Sas version 9.1 or higher

Descriptive statistics (n, mean, standard deviation) were calculated for
quantitative variables along with t-tests where appropriate; frequency counts by
category were to be given for qualitative variables along with Fisher’s exact
test where appropriate. Confidence intervals (CIs) were to be given where
appropriate. If not otherwise stated, these intervals are 2-sided in each case
and provide 95% confidence. Missing values were not replaced in the analysis of
efficacy. The sensitivities and specificities and respective 95% CIs for the
total population and 3 subgroups were calculated as average across the
assessments of 3 blinded readers taking into account the correlation between
multiple measurements (readers and segments) within the patient using an
extension of the approach by Obuchowski^{16 (link)} as described in Schwenke and Busse.^{17 (link)} Significance of differences was regarded if the 95% CIs for differences
did not overlap zero.
All analyses were performed using SAS Version 9.1 or higher (SAS Institute, Inc.,
Cary, NC, USA).

Student’s t-test or the Mann–Whitney U test were used for continuous variables, and the χ² test was used for categorical data. PFS was calculated using the Kaplan–Meier method. SAS version 9.1 or higher (SAS Institute Inc., Cary, NC, USA) was used for all statistical analysis.

The data were combined for an integrated analysis of the lumbar sample studies and from the indwelling catheter studies. Because each study and research group had different methods of sample collection, volume collected, and ELISAs, the data were transformed to a percentage of the mean in order to minimize the effects of the various extraneous factors. The data transformation was computed separately for Aβ40 and Aβ42.
It is well known that CSF amyloid concentrations are log-normally distributed [32 (link)] and all sample results were log-transformed. For the lumbar puncture results, the difference between the endpoint result and the baseline result was used as the primary response variable. For the repeated samples taken over 10–40 hours of indwelling catheter sampling, the concentrations were log-transformed and the mean concentration for each subject was computed. The difference from the mean concentration at each sampling time for each subject was computed. The differences were back-transformed and multiplied by 100 to obtain the percent concentration of the mean for each sample. The percent of the mean was used as the primary response variable.
All statistical programming and analysis was conducted in SAS version 9.1 or higher (SAS Institute Inc., Cary, NC, USA). The main statistical method used was the mixed procedure in SAS.