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Evaluation of two methods of bone age assessment in peripubertal children in Zimbabwe
Farirayi Kowo-Nyakoko1, Celia L Gregson2, Tafadzwa Madanhire3
1MRC Lifecourse Epidemiology Centre, University of Southampton, Southampton General Hospital, Tremona Road, SO16 6YD Southampton, UK; Biomedical Research and Training Institute, 10 Seagrave Road, Avondale Harare, Zimbabwe; Department of Medical Physics and Imaging Sciences, University of Zimbabwe- Faculty of Medicine and Health Sciences, Parirenyatwa Group of Hospitals, Mazowe Street, Harare, Zimbabwe.
Insights
The Tanner and Whitehouse 3 (TW3) method is more precise for assessing bone age (BA) in Zimbabwean children than the Greulich and Pyle (GP) method. TW3 is recommended for evaluating skeletal maturity in this population.
Area of Science:
- Pediatric endocrinology
- Radiology
- Growth and development
Background:
- Bone age (BA) assessment is crucial for diagnosing growth disorders in children.
- The Greulich and Pyle (GP) and Tanner and Whitehouse 3 (TW3) methods are standard for BA estimation using hand-wrist radiographs.
- Sub-Saharan Africa (SSA) has a lack of BA validation studies, despite potential impairments from conditions like HIV and malnutrition.
Purpose of the Study:
- To compare BA measurements using GP and TW3 methods against chronological age (CA) in Zimbabwean children.
- To determine the most applicable BA assessment method for peripubertal children in Zimbabwe.
Main Methods:
- A cross-sectional study involving 252 children (8.0-16.5 years) in Harare, Zimbabwe.
- Manual assessment of BA using both GP and TW3 methods on hand-wrist radiographs.
- Statistical analysis included paired sample t-tests, Bland-Altman plots, and reliability assessments (ICC, coefficient of variation).
Main Results:
- TW3 showed better precision (1.5% inter-operator, 1.5% intra-operator) compared to GP (3.7% inter-operator, 2.4% intra-operator).
- No systematic difference was found between CA and TW3 BA in girls, and a smaller difference in boys (-0.43 years) compared to GP (-0.76 years).
- Agreement between CA and TW3 BA was consistent across age groups, unlike GP where agreement improved with age.
Conclusions:
- The TW3 method demonstrated superior precision and better agreement with chronological age in Zimbabwean children and adolescents.
- TW3 is the preferred method for bone age assessment in this population.
- GP and TW3 methods are not interchangeable for BA estimation due to significant differences in results.
Objectives:
Bone age (BA) measurement in children is used to evaluate skeletal maturity and helps in the diagnosis of growth disorders in children. The two most used methods are Greulich and Pyle (GP), and Tanner and Whitehouse 3 (TW3), both based upon assessment of a hand-wrist radiograph. To our knowledge no study has compared and validated the two methods in sub-Saharan Africa (SSA), and only a few have determined BA despite it being a region where skeletal maturity is often impaired for example by HIV and malnutrition. This study aimed to compare BA as measured by two methods (GP and TW3) against chronological age (CA) and determine which method is most applicable in peripubertal children in Zimbabwe.
Methods:
We conducted a cross-sectional study of boys and girls who tested negative for HIV. Children and adolescents were recruited by stratified random sampling from six schools in Harare, Zimbabwe. Non-dominant hand-wrist radiographs were taken, and BA assessed manually using both GP and TW3. Paired sample Student t-tests were used to calculate the mean differences between BA and chronological age (CA) in boys and girls. Bland-Altman plots compared CA to BA as determined by both methods, and agreement between GP and TW3 BA. All radiographs were graded by a second radiographer and 20 % of participants of each sex were randomly selected and re-graded by the first observer. Intraclass correlation coefficient assessed intra- and inter-rater reliability and coefficient of variation assessed precision.
Results:
We recruited 252 children (111 [44 %] girls) aged 8.0-16.5 years. The boys and girls were of similar mean ± SD CA (12.2 ± 2.4 and 11.7 ± 1.9 years) and BA whether assessed by GP (11.5 ± 2.8 and 11.5 ± 2.1 years) or TW3 (11.8 ± 2.5 and 11.8 ± 2.1 years). In boys BA was lower than CA by 0.76 years (95 % CI: -0.95, -0.57) when using GP, and by 0.43 years (95 % CI: -0.61, -0.24) when using TW3. Among the girls there was no difference between BA and CA by either GP [-0.19 years (95 % CI: -0.40, 0.03)] or TW3 [0.07 years (95 % CI: -0.16, 0.29)]. In both boys and girls, there were no systematic differences between CA and TW3 BA across age groups whereas agreement improved between CA and GP BA as children got older. Inter-operator precision was 1.5 % for TW3 and 3.7 % for GP (n = 252) and intra-operator precision was 1.5 % for TW3 and 2.4 % for GP (n = 52).
Conclusion:
The TW3 BA method had better precision than GP and did not systematically differ from CA, meaning that TW3 is the preferred method of assessment of skeletal maturity in Zimbabwean children and adolescents. TW3 and GP methods do not agree for estimates of BA and therefore cannot be used interchangeably. The systematic differences in GP BA assessments over age means it is not appropriate for use in all age groups or stages of maturity in this population.
