INVOKED Power
Dihua Xu
September 19, 2016
Aim 1
Determine the effect of higher versus standard dose influenza vaccine on AKI
- Sample: All patients (n=8,800)
- Exposure: High vs standard dose vaccine
- Outcomes: AKI during hospitalization (present or absent; estimated to occur in 15-20% of 900 hospitalizations)
X-axis is the relative Risk Reduction for High Dose Vaccine (\(1 - p_H / p_S\)). Each curve assumes a proportion of AKI hospitalization over All hospitalization. Therefore, total AKI hospitalization will be calculated by 1296 (composite events for main trial) TIMES 0.7 (70% hospitalization, 30% death) TIMES AKI hosp rate (each curve) DIVIDED BY 9300 (total number of subjects in the main trial) * 8800 (total number of subjects in our trial). Power is calculated by comparing two proportions.
Aim 2
Determine the effect of higher versus standard dose influenza vaccine on death/cardiopulmonary hospitalizations in patients with CKD
- Sample: CKD patients (n=2,640)
- Exposure: High vs standard dose vaccine
- Outcomes: Death or Cardiopulmonary hospitalization (present or absent)
X-axis is the relative Risk Reduction for High Dose Vaccine (\(1 - p_H / p_S\)). Each curve assumes a proportion of CKD population in the whole cohort. Power is calculated by comparing two proportions.
Aim 3
3.1 Higher vs standard is associated with greater frequency of adequate immune response, as assessed by doubling of geometric mean antibody titers at 4 weeks
- Sample: CKD (n=200)
- Exposure: High vs standard dose vaccine
Outcomes: Doubling of geometric mean titer (present or absent)
3.3: Influenza vaccination is associated with the development of anti-HLA antibodies
- Sample: CKD (n= 200 patients)
- Exposure: High vs standard dose Vaccine
Outcomes: De novo anti HLA antibodies (present or absent)
I combined session 3.1 and 3.2 because both of them are comparing High versus Standard with an binary outcome. Each curve represent proportion of “present” in the standard dose, and X-axis is the relative Risk Reduction for High Dose Vaccine (\(1 - p_H / p_S\)). Power is calculated by comparing two proportions.