Effectiveness of cooling therapy (cryotherapy) on leg pain and self-efficacy in patients with chronic venous disease: A randomized controlled trial.

Pain and self-efficacy were secondary outcomes, and the sample size was powered for skin blood flow, temperature and ulcer incidence, not for these symptoms, so the trial may have been unable to detect meaningful differences. 29.0% of the intervention group and 28.3% of the control group dropped out by month 9, so results may not represent all randomized patients. The enrolling study nurse could not be blinded because the cooling and placebo cuffs felt different, and the pain and self-efficacy outcomes here were self-reported. Pain was measured at baseline and at months 1, 3, 6 and 9, which may not capture day-to-day variability. The self-efficacy scale was mostly about chronic disease management, with only two items specific to leg pain, so it may not measure pain confidence well. Many participants had other conditions and took pain medications, and the study did not ask whether pain medicines were for venous disease or other problems, so pain changes may not be specific to chronic venous disease. Participants received free compression wraps, leg elevation pillows, phone support, study visits and $400 compensation, which may have improved adherence to standard care more than usual practice. Subgroup findings for diabetes, thyroid disease and antihypertensive medication were exploratory and not adjusted for multiple testing. Other venous symptoms such as heaviness, swelling, cramping, burning, throbbing, itching and aching may have influenced pain scores, and the analyses may not have separated pain from these symptoms.

The authors declared no conflicts of interest.

Do not read the significant pain drops in both groups as proof that cooling works. The cooling and placebo groups improved similarly, and no significant between-group differences were found. The diabetes and thyroid subgroup effects were exploratory and not adjusted for multiple testing.