Hip
fractures are the most common fractures requiring surgical treatment
among adults. The highest incidences of hip fractures around the world
have been observed in Northern Europe and the USA [1].
The age-standardized incidence of hip fractures in women is roughly
twice as high as that in men, with some variability across the world [1]. In recent decades, the age-adjusted incidence of hip fractures has continuously decreased in high-incidence countries [2, 3].
According to a recent report from the four-decade Framingham Heart
Study with 10,552 participants, the main reason for the observed
decrease in hip fractures was a reduction in smoking and heavy drinking,
which were important risk factors for fractures [4]. However, due to the increased number of hip fractures in developing countries [1],
the worldwide overall annual number of hip fractures is still rising.
It has been estimated that, by the year 2050, a staggering 6.3 million
hip fractures worldwide will occur annually [5].
Several
studies have reported that mortality among elderly hip fracture
patients is higher than that of the age-adjusted general population and
also higher among males than females [6, 7]. The mortality is increased during the first postoperative year, and it remains high for the following years [8].
Hip fractures are associated with increased short-term and long-term
mortality. The post-hip-fracture mortality is 7–8% at 30 days [9, 10], 16–24% at 1 year [11, 12], 32–56% at 5 years [13, 14], and 80% at 10 years [15]. Reports evaluating survival beyond 10 years are scarce [16, 17].
The
reasons for the increased mortality and morbidity in low-energy hip
fracture patients entail several pre-fracture conditions: older age,
male sex, pre-fracture comorbidities, poor preoperative walking capacity
and activities of daily living, fracture type, low body mass index
(BMI), high ASA class, and non-multidisciplinary postoperative
rehabilitation [8, 10, 11, 18]. Alcohol consumption is associated with higher hip fracture risk and postoperative complications [4, 15].
The
aim of this study was to identify patient-specific factors affecting
postoperative short- and long-term survival, to study the survival in
relation to the mortality in the reference population, and to analyze
the mortality of the patients over a period of 14 years.
Methods:
The study was approved by the local ethics committee. We retrospectively analyzed all patients with a hip fracture (n = 506)
requiring operative treatment at Päijät-Häme Central Hospital in
Southern Finland (61° N) from January 1, 2005, to December 6, 2006
(Supplementary Fig. 1).
The exclusion criteria were a pathological fracture, age under
18 years, non-operative treatment, and an undefined time of the fracture
(Supplementary Fig. 1). The data were collected from electronic medical records.
All
hip fracture patients had a low-energy fracture as a result of
slipping, tripping, or falling from standing height or lower, as
documented in the medical records. Fractures caused by high-energy
injuries were excluded.
A low-energy hip fracture was identified as one of the following
diagnosis codes: femoral neck fractures (S72.0), pertrochanteric
fractures (S72.1), or subtrochanteric fractures (S72.2). Adult patients
with new low-energy hip fractures who underwent one of the following
procedures were analyzed: NFB10 (uncemented hemiarthroplasty); NFB20
(cemented hemiarthroplasty); NFJ50 (osteosynthesis of the neck with
cannulated screws); NFJ52 (osteosynthesis of the proximal femur with a
DHS or Medoff plate); NFJ54 (osteosynthesis with an intramedullary
nail); NFJ64 (osteosynthesis with additional screws or wires); NFB30
(uncemented primary total hip arthroplasty); NFB40 (hybrid total
arthroplasty); or NFB50 (cemented primary total hip arthroplasty). The
surgical procedure codes were collected according to the Nordic
Medico-Statistical Committee’s classification of surgical procedures
(NOMESCO). The medical records of all patients were checked manually
(R.T.).
The baseline characteristics of patients are shown in Table 1.
Patient-specific variables included the patient’s personal ID number,
sex, age, date of injury, American Society of Anesthesiologists (ASA)
class [19], body mass index (BMI; kg/m2),
selected comorbidities, fracture type, date of operation, type of
operation and implant, date of discharge, and death. BMI was divided
into four groups: < 20, 20–24.9, 25–29.9, and > 30 kg/m2.
Pre-existing selected comorbidities increasing the risk of falling were
identified from the medical records individually (alcohol involvement
[AI], Alzheimer’s disease, dementia, stroke, Parkinson’s disease,
previous intracranial hemorrhages [ICH], transient ischemic attack
[TIA], and severe psychiatric diseases with ongoing medication [e.g.,
schizophrenia]).
..Fracture classification
The
type of hip fracture was analyzed from the preoperative radiographs by
the study group (RT, JPK). The fractures were classified as femoral neck
fractures (S72.0), pertrochanteric fractures (S72.1), and
subtrochanteric fractures (S72.2). Femoral neck fractures were further
classified according to the Garden classification [20]. The type of trochanteric (S72.1) and subtrochanteric (S72.2) hip fractures was graded according to the AO classification [21]. We also evaluated the number of basicervical hip fractures [22].
Basicervical fractures were classified as pertrochanteric fractures
(S72.1). One radiograph in group S72.1 and 8 radiographs in group S72.2
were missing for AO classification (Supplementary Table 1).
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In a Swedish retrospective registry-based cohort study (n = 1493) regarding 1-year mortality, results similar to our present study were found [10].
Mortality was significantly associated with age, male sex, and ASA
class 3–5, but the type of fracture or operation method did not affect
the mortality estimates [10]. Different results have also been reported. A recent Finnish prospective study on home-dwelling hip fracture patients (n = 538) showed no sex-related differences in mortality at 4 and 12 months postoperatively [27]. Furthermore, one opposite result had been published—in an earlier prospective study (n = 106)
from Finland, the 1-year mortality was higher in women than in men (34%
vs 28%), although the difference was not significant [28].
Furthermore, a Norwegian study (n = 942,
mean age 81.2 years) reported that the elevated mortality at 1 year and
5 years postoperatively was significantly associated with male sex and
age over 80 years [7]. The overall mortality after the first year was 21% and after 5 years 59% [7]. In the present study (mean age 79 (SD 12.1 years), the corresponding results were similar, 22% and 57%, respectively.
A Danish national register study [17]
showed that the postoperative mortality after hip fractures varied
between 2000 and 2013 but did not decline. The mortality rate was 10% at
30 days, 16% at 90 days, and 27% at 1 year [17]. In Denmark, the median length of the postoperative acute hospital stay in 2014 (8 days) [17] was similar to that of our study (9 days).
