Thursday, April 9, 2009

RCT of Kyphoplasty

Lancet has the results of a multi-national randomized controlled trial of balloon kyphoplasty for vertebral compression fractures. This was an industry-funded trial of ~300 patients with 1-3 acute or subacute (less than 3 months old - mean was 6 weeks old), painful (4/10 or greater) VCFs who were randomized to KP or medical management/routine supportive care (meds, braces, therapy, etc.). They followed patients for 12 months, although the primary outcome was changes in the SF-36 quality of life scale at 30 days. Intention to treat analysis was used; as far as I can tell no one (not even the researchers administering the follow up surveys) was blinded.

Health-related quality of life was improved at 1 month (statistically and likely clinically significant) in the KP group; this had mostly attenuated by a year (although remained statistically significant). Pain improved markedly in the KP group in the short term: from (median) 7/10 before the procedure to ~3.5/10 immediately afterwards. By one month the difference was about 2/10 points between groups (3.5/10 vs. 5.5/10); this gap slowly closed over the year and was about 1/10 points at 12 months (3/10 vs. 4/10). At one month 65% of control group patients were taking opioids vs. 45% in the KP group; this difference was gone by 1 year (both ~30%).

There was one serious procedure related adverse event (hematoma); 27% had cement extravasation (all aysmptomatic). Overall, rates of adverse events were similar. Cancer/myeloma-related VCF patients were included in the study although only 1% of the subjects had these so one cannot draw any conclusions specifically about cancer-related VCFs.

These is the best study done on KP and the results are supportive of KP: rapid and marked pain relief that endures for a year although over months, as presumably the non-KP patients' fractures heal, the benefits attenuate. The benefits in overall health-related QOL are less pronounced, but they're there at least for a few months. It is also reassuring that patients well over a month out from their fractures appear to get good benefit, although they did not present any analysis of whether time-from-fracture was related to the magnitude of the benefit. The biggest concern for me was the lack of blinding; not even in those administering the survey instruments. Patient-blinding is difficult with interventions like these (although it has been done, e.g. at Mayo in the use of sham-procedures in their controlled trial of celiac plexus blocks) of course, but blinding of those doing the analyses and data collection is ideal. In addition, this does not answer the question of whether simple vertebroplasty (which doesn't use balloons) is as efficacious as the more-expensive KP.

ResearchBlogging.orgWardlaw, D., Cummings, S., Van Meirhaeghe, J., Bastian, L., Tillman, J., Ranstam, J., Eastell, R., Shabe, P., Talmadge, K., & Boonen, S. (2009). Efficacy and safety of balloon kyphoplasty compared with non-surgical care for vertebral compression fracture (FREE): a randomised controlled trial The Lancet, 373 (9668), 1016-1024 DOI: 10.1016/S0140-6736(09)60010-6

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