Timing of the Baseline Assessment Confounds Efficacy Claims for a Post-surgical Telehealth Mindfulness Intervention After Lumbar Surgery

To the Editor:

Brintz et al. present an important feasibility and acceptability study of a post-surgical telehealth mindfulness-based intervention (MBI) for patients undergoing lumbar spine surgery. ¹ Their attention to intervention adaptation and patient feedback is commendable. However, a key methodological choice may overstate the intervention’s clinical impact and, if not addressed, could lead readers to misinterpret its efficacy. The study collected data at three time points: preoperative baseline, approximately 2 weeks postoperatively (pre-intervention), and 3 months postoperatively. The MBI began only after surgery, during the early postoperative period. Despite this, the primary analyses compared preoperative baseline values to 3-month outcomes. This approach combines the effects of surgery itself—which commonly drives substantial early improvement in pain and function—with any effect of the MBI. Consequently, changes from preoperative to 3-month follow-up cannot be interpreted as evidence of MBI-related benefit. The authors note that “paired t-tests were conducted to examine within-participant change from pre-surgery to 3 months post-surgery… Results are reported at each time-point (pre-surgery, 2 weeks post-surgery, and 3 months post-surgery) and as mean differences from pre-surgery to 3 months post-surgery.” ¹ This confirms that inferential testing focused on pre-surgery to 3-month changes rather than the pre-intervention (2-week) to 3-month interval, which would more accurately reflect the MBI’s contribution. Best practice dictates that when an intervention begins after a clinical event, analyses should measure change from the pre-intervention assessment forward (i.e., 2 weeks post-op → 3 months). ² This ensures that surgical recovery effects are not misattributed to the intervention. Furthermore, minimal clinically important difference (MCID) thresholds derived from preoperative baselines likely overestimate clinically meaningful improvement due to surgical effects alone. ³

To strengthen the study’s valuable feasibility insights, it would be useful to clarify whether improvements observed from preoperative baseline to 3 months reflect surgery, the MBI, or both. Specifically:

• Would reanalysis of outcomes from the 2-week (pre-intervention) to 3-month interval yield a clearer picture of the MBI’s effects?

• Would recalculating MCID attainment using the 2-week baseline alter the proportion of participants achieving clinically meaningful benefit?

Addressing these questions could more accurately define the MBI’s potential and better inform future randomized trials. We commend the authors for this innovative feasibility study and the journal for supporting high-quality spine surgery research.