External Causes of Death among Persons with Developmental Disability: The Effect of Residential Placement
Am J Epidemiol
External Causes of Death among Persons with Developmental Disability: The Effect of Residential Placement 3
David Strauss 2 3
Robert Shavelle 2 3
Terence W. Anderson 1 3
Alfred Baumeister 0 3
0 The Kennedy Center, Vanderbilt University , Nashville, TN. Reprint requests to Dr. David Strauss , Department of Statistics, University of California , Riverside, CA 92521-0138
1 Department of Health Care and Epidemiology; Faculty of Med- icine, University of British Columbia , Vancouver, British Columbia , Canada
2 Department of Statistics, University of California , Riverside, CA
3 Received for publication May 15 , 1997, and accepted for publi- cation October 25, 1997. Abbreviations: CDER , Client Development Evaluation Report; ICD-9, International Classification of Diseases , Ninth Revision; SMR, standardized mortality ratio
The authors analyzed death rates from external causes (accidents, injuries, homicides, etc.) for persons with developmental disability in California. There were 520 such deaths during the 1981-1995 study period, based on 733,705 person-years of exposure; this represents all persons who received any services from the state. Compared with the general California population, persons with developmental disability were at lower risk of homicide, suicide, and poisonings (standardized mortality ratios, 0.31-0.68), but higher risk of pedestrian accidents, falls, fires, and, especially, drowning (standardized mortality ratio = 6.22). A major focus of the study was comparisons between different residential settings. Persons in semi-independent living had significantly higher risk than did those in their family home or group homes, with homicides rates being three times higher and pedestrian accidents rates being doubled, while persons in institutions had much lower risks with respect to most causes. Of the 28 deaths due to drug and medication overdoses, 79 percent occurred in supported living or small-group homes. Avoidable deaths could be reduced by making direct care staff more aware of the risks and better trained in acute care, along with improved monitoring of special incidents. Am J Epidemiol 1998; 147:855-62. death rate; group homes; mental retardation; residential facilities
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Developmental disabilities are those associated with
mental retardation, cerebral palsy, epilepsy, or other
neurologic conditions related to mental retardation and
requiring similar treatment. They generally originate
in early childhood and constitute a serious handicap to
the individual (1). The prevailing views of residential
arrangements for such persons have changed
dramatically in the last few decades. It had previously been
widely thought that large, state-run facilities were the
ideal placement for many persons with mental
disabilities, especially for those with serious impairments.
More recently, the movement for "normalization" and
"full inclusion" (2) has led many advocates to argue
for the closure of all state institutions in favor of
small-group homes ("community care"). Several states
have already closed their institutions, and in the
United States as a whole, the institutionalized
population has been reduced by 60 percent between 1967 and
1991 (3).
Although quality of care in institutions and in
community settings has been widely debated, the results
have been rather inconclusive (4-6). One widely
accepted proxy measure for quality of medical care is
mortality. Although several earlier studies compared
mortality rates in institutions and the community ( 7
10), none simultaneously controlled for the known risk
factors such as age and mobility. We recently
compared community and institutional mortality after
controlling for risk factors. During 1980-1992,
riskadjusted mortality for California adults aged 40 years
or over was 72 percent higher in the community (11).
A follow-up study for 1993-1994 showed an 82
percent increase (12). Among high-risk children in
California in 1980-1992, there was a 25 percent increase
in mortality (13). These studies raise the question of
causes of death. In particular, are avoidable deaths
more common in community care? In a recent New
Jersey study of 14 community deaths, nearly half were
judged to be avoidable (14). Such deaths are of special
interest because they may be reduced as a result of
policy intervention.
In this study we focus on one clearly identifiable
class of avoidable deaths, namely, those due to
external causes (accidents, homicides, etc.). The primary
issues are:
1. For external causes of death, such as drownings,
pedestrian accidents, homicides, etc., how do
mortality rates in the general population compare
with those among people with developmental
disabilities?
2. After adjustment for risk factors, such as age,
male gender, and aggressive behavior, what are
the relative mortality rates for external causes
among persons living in different residential
settings: parents' homes, group homes, institutions,
etc.?
3. How do mortality rates for the specific means of
externally caused deaths, such as drownings and
homicides, vary among persons in different
residential settings?
MATERIALS AND METHODS
The instrument
The source of the study data was the Client
Development Evaluation Report (CDER) (15). A CDER is
completed annually, and additionally on moving to a
different placement, for all persons receiving any
services from the California Department of
Developmental Services. There are many types of services,
including speech, behavioral, and physical therapies; board
and care; transportation; day programs; and respite
services for families. The CDER includes a 66-item
Evaluation Element grouped into six domains of
adaptive skills and behavior. These are motor and self-care
skills, along with social, emotional, cognitive, and
communication domains. The instrument is filled out
by the caregiver most familiar with the client, most
frequently the case worker. The reliability of the
CDER has been investigated elsewhere and considered
satisfactory (16-19).
In California, it is legally required that all deaths be
reported to the county authorities, who forward the
information to the state Department of Health
Services. Mortality information for this study was
obtained from computer tapes created annually by the
Department. We then identified the deceased persons
on these tapes who were also listed in the
developmental disabilities database. The tapes provide cause
of death information in the form of International
Classification of Diseases, Ninth Revision (ICD-9) codes
(20). From these, we focused on ICD-9 codes
E800E999, the "external" causes such as homicides,
accidents, injuries, and poisonings. Data on injury death
rates in the general California population were based
on tables supplied by the California Department of
Health Services.
Variables used in the study
Variables previously established to be important
predictors of mortality included age, gender, and level
of motor skills (11). As in the previous study (11), a
motor skills scale was constructed from five CDER
items: rolling and sitting, hand use, arm use, crawling
and standing, and ambulation. Each item was
originally scored on a scale of between four and nine
levels, but was transformed to a three-point scale:
high = 2; medium = 1; low = 0. When summed, this
resulted in a scale of 0-10, which was recoded as good
(score, 10), fair (score, 6-9), poor (score, 1-5), and
none (score, 0).
Variables that may be predictive of externally
caused deaths were also considered: aggression,
severity of self-injurious behavior, tendency to run away,
and hyperactivity. On the CDER, these items were
coded as 4-to 6-point scales, but were collapsed here
into binary or three-point scales on the basis of their
mortality rates. Also included in the study was severity
of mental retardation (21, 22), which is a potential
factor in externally caused deaths. The coding was
mild, moderate, severe, profound, and suspected, with
the last three being combined in this study as they are
elsewhere (23). "Suspected" is a California category
for individuals whose retardation has not formally
been assessed, and previous work has indicated that
this group should be classed with the severe and/or the
profound groups.
Residential placement information was obtained
from the Client Master File, a state data file linked to
the CDER records. Placements were grouped into
five categories: live in own home, semi-independent
living, community care, institutions, and others. Parent/
relative homes were counted as own home. In
semiindependent living, one or more persons with
developmental disability live in a separate residence, with
periodic visits by staff who provide various services.
Community care includes both small-group homes and
larger board-and-care facilities serving seven or more
people, although the small-group home is the
predominant model in California. These are generally
privately owned and operated. Institutions, now called
developmental centers in California, are state
operated. The institutions have been depopulated in recent
years, and almost all of the remaining residents have
serious behavioral or medical conditions. One
consequence of the depopulation is that an increasing
proportion of group-home residents also have such
conditions. The final residence category consisted of all
other types, including skilled nursing facilities,
intermediate care facilities, and penal institutions. These
groups were too small to permit separate analyses.
The sample
Our base population consisted of all persons with
developmental disabilities who received services from
the Department of Developmental Services at any time
during the 15-year period, January 1981 to December
1995. All persons in the study had been referred to one
of the 21 regional centers that contract with the state to
provide services to individuals in their area.
Exposure time
A basic feature of the study was the construction of
various mortality rates, computed by dividing the
number of deaths by the exposure time, or time at risk.
For each individual, exposure times were taken as the
intervals between the time of a CDER evaluation and
that of the next evaluation (or death, or end of the
study period, if either of these came first).
Intervals longer than 3 years were truncated at 3
years to eliminate the unacceptable, very long
intervals. Such intervals occasionally occurred, for
example, when an individual left the California system.
Because an individual's covariates, such as age and
behavioral variables, may change over time, we
associated each interval with the covariates from the
individual's CDER evaluation at the start of that interval.
Only externally caused deaths were considered, with
other deaths being treated in effect as censoring
events.
From this set of more than 1,000,000 intervals, we
retained only those for which 1) the subject's age was
between 15 and 59 years inclusive, and 2) the subject
had good or fair mobility and was not tube fed. The
excluded groups—children, the elderly, and those
with seriously reduced mobility or need for tube
feeding—were likely to have a different pattern of
externally caused deaths and would require separate study.
After these groups were excluded, there were 520
externally caused deaths from a total of 733,706
person-years of exposure, for an overall rate of 70.9
(per 100,000 person-years).
Statistical methods
We compared cause-specific mortality rates in our
sample with those in the general California population.
We adjusted for age and gender by reporting
standardized mortality ratios (SMRs) for each cause (24). Each
SMR was computed as {dlE{D}), where d is the actual
number of deaths in our sample and E{D} is the
expected number of deaths in our sample based on the
age- and gender-specific mortality rates for the
California population. Confidence intervals for the SMRs
were computed using standard methods (24).
For comparison of risks across residence groups, it
was necessary to adjust for risk covariates. Statistical
modeling rather than standardization was needed
because of the very large number of combinations of
covariate values. As is customary when modeling risk
rates based on occurrence/exposure data with
covariates, we used Poisson regression (25). According to
this, if there are dt deaths and «, person-years of
exposure for covariate value JC,, then dt follows a
Poisson distribution with mean exp (j3';c,). Here /3 is a
vector of unknown regression coefficients to be
estimated.
The Poisson regression was carried out using SAS
(26). The five residence types were coded with four
dummy variables, each representing a contrast with
community care. The latter was used as referent
because it was one of the largest groups and because
we were interested in comparing it with other
residence groups. The other covariates (aggression,
self-injurious behavior, etc.) were also coded using
dummy variables to contrast the milder levels
against the most severe group. The age variable was
coded into nine age groups: 15-19, 20-24,..., 55-59
years. It was found that a single linear term in age
sufficed, in that the model indicated a significant
linear increase in risk with age, but quadratic and
cubic terms did not make significant contributions.
After age, gender, and residence variables were
forced into the model, stepwise regression was used
to select further variables. The significance levels
for entry and removal were both 0.05.
Goodness-offit was assessed using the Hosmer-Lemeshow test
(27), which is most commonly used for the logistic
model, but can be shown to apply also to the case of
Poisson regression.
For comparison of cause-specific rates in different
types of residence while adjusting for the covariates,
observed numbers of deaths by cause and residence
were compared with expected numbers based on
mortality rates in the entire sample. Expected numbers
were computed in three stages: 1) The Poisson
regression model was used to compute the expected number
of deaths for each covariate pattern, with all placement
variables set to their means. This, in effect, adjusts the
covariate-specific risks to an "average" placement;
2) For each residence type, these expected numbers
were summed over all the exposure times to give an
expected total number of deaths on the basis of rates in
the whole sample; and 3) each total was then
partitioned among the causes in the same proportions as in
the whole sample. It can be shown that the ratios of
observed and expected numbers in each residence type
are SMRs.
Table 1 gives raw data, stratified by type of
residence, on the major variables considered here. As the
person-year exposure data indicate, the most common
placement was one's own home, followed by
community care, institutions, and semi-independent living.
Because we have included only data on persons with
fair or good motor abilities, many of the more
medically impaired persons have been excluded. As noted,
the latter are relatively more likely to live in
institutions than in the community. Table 1 does show the
much higher proportion of serious aggressive or
selfinjurious behavior in the institutions, along with high
proportions of severe or profound mental retardation.
As would be expected, persons placed in supported or
semi-independent living situations tend to be those
who are relatively high functioning and have fewer
behavioral problems. Table 1 also shows that the
highest externally caused mortality rate occurs in
semiindependent living and the lowest occurs in one's own
home. These, however, are crude rates unadjusted for
effects of other factors.
Table 2 shows mortality rates due to various
categories of injury in the general California population
Externally caused deaths
Exposure (person-years)
Crude mortality rate (per 100,000 person-years)
Aggression (%)
Has had one or more violent episodes causing
minor or serious injury within the previous year
Resorts to verbal abuse or threats, but has not
caused physical injuries
Episodes of displaying anger are undetected or
rare and appropriate to the situation
Severity of self-injurious behavior (%)
At least once a year
No injury or no such behavior exists
Running or wandering away (%)
At least once a year
Less than once a year, or not at all
Hyperactivity (%)
Is hyperactive, except when given individual
attention, or always
Controlled hyperactivity
No hyperactivity
TABLE 2. Mortality rates from injuries, by cause, for the
general California population and for persons with
developmental disabilities, 1981-1995
Raw Injury death rates
per 100,000
person-years
California* Dpevo.pd-tis.
0.27-0.46
0.21-0.43
0.46-0.98
2.94-5.39
2.17-3.68
4.84-7.85
3.11-7.67
* Source: California Department of Health and Welfare, 1995.
t Dev. dis. pop., developmental^ disabled population, based on
733,706 person-years.
$ Standardized mortality ratio (SMR) with standardization for
age and gender, comparing the developmentally disabled
population to the California general population.
and in our sample. The SMRs compare the two rates
after adjustment for age and gender differences.
Persons with developmental disability were at lower risk
than the general population for homicide, suicide, and
poisoning, but at substantially higher risk for deaths by
falls, pedestrian accidents involving automobiles,
fires, and drowning.
Table 3 shows the results of the Poisson regression
analysis of risk. Risk of externally caused death
increases slowly with age. Perhaps not surprisingly,
male gender is associated with a substantial 54 percent
increase in risk. Other factors that increase risk are
aggressive behavior (those with high aggression are at
about twice the risk of those at the low level of
aggression), and tendency to run away (48 percent
increase). All of these effects are statistically
significant (p < 0.01).
One focus of the study was the risk-adjusted
comparisons of the types of residence against the referent
group, community care. Residence in one's own home
was associated with a slightly lower level of risk (87
percent), but the difference was not statistically
significant. Semi-independent living was associated with
a significant increase in risk. Institutions were at a
significantly lower level of risk than community care
(p < 0.01), with the risk ratio being estimated at 58
percent. Equivalently, community care was associated
with a 72 percent increase in risk compared with
institutions (1/0.58 = 1.72).
The Poisson model allowed us to test for possible
time trends in the rates of external deaths, either
overall or specifically for some residence types. We
examined this by introducing dummy variables for three
5-year periods and also by fitting linear and quadratic
cubic terms in time. No discernable or statistically
significant trends were observed. The same result was
observed when we examined for time trends separately
within each residence type.
Figure 1 shows SMRs by cause in the four major
residence groups. As explained in Materials and
Methods, the ratios compare the actual numbers of deaths to
the expected numbers based on the entire sample. In
this way, adjustment is made for interplacement
differences in both exposure time and risk factors.
Figure 1 shows that persons in semi-independent
living had the highest risk for most causes, including
drowning, homicide, and pedestrian accidents. The
comparison of semi-independent living and parents'
home is noteworthy: Residents in semi-independent
living were at several times the risk of homicide, fatal
pedestrian accidents, and medication overdoses.
Community home residence was associated with lower
risks than own homes for homicide and suicide but
much higher risks of death due to inhalation or
suffocation as well as medication overdoses. Finally,
institutions had much the lowest risks with respect to most
causes. The exceptions were deaths due to inhalations
and suffocation and deaths due to falls. The reasons
for the high rate of fatal falls are not clear (and were
not clarified by inspection of the detailed ICD-9
codes); in particular, most California institutions are
Age group*
0.43-0.85
0.73-1.11
1.06-1.75
1.56-2.50
Semi-independent Own home Institution Other
Semi CC OH
Semi CC OH
Semi CC OH
Semi CC OH Inst
Falls (n=45)
Automobile
Passenger (n=42)
Medication & Drug
Overdose (n=33)
Pedestrian vs.
Automobile (n=59)
Drowning (n=70)
Inhalation/
Suffocation (n=63)
Homicide (n=59)
Semi CC OH
Semi CC OH
Semi CC OH Inst
Semi CC OH Inst
not multistoried, so the residents are not at increased
risk of falling down stairs.
A more refined grouping of ICD-9 codes of the
externally caused deaths, broken down by residence
type, may be obtained from the authors. We note here
that 1) the drownings were about equally divided
between swimming pool and bathtub incidents, with
no clear associations between location of drowning
and type of residence; and 2) 22 of the 28 deaths due
to overdoses of drugs or medications occurred in
group homes or independent living. There were seven
deaths due to tranquilizer overdoses (all in group
homes) and six due to overdoses of central appetite
depressants.
DISCUSSION
To our knowledge, this is the first study to analyze
causes of death among persons with developmental
disability, after adjustment for potential confounding
factors. Externally caused deaths, studied here, are of
interest because they serve as a measure of safety or
quality of supervision, just as mortality as a whole is a
proxy for quality of care.
The developmentally disabled population is
recognized to be a group requiring special protection. It is
therefore of interest that although its mortality is lower
than that of the general population regarding
homicide, suicide, and poisoning, it has much higher rates
of fatalities due to pedestrian accidents, falls, fires,
and, especially, drowning.
It is notable that the sequence of placements
according to degree of freedom/supervision, namely,
semiindependent living (least supervision), group homes,
family homes, and institution (greatest supervision), is
the same as the sequence according to mortality rates
from external causes. The lower rates of externally
caused deaths in institutions compared with the
various forms of community riving support the findings of
previous studies showing lower mortality overall in
institutions (11-13). Perhaps the debate over whether
institutions provide better supervision and medical
care than does the community should move to a
discussion of the costs and benefits of the generally more
dependable medical delivery system available in
institutions. There seem to be good reasons for states to
monitor and improve the quality of care in private
group homes. Fortunately, California is currently one
of the few states with a tracking systems that could be
used for the purpose (28).
This study was restricted to California, and
replication in other states or countries would be desirable.
In-depth case review would also be valuable. For
example, Kastner et al. (14) were able to review the
complete medical records for 14 deceased persons
who had been living in the community. Using death
certificates and other information, we have recently
compared 45 California community deaths with a
matching set for institutionalized persons (29). The
community deaths were much more likely to have
been acute or subacute (i.e., with onset a week or less
before death) and were judged to be, on average, more
avoidable.
The results of this study suggest that avoidable
deaths in community care could be reduced by
increased awareness of the risks and improved training
in emergency procedures, such as cardiopulmonary
resuscitation and the Heimlich maneuver. It would
also be appropriate for states or local authorities to
assess staff competence on a regular basis. Finally,
special incidents should be reported promptly and
incorporated into a computerized database so that
patterns may rapidly be identified.
ACKNOWLEDGMENTS
Supported in part by grants HD21056 and HD22953 from
the National Institute of Child Health and Human
Development. Provision of data by the California Departments of
Developmental Services and Health Services is gratefully
acknowledged.
REFERENCES
1. Grossman HJ , ed. Classification in mental retardation. Washington DC: American Association on Mental Deficiency , 1983 .
2. Wolfensberger W. The principle of normalization in human services . Toronto, Ontario, Canada: National Institute of Mental Retardation , 1972 .
3. Lakin C , Braddock D , Smith G . Trends and milestones: state institution closures . Ment Retard 1994 ; 32 : 77 .
4. Durkin MS . Beyond mortality: residential placement and quality of life among children with mental retardation . Am J Public Health 1996 ; 86 : 1359 - 60 .
5. Landesman S , Butterfield EC. Normalization and deinstitutionalization of mentally retarded persons: controversy and facts . Am Psychol 1987 ; 42 : 809 - 16 .
6. Landesman-Dwyer S. Living in the community . Am J Ment Defic 1981 ; 86 : 223 - 34 .
7. McCurley R , MacKay D , Scally B. The life expectancy of the mentally subnormal under hospital and community care . J Ment Defic Res 1972 ; 16 : 57 - 66 .
8. Miller C , Eyman RK . Hospital and community mortality rates among the retarded . J Ment Defic Res 1979 ; 22 : 137 - 45 .
9. O'Brien KF , Tate K , Zaharia ES . Mortality in a large southeastern facility for persons with mental retardation . Am J Ment Retard 1991 ; 95 : 397 - 403 .
10. Silverman WP , Zigman WB , Silver EJ . Adults with profound mental retardation and multiple handicaps: factors associated with mortality . In: Jacobs JW, Burchard SN , Carling PJ, eds. Community living for people with developmental and psychiatric disabilities . Baltimore , MD: Johns Hopkins University Press , 1992 : 82 - 93 .
11. Strauss DJ , Kastner T. Comparative mortality of people with mental retardation in institutions and the community . Am J Ment Retard 1996 ; 101 : 26 - 40 .
12. Strauss DJ , Kastner T , Shavelle R. Mortality of adults with developmental disabilities living in California institutions and community care , 1985 - 1994 . Ment Retard (in press).
13. Strauss DJ , Eyman RK , Grossman HJ . The prediction of mortality in children with severe mental retardation: the effect of placement . Am J Public Health 1996 ; 86 : 1422 - 9 .
14. Kastner T , Nathanson R , Friedman D. Mortality in persons with mental retardation living in the community . Am J Ment Retard 1993 ; 98 : 285 - 92 .
15. California Department of Developmental Services. Client Development Evaluation Report. Sacramento, CA: California Department of Developmental Services , 1978 .
16. Arias M , Ito E , Takagi N. Concurrent validity of the client development and evaluation report . In: Silverstein AB, Fluharty AL, eds. Pacific state archives. VIII. Pomona, CA: UCLA Developmental Disabilities Immersion Program , 1993 : 28 - 33 .
17. Harris CW , Eyman RK , Mayeda T. An interrater reliability study of the Client Development Evaluation Report (Final Report to the California Department of Developmental Services) . Pomona, CA: University of California at Los Angeles Mental Retardation Research Center , 1982 .
18. Widaman KF . Interrater reliability of adaptive behavior assessments: item and factor levels. Paper presented at the 92nd annual meeting of the American Psychological Association , Toronto, Ontario, Canada, August 25 , 1984 .
19. Widaman KF , Stacy AW , Borthwick SA . Multitraitmultimethod of evaluating adaptive and maladaptive behavior of mentally retarded people . Paper presented at the 109th annual meeting of the American Association on Mental Deficiency , Philadelphia, PA, May 29 , 1985 .
20. World Health Organization. International classification of diseases. Manual of the international statistical classification of diseases, injuries, and causes of death . Ninth Revision . Geneva, Switzerland: World Health Organization , 1977 .
21. Eyman RK , Grossman HJ , Chaney RH , et al. The life expectancy of profoundly handicapped people with mental retardation . N Engl J Med 1990 ; 323 : 584 - 9 .
22. Eyman RK , Grossman HJ , Chaney RH , et al. Survival of profoundly disabled people with severe mental retardation . Am J Dis Child 1993 ; 147 : 329 - 36 .
23. Strauss DJ , Zigman WB . Behavioral capabilities and mortality risk in adults with and without Down syndrome . Am J Ment Retard 1996 ; 101 : 269 - 81 .
24. Kahn HA , Sempos CT . Statistical methods in epidemiology . Oxford, England: Oxford University Press, 1989 .
25. Breslow NE , Day NE, eds. Statistical methods in cancer research, Volume 2. The design and analysis of cohort studies. Lyon , France: International Agency on Cancer Research , 1987 . ( IARC scientific publication no . 82).
26. SAS Institute, Inc. SAS/ STAT user's guide . Version 6,4th ed. Cary, NC: SAS Institute , Inc., 1989 .
27. Hosmer DW , Lemeshow S . Applied logistic regression. New York, NY : John Wiley & Sons, 1989 .
28. Zaharia ES , O'Brien KF . Mortality: an individual or aggregate variable ? Am J Ment Retard 1997 ; 101 : 424 - 9 .
29. Strauss DJ , Anderson TW , Shavelle RM , et al. Causes of death of persons with developmental disability placed from California institutions into community care . Ment Retard (in press).