Implementing a Digitally-enabled Community Health Worker Intervention for Patients With Heart Failure
Phase: NA
Conditions: Heart Failure，Congestive
Sponsor: Massachusetts General Hospital



4.4 Statistical Design and Power 
1. Statistical Analysis 
For Aim 1, transcription and interviewer/moderator notes will be uploaded into NVivo 10 for analysis. Dr. Carter 
and a research coordinator will first independently code patient data followed by CHW focus group data. The 
framework used will include an approach where two researchers will familiarize themselves with the raw data, 
independently identify key themes raised by respondents, and reapply this thematic framework by rearranging 
the raw data into themes and relationships. Associations between themes, user characteristics, and outcomes 
will be identified. Each coder will perform content analysis to capture themes associated with each focus group 
and patient interview. These will be compared by gender and age. Intercoder reliability will be achieved through 
an iterative process of comparing each level of coding (themes and codes) while discussing discrepancies and 
comparing results to the raw data until Kappa> 0.80 is achieved. Themes will be reviewed and discrepancies 
discussed with a third researcher, Dr. Donelan, with expertise in qualitative data. Dr. Thorndike will also perform 
an expert review of the data analysis and interpretation. Dr. Carter will review patient transcripts weekly with 
interviewer staff to discuss emerging themes, modify the patient interview instrument as needed, and assess for 
theoretical saturation. If necessary, Dr. Carter will make modifications to the patient interview instrument to 
increase the contextual relevance. Due to the small number of focus groups used (n=2), no modifications will be 
made to the CHW focus group instrument after the first focus group occurs. 
For Aim 2, interview transcriptions and interviewer notes will be reviewed weekly by Dr. Carter and themes will 
be categorized as described above in Aim 1 and in the Research Strategy section E.7. These themes will be 
used to refine the intervention prior to each new iteration (maximum of 3 study runs) informing the RCT 
intervention in Aim 3. Dr. Carter’s review of the REDCap core competency/activity log checklists and digital 
platform patient use data will also inform intervention refinement. 
For Aim 3, data analysis will include the following: Summary statistics for the acceptability and feasibility of the 
intervention will be reported with 95% confidence interval. For effectiveness of the intervention, the proportion 
with 30-day readmissions or missed appointments will be compared using Pearson’s χ2 tests and the number of 
ED visits will be compared using a Poisson model.  Other variables in the post-study questionnaires will be 
compared between the two groups in a separate analysis. The relationship between potential predictors and 
outcomes will be explored. In Dr. Carter’s prior CHW clinical trial, <3% of patients were lost to follow-up and 
similar rates are expected here. REDCap activity log and patient use assessments will also be summarized. 
For Aim 3, power calculations will be based on a sample n=50. The study will have a minimum of 83% power to 
detect a 40% difference between the two groups with a two-sided significant level of 0.05. As a pilot study, the 
sample size is not powered to detect small differences between the two groups. However, the study will provide 
estimates for the effect size which can be used in the future R01 study.