PREVALENCE OF LOW PLASMA IGF-I IN POLIOMYELITIS SURVIVORS

Objective: To compare plasma levels of insulin-like growth factor-I (I GF-I, also termed somatomedin C) in polio survivors and healthy contro l subjects and to determine their relation to selected clinical charac teristics. Design: Cross sectional study. Setting: Polio survivors liv ing in the community recruited from the Wisconsin Polio Support Group. Participants: A total of 124 polio survivors (49 males and 75 females ), ages 35 to 77 years, and 261 healthy control subjects (139 males an d 122 females) of similar age. Measurements: Plasma IGF-I levels were compared in polio survivors and age-matched control subjects. In the p olio survivor group, the relation of IGF-I to selected clinical charac teristics was examined before and after adjusting for covariates. Resu lts: Statistical analyses showed that the IGF-I concentrations were si gnificantly lower in the polio survivors than in the controls. This di fference was reflected in the means and standard errors of the two gro ups (0.45 +/- 0.02 vs 0.60 +/- 0.02 units/mL, P < 0.01), Plasma IGF-I below 0.35 units/mL in adults indicates little or no growth hormone se cretion. In polio survivors, 38% of the plasma IGF-I values were <0.35 units/mL compared with 19% in the healthy group. Univariate analysis showed that IGF-I in the polio survivors was significantly correlated with age, gender, and body mass index, and with dependency, pain, and difficulty in the activities of daily living (ADLs). The correlations with ADL dysfunction were independent of the correlations with age, ge nder, and body mass index. IGF-I level did not correlate with the subj ective report of recent decline in functional status. Conclusion: Lowe r levels of IGF-I are seen in polio survivors, and this finding correl ates with ADL dysfunction. The hyposomatomedinemic tendency of polio s urvivors may have an adverse effect on their neuromuscular function an d quality of life.