What is Incidence Rate and Why Does It Matter?
The incidence rate is the probability that a dog administered Librela could be affected by a suspected adverse drug reaction. A team of independent data scientists analyzed Zoetis claims. A lack of clarity regarding the number of dogs treated (as opposed to doses sold) likely masks a much higher incident rate.
Factoring in the lack of disclosure or transparency from Zoetis, and a victim reporting rate estimated at <5%, all available data yields an incident rate of 1/110. With a victim reporting rate that low it can be reasonably concluded the actual incident frequency is drastically higher than 1/110.
Are incident rates different for cats?
Solensia data has always stuck out because of its alleged* ADR (adverse drug reaction) incidence rate of 0.3% (1 in 333), a full 66% higher than Librela’s alleged* 0.18% (1 in 556). The other blinking red light has been Solensia’s extremely high raw ADR numbers.
Zoetis sells 3.5-4 doses of Librela for every dose of Solensia, so one would expect Solensia’s ADR numbers to be around a quarter (~5,000) of Librela’s (~20,000). Instead, as of this publication, ~10,000 cats have been affected by a Solensia sADR. It’s *double* of what one would expect.
This data demonstrates that these two medications (allegedly) adversely affect both species—thus the problem may lie not with the animals being treated but the monoclonal antibody itself. A high correlation across two species is a significant signal. There are various concepts across disciplines—confirming indicator, convergent validity, etc.—to describe this relationship and its eventual bearing on causality.