Comparison of pubertal assessment methods in 9-year-old Spanish children

Background Puberty is an important developmental milestone, and its timing has been associated with health outcomes across the life course. However, the gold standard for physical assessment, clinician-assessed Tanner staging, can be difficult to implement in large epidemiological studies, highlighting the need for alternatives. This study aimed to compare nurse assessments of Tanner stages with parental evaluations of Tanner stages and the Pubertal Development Scale (PDS, using the Carskadon and Shirtcliff algorithms) and to examine their associations with salivary testosterone and estradiol levels. Analyses were additionally stratified by body mass index (BMI) category. Methods The study included 396 Spanish children aged 9 years (50% girls; recruitment: 2013–2014). Cohen’s kappa (κ) was used to assess physical scale agreement (stage 1 vs. stage 2+), both overall and stratified by BMI categories (low-normal vs. high). Regression analyses estimated the prevalence ratio (PR) of initiated puberty associated with sex steroid hormone levels, overall and by BMI strata. Results Nurses determined that 68% of girls and 49% of boys had reached Tanner stage 2+. Agreement with nurse-assessed Tanner staging was almost perfect for parent-assessed. Tanner in girls (κ = 0.86) and substantial in boys (κ = 0.63), but lower for parent-reported PDS (κ range = 0.13–0.60), with moderate agreement in girls and slight to fair in boys. Comparable secondary sex characteristics showed good correlations with nurse-assessed Tanner for parental Tanner ( r = 0.85–1.00) and PDS ( r = 0.68–0.88) in both sexes. PDS and Tanner were associated with female testosterone, but only PDS with male testosterone and female estradiol (PR range = 1.21–2.11). Lower agreement between Tanner and PDS was observed in high-BMI girls (i.e., those with overweight or obesity). Conclusions Our findings support using parental Tanner and PDS as valid alternatives to clinician-assessed Tanner stages for evaluating sexual maturation at the age of 9, particularly in girls. Clinical trial number Not applicable.