The first study to examine the ability of the City Birth Trauma Scale to predict diagnostic PTSD has been published. Flavia Osorio and her team in Brazil compared the City Birth Trauma Scale to the Structured Clinical Interview for DSM-5 and found symptom scores of 29 or more had a diagnostic accuracy of 86.7%, with a sensitivity of 72% and specificity of 83% – see https://pubmed.ncbi.nlm.nih.gov/34570669/
More research is needed to see if the same cut-off score is applicable in other countries.