Which phenotype use can the validation design support?

A computable phenotype may show acceptable agreement with chart review yet remain unsuitable for its proposed use. Analytical validity asks whether the algorithm reproduces the reference labels. Clinical validity asks whether those labels identify the intended clinical state across relevant populations and sites. Intended use then determines which errors matter.

For cohort enrichment, moderate sensitivity may be acceptable if positive predictive value is high. Outcome ascertainment may require balanced sensitivity and specificity across exposure groups. Clinical decision support requires stronger evidence because errors can affect individual care. Portability studies also show that documentation and implementation differences can change performance after transfer.

When reporting phenotype validation, should authors name the intended use before selecting the reference standard and performance thresholds? Which claim should be withdrawn if the study reports chart-review agreement but does not test transportability, subgroup performance, or consequences of false classifications?