Screening tool
The optimal cut off value for the model positivity criterion was determined by comparison of test classification measures (sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV)) at different cut off values. We prioritized PPV and specificity over NPV and sensitivity, in order to minimize the number of women that are erroneously classified as having an adequate intake. A positive test result indicated an adequate calcium intake.
Finally, we combined the probability scores resulting from the prediction model into a risk assessment table with corresponding predictors and their intake frequency ranges. Risk scores were color coded for high (red), medium (orange) and low (green) probabilities of having an inadequate calcium intake.