Their scans showed a level of amyloid plaques very near the cutoff point for normal protein accumulation.
As in most studies, the 90th percentile of the normal population was considered as cutoff point.
The lowest quantile of the distribution gave the value defined as cutoff point between normal and impaired (lower) OGIS.
Cardiac iron overload was defined as R2*⩾50 1/s (corresponding T2*⩽20 ms), which was used as a cutoff point for normal and pathologically elevated cardiac iron.
In fact, the mean FMD value in those patients was over the cutoff point for normal endothelial function observed in our echocardiography laboratory.
This is consistent with the recommended >10% by the consensus report [ 4], despite the fact that the decision tree model derived the cutoff value from patient data while the consensus report established the cutoff point with normal subjects.
For statistical processing, several variables were converted to dichotomous values, based on experience, evidence from literature, or distribution of data following a normal Gaussian curve with a cutoff point at the mean.
Second, quantitative G6PD activity results for the reference test were categorized following WHO guidelines as normal or deficient using as cutoff point of 60% of the median activity observed in the corresponding population.
For specificity calculations, methylation in those samples can be interpreted as a normal methylation level when a cutoff point has been established based on analyses of methylation in the control group.
Finally, the proposed criterion of >7 h as the cutoff point for "normal" sleep duration is based on self-reported duration, whereas in large epidemiological studies, i.e., the SHHS or Coronary Artery Risk Development in Young Adults (CARDIA) study, the average objective sleep duration is ∼6 h, which is very similar to that of our sample (24, 25).
