Changing Prevalence of Cerebral Palsy

Coleen Boyle, Ph.D.

National Center on Birth Defects and Developmental Disabilities

Centers for Disease Control and Prevention

What impacts the rate of CP in very preterm infants?

• Birth rate (live births/1000)

• Birth weight/preterm birth distribution

• Survival in preterm/vlbw infants

• Prevalence of CP in preterm survivors

How have each of these factors changed overtime?

Factor #1: Birth rate

• Birth rate has decrease since 1960s, but number of reproductive age women has increased

• Changes in birth rate do not change rate; but will change absolute number of case children

Cerebral Palsy in Atlanta,Atlanta, 1975 - 1991

1975 -1977 1981 -1985

No. live birth/yr

No. case children

Cp rate

21,144

36

1.7

26,127

52

1.8

1986 -1991

36,457

77

2.0

Factor #2: Birthweight/preterm birth distribution

The rate of very preterm births (<32 weeks GA) in the U.S. has increased 9% from 1981 to 1999 (1.81% of all births in 1981 to 1.98% in 1999)

Whites – 12% (1.37 1.57)Blacks – unchanged (4.13 4.13)

Factor #3: VLBW/Preterm Infant Survival

Critical factor because this group is at highest risk of CP and other disability

Survival in Infants <1500g, Altanta, 1981-1996

0

10

20

30

40

50

60

70

80

90

1981 1982 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996

Low Birth Weight and DD Birth Weight

(gms)

Survivors

No.

Any DD

Rate/100

<1000 1189 18.3

1000 - 1499 2667 8.8

1500 - 2499 23,171 2.4

2500+ 330,178 0.8

Overall Disability at 30 MonthsWoods et al, 2000

25%

23%

2%

49%

Other DisabilitySevere DisabilityDiedNo disability

Woods et al, 2000 - RESULTS

• Development – 19% with Bayley >3 SD; 11% 2-3 SD

• Neuromotor – 10% with severe disabilities 14% other disabilities

• Sensory- 2% blind; 2% deaf; 5% no speech

Factor # 4: Prevalence of CP in preterm survivors

• Impact of prenatal factors: role of inflammation, infection

• Impact of antenatal care/intervention?– corticosteriods; surfactant; others

Source: Stanley, Blair & Alberman, 2000

Rates of CP in Neonatal Survivors

Source: Stanley, Blair & Alberman, 2000

Source: Stanley, Blair + Alberman, 2000

Source: Stanley, Blair & Alberman, 2000

Source: O’Shea 1998 Pediatrics

1983-1985

<1000 g1000-1499 gTotal

1988-1989

<1000 g1000-1499 gTotal

1990-1994

<1000 g1000-1499 gTotal

152742

161531

272653

266616882

208429637

56011081668

564448

773549

482332

No. ofchildrenwith CP

No. ofsingleton

survivors <1500 g

Prevalence per1000 survivors

<1500 g

Table. Prevalence of moderate or severe CP in singleton weighing< 1500 g born in 4 northern California counties

Source: Grether: J Pediatr, 136; 2000:133

59

36

20

1319

7 8

03

1319

7

0

10

20

30

40

50

60

70

79-84 84-89 89-94% Dying CP Blindness Bayley

MDI <68

Outcome at 1 yr in infants weighing 501 – 800 gm,

North Carolina

Source: O’Shea et al. Pediatrics 1998:101

44

6.5

62

5.9

67

6.0

0

10

20

30

40

50

60

70

80

1975 - 77 1981 - 85 1986 - 91

Pe

rce

nt

% Survivors and Prevalence of CP in Infants <1500 g,Atlanta, 1975-1991 births

0

6.1

5.0

6.45.8

1

2

3

4

5

6

77.0

7.5

1975 - 77 1981 - 85 1986 - 91

8

Prevalence of CP <1500 g survivors,Atlanta, 1975 –1991, by race

Pe

rce

nt

white

black

Characteristics of CP in infants <1500 g,Atlanta, 1975 - 1991

% Isolated CP % Spastic diplegia

1975 – 1977

1981 – 1985

1986 - 1991

41

46

51

7

36

32

Trends in CP – Conclusions

• Factor 1: Birth rate stable; rise in the number of reproductive age women

• Factor 2: Proportion of very preterm births has increased

• Factor 3: Infant mortality in very preterm infants continues to improve

• Factor 4: Increase - mid to late 1980’s; decrease in early 1990’s