Variability and reliability of single serum IGF-I measurements: impact on determining predictability of risk ratios in disease development - PubMed (original) (raw)

Variability and reliability of single serum IGF-I measurements: impact on determining predictability of risk ratios in disease development

Daniela Milani et al. J Clin Endocrinol Metab. 2004 May.

Abstract

In recent years, a number of investigators have studied the relationship between IGF-I and risk of developing cancer, diabetes or cardiovascular disease. Upper tertile, quartile, and quintile IGF-Is were associated with higher risk of developing cancer, and lowest quartile with cardiac disease and diabetes. As part of a study to correlate serum IGF-Is and growth hormone dynamics in aging, we measured fasting serum IGF-I at baseline and two weeks later in a group of 84 normal volunteers between the ages of 50 and 90 years. Although the correlation between the two IGF-Is was high (r=0.922; p<0.0001) there were substantial differences between the two IGF-I values ranging from -36.25 to +38.24% between individual IGF-I values at the two blood draws and a significant difference between the mean IGF-Is at visits I and 2 (mean 120.28+/-53.5 vs. 114.95+/-50.03; p=0.03). When considered in quartiles, IGF-I changed from one quartile to another in 34/84 (40.5%) of the volunteers. When the group was divided in halves, tertiles,quartiles, or quintiles there was an increasing number of subjects who changed from one subdivision to another as the number of gradations increased. These results suggest that the predictive outcomes of earlier studies that used single IGF-I samples for analysis of risk ratios according to tertiles, quartiles, or quintiles could have been different if a second IGF-I was used to establish the risk ratio. The results also suggest that variability in IGF-I should be taken into account when designing such studies.

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Figures

Figure 1

Figure 1

Percent Change of IGF-I from Visit 1 to Visit 2

Figure 2

Figure 2

Subjects who changed quartile from visit 1 (IGF-I_V1) to visit 2 (IGF-I_ V2). Arrows indicate direction of change for each subject. Quartile 1 (Q1) range: 45-92 ng/ml. Quartile 2 (Q2) range: 93-107 ng/ml. Quartile 3 (Q3) range: 108-139 ng/ml. Quartile 4 (Q4) range: 140-351 ng/ml.

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References

    1. Chan JM, Stampfer MJ, Giovannucci E, Gann PH, Ma J, Wilkinson P, Hennekens CH, Pollak M. Plasma insulin-like growth factor-I and prostate cancer risk: A prospective study. Science. 1998;279:563–566. - PubMed
    1. Hankinson SE, Willett WC, Colditz GA, Hunter DJ, Michaud DS, Deroo B, Rosner B, Speizer FE, Pollak M. Circulating concentrations of insulin-like growth factor-I and risk of breast cancer. Lancet. 1998;351:1393–1396. - PubMed
    1. Janssen JA, Lamberts SWJ. Insulin-like growth factor-I and risk of breast cancer. Lancet. 1998;352:490. - PubMed
    1. Harman SM, Metter EJ, Blackman MR, Landis PK, Carter HB. Serum levels of insulin-like growth factor I (IGF-I), IGF-II, IGF-binding protein-3, and prostate-specific antigen as predictors of clinical prostate cancer [In Process Citation]. Journal of Clinical Endocrinology and Metabolism. 2000;85:4258–4265. - PubMed
    1. Toniolo P, Bruning PF, Akhmedkhanov A, Bonfrer JM, Koenig KL, Lukanova A, Shore RE, Zeleniuch-Jacquotte A. Serum insulin-like growth factor-I and breast cancer [In Process Citation]. International Journal of Cancer. 2000;88:828–832. - PubMed

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