Trends in Unintentional Fall-Related Traumatic Brain Injury Death Rates in Older Adults in the United States,1980

Abstract

Unintentional fall-related traumatic brain injury (TBI) death rate is high in older adults in the United States, but little is known regarding trends of these death rates. We sought to examine unintentional fall-related TBI death rates by age and sex in older adults from 1980 through 2010 in the United States. We used multiple-cause mortality data from 1980 through 2010 (31 years of data) to identify fall-related TBI deaths. Using a joinpoint regression program, we determined the joinpoints (years at which trends change significantly) and annual percentage changes (APCs) in mortality trends. The fall-related TBI death rates (deaths per 100,000 population) in older adults ages 65–74, 75–84, and 85 years and above were 2.7, 9.2, and 21.5 for females and 8.5, 18.2, and 40.8 for males, respectively, in 1980. The rate was about the same in 1992, yet increased markedly to 5.9, 23.4, and 68.9 for females and 11.6, 41.2, and 112.4 for males, respectively, in 2010. For males all 65 years years of age and above, we found the first joinpoint in 1992, when the APC for 1980 through 1992, –0.8%, changed to 6.2% for 1992–2005. The second joinpoint occurred in 2005, when the APC decreased to 3.7% for 2005–2010. For all females 65 years of age and above, the first joinpoint was in 1993 when the APC for 1980 through 1993, –0.2%, changed to 7.6% from 1993 to 2005. The second joinpoint occurred in 2005 when the APC decreased to 3.8% for 2005–2010. This descriptive epidemiological study suggests increasing fall-related TBI death rates from 1992 to 2005 and then a slowdown of increasing trends between 2005 and 2010. Continued monitoring of fall-related TBI death rate trends is needed to determine the burden of this public health problem among older adults in the United States.

Introduction

Traumatic brain injury (TBI) death is an important public health problem that can be caused by various external causes of injury, such as motor vehicle crashes, falls, firearms, being struck by objects, and so on. The main external cause of injury resulting in TBI deaths differs by age group.^1

–7 According to the most recent surveillance data in the United States, motor vehicle-related TBI death rates were highest among people ages 15–24 years (12 per 100,000 population) and fall-related TBI death rates were highest among adults≥75 years (30 per 100,000 population) for years 1997–2007.⁸ A cross-sectional study indicated that the fall-related TBI death rates (deaths per 100,000 population) for people ages 65–69, 75–79, and 85–89 years were 8, 26, and 80 for males and 4, 14, and 43 for females, respectively, in 2005.⁹ However, little is known about the temporal trends in fall-related TBI death rates among older adults in the United States. An early study revealed that fall-related TBI death rates increased from 19 in 1989 to 31 in 1998 in older adults 80 years of age and above.¹⁰ To update information on the current trends by sex and age group, we examined fall-related TBI death rates in older adults from 1980 through 2010 in the United States.

Methods

Data source

We analyzed the Multiple-Cause Mortality Files compiled by the National Center for Health Statistics of the United States for years 1980 through 2010 (31 years of data).¹¹ Multiple-cause mortality data are advantageous over traditional underlying cause of death mortality data, which include only the information on external cause of injury (i.e., motor vehicle crashes, falls, drowning, and so on) without information on nature of injury (i.e., TBI, hip fracture, strain, and so on). Only through the multiple-cause mortality data, which include up to 20 diagnoses reported on the death certificate, could we obtain information on both external cause of injury and nature of injury to define fall-related TBI death.

There are two formats for the coding of multiple conditions in the multiple-cause mortality data: the entity-axis format and the record-axis format. The entity-axis format records not only International Classification of Diseases (ICD) codes, but also information on the exact position of the condition reported by the certifier on the death certificate. The record-axis format records the ICD codes after automated coding, which deletes duplicate codes and combines entities where appropriate. We used entity axis records to identify fall-related TBI death.

Measurement and analysis

We followed Thomas and colleagues' operational definition of fall-related TBI death,⁹ that is, a death in which a fall was assigned as the underlying cause of death and included mention of TBI on the death certificate. The ICD-9 and -10 codes (International Classification of Diseases, Ninth and Tenth Revision) for TBI were based on the study of Coronado and colleagues.⁸ The ICD-9 codes for TBI were 800–804, 850–854, 905.0, 907.0, and 873. The ICD-10 codes for TBI are S01.0–S01.9, S02.0, S02.1, S02.3, S02.7–S02.9, S04.0, S06.0–S06.9, S07.0, S07.1, S07.8, S07.9, S09.7–S09.9, T01.0, T02.0, T04.0, T06.0, T90.1, T90.2, T90.4, T90.5, T90.8, and T90.9. The ICD-9 codes for falls are E880–E886 and E888. The ICD-10 codes for falls are W00–W19. The ICD-9 classification scheme was used for years 1980 through 1998, and the ICD-10 classification scheme was used for years 1999 through 2010.

We first calculated fall-related TBI death rates by sex and age groups (65–74, 75–84, and 85 years and above). The denominator of death rate, that is, the population for each sex-age group in each year were obtained from “Population Data Dictionary 1969–2011” maintained by the National Cancer Institute (http://seer.cancer.gov/popdata). For trends analysis, we used the age structure of the year 2000 as the standard to compute age-adjusted death rates for valid comparisons of death rates across years.

Trends in fall-related TBI death rates were evaluated using joinpoint regression analysis (Joinpoint Regression Program, Version 4.0.4, May 2013; Statistical Methodology and Applications Branch, Surveillance Research Program, National Cancer Institute).¹² Joinpoint regression was fitted to estimate average annual percent changes (APCs) and identify joinpoints at which significant changes in trends occurred. A maximum of three joinpoints was allowed for each estimation and for each segment APC was computed using a log-linear model. In addition, 95% confidence intervals (CIs) were calculated for each estimate of APC and were used to determine whether the APC for each segment differed significantly from zero.

This study was exempted of review by the institution review board of the National Cheng Kung University Hospital (Tainan, Taiwan) because the data were obtained from a publicly available source.

Results

In 1980, only 1380 males (15.8 deaths per 100,000 population) and 1028 females (7.3 deaths per 100,000 population) 65 years of age and above died from fall-related TBI; yet, the number of deaths increased by a factor of 4 to 5485 males (34.4 deaths per 100,000 population) and 5041 females (19.8 deaths per 100,000 population) by 2010. The numbers and rates of fall-related TBI death by age and year for females and males are illustrated in Tables 1 and 2, respectively.

Table 1.

Unintentional Fall-Related Traumatic Brain Injury Death Rates a among Older Adult Females in the United States

	≧65 years		65–74 years		75–84 years		≧85 years
Year	No.	Rate	No.	Rate	No.	Rate	No.	Rate
1980	1028	7.3	239	2.7	448	9.2	341	21.5
1982	1021	6.7	298	3.3	403	7.8	320	18.6
1984	1127	7.1	275	2.9	490	9.0	362	19.6
1986	1109	6.7	243	2.5	453	7.9	413	21.0
1988	1165	6.7	259	2.6	466	7.7	440	21.2
1990	1201	6.6	231	2.3	510	8.1	460	20.8
1992	1316	6.8	254	2.5	521	7.9	541	22.6
1994	1424	7.1	262	2.5	582	8.6	580	22.5
1996	1788	8.5	305	2.9	683	9.7	800	29.3
1998	2193	10.1	369	3.6	881	12.1	943	32.7
2000	2380	10.7	370	3.7	950	12.6	1060	35.0
2002	2961	13.1	431	4.3	1207	15.7	1323	43.0
2004	3623	15.7	518	5.1	1451	18.7	1654	52.2
2006	3945	16.6	541	5.2	1620	21.0	1784	53.3
2008	4520	18.4	620	5.6	1724	22.5	2176	61.6
2010	5041	19.8	695	5.9	1773	23.4	2573	68.9

Deaths per 100,000 population.

Table 2.

Unintentional Fall-Related Traumatic Brain Injury Death Rates a among Older Adult Males in the United States

	≧65 years		65–74 years		75–84 years		≧85 years
Year	No.	Rate	No.	Rate	No.	Rate	No.	Rate
1980	1380	15.8	574	8.5	525	18.2	281	40.8
1982	1266	14.2	502	7.2	480	15.8	284	39.6
1984	1291	13.7	512	7.1	507	15.8	272	36.4
1986	1302	13.6	479	6.4	512	15.1	311	39.9
1988	1413	14.2	500	6.5	563	15.7	350	43.2
1990	1412	13.6	499	6.3	559	14.8	354	41.6
1992	1490	13.7	506	6.2	600	15.0	384	41.9
1994	1754	15.6	520	6.2	738	17.6	496	50.3
1996	2071	17.5	609	7.3	875	19.6	587	55.4
1998	2329	18.8	623	7.5	1027	21.8	679	59.2
2000	2602	20.3	636	7.7	1181	24.1	785	63.5
2002	3252	24.5	804	9.6	1445	28.3	1003	77.7
2004	3869	28.1	939	11.0	1703	32.4	1227	89.0
2006	4310	29.8	958	10.8	1925	35.9	1427	94.0
2008	5031	33.2	1088	11.5	2128	39.3	1815	109.2
2010	5485	34.4	1183	11.6	2266	41.2	2036	112.4

Deaths per 100,000 population.

Figure 1 shows the estimated trends for fall-related TBI death rates by sex and age according to the joinpoint regression model. The joinpoints (years at which trends change significantly) and annual percentage changes (APCs) are presented in Table 3. For males 65 years of age and above, we found the first joinpoint in 1992 when the APC for 1980 through 1992, −0.8% (no significant difference to zero), changed to 6.2% (significant difference to zero) for 1992–2005. The second joinpoint occurred in 2005 when the APC decreased to 3.7% (significant difference to zero) for 2005–2010. For females 65 years of age and above, the first joinpoint was in 1993 when the APC for 1980 through 1993, −0.2% (no significant difference to zero), changed to 7.6% (significant difference to zero) for 1993–2005. The second joinpoint occurred in 2005 when the APC decreased to 3.8% (significant difference to zero) for 2005–2010. The slowdown of increasing trends was most prominent for the oldest age group of adult males (85 years and above), with an APC of 1.5% (no significant difference to zero) since 2008. For females, the slowdown was most prominent for older adult females ages 65–74 years for whom the APC was 1.8% (no significant difference to zero) since 2005.

FIG 1.

Estimated trends for fall-related traumatic brain injury death rates by sex and age according to joinpoint regression.

Table 3.

Annual Percentage Change (APC) in Unintetnional Fall-Related Traumatic Brain Injury Death Rates According Joinpoint Regression Model

	Trend 1		Trend 2		Trend 3
Age (years)	Period	APC (95% CI)	Period	APC (95% CI)	Period	APC (95% CI)
Males
≥65	1980–1992	−0.8a (−1.5 to −0.2)	1992–2005	6.2a (5.7 to 6.7)	2005–2010	3.7a (2.4 to 5.0)
65–74	1980–1993	−1.9a (−2.7 to −1.1)	1993–2005	5.0a (4.1 to 5.9)	2005–2010	2.1 (−0.3 to 4,5)
75–84	1980–1992	−1.1a (−1.6 to −0.5)	1992–2005	6.7 (6.3 to 7.1)	2005–2010	3.8a (2.7 to 4.9)
≥85	1980–1991	0.3 (−0.8 to 1.4)	1991–2008	6.0a (5.6 to 6.5)	2008–2010	1.5 (−4.8 to 8.3)
Females
≥65	1980–1993	−0.2 (−0.8 to 0.5)	1993–2005	7.6a (7.0 to 8.3)	2005–2010	3.8a (2.4 to 5.1)
65–74	1980–1993	−1.7a (−2.5 to −0.8)	1993–2005	7.0a (6.0 to 8.0)	2005–2010	1.8 (−0.8 to 4.3)
75–84	1980–1993	−0.5 (−1.3 to 0.3)	1993–2006	7.9a (7.2 to 8.6)	2006–2010	2.2 (−0.3 to 4.9)
≥85	1980–1993	1.1a (0.1 to 2.1)	1993–2004	7.6a (6.6 to 8.7)	2004–2010	5.4a (3.8 to 6.9)

Significant difference from zero.

CI, confidence interval.

Discussion

Despite the decrease of overall age-adjusted TBI death rate in the United States from 19.9 per 100,000 population in 1995 to 16.6 in 2009,¹³ the findings of this study indicate that the number and rate of fall-related TBI deaths among older adults increased persistently from 1980 through 2010. Fall-related TBI death rates increased markedly since 1992. The magnitude of increase between 1992 and 2005 was more prominent for females older than 65 than for men older than 65. The average APC was 7.6% for females and 6.2% for males. Fortunately, this increasing trend has slowed down since 2005, when the APC dropped to 3.8% for females and 3.7% for males.

The increase of fall-related TBI death rates might be partially owing to increase of incidence rates and partly to increase of case fatality rates. We could not get data on fall-related TBI incidence rate; however, we can get data on nonfatal fall hospitalization rates (per 100,000 population) from WISQARS (Web-based Injury Statistics Query and Reporting System) maintained by the National Center for Injury Prevention and Control as proxy.¹⁴ According to WISQARS, the age-adjusted hospitalization rates for older adults 65 years and above owing to unintentional fall was 736.2 for males and 1090.3 for females in 2001. These rates increased to 1114.0 for males and 1676.1 for females in 2010, with a 51% increase for males and a 53.7% increase for females. This was very similar to the magnitude of increase for fall-related TBI death rates from 2001 to 2010 estimated in this study: 54.0% increase for males and 68.7% increase for females. This implies that the increase in death rates may have been driven by an increase in incidence rates of fall-related TBI with little change in fatality rate through this period.

Possible explanations for the increase in the incidence of fall-related TBI death rates were proposed in previous studies.^15
–17 First, the young older adults ages 65–74 years may have better health and functional statuses, compared with previous cohorts, and thus engage in more activities that put them in higher risk of falls. Second, more adults 85 years and older may survive and coexist with more medical problems, suffering from poorer mobility and neuromuscular function, and use of drugs that increase the risk of falls. The above-mentioned two factors not only result in the increased incidence of fall-related TBI incidence, but also in the increased severity of injury and fatality rates.

Although trends in fall-related TBI death rates persistently increased between 1992 and 2005, we noted a slowdown since 2005. However, the 95% CIs of APCs since 2005 were wide because there were only a few observed years. A longer period of observation is needed to determine the future mortality trends. The exact reasons for slowing of the increasing trends are unknown. The slowdown might be owing to efforts to prevent both falls and TBI during the previous decades.¹³ Despite the slowdown of mortality trends since 2005, the absolute number deaths caused by fall-related TBI increased. Health care resources devoted to the care of older adults who have sustained fall-related TBI should not diminish in the near future.

Several limitations to this study should be noted. First, both falls and TBI might be under-reported on death certificates. One evaluation study indicated that the sensitivity of death-certificate–based TBI surveillance was 78%, and the majority (62%) of missed cases was owing to listing “multiple trauma” as the cause of death. Death certificate surveillance was more likely to miss TBI-related deaths among traffic crashes, falls, and persons 65 years of age or above.¹⁸ In other words, the fall-related TBI death rates estimated in this study might be underestimated.

Another limitation is that no information for the interval between the fall and date of death is available. This interval may range from days to years. Therefore, death rate trends may differ from incidence rate trends. A third limitation is that reported information was not specific enough that we could analyze the association between mechanisms of falls with TBI. A previous study indicated that in one fifth of the deaths for which fall was selected as the underlying cause of death, the fall was classified as an unspecified fall (ICD-10 code W19).¹⁹ Reports of TBI information on death certificates were similarly unspecific.¹⁸

In conclusion, this descriptive epidemiological study suggests increasing trends in fall-related TBI death rates from 1992 to 2005 and then a slowdown of increasing trends between 2005 and 2010. The exact reasons for slowing of the increasing trends are unknown and might be owing to efforts to prevent both falls and TBI during the previous decades. A longer period of observation is needed to determine the future mortality trends and the burden of this public health problem among older adults in the United States. To better prevent fall-related TBI deaths, we have to further examine whether the increase in fall-related TBI deaths was a result of higher exposure to risky activities or higher prevalence of comorbidities among older adults.

Footnotes

Author Disclosure Statement

No competing financial interests exist.

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Trends in Unintentional Fall-Related Traumatic Brain Injury Death Rates in Older Adults in the United States,1980–2010: A Joinpoint Analysis

Abstract

Introduction

Methods

Data source

Measurement and analysis

Results

Discussion

Footnotes

Author Disclosure Statement

References