Lay Coach-Led Early Palliative Care for Underserved Advanced Cancer Caregivers: The Project ENABLE Cornerstone RCT

Multi-Year Funded Merit Award - Years 6-7: For this 2-year merit award funding, we propose to continue enrollment beyond 24-weeks and extend follow-up with participants long-term, through the patient's end of life and for 24 weeks post-patient death to test the effectiveness of Cornerstone on caregiver and patient outcomes compared to usual care.

Aim 1: Test the long-term effects of Cornerstone on caregiver outcomes at the patient's end of life.

Hypothesis Primary: Compared to usual care, Cornerstone caregiver participants will report lower distress as measured by the Hospital Anxiety and Depression Scale in the 24 weeks prior to death. We considered: A) a terminal decline longitudinal design with baseline and at least two time points prior to a patient's end of life (weeks 24 and 12 prior to death) comparing CGs randomized to ENABLE Cornerstone vs. usual care; B) 80% power, (1-β=.8) to detect a between-group mean difference, if it exists, in the outcome scales included in Specific Aim 1 (CG distress, QOL, burden); C) a significance level adjusted with a False Discovery Rate approach (5% FDR) assuming intervention effects on at least half of the effective outcome scales included in Specific Aim 1, i.e., α=.05×.5=.025; D) intra-subject correlation of ρ=.5 between repeated measurements; and E) data from 150 CGs with deceased patients (approximately equally split between study groups), composed of 67 deaths that occurred during the initial 104 study weeks plus additional 83 patient deaths during 132 additional weeks of recruitment and follow-up. Under these assumptions, for a continuous outcome such as the primary outcome scales (HADS-Anxiety and HADS-Depression), the variance of the within-subject average of three assessments prior to death is V_avg=(σ^2⁄3)(1+2ρ), where σ^2 is the variance of the outcome and ρ is the intra-subject correlation. Standardizing the outcome (σ^2=1) to compute a detectable difference as an effect size (Cohen's d), results in the variance of the within-subject average estimated at V_avg=(1⁄3)∙(1+2∙.5)=.67. Thus, the detectable time-averaged mean difference between the study groups over the three timepoints, given a sample size n for each of the two study groups, can therefore be estimated as d=(Z_(α⁄2)-Z_(1-β))∙(√((2V_avg)⁄n)), where Zk is the kth percentile of the standard normal distribution. So, with a sample size of n=75 per study group the detectable difference is d≈.34; and in terms of precision of the estimate, with a standard error of ├ √((2V_avg)⁄n)┤= .13 the sample size allows a 97.5% confidence interval for d of half-width .30.

Hypotheses Secondary: Compared to usual care, Cornerstone participants will report better a) QOL (PROMIS Global Health 10)40,54 and b) lower burden (Montgomery-Borgatta Burden Scale)39 in the 24 weeks prior to death.

Aim 2: Test the long-term effects of Cornerstone on patient outcomes at end of life.