# Can pROC coord function return an approximate threshold for sensitivity when not available in the coords matrix?

I am currently using pROC in R to construct ROC curves and extract optimal coordinates for binary classification.

I want to set a manual sensitivity of 90% however I receive NA for this threshold when I run the following code yet performance metrics (sensitivity, specificity, etc.) are still being returned:

pROC::coords(roc_curve, x = 0.9, transpose = FALSE,
ret = 'all', input = "sensitivity")


Is there a reason the threshold for this sensitivity is not returned while other metrics are? Unfortunately, the next nearest sensitivity is either 95% or 82%. I was contemplating whether interpolation for these sensitivities is possible or if another method would be more appropriate?