Can IGF-1 serve as a reliable skeletal maturity indicator? A meta-analysis.

BACKGROUND Many clinical studies have evaluated the role of biochemical mediators like insulin-like growth factor 1 (IGF-1) in assessment of skeletal maturity. But still the reliability of IGF‑1 as an indicator of skeletal maturity remains controversial. OBJECTIVE To assess the correlation between IGF‑1 and different radiographic skeletal maturity indicators. SEARCH METHODS Seven electronic databases (PubMed, Scopus, EMBASE, Medline, Cochrane CENTRAL, Web of Science and SciELO) were searched until January 2020 without any restriction based on language or date of publication. SELECTION CRITERIA The study design included cross-sectional and longitudinal studies comparing IGF‑1 and other skeletal maturity indicators (SMIs). DATA COLLECTION AND ANALYSIS Data extraction was done by two reviewers independently; 15 studies were eligible to be included in the quantitative synthesis. RESULTS There was significant positive correlation between IGF‑1 and different SMIs until puberty which was 0.95 (confidence interval [CI] = 0.89, 1.02) for males and 0.87 (CI = 0.77, 0.97) for females. A negative correlation between IGF‑1 and different SMIs was found after puberty which was -0.86 (CI = -0.97, -0.75) for males and -0.89 (CI = -0.98, -0.81) for females. The type of SMI compared and type of IGF‑1 sample used accounted for the high heterogeneity found across the studies. Chronological age and number of months passed after puberty showed moderate negative correlation with mean IGF‑1 levels which were -0.57 (CI = -0.67, -0.47) and -0.54 (CI = -0.66, -0.42). Annual increments in mandibular length showed significant positive correlation of 0.69 (CI = 0.48, 0.90). CONCLUSIONS IGF‑1 would serve as a promising alternative to conventional radiographic skeletal maturity indicators and in predicting the amount of residual mandibular growth.