Letter regarding “Value of repeated health screening in 259 apparently healthy mature adult and senior cats followed for 2 years”

The article by Mortier et al. is a well-written report of a useful study that provides important epidemiologic data regarding detection of common health conditions in mature and senior cats. However, the authors imply at several points that screening apparently healthy cats is necessarily beneficial, that it is worthwhile as long as abnormalities are detected, and that their results “argue for greater health screening in cats ≥7 years of age” because “all cats [of this age] would benefit.”

This is an oversimplified and potentially misleading characterization of screening programs and of the findings. It ignores many factors that influence the likelihood of achieving the true goals of screening, which are to decrease mortality and other negative impacts of disease and improve patient outcomes.

The current study does not provide evidence that the screening employed would meet those aims, or that the benefits of such a program would exceed the harms. Demonstrating such benefits would require comparing outcomes in cats that are screened with those that are not. Although it is plausible that detection of disease before observable clinical signs might lead to better outcomes, this outcome cannot be assumed, and it may not turn out to be true. Screening often has been shown to result in overdiagnosis and net harm in humans,¹ and the same may be true in veterinary patients.² This study also does not answer the crucial question of whether outcomes for the subjects would be better, on average, if the conditions identified are diagnosed when still occult or at a later time when the cats present with clinical signs.³

Finding the optimal balance between screening that not only detects abnormalities but improves clinical outcomes and the alternative (ie, increased misdiagnosis, overdiagnosis, cost of care, and potential direct patient harm) requires evidence not available in this report. This includes evidence that earlier detection and intervention results in better outcomes and, ideally, prospective studies comparing long-term outcomes in patients with and without screening. Evidence in human medicine shows that screening benefits some patients, harms others, and can substantially increase healthcare costs and, without adequate information, it is impossible to determine whether the net impact of screening in veterinary patients is beneficial, harmful, or neutral.