Nationwide Decline in Incidence of Hip Fracture

Authors

  • Pekka Kannus MD, PhD,

    Corresponding author
    1. Injury and Osteoporosis Research Center, UKK Institute for Health Promotion Research, Tampere, Finland
    2. Medical School, University of Tampere, and Division of Orthopaedics and Traumatology, Department of Trauma, Musculoskeletal Surgery and Rehabilitation, Tampere University Hospital, Tampere, Finland
    • UKK Institute, PO Box 30, FIN-33501 Tampere, Finland
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  • Seppo Niemi,

    1. Injury and Osteoporosis Research Center, UKK Institute for Health Promotion Research, Tampere, Finland
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  • Jari Parkkari,

    1. Tampere Research Center of Sports Medicine, UKK Institute for Health Promotion Research, Tampere, Finland
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  • Mika Palvanen,

    1. Injury and Osteoporosis Research Center, UKK Institute for Health Promotion Research, Tampere, Finland
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  • Ilkka Vuori,

    1. Injury and Osteoporosis Research Center, UKK Institute for Health Promotion Research, Tampere, Finland
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  • Markku Järvinen

    1. Medical School, University of Tampere, and Division of Orthopaedics and Traumatology, Department of Trauma, Musculoskeletal Surgery and Rehabilitation, Tampere University Hospital, Tampere, Finland
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  • The authors state that they have no conflicts of interest.

Abstract

This epidemiologic study determined the trend in the number and incidence (per 100,000 persons) of hip fracture among older adults in Finland, an EU country with a well-defined white population of 5.2 million, between 1970 and 2004. The results show that the alarming rise in the fracture incidence from early 1970s until late 1990s has been now followed by declining fracture rates. Reasons for this are largely unknown, but a cohort effect toward a healthier aging population and increased average body weight and improved functional ability among elderly Finns could partly explain the phenomenon.

Introduction: Although osteoporotic fractures of older adults are said to be a major public health concern in modern societies with aging populations, fresh nationwide information on their secular trends is limited.

Materials and Methods: This epidemiologic study determined the current trend in the number and incidence (per 100,000 persons) of hip fracture among older adults in Finland, an EU country with a well-defined white population of 5.2 million, by taking into account all persons ≥50 years of age who were admitted to our hospitals for primary treatment of such fracture in 1970–2004.

Results: The number of hip fractures among ≥50-year-old Finns rose very constantly between 1970 (1857 fractures) and 1997 (7122 fractures), but since then, the rise has leveled off (7083 fractures in 2004). After this and because of a continuous rise in population at risk, the crude incidence of hip fracture (showing a clear rise in 1970–1997) decreased between 1997 and 2004, from 438 (per 100,000 persons) in 1997 to 374 in 2004. Concerning the age-adjusted fracture incidence, findings were similar. Until 1997, the age-adjusted incidence of hip fracture clearly increased in both women and men, but thereafter, this incidence declined in both sexes: in women, from 494 in 1997 to 412 in 2004, and in men, from 238 in 1997 to 223 in 2004.

Conclusions: The rise in the incidence of hip fracture in Finland from the early 1970s until the late 1990s has been followed by declining fracture rates. Exact reasons for this are unknown, but a cohort effect toward a healthier aging population and increased average body weight and improved functional ability among elderly Finns cannot be ruled out.

INTRODUCTION

Hip fractures in elderly people are a worldwide concern, and aging populations are increasing the burden of these fractures on our health care systems.(1,2 Hip fractures are a problem, not only economically, but especially on the health and well being of elderly people, because hip fractures represent one of the most important causes of long-standing pain, functional impairment, disability, and death in this population. In addition, a hip fracture, or even a mere fear of fracture consequences, can cause significant mental suffering and psychological burden to these people.(3

It seems to be generally agreed that the number of hip fractures is rising in many countries in conjunction with aging of the population.(1,2 However, very important for the prediction of the true increases in the number of patients requiring treatment for hip fracture during the coming decades is the exact knowledge whether the number of fractures is rising more rapidly than can be accounted for by demographic changes alone.

Previously we reported that the number and age-adjusted incidence of hip fracture among Finns ≥50 years of age sharply rose between 1970 and 1997.(1 We have now followed the population another 7 years (to the end of 2004) and want to bring into immediate attention some interesting news: the alarming rise in fracture incidence has leveled off.

MATERIALS AND METHODS

As previously stated,(1 the data of the hip fractures originate 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 reportedly reliable data for severe injuries in Finland, a country with a well-defined white population of 5.2 million people.(1,4,5 To calculate the incidence rates of fracture, annual midyear populations were taken from The Official Statistics of Finland, the statutory, computer-based population register of the country.(6

Hip fractures were recorded by assessing primary and secondary diagnoses with the code-class 820 of the International Classification of Diseases versions 8 (ICD-8; 1970–1986) and 9 (ICD-9; 1987–1995) and the code class S72 of the ICD-10 (1996–2004) for identification of proximal femur fractures.(1 Incidence rates of hip fracture were calculated for both sexes and were expressed as the number of cases per 100,000 ≥50-year-old persons per year. In calculation of the age-adjusted fracture rates, age adjustment was done by direct standardization using the mean population between 1970 and 2004 as the standard population.

The hip fracture data were drawn from the entire ≥50-year-old population of Finland, which was 1,137,945 in 1970 and 1,896,056 in 2004. The given absolute numbers and incidence rates of hip fractures were thus not cohort-based estimates but complete population results, and therefore, the study, in full agreement with previous studies,(1,7 did not use statistical analyses with CIs characteristically needed in cohort or sample-based estimations.

RESULTS

The number of hip fracture among ≥50-year-old or older Finns rose considerably between 1970 and 1997, but since then, the rise has leveled off (Fig. 1A). After this development and because of a continuous rise in population at risk, the crude incidence of hip fracture decreased in Finland between 1997 and 2004 (Fig. 1A). Concerning the age-adjusted fracture incidence, findings were similar. Until 1997, the age-adjusted incidence of hip fracture clearly rose in both women and men, whereas thereafter, the incidence declined in both sexes (Fig. 1B). The decline was especially clear in women.

Figure Figure 1.

Hip fractures in Finland in people ≥50 years of age between 1970 and 2004. (A) Number and crude incidence (per 100,000 persons). (B) Age-adjusted incidence (per 100,000 persons). The latest year of the original report or 1997(1 is indicated with a dotted vertical line.

If the age-adjusted incidence of hip fracture continues to rise at the average rate observed in 1970–2004 and the size of the ≥50-year-old population of Finland increases as predicted (from 1.90 million in 2004 to 2.38 million in 2030),(8 the number of hip fractures in this population will be −3-fold higher in 2030 (21,000 fractures) than in 2004 (7100 fractures). If, however, the incidence of fractures were to become stabilized to the 2004 level, the number of hip fractures in Finland would be −12,600 in 2030.

DISCUSSION

This fresh epidemiologic study shows that the rise in the incidence of hip fractures in Finland from the early 1970s to the late 1990s has been followed by declining fracture rates. In other words, Finland has now faced a clear change in the secular trend of older adults' hip fractures.

Our long-term statistics, which are the very first full-scale nationwide data available from 1970–2004, are in line with smaller short-term reports from Scandinavia comparing rates of hip fractures from some years of 1980s to corresponding years of 1990s.(9,10 Interestingly, for an unknown reason, the decline in the fracture rates seems to have occurred several years later in Finland than in these Swedish(9 and Norwegian reports.(10 Recently, two small studies from Denmark and a short-term follow-up from Ontario, Canada, have also suggested that the decline in the incidence of hip fracture has started not until the later part of the 1990s.(11–13

The exact reasons for the secular change in the risk of hip fracture are unknown. A cohort effect toward healthier elderly populations in the developed countries cannot be ruled out: in earlier birth cohorts, the early-life risk factors for fracture, such as perinatal nutrition, may have had stronger impact on the late-life fracture risk than in the others.(2 A second reason could be the risen average body weight and body mass index (BMI): in all adult age groups of our population, the prevalence of obesity has increased since the 1980s.(14 A low BMI is a strong risk factor of hip fracture, and it has been estimated that a one unit increase in the BMI of a population could result in an −7% decrease in the fracture incidence, the effect being greatest with gain in weight among the thinnest older adults.(15,16

A third reason for the observed decline in the age-adjusted incidence of hip fracture could be improved functional ability in the elderly Finnish population in the 1990s.(17 Poor neuromuscular function is a strong risk factor for hip fracture and any improvement in this predictor is likely to reduce the risk of falling and fractures.(15,16

A fourth explanation could arise from more specific actions to prevent and treat osteoporosis: nonsmoking campaigns, exercise, calcium, vitamin D, hormone replacement therapy, and bone-specific drugs may have started to improve bone mass and strength during the decade of the 1990s.(13,18 However, care must be taken when considering these factors as potential explanation for the declining risk of hip fracture, because there is neither clear signs nor good evidence for their secular change in Finland or the factor was yet so uncommon in our elderly population in 1990s that its role must have been minor in explaining the decreased fracture incidence.

Finally, effects of recent programs and interventions to prevent falling and minimize fall severity by strength and balance training, vitamin D and calcium supplementation, reduction in psychotropic medication, correction of visual impairment, modification of environmental hazards, and use of hip protectors and gait-stabilizing devices cannot be completely ruled out when discussing the reasons for the declining rates of hip fractures.(19–24 However, the same limitations apply here as noted above for osteoporosis and its potential modifiers.

Only the coming years will show whether the above noted favorable trend in the incidence of hip fracture continues. However, because the rapid and continuous aging of the population is likely to increase the absolute number of hip fractures in the future, effective fracture-preventing measures and strategies are needed to control the development.

Acknowledgements

This study was funded by the Medical Research Fund of Tampere University Hospital, Tampere, Finland, the Juho Vainio Foundation, the Paulo Foundation, and the Finnish Ministry of Social Affairs and Health, Helsinki, Finland.

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