A Cochrane review included 7 studies (6 primary cryoplasty and one adjunctive cryoplasty study) with total of 478 subjects. Follow-up ranged from 30 days to 3 years. Target lesion patency measured at various time points in 2 primary cryoplasty studies showed no statistically significant difference between the treatment groups. The adjunctive cryoplasty study showed that cryoplasty was associated with improved patency only at 6 months (OR 5.37, 95% CI 1.09 to 26.49, 1 study, n = 90), not at other time points. Restenosis measured per patient (2 primary cryoplasty studies) showed no statistically significant difference between the treatments. Restenosis measured by lesion (2 primary cryoplasty trials) showed a statistically significant difference only within 24 hours of the procedure (OR 0.08, 95% CI 0.04 to 0.18, 1 study, n = 192) favouring cryoplasty.
Need for re-intervention was not significantly different in primary cryoplasty trial participants (per participant: OR 0.27, 95% CI 0.05 to 1.52; 2 studies, n = 241, I2 = 89%; per lesion: OR 0.59, 95% CI 0.06 to 5.69; 3 studies, n = 307, I2 = 94%). The adjunctive cryoplasty trial did not report on need for intervention. Immediate success of procedure (within 24 hours) was not significantly different in primary cryoplasty trial participants (per participant: OR 1.63, 95% CI 0.14 to 19.55; 3 studies, n=266, I2 = 95%; per lesion: OR 1.81, 95% CI 0.19 to 17.36, n = 307, I2 = 90%). The adjunctive cryoplasty trial reported 100% success. Limb loss, deaths from all causes and the risk of complications immediately after treatment showed no statistically significant differences between the treatments.
Comment: The quality of evidence is downgraded by study limitations (lack of allocation concealment and blinding), by inconsistency (variability in results), and by imprecise results (few patients and outcome events).