Signal Prioritisation

Validating a signal answers "is this worth investigating," but it doesn’t answer "how urgently, relative to everything else on the team’s plate." Any active PV organisation is managing multiple validated signals simultaneously, against a fixed amount of medical reviewer time, and prioritisation is the deliberate process of deciding which signals get investigated first, second, and eventually, rather than treating every validated signal as equally urgent.

That prioritisation weighs several factors together rather than any single one in isolation. Severity carries substantial weight — a modestly strong signal for a potentially fatal or irreversible outcome typically outranks a much stronger statistical signal for a minor, fully reversible one, because the cost of a delayed response is so much higher in the first case. Strength of evidence matters too — a signal supported by convergent evidence from multiple sources (as Lesson 7.2 covered) generally outranks one resting on a single data source, all else equal.

Population exposure is a factor that surprises people encountering this for the first time: a comparatively weak signal on a very widely prescribed drug can genuinely outrank a stronger signal on a niche, rarely-used one, simply because the number of patients potentially affected is so much larger in the first case. A rare event pattern in a drug taken by millions of patients represents a much larger absolute public health exposure than the same statistical strength of signal in a drug taken by a few thousand.

And prioritisation isn’t a one-time decision — it’s revisited as new evidence accumulates. A signal ranked as lower priority today, when evidence was thin, can move up the queue substantially as more cases accrue, as literature support emerges, or as a related signal in the same drug class strengthens the biological plausibility case. Documenting the prioritisation reasoning, and updating it as circumstances change, is itself part of a defensible signal management process — exactly the kind of record an inspector or auditor will look for.