Suppose, in the monitoring scenario already suggested, 20 of 100 people have the target phenotype and the cutoff has 80% sensitivity and 90% specificity, all hypothetical inputs. The cutoff would select 24 people for monitoring: 16 with the phenotype and eight without it, while missing four with the phenotype. That gives a concrete workload, but judging whether 20% prevalence makes this reasonable still requires deciding whether the monitoring saved justifies those four missed cases.
Geography should remain a descriptive stratum unless constituent profiles and pathway readouts vary consistently by origin, since that evidence determines whether origin can support mechanistic subgrouping.
That distinction changes the validation target. If the markers form a pathway, validation should test temporal ordering and whether the upstream marker adds predictive value through the proposed downstream changes. If they are parallel consequences of disease burden, the panel can still be evaluated as a multivariable risk signature, but shifts in one marker should not be interpreted as evidence that the others will follow. The downstream decision is therefore whether to use the panel for mechanistic stratification or only for outcome prediction.
