Examples for outcomes depending on lengths of follow-up and frequency of events
| Outcome | Short follow-up | Long follow-up | ||
|---|---|---|---|---|
| Rare events | Frequent events | Rare events | Frequent events | |
| Death | Population: Hypertrophic cardiomyopathy Intervention: Physical activity Aim: Incidence of sudden death after recreational sports Practical: Ethical concerns against experimental allocation | Population: Malignancies Intervention: Unrelated and mismatched haematopoietic stem cell transplantation Aim: Incidence of death due to graft rejection Practical: Ethical concerns may arise to randomise patients | Population: Acquired severe aplastic anaemia Intervention: Long-term immunosuppressive therapy Aim: Incidence of secondary malignancies Practical: Ethical concerns against randomised allocation | Population: High-risk neuroblastoma Intervention: Retinoic acid as postconsolidation therapy after high-dose chemotherapy followed by autologous haematopoietic stem cell transplantation Aim: Event-free survival in comparable groups Practical: Randomised allocation is required to provide comparable groups |
| Disease | Population: Neuroblastoma Intervention: Watchful waiting Aim: Incidence of spontaneous regression Practical: Ethical concerns against experimental allocation | Population: Malignancies Intervention: Unrelated and mismatched haematopoietic stem cell transplantation Aim: Incidence of acute graft vs host disease Practical: Randomised allocation is required to provide comparable groups | Population: Malignancies Intervention: Radiotherapy Aim: Incidence of myelodysplastic syndrome Practical: Ethical concerns against randomised allocation | Population: Diabetic foot ulcer Intervention: Negative pressure wound therapy Aim: Incidence of wound closure Practical: Randomised allocation is required to provide comparable groups |
| Discomfort Disability Dissatisfaction | Population: Acquired severe aplastic anaemia Intervention: Matched sibling donor haematopoietic stem cell transplantation Aim: Incidence of graft failure as an early and rather unexpected serious complication only observed in the transplant group not in the non-transplant group Practical: Ethical concerns against experimental allocation | Population: Low-risk localised prostate Intervention: Radical prostatectomy Aim: Incidence of erectile dysfunction and urinary incontinence Practical: Randomised allocation provides comparable groups | Population: Advanced prostate cancer Intervention: hormonal androgen deprivation therapy Aim: Incidence of emotional distortion Practical: Randomised allocation provides comparable groups | Population: Diabetic foot ulcer Intervention: Negative pressure wound therapy Aim: Incidence of amputation Practical: Randomised allocation is required to provide comparable groups |