Postnatal Causes of Developmental Disabilities in Children Aged 3- 10 Years -- Atlanta, Georgia, 1991

Primary prevention of developmental disabilities requires knowledge of the specific causes of these conditions. Postnatal causes account for 3%-15% of all developmental disabilities and often are preventable (1). To assess the prevalence and determine the specific etiology of postnatally acquired developmental disabilities, CDC analyzed data from its ongoing Metropolitan Atlanta Developmental Disabilities Surveillance Program (MADDSP) for 1991 (the most recent year for which complete data were available). This report summarizes the findings of the analysis, which indicate that bacterial meningitis and child battering were the leading postnatal causes of developmental disabilities and that children with postnatally acquired developmental disabilities had a higher average number of disabilities than all other children with developmental disabilities.

MADDSP identifies all children aged 3-10 years residing in five counties of metropolitan Atlanta (Clayton, Cobb, DeKalb, Fulton, and Gwinnett {total 1990 estimated population of children aged 3-10 years: 252,377}) with any of four developmental disabilities: cerebral palsy, mental retardation, moderate-to-severe hearing impairment, and moderate-to-severe vision impairment. Children with these conditions are identified through a systematic review of records at public schools, hospitals, and other public or private programs for children with disabilities. Detailed information about the underlying cause associated with each developmental disability is abstracted for all children identified with a developmental disability. For this analysis, a developmental pediatrician reviewed all abstracted information to determine whether children had a disability with a postnatal cause. A postnatal cause was defined as any event that occurred from age 30 days through 10 years.

Of the 2685 children identified with a developmental disability in 1991, a total of 122 (4.5%) had at least one with a postnatal cause (Table_1); overall, these children had a total of 186 postnatally acquired developmental disabilities (Table_2). No children had more than one postnatal cause for their disability. The percentages of developmental disabilities accounted for by postnatal causes ranged from 3.5% (mental retardation) to 12.4% (hearing impairment).

The most common postnatal causes of developmental disability were bacterial meningitis and child battering, which accounted for 57 (30.6%) and 27 (14.5%) postnatally acquired developmental disabilities, respectively (Table_2). The highest average number of disabilities per affected child was in those who had a developmental disability caused by a near-drowning incident (2.3). Stroke, child battering, bacterial meningitis, and motor-vehicle crashes also accounted for high average numbers of developmental disabilities per affected child (1.9, 1.8, 1.8, and 1.7, respectively). Of the three major etiologic groupings analyzed (infectious diseases, chronic diseases, and injuries), injuries accounted for the greatest proportion of postnatal cases of each developmental disability except hearing impairment.

To assess the severity of different types of developmental disabilities, the number of developmental disabilities in children with such conditions attributable to a postnatal cause was compared with the number in those with such conditions attributable to other causes. The prevalence of two or more developmental disabilities was more than twofold higher among children with postnatally acquired developmental disabilities than those with developmental disabilities attributable to other causes (42.6% versus 17.0%) (Table_3).

Reported by: Developmental Disabilities Br, Div of Birth Defects and Developmental Disabilities, National Center for Environmental Health, CDC.

Editorial Note

Editorial Note: This analysis of MADDSP data identified distinct causes for the four postnatally acquired developmental disabilities analyzed, most of which are preventable. Among children in metropolitan Atlanta, the proportions of developmental disabilities attributable to postnatal causes are consistent with previous studies (1-4). In addition, the MADDSP data indicate that children with a postnatally acquired developmental disability were more likely to have multiple disabilities than other children identified with developmental disabilities, suggesting that postnatally acquired developmental disabilities have a greater impact on a child's health status than other developmental disabilities.

In metropolitan Atlanta, of the specific causes of postnatally acquired developmental disabilities, bacterial meningitis caused the greatest number of those disabilities, and Haemophilus influenzae serotype b (Hib) accounted for 47% of meningitis-related developmental disabilities. Hib vaccine was licensed for use in infants in the United States in 1990 and has been distributed widely (5); however, the 1991 MADDSP data include information about children born during 1981-1988 (before the vaccine became available). The continued identification of Hib cases by MADDSP should prompt intensification of prevention programs.

Child battering, including shaken baby syndrome, accounted for the second largest number of postnatally acquired developmental disabilities and a high average number of developmental disabilities for each affected child. The reported number of child battering cases is probably an underestimate because of the inability of the medical delivery system to identify all cases of abuse. Developmental disabilities caused by other types of injuries may be reduced through intensified implementation of existing prevention efforts (e.g., mandatory restraint systems for infants and toddlers to reduce the severity of motor-vehicle crash-related injuries). The detection of five children with postnatally acquired developmental disabilities associated with sickle cell anemia underscores the need for increased awareness about the severity of the consequences of sickle cell disease and the role of transfusion therapy for preventing recurrent stroke among children with this disease (6).

The reported percentage of postnatally acquired developmental disabilities most likely underrepresents the actual percentage of such cases. Although the MADDSP methodology included a comprehensive review of records from multiple sources in a population-based setting, the cause was defined as "other than postnatal" when etiologic information was confusing, conflicting, or missing. In addition, postnatal events for which the causal link was more difficult to establish in individual cases (e.g., poor nutrition or an impoverished social environment {7}) were not included in this analysis.

Surveillance for developmental disabilities should include information about the specific underlying cause(s). Because most postnatally acquired developmental disabilities are potentially preventable, knowledge of specific causes can be used to design cause-specific interventions. Surveillance systems such as MADDSP provide a population-based method for monitoring trends in disability causation and the effectiveness of intervention programs. MADDSP can be adapted for monitoring trends in other cities or states.

References

1. Lipkin PH. Epidemiology of the developmental disabilities. In: Capute AJ, Accardo PJ, eds. Developmental disabilities in infancy and childhood. Baltimore, Maryland: Brookes, 1991: 43-67.

2. McLaren J, Bryson SE. Review of recent epidemiological studies of mental retardation: prevalence, associated disorders, and etiology. Am J Ment Retard 1987;92:243-54.

3. Davidson J, Hyde ML, Alberti PW. Epidemiology of hearing impairment in childhood. Scand Audiol Suppl 1988;30:13-20.

4. Drews CD, Yeargin-Allsopp M, Murphy CC, Decoufle P. Legal blindness among 10-year-old children in metropolitan Atlanta: prevalence, 1985 to 1987. Am J Public Health 1992;82:1377-9.

5. Adams WG, Deaver KA, Cochi SL, et al. Decline of childhood Haemophilus influenzae type b (Hib) disease in the Hib vaccine era. JAMA 1993;269:221-6.

6. Pegelow CH, Adams RJ, McKie V, et al. Risk of recurrent stroke in patients with sickle cell disease treated with erythrocyte transfusions. J Pediatr 1995;126:896-9.

7. Shah PM. Prevention of mental handicaps in children in primary health care. Bull World Health Organ 1991;69:779-89.

TABLE 1. Prevalence rate * of developmental disabilities (DDs) among children aged 3-10 years,
by type of developmental disability -- Atlanta, Georgia, Metropolitan Atlanta Developmental
Disabilities Surveillance Program, 1991 +
===================================================================================================
                       Postnatal causes     All causes
                       ----------------   -------------        % DDs with
Type of DD                No.    Rate      No.     Rate     postnatal causes
---------------------------------------------------------------------------------------------------
Cerebral palsy            58      0.2      599     2.4             9.7
Mental retardation        77      0.3     2193     8.7             3.5
Hearing impairment
 (moderate to severe)     35      0.1      283     1.1            12.4
Visual impairment
 (moderate to severe)     17     <0.1      209     0.8             7.7
Total                    122      0.5     2685    10.6             4.5
---------------------------------------------------------------------------------------------------
* Per 1000 children aged 3-10 years.
+ Disability groups are not mutually exclusive; therefore, a child can be represented in more than
  one group.
===================================================================================================

TABLE 2. Number and percentage of children aged 3-10 years with selected postnatally acquired developmental
disabilities (PADDs), by specific cause -- Atlanta, Georgia, Metropolitan Atlanta Developmental Disabilities
Surveillance Program, 1991 *
==============================================================================================================

                 Cerebral     Mental       Hearing       Vision        Total        Total
                   palsy    retardation   impairment   impairment      PADDs       children    Average no.
               -----------  -----------  -----------   -----------  -----------  ------------   PADDs per
Cause           No.   (%)   No.    (%)   No.     (%)    No.   (%)    No.   (%)    No.    (%)     child
--------------------------------------------------------------------------------------------------------------
Infectious
 disease
  Bacterial
   meningitis + 18 ( 31.0)  23  ( 29.9)  11   ( 31.4)    5  ( 31.3)  57 ( 30.6)   32   ( 26.2)    1.8
  Otitis media   0   --      0     --    21   ( 60.0)    0     --    21 ( 11.3)   21   ( 17.2)    1.0
  Encephalitis   0   --      2  (  2.6)   0      --      0     --     2 (  1.1)    2   (  1.6)    1.0
  Total         20 ( 34.5)  27  ( 35.1)  34   ( 97.1)    5  ( 31.3)  86 ( 46.2)   58   ( 47.5)    1.5

Chronic
 disease
  Stroke &       8 ( 13.8)   5  (  6.5)   0      --      2  ( 12.5)  15 (  8.1)    8   (  6.6)    1.9
  Brain tumor    0    --     1  (  1.3)   0      --      2 @( 12.5)   3 (  1.6)    3   (  2.5)    1.0
  Total          8 ( 13.8)   7  (  9.1)   0      --      4  ( 25.0)  19 ( 10.2)   12   (  9.8)    1.6

Injury
 Child
  battering     10 ( 17.2)  14  ( 18.2)   0      --      3  ( 18.8)  27 ( 14.5)    15  ( 12.3)    1.8
 Near drowning   3 (  5.2)   3  (  3.9)   0      --      1  (  6.3)   7 (  3.8)     3  (  2.5)    2.3
 Motor-
  vehicle crash  6 ( 10.3)   3  (  3.9)   0      --      1  (  6.3)  10 (  5.4)     6  (  4.9)    1.7
 Hit by motor
  vehicle        3 (  5.2)   7  (  9.1)   1   (  2.9)    0     --    11 (  5.9)     8  (  6.6)    1.4
 Fall            2 (  3.4)   6  (  7.8)   0      --      0     --     8 (  4.3)     7  (  5.7)    1.1
 Total          30 ( 51.7)  43  ( 55.8)   1   (  2.9)    7  ( 43.8)  81 ( 43.5)    52  ( 42.6)    1.6

Total           58 (100.0)  77  (100.0)  35   (100.0)   16  (100.0) 186 (100.0)   122  (100.0)    1.5
--------------------------------------------------------------------------------------------------------------
* Etiologic events with only one attributable case and "not otherwise specified" head injuries were excluded
  from the table by cause but are included in overall totals. Disability groups are not mutually exclusive.
+ Of the 57 total disabilities in the 32 children who had meningitis, Haemophilus influenzae serotype b caused
  27 of the disabilities in 15 children.
& Of the 15 total disabilities in the eight children who had stroke, sickle cell anemia caused nine
  disabilities in five children.
@ Includes one case of pseudotumor cerebri and one case of tumor on the optic chiasm.
==============================================================================================================

TABLE 3. Number and percentage of children aged 3-10 years with
developmental disabilities (DDs), by number of disabilities and etiology
-- Atlanta, Georgia, Metropolitan Atlanta Developmental Disabilities
Surveillance Program, 1991
===========================================================================
                                       Etiology
                  ---------------------------------------------------------
                     Postnatal          Other            Total
                  ---------------  ---------------  -----------------------
No. DDs            No.     (%)      No.     (%)      No.     (%)
---------------------------------------------------------------------------
One                 70   ( 57.4)   2127   ( 83.0)   2197   ( 81.8)
Two                 40   ( 32.8)    340   ( 13.3)    380   ( 14.2)
Three to four       12   (  9.8)     96   (  3.7)    108   (  4.0)

Total              122   (100.0)   2563   (100.0)   2685   (100.0)

Average no. DDs
   per child           1.5              1.2              1.2
===========================================================================

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