Prevalence of Low Plasma IGF‐I in Poliomyelitis Survivors

Objective: To compare plasma levels of insulin‐like growth factor‐I (IGF‐I, also termed somatomedin C) in polio survivors and healthy control subjects and to determine their relation to selected clinical characteristics. Design: Cross sectional study. Setting: Polio survivors living 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 and 122 females) of similar age. Measurements: Plasma IGF‐I levels were compared in polio survivors and age‐matched control subjects. In the polio survivor group, the relation of IGF‐I to selected clinical characteristics was examined before and after adjusting for co‐variates. Results: Statistical analyses showed that the IGF‐I concentrations were significantly lower in the polio survivors than in the controls. This difference was reflected in the means and standard errors of the two groups (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 secretion. 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, gender, and body mass index. IGF‐I level did not correlate with the subjective report of recent decline in functional status. Conclusion: Lower levels of IGF‐I are seen in polio survivors, and this finding correlates with ADL dysfunction. The hy‐posomatomedinemic tendency of polio survivors may have an adverse effect on their neuromuscular function and quality of life.