"mild severity" is a correct and usable phrase in written English.
You could use it when making comparisons between different forms of severity. For example, "His illness was of mild severity and so was able to be treated with medications."
Color photographs of representative mild (severity score = 1) and severe (severity score = 2) skin lesions are shown in Supplemental Material, Figure S1 (http://dx.doi.org/10.1289/ehp.1205381).org/10.1289/ehp.1205381
CTS of mild severity is commonly treated with wrist splint but for moderately severe symptoms surgical treatment is often required [ 3].
The utilization was lowest (13.83%) for those with very severe disability, whereas that was the highest (19.38%) for those with mild severity.
We demonstrated semantic hyperpriming in stabilized schizophrenic patients with mild severity of symptoms.
Treatment response was defined as achieving a CGI-S score of ≤2 (mild severity to no symptoms); remission was defined as a CGI-S score = 1 (no symptoms).
The severe group (IA/LV > 19%%) had significantly lower MAP and higher lactate values than the mild severity group (Fig. 87, top panel).
The effect of the traumatic brain injury of mild severity (mTBI) on the cognitive functions influences on the educational activities of adolescents in school and the quality of life in general.
Pathological disturbances represent an exaggeration of normal age-related changes, as exemplified by discriminative objective findings in sleep architecture and consolidation when comparing individuals with Alzheimer's disease (AD) of even mild severity to controls.
In RB-ILD there is centrilobular or paraseptal emphysema in the upper lobes, which is of mild severity despite the fact that most of the patients are heavy smokers.
We studied 43 individuals with AD of mild severity and 22 individuals without dementia on a battery of tests designed to measure multiple aspects of basic and higher-order visual perception and cognition.
All local PIRs were of mild severity.
