Early PUSH Response, Maintenance, and Short-term Wound Dynamics: A Secondary Landmark Analysis of the RISE_UP Randomized Trial

Abstract

Introduction. Serial assessment with the Pressure Ulcer Scale for Healing (PUSH) supports monitoring of pressure ulcers, but the interpretation of early improvement and short-term fluctuations remains uncertain. This study examined whether day-7 and day-14 PUSH improvement was associated with improvement at approximately 4 weeks, whether early responses were maintained, and whether early improvement identified faster subsequent change.

Methods. This exploratory post hoc landmark analysis used data from the RISE_UP randomized trial, which compared standard care with or without adjunctive blue-light photobiomodulation in 48 rehabilitation inpatients with stage 2 or stage 3 pressure ulcers. Assessments through day 35 were included. Early and week-4 responses were defined as any PUSH reduction from baseline. Documented closure was carried forward as PUSH = 0; other missing outcomes were not imputed in the main analysis. Risk ratios were adjusted for treatment group, ulcer stage, and baseline PUSH. Additional analyses examined response maintenance, incremental post-landmark change, subsequent slopes, and visit-to-visit worsening.

Results. Forty-three participants contributed to both landmark analyses. At day 7, 23/25 early responders (92.0%) remained improved at week 4, compared with 9/18 nonresponders (50.0%; adjusted risk ratio, 1.86; 95% confidence interval, 1.10–3.14). At day 14, corresponding proportions were 25/29 (86.2%) and 7/14 (50.0%; adjusted risk ratio, 1.89; 95% confidence interval, 1.003–3.573). Among early responders, 64.0% at day 7 and 75.9% at day 14 remained below baseline at every subsequent assessment. Early change showed negligible correlations with incremental post-landmark improvement, and adjusted slope analyses provided no clear evidence of faster subsequent improvement. Across all 48 participants, 38 (79.2%) experienced at least one visit-to-visit PUSH increase of ≥1 point, affecting 78/432 transitions (18.1%).

Discussion. Early response was associated with improvement at follow-up but did not clearly identify faster subsequent improvement. Delayed responses and frequent fluctuations limit the interpretation of isolated assessments. The small, single-centre sample, exploratory design, and response threshold without established clinical importance warrant cautious interpretation. Early PUSH changes should be interpreted within serial wound assessments. Absence of early improvement alone does not establish treatment failure. Prospective external validation is required before early-response thresholds can guide clinical decisions.