Complexity of analgesic regimen: The number of dif-
ferent analgesics, number of points in time as well as the
number of other medications will be calculated for each
patient.
Data analysis: Data files will be analyzed using IBM
SPSS Statistics 19.0. Data will be systematically ex-
amined for out of range values and data inconsistencies.
Appropriate descriptive statistics will be calculated for
all study variables. The analysis will follow an in-
tent-to-treat strategy with a level of significance at 0.05.
Although withdrawal is expected to be a random process,
participants who completed the study and those who did
not will be compared based on demographics, treatment
group and other salient variables. Change scores for each
patient as well as Cohen’s d will be calculated for each
variable of interest. To determine differences between
the change scores of the pre- and the post-assessments
regarding average and worst pain intensity between the
two groups, regression analysis will be applied.
2.9. Qualitative Substudy
Recruitment: A sample of 10 - 12 patients seems rea-
sonable to reach sufficient redundancy in the data. In the
beginning, consecutive patients will be invited to partic-
ipate. Later, purposive sampling will be used to ensure
variation (e.g., regarding age, gender, education, occupa-
tion, living situation, tumor entity and disease status).