Extent of individual expenses considered acceptable for participation in a clinical study.
The mean maximum travel time for regular outpatient or day-clinic visits at the study center (n = 30) was calculated to be 4.5 h (range 1-18 h, mean: mild 3.9 h, severe 5.71 h; younger 5.3 h, older 4.5 h). The maximally tolerated frequency of study visits (n = 29) was every 5.5 weeks (range 1–12 weeks) and of blood taking (n = 28) every 5.0 weeks (range every 1–12 weeks). Skin biopsies (n = 26) were considered to be taken not more often than every 17.0 weeks (range 4–104 weeks). Two patients (7.7%) stated to not allow this intervention at all (dots on the x-axis). Inpatient admission for 3.4 consecutive days (0–30 days; n = 25)) every 14.5 weeks (range 4–52; n = 24) was reported to be acceptable during the study period. According to this survey, a maximum of 1.2 dressing changes or applications of investigational topical treatments per day as well as 1.8 (range 1–5) study calls per week would be acceptable (n = 28)