Biomedical subjects

Colin Cryer

Publications and source records attributed to Colin Cryer.

5 recordsLinked to original sources

PubMed2005

Effects of service delivery versus changes in incidence on trends in injury: a demonstration using hospitalised traumatic brain injury.

Though injury incidence and hospitalisations are likely to be correlated, a range of factors other than incidence of injury in a population may influence trends in hospitalised injuries. These include technical changes in the hospital data's coverage, and real changes in the incidence of hospitalisations independent of the population incidence. This paper addresses the latter using the example of traumatic brain injury (TBI) hospitalisations in New Zealand. Data were New Zealand public hospitals inpatient discharges. Five measures of TBI severity were used. The relative rate of minor to serious TBI hospitalisations declined by approximately 2-6% per year from 1988 to 1998. This decline is observed across different mechanisms and the two severity measures used in the detailed analysis. The relative decline in minor to serious TBI is likely to be related to a change in the probability of admission rather than a change in the population TBI incidence. As most TBI hospitalisations are minor this suggests the trend in TBI hospitalisations was significantly influenced by factors other than changes in population incidence. Any analysis of routinely collected secondary injury data needs to consider case selection carefully, especially if trends are being examined. Applying a severity threshold should give more reliable trends.

Adolescent↗

PubMed2005

Injury outcome indicators--validation matters.

INTRODUCTION: There is concern that many national non-fatal injury indicators currently in use are misleading. OBJECTIVE: To make the case for the validation of existing unvalidated indicators, as well as the validation of new indicators before they are promulgated. METHOD: The International Collaborative Effort on Injury Statistics (ICE) Criteria were used for investigating the validity of indicators. Examples of indicators that have been found to be valid using these criteria are presented. In contrast, examples of national road safety indicators are also presented, whose validity is questionable. Trends in road safety indicators with and without threats to validity are contrasted. RESULTS: The New Zealand Injury Prevention Strategy (NZIPS) serious injury indicators are presented as indicators with no identifiable threats to validity. National road safety indicators from Canada, New Zealand and the United Kingdom, with identifiable threats to validity, are also presented. When trends for the valid NZIPS motor vehicle traffic crash indicators are compared with the New Zealand national road safety indicators, which have identifiable threats to validity, they show contrasting trends. This raises concerns that the current national indicators are potentially misleading. CONCLUSION: Validation does matter. For any indicator, it is important that it is clearly defined and specified. The specification should make it clear what parameter the indicator aims to reflect. Before use, the indicator should be validated against this target parameter. That parameter, and the indicators aimed to estimate it, should focus attention on important injuries, ie. injuries that are associated with significant mortality, threat-to-life, threat-of-disablement, loss of quality of life, or increased cost.

Accidents, Traffic↗

PubMed2005

Why modelling a complex intervention is an important precursor to trial design: lessons from studying an intervention to reduce falls-related injuries in older people.

OBJECTIVES: To develop a cost-effectiveness model of a complex intervention from pilot study data in order to inform the viability and design of a subsequent falls prevention trial. METHODS: We used two models; the first estimated the probability of falling over a 12-month period based on a probability tree; the second used Markov simulation to assess the impact of the programme over time. RESULTS: The first model indicated that our intervention would reduce the proportion falling by only 2.8% over a 12-month period. The major reason for this small effect was that less than a quarter of older people at risk of falling were assessed using our screening tool. Even if policy-makers were willing to spend 30,000 pounds per quality-adjusted life-year gained, there is only a 40% chance that the intervention would be cost-effective. Sensitivity analyses showed that the only scenarios that produced a substantial increase in the effect of the intervention were those in which all older people are assessed. CONCLUSIONS: The model-building approach described in this paper is vital when designing complex trials and where a trial is not possible. Information from the modelling can be used to re-design the intervention. The effectiveness of our proposed intervention appears very small due to its inability to reach those at risk of falling. It is most likely not to be cost-effective. If inability to reach the target group is a weakness common to other similar interventions, this suggests an area for further research.

Accidental Falls↗

PubMed2004

Development and preliminary examination of the predictive validity of the Falls Risk Assessment Tool (FRAT) for use in primary care.

BACKGROUND: There is no validated assessment of an older person's risk of falling that is easily applied in primary care. We aimed to develop a two-part tool for use in primary care or the community. Part 1 includes a rapid assessment of the individual's risk of falling for administration by clinical or non-clinical staff. Part 2 (for clinical staff) includes guidance on further assessment, referral and interventions. We assessed the predictive validity of part 1. METHODS: The tool was developed by an expert panel following the updating of an existing systematic review of community-based prospective studies identifying risk factors for falling and modified in accordance with the feedback from extensive piloting. We assessed predictive validity by a questionnaire survey sent at baseline and 6 months to a random sample of 1000 people aged over 65 in one Primary Care Group area. RESULTS: Five items were included in part 1: history of any fall in the previous year, four or more prescribed medications, diagnosis of stroke or Parkinson's disease, reported problems with balance, inability to rise from a chair without using arms. The presence of three or more risk factors had a positive predictive value for a fall in the next 6 months of 0.57 (95 per cent confidence interval 0.43-0.69). Less than three risk factors had a negative predictive value of 0.86 (0.82-0.89), and a specificity of 0.92 (0.88-0.94). CONCLUSION: The tool may be useful for identifying people who would benefit from further assessment of their risk of falling and appropriate intervention.

Accident Prevention↗

PubMed2003

Measuring road traffic safety performance: monitoring trends in nonfatal injury.

Traditional indicators used to monitor trends in nonfatal injury are influenced by a range of factors other than the incidence of injury. Indicators based on threat-to-life scales offer a means of addressing this problem. The aim of the research described in this article was to compare trends in the official indicators with trends in selected threat-to-life indicators. We compared indicators based on the New Injury Severity Score and the International Classification of Diseases-based Injury Severity Score with the official New Zealand indicators; namely, (1) reported injuries, (2) reported injuries per 10,000 vehicles, (3) reported injuries per 100,000 people, and (4) number hospitalized (discharges). All the official indicators suggest that there has been a substantive decline in nonfatal Motor Vehicle Traffic Crashes (MVTCs) for the period 1988-2000, but a notable increase in 2001. The latter appear to be artifactual increases due to changes in patterns of data collection and do not reflect any real changes in incidence. Further support for this is provided by the results for the two threat-to-life indicators, which suggest that the decline observed for 1988-98 may have been attributable to a decline in the ascertainment or occurrence of minor injuries since those injuries, which represent a significant threat to life, have not declined to the same degree. Given the prominence of motor vehicle crashes as a cause of unnecessary morbidity, more thought needs to be given to deriving valid indicators for measuring trends in serious nonfatal injury.

Accidents, Traffic↗