Analysis script for the See Sodium to Treat (SSTT) study

Abstract

# See Sodium to Treat (SSTT) — Analysis Code This repository contains the statistical analysis code for the SSTT study,which investigated the effect of oral potassium chloride (KCl) supplementationon muscle sodium content and blood pressure in patients with hypertension. ## Contents | File | Description ||------|-------------|| `SSTT_script_upload.R` | Main analysis script (R). Reproduces Table 1, Table 2, and the Figure 3 / Online Supplemental Figure 1 regression statistics. || `sessionInfo.txt` | R and package versions used to produce the reported results. | ## Data The analysis requires the following data files, placed in the working directory: | File | Description ||------|-------------|| `SSTT_wide.RData` | Processed wide-format data (one row per participant; outcomes at Visit 1 and Visit 2). || `SSTT_long.RData` | Processed long-format data (one row per participant-visit). || `SSTT_data.xlsx` | Source data including demographics, medications, and aldosteronism subtype (PA/SA). | **Data availability:** The study data are individual-level clinical data and areavailable to qualified researchers on request to the study sponsor with a validresearch protocol (see the Data Availability statement in the manuscript). Thedata files are **not** included in this repository. ## How to run 1. Install R (version 4.6.0 or compatible) and the required packages:```r install.packages(c("tidyr", "dplyr", "readxl", "table1", "lme4", "emmeans", "pbkrtest"))```2. Place the three data files (above) in your working directory.3. Set the working directory in `SSTT_script_upload.R` (uncomment and edit the `setwd()` line), or run R from that directory.4. Run the script:```r source("SSTT_script_upload.R")``` ## What the script produces - **Table 1** — baseline comparisons (Student's t-test for continuous variables; Fisher's exact test for categorical variables; Welch and Mann-Whitney U are shown as a non-determinative robustness check).- **Prescribed KCl dose** — between-group Welch two-sample t-test.- **Table 2** — linear mixed-effects model contrasts (within-group effect of KCl, Visit 2 vs Visit 1; between-group HA vs EH at each visit), with Kenward-Roger degrees of freedom (via pbkrtest) and exact p-values.- **Figure 3 / Online Supplemental Figure 1** — linear regressions of the change in muscle Na relative to changes in plasma K and the plasma Na/K ratio, overall and by group.- **Session information** — R and package versions (`sessionInfo()`). ## Software versions Analyses were performed in R version 4.6.0. Exact package versions are recordedin `sessionInfo.txt` and at the end of the R script.