# Exploratory Study into the Classification Agreement between Self-Reported Age of Menarche and Calculated Maturity Offset in Adolescent Girls: A Two-Year Follow-Up Study

## TL;DR

This study explores how well self-reported age of menarche matches calculated maturity in South African girls over two years.

## Contribution

The study introduces a non-invasive method for classifying maturity status using statistical analysis in adolescent girls.

## Key findings

- Statistical methods showed potential to categorize maturity groups using maturity offset equations.
- Classification accuracy declined significantly with increased age beyond peak height velocity (PHV).
- Results suggest caution in applying maturity offset equations across different populations due to unique growth patterns.

## Abstract

Menarche is a significant pubertal event influencing girls’ participation in physical activity. As menarche is a sensitive matter, a non-invasive substitute is needed to help classify girls’ maturity status and provide physical literacy to them in this regard. The objective of this exploratory study was to investigate the classification agreement between self-reported age of menarche and calculated maturity offset in adolescent girls from South Africa by making use of various statistical methods. Fifty-eight girls, n = 13 pre- and n = 45 post-menarche (Status Quo method) aged 13.51 ± 3.51 years at baseline, were analyzed (2010–2012). Independent t-testing, cross-tabulation, Roc Curve statistics and logistic regression were used to analyze the classification agreement between markers. All four statistical methods revealed the potential to categorize different maturity groups through the maturity offset equation, although the accuracy declined with increased age. A realized power of 0.92 was found for the group in the first year of the study, with a gradual and significant decline over time. Cross-tabs showed a significant moderate predictive effectiveness (Chi-square = 0.042) during T1, closer to PHV (13.51 years) although also declining significantly with increased age (T2, 14.51 years) beyond PHV (Chi-square = 0.459). Although positive results were found, caution must be used when using maturity offset equations in different homogenic populations due to their unique growth characteristics.