Post-Polio Health (ISSN 1066-5331)
Vol. 11, No. 1, Winter 1995
Post-Polio Research
The Latest from the Later Life Effects (LLE) Study
Joan L. Headley
In 1990, I read about a five-year study funded by the National Institute on Disability and Rehabilitation Research (NIDRR), Later Life Effects of Early Life Disability: Comparison of Age-Matched Controls on Indicators of Physical, Psychological and Social Status (LLE Study), and was intrigued.
Many studies and surveys of post-polio sequelae are criticized because the sample is not selected randomly; there is no comparison to non-polio individuals; and data are not collected over time in a longitudinal design. Because the Later Life Effects (LLE) study included a control group, I called co-investigator Margaret L. Campbell, PhD, and offered our network to her, immediately catching some of her enthusiasm.
Five years have lapsed and the final 168-page report of hypotheses, procedures, comparisons, results, summaries, and conclusions has been released.
Campbell's colleagues, Bryan Kemp, PhD, and Kenneth Brummel-Smith, MD, are now preparing major articles for publication on the "stress-buffering effects of family functioning on physical independence and psychological wellbeing in the later years." Campbell and Victor Ettinger, MD, are also putting final touches on an article comparing the risk of osteoporosis for female polio survivors and sexand-age-matched controls, ages 50 to 88. Hopefully, the results of this analysis will assist us (women with polio) in making better health care decisions surrounding menopause which, interestingly, lists among its symptoms fatigue, decrease in ability to concentrate, and problems with sleep.
While waiting for these major articles, I decided to highlight some of the conclusions. But first I would like to include Dr. Campbell's description of the "life course perspective" and share a pertinent quote.
The Life Course Perspective
"Unlike more traditional rehabilitation models, which emphasize physical impairment or functional limitations, the life course perspective enhances our understanding of the meaning and consequences of polio by placing polio-related events, such as acute onset and period of 'physical best,' within the broader context of the individual's whole life and the social and family resources individuals have available to cope with their changing needs and circumstances."
Why Study Polio?
"The importance of studying chronic polio, however, is due as much for its precedence as it is to its prevalence. Developing a better understanding of the later life effects of polio can serve as an important prototype for studying the secondary complications associated with other long term physical disabilities, such as cerebral palsy, rheumatoid arthritis, and spinal cord injury"
Who Was Studied?
The focus is on aging with a disability, so the minimum age for participation was 50 and the historical period of onset was noted. (21.5% had polio between 1906 and 1929; 24% during the '30s; 35.5% during the '40s; 19% during the '50s.) Sixty-five percent were female, 35% male, reflecting the consistent finding that females are disproportionately represented in survey studies.
The average polio survivor studied was 11.9 years old at time of acute onset, and 50.9 years have lapsed since the original polio. The average year when they had polio was 1939, and they spent 26 weeks in the hospital.
Thirty-eight percent were recruited from the newspaper; 46% support groups; 16% friends/personal contacts. Ninety-eight percent of the polio survivors were Caucasian. In other words, the participants were not selected randomly.
Twenty-two (22.3) percent had no or one limb affected at acute onset; 40.5% two limbs; 37.2% three or four limbs. Fifty-eight (57.8) percent met all five criteria for post-polio syndrome (see Halstead, page 2, shaded box); 25% reported no new physical health problems and no new functional loss in activities of daily living (ADL); while 17.2% acknowledged the onset of new health problems, but no new loss of function. These three groups were categorized as "PPS," "no," and "maybe."
Findings
- Consistent with earlier epidemiological studies done in the 1940s, lower extremity involvement was more prevalent than upper extremity involvement, and the left lower extremity was more likely to be affected than the right.
- Taking all types of change in method of locomotion (walking, using crutches, canes, wheelchairs, etc.) into account, a total of 68% of the polio sample declined in mobility status between their time of "physical best" and the time of participation in the study (or T.O.M.).
- Depression scores observed were well within the normal range for all polio sub groups with the exception of one. Only those who contracted polio after 1940, and before the age of 10, had scores which exceeded the threshold for clinically significant symptoms. It is important to point out that clinical symptoms are not synonymous with a diagnosis of clinical depression. Women meeting the criteria for PPS had significantly higher depression scores compared to their female counterparts in the "no" and "maybe" categories. Women with PPS also had significantly higher mean depression scores than men with PPS. Males meeting the criteria for PPS did not report more depressive symptoms than did men without PPS.
- There was a newly-detected weaker association between depressive symptoms and a basic physical health indicator, TSH level. This last association underscores the need to perform thyroid screening tests for persons aging with polio in order to assure a correct diagnosis and treatment.
- As both the age at acute onset and the historical period (or decade in which polio occurred) increase so does the percentage of the sample with three and four limbs affected. In other words, of those who got polio during infancy and before 1930, over 40% were mildly impaired. However, only 20% of those who contracted polio in adulthood and during the peak of the epidemics in the '50s were mildly impaired.
- The data indicate that there was no mean difference in current chronological age between those who meet the criteria for PPS and those who do not. This finding is important because it suggests that contrary to early speculation in the literature neither "aging" per se nor the mere passage of time are adequate explanation for who is most at risk for later life effects of polio.
- Regardless of the time interval between acute onset and T.O.M., those most at risk for experiencing the new health problems and functional losses associated with PPS are those who were most severely impaired at acute onset and who recovered the most between initial rehabilitation and their period of "physical best" for stability.
These findings are important because they provide initial empirical support for the first half of the prediction by Jacquelin Perry MD, as to who is most at risk for developing the later life effects of polio. According to Perry, polio survivors most likely to experience PPS are those who were most impaired at acute onset - which is consistent with our data – and who recovered the most between onset and time of physical best.
Data support the conclusion that both the age of onset and severity of acute onset are significantly related to the functional independence and psychological well being of survivors an average of 51 years later. In general, it is a combination of being both older and more severely impaired at acute onset that increases the chances of depressive symptoms and of being more functionally limited when compared to those who were equally impaired at onset but who contracted polio before the age of nine.
The Next Five Years
The Rehabilitation and Research Training Center (RRTC) on Aging with Disability was funded by NIDRR for another five years to continue their investigation of later life effects and secondary conditions associated with long-term disability. In the second funding cycle, both the sample size and number of disabling conditions have been expanded from the previous polio and stroke survivors to include approximately 1,000 individuals aging with cerebral palsy (N=120), polio (N=400), rheumatoid arthritis (N=250), and stroke (N=225).
Margaret L. Campell, PhD, may be reached at the RRTC on Aging with Disability, Rancho Los Amigos Medical Center, 7600 Consuelo St., Downey, CA 90242.
