Time Trends in Severe Head Injuries Among Elderly Finns

To the Editor: A great majority of fatal head injuries in elderly people are related to falls.^{1 - 2} Previously we reported that the number of Finns aged 60 years or older who were admitted to hospitals due to a fall-induced head injury rose during 1970-1995.³ We have now followed up the population aged 80 years or older for 4 more years to assess whether the number of head injuries is increasing more rapidly than can be accounted for by demographic changes alone, by calculating the age-adjusted and age-specific incidence of injury per 100 000 persons aged 80 years or older between 1970 and 1999. For data validation and comparison, the age-adjusted incidences of hip fracture were also calculated for this population.

We obtained data on fall-induced severe head injuries from the Finnish National Hospital Discharge Register. This statutory, computer-based register is the oldest nationwide discharge register in the world (in operation since 1967), and provides reliable data for severe injuries of the Finnish population of 5 million people.^{2 - 5}

Throughout the study years, a fall-induced severe head injury of a person 80 years of age or older was defined as a head injury that occurred as a consequence of a fall from standing height of 1 m or less and that resulted in hospitalization. Injuries caused by vehicular trauma were excluded, as were other high-energy traumas. In calculating the age-adjusted injury incidences, the age adjustment was done by means of direct standardization using the mean population of persons aged 80 years or older between 1970 and 1999 as the standard population. The age-specific incidences were calculated in 5-year age groups (80-84, 85-89, and ≥90 years).

The total number of Finns aged 80 years or older with a fall-induced severe head injury increased considerably during the study, from 60 women and 25 men in 1970 to 619 women and 222 men in 1999. The relative increases were 932% and 788%, respectively. Across the study period, the age-adjusted incidence of injury (per 100 000 persons aged 80 years or older) was similar in both sexes but showed a clear increase from 1970 to 1999: from 169 to 478 in women (183% increase), and from 170 to 467 in men (175% increase) (Figure 1). A similar finding was observed in age-specific incidences. In women, the mean injury incidence rate (per 100 000 persons) in the period 1970 through 1974 were 176, 194, and 263 in the age groups of 80-84, 85-89, and 90 years or older, respectively, vs 394, 529, and 566 in the period 1995 through 1999. In men, these incidence rates in the period 1970 through 1974 were 164, 143, and 281, vs 436, 546, and 706 in the period 1995 through 1999.

The hip fracture data mirrored the head injury data. In women, the age-adjusted incidence of hip fracture (per 100 000 persons aged 80 years or older) was 1445 in 1970, compared with 2406 in 1999; in men, these incidences were 682 and 1458, respectively.

This study shows that the rates of both raw and age-adjusted fall-induced severe head injuries of persons aged 80 years or older increased dramatically during the study period. These data corroborate previous observations on the development of fall-related injuries in elderly people^{1 - 3 ,6} but cannot reveal the exact reasons for the increase in the age-adjusted or age-specific incidence of injury. It has been suggested that an increase in the average risk of falling may partly explain the phenomenon, or that elderly people now have more serious consequences of falling than their predecessors.^{1 - 3} In other words, on average, elderly persons may now be less healthy and functionally less capable than in the past. The number of fall-induced severe head injuries among Finns aged 80 years or older shows a rise with a rate that cannot be explained merely by demographic changes, and a better understanding of this phenomenon is needed.