Prediction of Hip Fracture in Prediction of Hip Fracture in Elderly Elderly

Men and Women by Fall-related Men and Women by Fall-related Factors Factors

ND Nguyen, C Pongchaiyakul, JR Center, JA Eisman, TV Nguyen

Bone and Mineral Research Program Garvan Institute of Medical Research

Background• Various risk factors for hip fracture, including low

bone mineral density (BMD), have been identified in women, the situation in men remained unknown.

• Hip fracture is largely resulted from a fall.• It is not known whether fall-related factors (muscle

strength, postural instability) predict hip fracture.

Aims

• To assess the predictiveness and association between fall-related factors and hip fracture in elderly men and women

Study Design and MethodsStudy design

Longitudinal population-based epidemiological study

Setting Dubbo city, Australia

Participants960 women and 689 men aged 60+ (as at 1989) of Caucasian background

Outcome measure Incidence of hip fracture: ascertained by X-ray report

Risk factors– Femoral neck BMD: by DEXA– Postural sway: by sway-meter – Quadriceps strength: maximum isometric contraction

A non-fracture case A hip fracture case

Postural sway test by the swaymeter

Data analysis• Incidence of hip fracture was expressed per 1000

person-years assuming a the Poisson distribution.• Cox’s proportional hazards model was used to estimate

relative risk (RR)• Individual risk factors were dichotomized into presence

or absence. A combined risk score was derived as the sum of all individual risk factors for each individual.

ResultsWomen

Men

Rat

es o

f Hip

Fra

ctur

e (p

er 1

000

pers

on-y

ears

)

0

2

4

6

8

10

12

14

16

18

20

Women Men

• Duration of follow-up: 12 y (6, 13) • 115 (86 F, 29M) hip fractures were ascertained

Results

Incidence of hip fracture per 1000 person-yrs

* mean ± SD; ‡ n (%); † median (Q1, Q3); a significant difference between hip fracture and no fracture at P<0.001 for both sexes

Women MenHip fractures No fractures Hip fractures No fractures(n=86) (n=874) (n=29) (n=660)

Age (y)* a 78.0 ± 7.7 70.3 ± 7.4 77.9 ± 7.5 69.8 ± 6.1Height (cm)* a 155.5 ± 6.6 160.0 ± 6.2 169.5 ± 7.5 173.6 ±6.9Weight (kg)* a 55.4 ± 11.0 66.2 ± 12.4 72.0 ± 14.2 78.9 ± 2.4BMI (kg/m2)* a 23 ± 4 26 ± 5 25 ± 4 26 ± 4FNBMD (g/cm2)* a 0.64 ± 0.10 0.80 ± 0.13 0.73 ± 0.17 0.93 ± 0.15Prior fracture (yes)‡ a 18 (20.9) 85 (9.7) 9 (31.0) 39 (4.7)Fall in the last 12 mo‡ a 55 (64.0) 407 (34.0) 13 (44.0) 191 (24. 0)Body sway (mm2)† a 2208 (1010,14840) 1128 (714,1972) 3355 (1066,21700) 1036 (63,1760)Quadriceps strength (kg)† a 14 (10, 18) 20 (14, 25) 24 (14, 30) 34 (26, 44)

Calcium intake (mg/d)† 528 (369, 791) 564 (408, 793) 483 (333, 783) 596 (412, 804)Menarche age (y)† a 14 (13, 15) 13 (12, 14)Menopause age (y)† 48 (41, 51) 48 (3, 51)

Table 1: Baseline characteristics of participants as at 1989

Risk factors for hip fracture after adjustment for FNBMD and sex

0 1 2 3 4 5 6 7 8 9 10

Quadriceps strength (Q1 vs others, kg)

Postural sway (Q4 vs others, mm2)

Fall in the previous year

Prior fracture

Age (+ 5y)

Risk factors:

Relative risk

Femoral neck BMD (-0.12 g/cm2)

Incidence of hip fracture by FNBMD (T-scores) and number of risk factors

0

10

20

30

40

50

60

Rat

e of

Hip

frac

ture

(per

100

0 pe

rson

-yea

rs)

Numbe

r of r

isk sc

ore

FNBMD (T-score)

3

2

1

> -1.0-2.4 to -1.1

< -2.5

50.2

32.7

6.6

11.4

4.5

1.1

0.3

0.0

3.2

Conclusions• Falls and fall-related factors were important

predictors of hip fracture in women and men.

• Individuals with multiple risk factors with or without low BMD had the highest risk of hip fracture.

• Women and men had common risk factors for hip fracture.