8.2. Primary Analyses (Survival) T he survival outcome from subjects in each experimental arm, Arm V and Arm VG, will be compared separately to the survival outcome from subjects in the control arm, Arm P. If either of these comparisons passes the statistical criterion specified previously, then the trial will be regarded as having met the statistical criterion for success. This section defines the statistical method and criterion for each of these s urvival analyses. T he survival analysis objective is to ascertain whether the survival time distribution for subjects randomized to the experimental arm is consistent with longer survival as compared to subjects randomized to the control arm. All randomiz ed subjects will be included in the primary survival analysis according to the randomized arm (intent- to-treat). 8.2.1. Imputation of Missing Efficacy Data I n general, there will be no imputation of missing data in efficacy analyses other than the primary endpoi nt (overall survival). I mputation of the primary endpoint may depend on the date of the first occurrence of an event associated with the endpoint. When the event has yet to occur the analysis will nonetheless require an analytical date be available for the analysis. These are known as censored or truncated dates. A censored date is the date of the most recent assessment for the event for a subject for which the event of interest has yet to occur and for which additional time may lead to observation of the event of interest. A truncated date is the date of a competing event that precludes the observation of the event of interest. The distinction between designating an analytical date as censored or truncated will depend on the purpose of the analysis and will be designated for each analysis. For example, if death is the event of interest and a subject is still alive and being followed for the date of death then the date last known alive is a censored date, whereas the date a subject withdraws consent for cont inued follow-up of vital status (a competing event) is a truncated date. The nature of the competing event will dictate whether the Bavarian Nordic, Inc. Statistical Analysis Plan Amendment 1 Protocol: BNIT -PRV -301 Date Issued: 29 June 2015 C onfidential 13 Revised: June 2015 competing event is permanent. For example, the date of death for a subject who has withdrawn consent may later become known passively from governmental death records. D ates associated with the primary endpoint with missing day of the month will be completed by imputing the missing day of the month as the 15th day of that month, provided another date to be used in the computation of an interval is not in the same month. If the day of the month is missing and the other date is in the same month, then the missing day of the month will be taken as half the distance to the beginning or end of the month (depending on expected sequenc e). If both dates to be used in the computation of an interval are missing day of the month then an interval of 15 days (plus or minus) will be used. D ates associated with the primary endpoint with both month and day of month missing will be imputed as Ju ly 1 of the known year provided another date in the same year is to be used in the computation of an interval. If both the month and day of the month are missing and another date in the same year is to be used in the computation of an interval, then the missing date components will be taken as the half the distance from the other date until the beginning or end of the year (depending on expected sequence). If both dates to be used in the computation of an interval are missing both month and day of the month then an interval of 180 days (plus or minus) will be used. 8.2.2. Survival Analysis Method I mputation of missing date parts will follow the rules previously specified. Competing events for death are “definite” lost to follow -up and withdrawal of consent for continued vital status assessments. Both of these competing events are subject to revision for an individual subject with the passage of time. T he primary analyses will be performed on the ITT set and will analyze subjects according to the randomized arm. The primary analysis will be repeated on the FAS as a sensitivity analysis. T he primary test of each endpoint will consist of a stratified logrank test for the test of the null hypothesis (STRATA <stratification -variable> / TEST=LOGRANK;). See Section 4.2 for the definition of the stratification variable. The significance of the logrank test will be assessed by referring the one-sided stratified logrank test P 1 to 0.0125, and the comparison will be said to meet statistical criterion if P 1 < 0.0125. N otes: •These analyses must be stratified: Anderson et al.