The Tanner Scale: Why It Should Not Be Used As An Age Determiner.

Age and Stage: Not A Direct Correlation.

Dr. Tanner In the late 1940s when Dr. James Mourilyan Tanner developed his Tanner System, virtually nothing was known about typical growth and development in children, including their puberty and maturity stages.

With his research, Dr. Tanner made important inroads into childhood development, identifying stages of development for both girls and boys, and these stages comprise the contents of “The Tanner Scale” or “Tanner Stages’, utilized by various types of doctors and SANE nurses, worldwide. The Tanner Scale is used to define sexual maturity using visual indicators in the development of the pubic and chest areas of a subject individual.

Because of its nature, the Tanner Scale is therefore widely used in courts by the prosecuting side in cases involving the possession, distribution or viewing of indecent images associated with child pornography offences.

However, there is a tendency in court to make the leap from the Tanner-Identifying, sexual-maturation stages to utilizing this scale to estimate approximate age of the victim. In a letter to the editor of the journal of “Pediatrics”, Vol 102, No. 6, December 1998, pp. 1494, Arlan L. Rosenbloom, MD, Department of Pediatrics, University of Florida College of Medicine in Gainesville writes, regarding the “Misuse of Tanner Puberty Stages to Estimate Chronological Age”.

“Rosenbloom’s letter refers to several US federal cases of alleged child pornography, in which seized materials were used as evidence against individuals identified in ‘sting’ operations, wherein government agents take over pornographic business: “In these cases the staging of sexual maturation (Tanner stage) has been used not to stage maturation, but to estimate probable chronological age. This is a wholly illegitimate use of Tanner staging: no equations exist estimating age from stage, and even if they did, the degree of unreliability in the staging the independent variable would introduce large errors into the estimation of age, the dependent variable. Furthermore, the unreliability of the stage rating is increased to an unknown degree by improperly performed staging, that is, not at a clinical examination but through non-standardized and, thus, unsuitable photographs.”

Dr. Patricia Speck, DNSc, APN, FNP-BC, DF-IAFN, FAAFS, FAAN, reinforces, “Tanner Scales are developmental scales, not defined by chronologic age, and are therefore not predictive of chronologic age. The bulk of children’s development follows the range of ages in the literature, but there are extremes on either side of the bell curve (outliers) and some development stages persist into adulthood, now known as a reflection of epigenetic and genetic environments.”

Dr. Speck further advises: “The RN is not prepared to interpret implications of Tanner Stage number assignment in the SANE role but is expected to know the variety of possible reasons for the outlier.”

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