INCRERASED MORTALITY WITH PERSONS WITH CEREBRAL PALSY
Although it is generally believed that as a group, persons in the U.S. with cerebral palsy (C.P.) have a higher mortality rate than the general population, the specific causes are still poorly documented. It is also believed that as a group, persons with cerebral palsy die at a younger age than the general population (some authorities say 10 years younger). The reasons for the inadequate information include the different definitions used for cerebral palsy by various professionals responsible for signing the death certificate, differences in opinion about the cause-effect relationship between cerebral palsy and death, and the need for a large enough population of persons with cerebral palsy. There are also the problems of different causes of death and the different rates of death at various age groups and for various types and degrees of disability.

A joint team of statistical and clinical experts addressed these issues by studying a population of 182,263 individuals withy developmental disabilities who received services from the State of California between January 1980 and December 1995 . The time of reported death that was studied was the 10-year period, 1986-1996. An evaluation team assessed the clinical status of each person: 45,292 individuals were identified as having died during the 10-year study period. Since data are available only on persons who received services from the State, the group has a higher proportion of persons with more severe disability than a general group or persons with disabilities due to cerebral palsy. For analysis, the group studied were divided into two groups those with “severe disability” and those with “not severe disability.”

The “unique” population characteristics of the group studied were

• There were 10% more males than females in the study group (usually a 50-50 distribution).
• 32% had “severe disability” (usually about 25%).
• 77% of the persons with severe cerebral palsy had quadriplegia (a higher than usual proportion).

The results of the study indicated:

When looking at death rate:

• For persons with “not severe palsy,” there was close to a 40% increase in death at ages 0-4; a 33% increase at ages 5-14; and a 2 to 5 percent increase in the age group 15 or older.
• For persons with “severe cerebral palsy,” there was close to a 97% increase in death at ages 0-4, a 108% increase at ages 5-14 and a 3 to 16 percent increase in the age group 15 or older.

When looking at causes of death.

• There was a substantial increase in causes of deaths in both groups at all ages.
• There was a substantial increase in nearly all types of cancer (breast, digestive organs, genito-urinary, brain) through ages 0-54. Brain cancer was particularly high in both groups between ages 0-34, with the severe disability group having a high occurrence of brain cancer.

• There was some increase at all ages in deaths due to circulatory system disease (heart disease, stroke) in both groups with a steady decline with age; the age group 0-34 had a substantially higher death rate due to circulatory diseases than expected.

• There was a substantial increase at all ages in deaths due to respiratory diseases of all types in both groups, with a steady decline in age. However, although death due to respiratory disease is high, it isn’t as high as it is generally though to be. There was a substantial increase in deaths due to digestive system disorders, particularly due to either disease of the esophagus or intestinal obstruction. These was an exceptionally high death rate in the group with severe disabilities.
• There was a higher than expected mortality due to pedestrian accidents (e.g., falls) and to drowning.

In this population, the three principal causes of death were (1) cancer, (2) circulatory system disorders and (3) respiratory disturbances. In the general population, they are (1) circulatory system disorders, (2) cancer and (3) stroke.

Comment:

The causes of death in persons with cerebral palsy are significantly influenced by age, type of disability, degree of disability and the environment in which they live (availability and quality of caregiver services, healthcare and community services; and the risk factors to which they are exposed). This study of a select population of persons with cerebral palsy indicates that cancer and heart disease are the principal cases of death, as they are for all persons in the U.S. However, the death rates due to these causes are substantially higher than for the general population. Unlike the general population, there is also a significant increase in death rates due to digestive disorders and to accidental trauma. The higher occurrence of deaths due to respiratory disease and to accidental trauma is not surprising; but the much higher death rates due to cancer and to circulatory diseases at all ages is unexpected.

From an epidemiological scientific viewpoint, one could argue that the population studied was not “characteristic” of the entire U.S. population of persons with disabilities due to cerebral palsy; this population had a higher percentage of persons with severe disability. Nevertheless, it is an excellent study and the results provide important information about causes of death and lead to important questions about why these occur and how to prevent them. Are persons with disabilities more subject to death from these causes than are the general population because of difficulty with diagnosis or do the disabilities affect the outcome of clinical therapy? If so, why? Is appropriate medical therapy not being made available to this group of people? If not, why not? Also, if not, would the availability of better therapy change the outcome? These are research questions demanding additional attention. The UCP Research and Educational Foundation will try to see they receive the attention needed.