Discussion

Based on NPHS data, more than 10% of the adult Canadian population annually experience an ALI, with the proportion increasing from 10.5% in 1996 to 12.8% in 2006. According to the definition of ALI as activity-limiting injuries, all people with ALI experienced a certain amount of disruption of their daily activities with the impact varying according to the type and severity of their injury and depending on their customary type of activity.19–22 About 20% of ALIs were fractures and dislocations, many of whom necessitated a period of altered activity. Older people were more likely to report fractures than the younger age groups. The most common injuries were sprains and strains, the impact of which also varied a great deal depending on type and severity.23 ,24 An important impact of injuries is on the workplace through absenteeism and on the family through the disruption of customary activities.25 ,26 Besides the impact of injuries on every day activities, there was also an impact on the healthcare system.27 In our data, in 2000, about two thirds of people with ALI sought some kind of medical care. The evidence was presented showing that the impact of ALI might be even more far-reaching, as seen by the higher levels of medical care, and continued pain remaining 2 years after the ALI were reported.

Other researches on injuries have used a variety of definition of injuries, based on different sources of information. Questions in the NPHS were able to put these other measures in perspective. For example, some studies used hospital-based data,28 but the present study showed that only about 5% of ALI were resulted in a hospital admission within the first 48 h after the event. Assuming that all injury cases that require hospitalisation were within the activity-limiting rubric, it is clear that studies using only hospital data would include only a small portion of data on important injuries.29 However, the hospitalised injury cases will be the more severe ones which are responsible for a disproportional share of the healthcare cost and disability.25 Other studies have used ED visits as a unit of measurement.9 The present study showed that less than one third of ALI cases went to an ED to obtain treatment. Again, the latter were the more severe injury cases or those needing specialised treatment, for example, casts on fractures, and thus had a greater impact on daily life and cost. Another source of data commonly used has been mortality data. Although deaths are definitely activity-limiting, obviously, none were included in this study. Fatal injuries reflect a different range of injuries than those for ALI. For example, in an US study, firearm-related injuries were 22% of all injury deaths, second only to traffic accident related injuries, but firearms amounted to less than 1% for non-fatal injuries.11 Thus, different measuring units for measuring injury rates will target different slices of the spectrum of injuries and provide different results. ALI are of special public health importance, but are not sufficiently studied.

Another level of impact resulting from ALI would consist of impact on the healthcare system. Approximately 60% of people with ALI obtained medical care of some type. Of these, approximately one third of persons with ALI went to ED to experience the often long wait before receiving treatment. Back at home the patient would not only experience the pain and disability of the ALI, but also the need to negotiate the healthcare system, such as making appointments with physicians, specialists, physiotherapists, etc, finding transportation, often needing someone to accompany them.30–33 Even though the proportion of the population with ALI increased over the years 2000–2006, decreases were seen in the use of primary care and in the hospital ED visits as well as in the hospitalisation. This decrease in healthcare use could be an indication either of greater difficulty in accessing healthcare, or that the nature of ALIs has moderated over the years. Berdahl et al34 found variation by ethnic group and sex, both in the reporting of work-related injuries and in the seeking of medical care and the change in ethnic composition over the years could also be a factor in the NPHS data.34–36 In any case, ALI are suffered by a large proportion of the population annually, and a majority of these seek medical treatment whether it is primary care, ED or hospital care. Clearly, this entails a large cost to the healthcare system and any prevention would not only improve quality of life of the putative victims but also would result in significantly lower healthcare costs.

Another type of impact would be long-term changes after the injury. The ‘before and after’ data available in the NPHS consisted of comparing the cross-sectional data from the interview cycle before the ALI with the data of the cycle reporting the ALI and with the next cycle after the ALI. While the interviews for each respondent could be linked for the ‘before and after’ cycles it was more difficult to determine which changes in attributes in the year of the ALI or subsequent years were sequelae of the ALI. For example, it might make sense that the increasing obesity of people with ALI be linked to after-effects, for example,37 because of inactivity resulting from the ALI but, in fact, similar changes were happening in the overall population. Given these caveats, we can note that no changes were found for smoking and little change in excessive alcohol use. Most likely to show long-term effects because of ALI were visits to medical doctors and ongoing pain. People with ALI showed increasing likelihood of visiting a MD at least five times during the year which continued for the subsequent cycle. Similarly pain increased in the cycle with the ALI and remained high over the years. Although this is weak evidence, it confirms work on long-term effects of other researchers38 ,39 and again emphasises the impact of ALI in the population.

Injuries have been found to lead to loss of productivity, medical costs, compensation costs and long-term health problems and disability,40–42 which were confirmed by the present results for the Canadian population. Many injuries can be prevented and a better understanding of all aspects of injuries will lead to better ways of prevention or the minimising of their effects. However, collaboration and cooperation is needed.43 The European Union has committed itself to reducing number of traffic fatalities from 45 000 to 25 000 by 2010, which as several reports point out, will require strong measures against use of alcohol44–47 and illicit and medicinal drugs before driving.48 A difficulty in injury prevention is the multifaceted aspect of injuries. For example, a fall may have many causes, such as unsafe working conditions or slippery stairs at home. Each of these issues would require different approaches to prevention. Similar diversities are found for most other types of injuries. With all difficulties inherent in devising effective interventions, prevention is still the best approach to lower the tremendous impact of ALI on the Canadian population.

The NPHS data have important strengths, such as its representativeness of the Canadian population and its longitudinal nature. Because of the longitudinal design, it was possible to identify new ALI, meaning no ALI in the previous interview, and compare risk factors before and after the event, as well as its consequences. The ‘before and after’ comparisons of the same person allowed for matched analysis at different times. Important also is the extensive and consistent information available on each respondent over the multiple cycles of the survey, such as type of ALI, and the medical care needed. Besides strengths, the NPHS also has limitations. One issue is the lack of distinction between intentional and unintentional injuries. Another issue is that of self-reported data. Part of self-reporting is recall of events. Recall of having had an ALI has been shown elsewhere to be less accurate with increasing time and is also likely to vary with the severity of the injury.49 ,50 Both of these would likely lead to an under-reporting of ALI. In spite of its limitations the NPHS gives an invaluable view of the level of serious injury in the Canadian adult population over a 12-year time period.

Another strength of these data is the use of ALI as a measurement of injury. There are various units of measurement in measuring rates of injury in a population. The unit of measurement used in the present study consists of the most serious ALI over the previous 12 months, excluding repetitive strains injuries. The use of ALI means the delimitation of a particular kind of injury in the spectrum of injuries as a concept meaningful to both respondent and researchers. In addition, it identifies a type of injury sufficiently severe to impact a person's regular routine.