Differences in complication rates among the centres in the SPACE study

Neuroradiology. 2008 Dec;50(12):1049-53. doi: 10.1007/s00234-008-0459-6. Epub 2008 Sep 23.


Introduction: Despite the high grade of standardisation of study protocols, there is still room for variability among the centres in specific treatment aspects. We evaluated the treatment risk in stent-protected angioplasty of the carotid versus endarterectomy (SPACE) associated with the specific patient enrollment rates of the centres.

Materials and methods: The analysed endpoints were ipsilateral stroke or death [primary outcome event (pOE)] and any stroke or death [secondary outcome event (sOE)] until 30 days after treatment. A binary logistic regression analysis with random effects was performed separately for each treatment arm. The centres were secondarily categorised in three classes: I) > or = 25 patients enrolled, II) ten to 24 patients and III) <10 patients and a hierarchic log linear model was fitted to test the three-way interaction of treatment, number of patients per class and outcome.

Results: The random effects logistic regression analysis in the carotid artery stenting (CAS) arm proved a significant increase in pOE with decreasing number of patients enrolled (-0.0190 +/- 0.0085, p = 0.025, deviance 35.7 with 32 df), whereas no such effect was found in the carotid endartectomy (CEA) arm (-0.010 +/- 0.008, p = 0.24, deviance 39.78 with 32 df). In the log linear model, there was a significant interaction between treatment, number of patients per centre and sOE (p = 0.023). The odds ratios for sOE in the enrollment classes (CAS vs. CEA) were 0.98 (95% CI 0.50-1.94, p = 0.95) for class I, 1.13 (95% CI 0.47-2.77, p = 0.77) for class II and 11.56 (95% CI 1.40-253.45, p = 0.01) for class III centres.

Conclusion: Despite rigorous standardisation and quality requirements for operator qualification, there seemed to be a decrease in complication rate with increasing patient enrollment numbers in the CAS arm while this signal could not be detected in the CEA arm of SPACE.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angioplasty, Balloon / adverse effects*
  • Angioplasty, Balloon / statistics & numerical data
  • Carotid Stenosis / therapy*
  • Clinical Protocols
  • Endarterectomy, Carotid / adverse effects*
  • Endarterectomy, Carotid / statistics & numerical data
  • Humans
  • Logistic Models
  • Patient Selection
  • Risk Factors
  • Sample Size
  • Stents / adverse effects*
  • Stents / statistics & numerical data
  • Stroke / epidemiology*
  • Treatment Outcome