On extracting information about hadron-nuclear interaction from hadronic atom level shifts

It is argued, that adjusting strong potentials directly to observed hadronic atom level shifts may lead to significantly different scattering lengths, than those, predicted by the Deser formula. On the example of the 1s level shift of kaonic hydrogen it is demonstrated, that the usually adopted Deser values deduced from the two recent measurements in KEK and by the DEAR Collaboration $a_D({\rm KEK}) = 0.78 - 0.49i$ fm and $a_D({\rm DEAR}) = 0.47 - 0.3i$ fm should be replaced by $a_s({\rm KEK})\simeq 0.85 - 0.62i$ fm and $a_s({\rm DEAR})\simeq 0.49 - 0.35i$ fm, correspondingly.