SIR—Fall-related injuries are a common cause of morbidity and mortality [1, 2]. The number of falls increases with age [3–5] so that 59% of community-dwelling women and 33% of men over 85 fall at least once annually [6–9]. Falls account for 10% of visits to emergency departments [2], where one of the most common injuries is a fracture [10–12]. Muscle strength, balance and functional capacities are traits that have been suggested as predictive factors for falls [13], predominantly evaluated in women and high-risk cohorts [13]. This study therefore evaluated whether physical performance tests and estimates of physical activity could discriminate male fallers from non-fallers.
Methods
The Osteoporotic Fractures in Men (MrOS) Study is a multi-centre study including community-dwelling men aged above 65 years. The subjects had to walk without aid and be without bilateral hip replacements [14]. Ethnicity was defined by the participants. MrOS Hong Kong includes 2,000 Chinese men aged 65–92 with Asian ethnicity. Stratified sampling was adopted to have 33% of subjects in each age groups: 65–69, 70–74 and ≥75 years. MrOS United States includes 5,995 men aged 65–100 from six sites [15, 16]. A total of 5,441 men were Caucasians, 254 Black, 196 Asians, 127 Hispanic, 57 Native American and 15 Pacific Islanders/Hawaiians. MrOS Sweden includes 3,014 men aged 69–81 from three sites [17]. More than 99% were Caucasians. All participants provided written informed consent, and the study was approved by the ethics committee at each site (Malmo, Gothenburg, Uppsala, Hong Kong, Birmingham, Minneapolis, Palo Alto, Monongahela Valley, Portland and San Diego). Height and weight were measured by balance beam or digital scale and Harpenden stadiometer. Body mass index (kg/m2) was calculated as weight divided by height squared. Falls during the preceding 12 months and daily activities were evaluated by a questionnaire, physical activity by the Physical Activity Scale for the Elderly (PASE) [18].
A Jamar® hydraulic hand dynamometer (5030J1), Jackson, MI, USA was used in the grip strength measurement. Two trials of each hand were performed. The better of the two results for each hand was used. The measurement was not performed if the subject had current arthritis or pain in the wrist or hand or had undergone fusion, arthroplasty, tendon repair, synovectomy or related surgery of the upper extremity in the 3 months preceding the measurements (n = 222). A straight-backed chair without arms, with a seat height of 45 cm, was used in the timed stands test. The time to complete five chairs stands (s) without using arms to rise was recorded. In the 6-m walk test and the 20-cm narrow walk test, a walking course was laid out on the floor. In the first test, the participants walked 6-m with their usual pace. The duration of the walk was measured as well as the number of steps. Steps were counted by counting both right and left steps and included the initial starting step and the step that first touched the floor across the finish line. Two-scored trials were performed and the better of the results was used. In the 20-cm narrow walk test, the participants walked the 6-m course within a 20-cm narrow path. Two-scored trials were performed and the performance was scored for time if there were no more than two deviations from the path. In US up to three tests were performed and two successful tests were demanded to be included. This design resulted in 1,049 missing narrow walk tests.
Data are presented as mean with 95% confidence interval (95% CI) or proportions (%). In country comparisons ages 69–81 years were included to achieve comparable country-specific data. Analyses of variance were used to test whether there were differences across the 5-year age groups. Adjustment for country was done by analyses of covariance, if there were country-specific differences. Chi-square test was used to test group differences in proportions between countries and between each 5-year groups with logistic regression. Z-scores were calculated in each individual, based on age, country and measuring site. Odds ratio (OR) was calculated by logistic regression to estimate fall risk in association with Z-score hand grip strength. Area under curve (AUC) was calculated from the receiver operating characteristic curve (ROC). P < 0.01 was regarded as a statistical significant difference.
Results
A total of 2,070 men in MrOS (18.8%) reported a fall during the year preceding the baseline investigation, whereas 8,928 (81.2%) reported no falls. The 1-year fall prevalence rate was highest in USA (21.2%), lower in Sweden (16.5%) and lowest in Hong Kong (15.4%) (P < 0.001).
Fallers in the age group 64–69 were taller and heavier (both P < 0.01) than non-fallers. Fallers scored in general an inferior result than non-fallers in the physical performance tests from age 70 and onwards, in ages from 85 and onwards reaching statistical significant inferior result only in hand grip strength (P < 0.01), Fallers did more daily sitting than non-fallers, reaching significance from 75 years and above (P < 0.01) (Table 1). Level of physical exercise was only different for light exercise in the age group 75–79 years (P < 0.001), similar as for habitual physical activity, see the table Appendix 1 in the Supplementary data available in Age and Ageing online.
Table 1.
Comparison between men with a fall and those with no falls including demographics, anthropometry, physical functional tests, walking, lying and sitting habits during the previous 12 months
| 64–69 years | P-value | 70–74 years | P-value | 75–79 years | P-value | 80–84 years | P-value | 85+ years | P-value | Difference between age groups P-value* | |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Fallers (n) | 402 | 628 | 641 | 298 | 101 | ||||||
| Non-fallers (n) | 2,035 | 3,142 | 2,644 | 902 | 205 | ||||||
| Age (years) | |||||||||||
| Fallers | 67.2 (67.1, 67.4) | 0.45 | 72.2 (72.0, 72.3) | 0.23 | 77.1 (77.0, 77.2) | 0.49 | 81.5 (81.4, 81.7) | 0.02 | 87.5 (86.9, 88.0) | 0.11 | 0.18 |
| Non-fallers | 67.2 (67.1, 67.2) | 72.1 (72.0, 72.1) | 77.0 (77.0, 77.1) | 81.3 (81.2, 81.4) | 87.0 (86.7, 87.3) | ||||||
| Difference fallers/non-fallers | 0.1 (−0.1, 0.2) | 0.1 (−0.1, 0.2) | 0.0 (−0.1, 0.2) | 0.2 (0.0, 0.4) | 0.5 (−0.1, −1.0) | ||||||
| Height (cm) | |||||||||||
| Fallers | 173.7 (172.9, 174.5) | <0.001 | 173.1 (172.5, 173.8) | 0.33 | 172.5 (171.9, 173.1) | 0.35 | 170.9 (170.1, 171.7) | 0.46 | 170.5 (168.9, 172.0) | 0.08 | 0.04 |
| Non-fallers | 172.2 (171.8, 172.6) | 172.8 (172.5, 173.1) | 172.2 (171.9, 172.5) | 171.3 (170.8, 171.7) | 168.8 (167.8, 169.8) | ||||||
| Difference fallers/non-fallers | 1.5 (0.6, 2.4) | 0.3 (−0.3, 1.0) | 0.3 (−0.3, 1.0) | −0.4 (−1.3, 0.6) | 1.7 (−0.2, 3.5) | ||||||
| Weight (kg) | |||||||||||
| Fallers | 82.3 (80.7, 83.9) | 0.006 | 81.3 (80.1, 82.5) | 0.01 | 79.1 (78.0, 80.2) | 0.01 | 76.2 (74.8, 77.6) | 0.91 | 71.9 (69.9, 74.0) | 0.99 | 0.34 |
| Non-fallers | 79.9 (79.2, 80.6) | 79.6 (79.1, 80.1) | 77.5 (77.0, 78.0) | 76.1 (75.3, 77.0) | 72.0 (70.2, 73.7) | ||||||
| Difference fallers/non-fallers | 2.5 (0.7, 4.2) | 1.7 (0.5, 3.0) | 1.6 (0.4, 2.7) | 0.1 (−1.6, 1.7) | 0.0 (−2.9, 2.9) | ||||||
| Body mass index (kg/m2) | |||||||||||
| Fallers | 27.1 (26.7, 27.6) | 0.12 | 27.0 (26.7, 27.3) | 0.01 | 26.5 (26.2, 26.8) | 0.01 | 26.1 (25.6, 26.5) | 0.46 | 24.7 (24.1, 25.3) | 0.27 | 0.44 |
| Non-fallers | 26.7 (26.6, 27.0) | 26.5 (26.4, 26.7) | 26.1 (25.9, 26.2) | 25.9 (25.6, 26.1) | 25.2 (24.7, 25.7) | ||||||
| Difference fallers/non-fallers | 0.4 (−0.1, 0.8) | 0.5 (0.1, 0.8) | 0.4 (0.1, 0.7) | 0.2 (−0.3, 0.7) | −0.4 (−1.3, 0.4) | ||||||
| Right-handgrip strength (kg)** | |||||||||||
| Fallers | 41.1 (40.2, 42.0) | 0.45 | 38.1 (37.4, 38.7) | <0.001 | 35.6 (34.9, 36.2) | <0.001 | 33.0 (32.0, 34.0) | 0.006 | 28.9 (27.5, 30.3) | 0.006 | 0.002 |
| Non-fallers | 40.7 (40.3, 41.1) | 39.9 (39.5, 40.2) | 37.3 (37.0, 37.6) | 34.5 (34.0, 35.1) | 31.3 (30.3, 32.3) | ||||||
| Difference fallers/non-fallers | 0.4 (−0.6, 1.4) | −1.8 (−2.5, −1.0) | −1.8 (−2.5, −1.0) | −1.6 (−2.6, −0.5) | −2.4 (−4.2, −0.6) | ||||||
| Left-handgrip strength (kg) | |||||||||||
| Fallers | 39.1 (38.2, 40.0) | 0.63 | 36.9 (36.2, 37.6) | <0.001 | 34.3 (33.6, 34.9) | <0.001 | 31.6 (30.7, 32.5) | 0.01 | 27.7 (26.5, 28.9) | 0.01 | 0.02 |
| Non-fallers | 38.9 (38.5, 39.3) | 38.2 (37.9, 38.5) | 35.9 (35.6, 36.2) | 32.9 (32.4, 33.4) | 29.7 (28.8, 30.7) | ||||||
| Difference fallers/non-fallers | 0.2 (−0.7, 1.2) | −1.3 (−2.0, −0.6) | −1.7 (−2.4, −0.9) | −1.3 (−2.3, −0.3) | −2.0 (−3.6, −0.4) | ||||||
| Timed stands test (s) | |||||||||||
| Fallers | 11.0 (10.6, 11.4) | 0.11 | 12.4 (12.1, 12.8) | 0.007 | 13.0 (12.7, 13.4) | 0.03 | 13.5 (12.9, 14.2) | 13.8 (12.9, 14.8) | 0.36 | 0.50 | |
| Non-fallers | 10.6 (10.5, 10.8) | 11.9 (11.8, 12.1) | 12.6 (12.4, 12.8) | 12.6 (12.3, 12.9) | 13.3 (12.6, 14.0) | ||||||
| Difference fallers/non-fallers | 0.3 (0.0, 0.7) | 0.5 (0.2, 0.8) | 0.4 (0.1, 0.8) | 0.9 (0.3, 1.5) | 0.01 | 0.5 (−0.7, 1.7) | |||||
| Six meter walking test (s) | |||||||||||
| Fallers | 5.3 (5.1, 5.4) | 0.23 | 5.6 (5.4, 5.7) | <0.001 | 5.8 (5.7, 6.0) | 0.003 | 6.3 (6.0, 6.5) | <0.001 | 7.1 (6.7, 7.5) | 0.05 | 0.12 |
| Non-fallers | 5.2 (5.1, 5.2) | 5.3 (5.2, 5.3) | 5.6 (5.5, 5.7) | 5.8 (5.7, 5.9) | 6.6 (6.3, 6.9) | ||||||
| Difference fallers/non-fallers | 0.1 (0.0, 0.2) | 0.3 (0.2, 0.4) | 0.3 (0.1, 0.4) | 0.4 (0.2, 0.6) | 0.5 (0.0, 1.0) | ||||||
| Steps needed for 6-m walk (n) | |||||||||||
| Fallers | 9.5 (9.3, 9.6) | 0.33 | 9.9 (9.7, 10.1) | <0.001 | 10.3 (10.1, 10.5) | <0.001 | 10.8 (10.6, 11.1) | 0.001 | 12.2 (11.5, 12.8) | 0.08 | 0.008 |
| Non-fallers | 9.4 (9.3, 9.4) | 9.5 (9.4, 9.5) | 9.8 (9.8, 9.9) | 10.3 (10.2, 10.5) | 11.5 (11.2, 11.9) | ||||||
| Difference fallers/non-fallers | 0.1 (−0.1, 0.2) | 0.4 (0.3, 0.6) | 0.4 (0.3, 0.6) | 0.5 (0.2, 0.8) | 0.7 (0.0, 1.3) | ||||||
| Twenty centimetre narrow walk test (s) | |||||||||||
| Fallers | 5.8 (5.7, 6.0) | 0.48 | 6.4 (6.1, 6.6) | <0.001 | 6.5 (6.3, 6.7) | 0.006 | 7.2 (6.8, 7.5) | 0.008 | 9.4 (6.9, 11.9) | 0.32 | <0.001 |
| Non-fallers | 5.9 (5.8, 6.0) | 5.9 (5.8, 6.0) | 6.2 (6.1, 6.3) | 6.7 (6.5, 6.8) | 8.2 (7.6, 8.7) | ||||||
| Difference fallers/non-fallers | −0.1 (−0.3, 0.1) | 0.5 (0.3, 0.7) | 0.3 (0.1, 0.5) | 0.5 (0.1, 0.9) | 1.3 (−0.5, 3.0) | ||||||
| Walk for exercise (km) | |||||||||||
| Fallers | 2.4 (2.1, 2.6) | 0.93 | 2.9 (2.7, 3.1) | 0.04 | 2.6 (2.4, 2.8) | 0.02 | 2.4 (2.1, 2.7) | 0.69 | 1.6 (1.2, 2.0) | 0.22 | 0.63 |
| Non-fallers | 2.4 (2.3, 2.5) | 3.1 (3.0, 3.3) | 2.9 (2.8, 3.0) | 2.4 (2.3, 2.6) | 1.9 (1.6, 2.2) | ||||||
| Difference fallers/non-fallers | 0.0 (−0.3, 0.3) | −0.3 (−0.5, 0.0) | −0.3 (−0.5, 0.0) | −0.1 (−0.4, 0.3) | −0.3 (−0.8, 0.2) | ||||||
| Walk as daily routine (km) | |||||||||||
| Fallers | 2.4 (2.1, 2.6) | 0.93 | 2.9 (2.7, 3.1) | 0.04 | 2.6 (2.4, 2.8) | 0.02 | 2.4 (2.1, 2.7) | 0.69 | 1.6 (1.2, 2.0) | 0.21 | 0.80 |
| Non-fallers | 2.4 (2.3, 2.5) | 3.1 (3.0, 3.3) | 2.9 (2.8, 3.0) | 2.4 (2.3, 2.6) | 1.9 (1.6, 2.2) | ||||||
| Difference fallers/non-fallers | 0.1 (−0.3, 0.3) | −0.3 (−0.5, 0.0) | −0.3 (−0.5, 0.0) | −0.1 (−0.4, 0.3) | −0.3 (−0.8, 0.2) | ||||||
| Daily lying (h) | |||||||||||
| Fallers | 8.1 (8.0, 8.3) | 0.42 | 8.2 (8.1, 8.4) | 0.07 | 8.2 (8.1, 8.4) | 0.73 | 8.5 (8.3, 8.7) | 0.20 | 8.9 (8.5, 9.2) | 0.31 | 0.41 |
| Non-fallers | 8.1 (8.0, 8.1) | 8.1 (8.1, 8.2) | 8.3 (8.2, 8.3) | 8.3 (8.2, 8.5) | 8.6 (8.4, 8.9) | ||||||
| Difference fallers/non-fallers | 0.0 (−0.1, 0.2) | 0.1 (0.0, 0.3) | 0.0 (−0.2, 0.1) | 0.2 (−0.1, 0.4) | 0.2 (−0.2, 0.6) | ||||||
| Daily sitting (h) | |||||||||||
| Fallers | 6.5 (6.2, 6.8) | 0.26 | 6.3 (6.0, 6.5) | 0.02 | 6.5 (6.2, 6.7) | 0.006 | 6.8 (6.4, 7.1) | 0.009 | 7.0 (6.4, 7.5) | 0.01 | 0.29 |
| Non-fallers | 6.3 (6.1, 6.4) | 6.0 (5.9, 6.1) | 6.1 (6.0, 6.2) | 6.2 (6.1, 6.4) | 6.1 (5.7, 6.4) | ||||||
| Difference fallers/non-fallers | 0.2 (−0.1, 0.5) | 0.3 (0.1, 0.5) | 0.3 (0.1, 0.6) | 0.5 (0.2, 0.9) | 0.9 (0.2, 1.6) | ||||||
Data are presented as mean (95% CI) and mean difference (95% CI) with P-values for the difference for each age group, except where otherwise stated.
*ANOVA test for differences between fallers and no fallers across the age groups.
**Significant difference was found between countries for grip strength, so data are adjusted for country.
Scoring below –2 SD in left hand grip strength test was associated with an OR of 2.0 (95% CI: 1.5–2.7) for having sustained a fall while scoring between +1 and +2 SD was associated with an OR of 0.9 (95% CI: 0.7–1.0) (Table 2). The ROC curves revealed that even if the physical performance tests discriminated fallers and non-fallers, the discriminative ability for a specific individual was low, with AUC ranging between 0.53 and 0.55 (95% CI ranging from 0.52 to 0.57 in the different tests, respectively).
Table 2.
Odds ratios (OR) by a change in hand grip strength by one Z-score, calculated within each country based on age and measuring site
| Z-scores | >+2 | +2 to +1 | +1 to −1 (reference group) | −1 to −2 | −<2 |
|---|---|---|---|---|---|
| MrOs International | |||||
| Right-hand grip strength | 0.72 (0.50, 1.05) | 0.84 (0.72, 0.98) | 1.0 | 1.27 (1.10, 1.46) | 1.65 (1.25, 2.18) |
| Left-hand grip strength | 1.04 (0.76, 1.43) | 0.86 (0.73, 1.00) | 1.0 | 1.36 (1.19, 1.57) | 2.02 (1.54, 2.66) |
| MrOs Hong Kong | |||||
| Right-hand grip strength | 1.11 (0.38, 3.28) | 1.00 (0.67, 1.50) | 1.0 | 1.09 (0.73, 1.63) | 0.89 (0.31, 2.58) |
| Left-hand grip strength | 1.62 (0.69, 3.81) | 0.91 (0.58, 1.42) | 1.0 | 0.92 (0.61, 1.40) | 2.09 (0.80, 5.38) |
| MrOs United States | |||||
| Right-hand grip strength | 0.75 (0.48, 1.16) | 0.84 (0.69, 1.02) | 1.0 | 1.15 (0.96, 1.38) | 1.42 (0.99, 2.02) |
| Left-hand grip strength | 1.02 (0.69, 1.52) | 0.79 (0.65, 0.97) | 1.0 | 1.34 (1.12, 1.59) | 1.79 (1.26, 2.55) |
| MrOs Sweden | |||||
| Right-hand grip strength | 0.48 (0.21, 1.11) | 0.68 (0.47, 0.94) | 1.0 | 1.58 (1.20, 2.06) | 2.50 (1.50, 4.15) |
| Left-hand grip strength | 0.77 (0.38, 1.57) | 0.90 (0.65, 1.24) | 1.0 | 1.59 (1.21, 2.09) | 2.40 (1.46, 3.92) |
For MrOS International ages 64–100 years were included and for the country-specific evaluation ages 69–80 years as to achieve comparable cohorts. Data presented as OR with 95% confidence interval (95% CI) within brackets.
The fallers versus non-fallers differences in age, height, weight or BMI were no different in the three countries. There were a group differences in most tests between fallers and non-fallers in the USA and Sweden (all P < 0.001) but not in Hong Kong, see the table Appendix 2 in the Supplementary data available in Age and Ageing online. The daily walking distance in Sweden was greater in non-fallers than in fallers (P < 0.01) and the daily duration of sitting in USA and Sweden was longer in fallers than in non-fallers (both P < 0.01) (Appendix 3; Supplementary data are available in Age and Ageing online) while there were no differences in physical training or habitual physical activity, see the table Appendix 3 in the Supplementary data available in Age and Ageing online.
Discussion
This study supports that there is a group difference when comparing tests of physical ability in fallers and non-fallers in ages from 70 years and above (Table 1). Given the known problems with accuracy of recall of falls in the past, it is likely that the numbers of falls recorded is if anything was underestimated. It is also possible that the lower performance rate may be the result of a previous fall. But the outcome of this study could probably be generalised based on the sampling procedure, the sample size, even if the racial mix in the USA does not match the apparent nominal mix as described by the US Census Bureau, reporting an overall proportion for 2009 for black persons of 12.9%, and the fact that the trial supports publications of a annual fall incidence of 22–29% in elderly men [18–22], The slightly lower fall prevalence reported in MrOs could depend on differences in ethnic proportions and ages compared with cited studies. MrOs also included men who voluntarily agreed to participate in extensive measurements maybe excluding the frailest. The high attendance rate in MrOs [17] may also better reflect the proportion of fallers than studies with lower attendance rate [18–22] and a 12-month recall period may better reflect the fall prevalence than longer recall periods. Also, a retrospective design as in this and other studies [20] may lead to different inferences compared with prospective studies [18, 19, 21, 22].
The fallers aged 70 or above performed inferior in the performance tests than non-fallers, in ages above 85 only in grip strength tests. The same pattern is seen separately in the USA and Sweden but not in Hong Kong (Appendices 2 and 3 are available as Supplementary data in Age and Ageing online). The association of gradually higher fall prevalence with a lower grip strength test (Table 2) strengthens the view that there is an association between the test and fall risk. However, the ROC analyses indicate that we could not discriminate the different tests from each other. The calculations and the form of the curves also indicate that there is no clear cut-off point so that the test could in a large extent result in both false positive results, leading to a significant degree waste of fall prevention resources, but also false negative results, leading to significant morbidity following falls in subjects who were not believed to be at risk. That is, the tests should predominantly be used in epidemiological studies to identify groups with high fall prevalence but decisions about fall prevention for an individual based on the tests must be questioned.
In conclusion, this study indicates that there in the USA and Sweden are group differences in physical performance tests when comparing fallers and non-fallers in individuals aged 70 or above, above 85 only in grip strength tests.
Key points.
The prevalence of fallers differed across countries.
There is a group difference in physical performance tests when comparing fallers and non-fallers in the USA and Sweden but not in Hong Kong.
Differences in physical function across countries did not explain the international variation in fall prevalence.
Conflicts of interest
None declared.
Funding
The Osteoporotic Fractures in Men (MrOS) Study is supported by National Institutes of Health funding. The following institutes provide support: the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIA MS), the National Institute on Aging (NIA), the National Center for Research Resources (NCRR), and NIH Roadmap for Medical Research under the following grant numbers: U01 AR45580, U01 AR45614, U01 AR45632, U01 AR45647, U01 AR45654, U01 AR45583, U01 AG18197, U01-AG027810, and UL1 RR024140. In Sweden the MrOs Study is supported by The Swedish Research Council, The Center for Athletic Research, The Påhlsson Foundation, The Kock Foundation and The Malmö University Hospital Foundations. None of the supporters participated in the design, conduct of the study, collection of data, management, analyses, interpretations of data, preparation of the manuscript, review or approval of the manuscript.
Supplementary data
Supplementary data mentioned in the text is available to subscribers in Age and Ageing online.
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