Colin Cryer

Guidelines for the prevention of falls in people over 65

General practice p 994 Older people frequently fall. This is a serious public health problem, with a substantial impact on health and healthcare costs.1 These guidelines translate trial evidence about prevention of falls into recommendations that can be implemented in different settings, with the aim of reducing the rate of falls and injurious falls in people over 65 (see boxes 2 3). #### Summary points Multifaceted interventions reduce falls in older people (those over 65) Home assessment of older people at risk of falls without referral or direct intervention is not recommended Assessment of high risk residents in nursing homes with relevant referral is effective Evidence from well designed single trials shows that assessment and modification of risk factors of older people who have presented to an accident and emergency department after a fall and the provision of hip protectors in residents of nursing homes are effective We updated two previous systematic reviews to include any new evidence up to March 1998. 4 5 We electronically searched Medline for all randomised controlled trials and systematic reviews by using the terms fall(s), accidental falls, fracture, elderly, aged, older, and senior. We followed up relevant references in papers, and we contacted researchers in prevention of falls for information about other trial evidence and about studies from journals not catalogued by the National Library of Medicine. For inclusion, studies had to be randomised controlled trials of interventions designed to minimise or prevent exposure to the risk factors for falling (or fracture) in people aged 65 years or over living in either community or residential care. Outcomes had to include the number of people who had fallen or the number of falls or fractures. We excluded drug or dietary treatments for the prevention of fractures. Trials that fulfilled the inclusion criteria were reviewed and summarised …

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.

HEAD INJURIES TO BICYCLISTS AND THE NEW ZEALAND BICYCLE HELMET LAW

The purpose of this study was to examine the effect of helmet wearing and the New Zealand helmet wearing law on serious head injury for cyclists involved in on-road motor vehicle and non-motor vehicle crashes. The study population consisted of three age groups of cyclists (primary school children (ages 5-12 years), secondary school children (ages 13-18 years), and adults (19+ years)) admitted to public hospitals between 1988 and 1996. Data were disaggregated by diagnosis and analysed using negative binomial regression models. Results indicated that there was a positive effect of helmet wearing upon head injury and this effect was relatively consistent across age groups and head injury (diagnosis) types. We conclude that the helmet law has been an effective road safety intervention that has lead to a 19% (90% CI: 14, 23%) reduction in head injury to cyclists over its first 3 years.

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.

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.

Measuring the population burden of fatal and nonfatal injury.

The value of measuring the population burden of fatal and nonfatal injury is well established. Population health metrics are important for assessing health status and health-related quality of life after injury and for integrating mortality, disability, and quality-of-life consequences. A frequently used population health metric is the disability-adjusted life-year. This metric was launched in 1996 in the original Global Burden of Disease and Injury study and has been widely adopted by countries and health development agencies alike to identify the relative magnitude of different health problems. Apart from its obvious advantages and wide adherence, a number of challenges are encountered when the disability-adjusted life-year is applied to injuries. Validation of disability-adjusted life-year estimates for injury has been largely absent. This paper provides an overview of methods and existing knowledge regarding the population burden of injury measurement. The review of studies that measured burden of injury shows that estimates of the population burden remain uncertain because of a weak epidemiologic foundation; limited information on incidence, outcomes, and duration of disability; and a range of methodological problems, including definition and selection of incident and fatal cases, choices in selection of assessment instruments and timings of use for nonfatal injury outcomes, and the underlying concepts of valuation of disability. Recommendations are given for methodological refinements to improve the validity and comparability of future burden of injury studies.

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.

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.

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.

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.