 and 6. CONCLUSION: This study highlights the problems of persuading older people living in residential care homes to wear hip protectors. They have been shown to prevent hip fracture in nursing home (high risk) populations, and a recent trial showed their effectiveness in a mixed geriatric population. People living in residential care homes are also at greater risk of falling and fracturing than their counterparts living in the community. Initiatives to prevent hip fracture within residential care homes are also justified.

Are we blind to injuries in the visually impaired? A review of the literature.

OBJECTIVES: To review the literature on the risks and types of injuries associated with visual impairment, and to identify pertinent areas for future research. METHODS: A search of bibliographic databases was conducted in April 2000 for studies published since 1980 and selected studies that met two or more of the following criteria: formal ophthalmic assessment was used; adjustment for confounding variables; large sample size including numbers of visually impaired; and clear definitions and outcomes. RESULTS: Thirty one studies were selected. The majority of these studies (20) assessed falls (including eight on hip fracture and four on multiple falls), eight studies reported traffic related injuries, and three studies assessed occupational injury. The evidence on falls, which relate predominantly to older people, suggests that those with reduced visual acuity are 1.7 times more likely to have a fall and 1.9 times more likely to have multiple falls compared with fully sighted populations. The odds of a hip fracture are between 1.3 and 1.9 times greater for those with reduced visual acuity. Studies of less severe injuries and other causes of injury were either poorly designed, underpowered, or did not exist. CONCLUSIONS: There are substantial gaps in research on both injuries to which people with visual impairment are especially susceptible and in evaluating interventions to reduce these injuries. It is recommended that in future studies the minimum data captured includes: formal ophthalmic assessment of visual fields and visual acuity, outcome measurement, control for confounders, and the costs of health care resource use and any interventions.

Effects of chronic estrogen-receptor blockade on ovine perinatal pulmonary circulation.

Prolonged infusions of 17beta-estradiol reduce fetal pulmonary vascular resistance (PVR), but the effects of endogenous estrogens in the fetal pulmonary circulation are unknown. To test the hypothesis that endogenous estrogen promotes pulmonary vasodilation at birth, we studied the hemodynamic effects of prolonged estrogen-receptor blockade during late gestation and at birth in fetal lambs. We treated chronically prepared fetal lambs with ICI-182,780 (ICI, a specific estrogen-receptor blocker, n = 5) or 1% DMSO (CTRL, n = 5) for 7 days and then measured pulmonary hemodynamic responses to ventilation with low- and high-fraction inspired oxygen (FI(O(2))). Treatment with ICI did not change basal fetal PVR or arterial blood gas tensions. However, treatment with ICI abolished the vasodilator response to ventilation with low FI(O(2)) [change in PVR -30 +/- 6% (CTRL) vs. +10 +/- 13%, (ICI), P < 0.05] without reducing the vasodilator response to ventilation with high FI(O(2)) [change in PVR, -73 +/- 3% (CTRL) vs. -77 +/- 4%, (ICI); P = not significant]. ICI treatment reduced prostacyclin synthase (PGIS) expression by 33% (P < 0.05) without altering expression of endothelial nitric oxide synthase or cyclooxygenase-1 and -2. In situ hybridization and immunohistochemistry revealed that PGIS is predominantly expressed in the airway epithelium of late gestation fetal lambs. We conclude that prolonged estrogen-receptor blockade inhibits the pulmonary vasodilator response at birth and that this effect may be mediated by downregulation of PGIS. We speculate that estrogen exposure during late gestation prepares the pulmonary circulation for postnatal adaptation.

The work-related fatal injury study: numbers, rates and trends of work-related fatal injuries in New Zealand 1985-1994.

AIMS: To determine the number and rates of work-related fatal injuries by employment status, occupation, industry, age and gender in New Zealand 1985-1994. METHODS: Potential cases of work-related injury deaths of persons aged 15-84 years were identified from the national electronic mortality data files. Main exclusions were deaths due to suicide and deaths due to motor vehicle crashes. The circumstances of the deaths of each fatal incident meeting inclusion criteria were then reviewed directly from coronial files to determine work-relatedness. RESULTS: The rate of work-related fatal injury in New Zealand was 5.03/100000 workers per year for the study period. There was a significant decline in crude rate over the study period. However, this was in substantial part accounted for by changes in occupation and industry mix. Older workers, male workers, self-employed workers, and particular occupational groups, all had substantially elevated rates. Agricultural and helicopter pilots, forestry workers and fishery workers had the highest rates. Farmers, forestry workers, and fishery workers also had high numbers of deaths, together accounting for nearly 40% of all deaths. CONCLUSIONS: This study has demonstrated that work-related fatal injury remains a pressing problem for New Zealand. Several areas in urgent need of prevention efforts were highlighted.

Sample size calculations for intervention trials in primary care randomizing by primary care group: an empirical illustration from one proposed intervention trial.

Because of the central role of the general practice in the delivery of British primary care, intervention trials in primary care often use the practice as the unit of randomization. The creation of primary care groups (PCGs) in April 1999 changed the organization of primary care and the commissioning of secondary care services. PCGs will directly affect the organization and delivery of primary, secondary and social care services. The PCG therefore becomes an appropriate target for organizational and educational interventions. Trials testing these interventions should involve randomization by PCG. This paper discusses the sample size required for a trial in primary care assessing the effect of a falls prevention programme among older people. In this trial PCGs will be randomized. The sample size calculations involve estimating intra-PCG correlation in primary outcome: fractured femur rate for those 65 years and over. No data on fractured femur rate were available at PCG level. PCGs are, however, similar in size and often coterminous with local authorities. Therefore, intra-PCG correlation in fractured femur rate was estimated from the intra-local authority correlation calculated from routine data. Three alternative trial designs are considered. In the first design, PCGs are selected for inclusion in the trial from the total population of England (eight regions). In the second design, PCGs are selected from two regions only. The third design is similar to the second except that PCGs are stratified by region and baseline value of fracture rate. Intracluster correlation is estimated for each of these designs using two methods: an approximation which assumes cluster sizes are equal and an alternative method which takes account of the fact that cluster sizes vary. Estimates of sample size required vary between 26 and 7 PCGs in each intervention group, depending on the trial design and the method used to calculate sample size. Not unexpectedly, stratification by baseline value of the outcome variable decreases the sample size required. In our analyses, geographic restriction of the population to be sampled reduces between-cluster variability in the primary outcome. This leads to an increase in precision. When allowance for variable cluster size is made, the increase in precision is not as great as would be expected with equal cluster sizes. This paper highlights the usefulness of routine data in work of this kind, and establishes one of the essential prerequisites for our proposed trial and other trials using primary outcomes with similar between-PCG variation: a feasible sample size.