Systematic review and simulation study of ignoring clustered data in surgical trials. BJS 2018; 105: 182-191.
Published: 5th February 2018
Authors: S. Dell‐Kuster, R. A. Droeser, J. Schäfer, V. Gloy, H. Ewald, S. Schandelmaier et al.
Multiple surgical procedures in a single patient are relatively common and lead to dependent (clustered) data. This dependency needs to be accounted for in study design and data analysis. A systematic review was performed to assess how clustered data were handled in inguinal hernia trials. The impact of ignoring clustered data was estimated using simulations.
PubMed, Embase and the Cochrane Library were reviewed systematically for RCTs published between 2004 and 2013, including patients undergoing unilateral or bilateral inguinal hernia repair. Study characteristics determining the appropriateness of handling clustered data were extracted. Using simulations, various statistical methods accounting for clustered data were compared with an analysis ignoring clustering by assuming 100 hernias, with a varying percentage of patients having bilateral hernias.
Of the 50 eligible trials including patients with bilateral hernias, 20 (40 per cent) did not provide information on how they dealt with clustered data and 18 (36 per cent) avoided clustering by assessing the outcome by patient and not by hernia. None of the remaining 12 trials (24 per cent) considered clustering in the design or analysis. In the simulations, ignoring clustering led to an increased type I error rate of up to 12 per cent and to a loss in power of up to 15 per cent, depending on whether the patient or the hernia was the randomization unit.
Clustering was rarely considered in inguinal hernia trials. The simulations underline the importance of considering clustering as part of the statistical analysis to avoid false‐positive and false‐negative results, and hence inappropriate study conclusions.Full text
You may also be interested in
Time to calcitonin normalization after surgery for node‐negative and node‐positive medullary thyroid cancer.
Authors: A. Machens, K. Lorenz, H. Dralle
Notes: Sensitive as prognostic tool
Authors: R. Miller, J. C. R. Wormald, R. G. Wade, D. P. Collins
Contralateral surgery in patients scheduled for total thyroidectomy with initial loss or absence of signal during neural monitoring.
Authors: A. Sitges‐Serra, L. Gallego‐Otaegui, J. Fontané, L. Trillo, L. Lorente‐Poch, J. Sancho et al.
Authors: L. M. Almond, F. Tirotta, H. Tattersall, J. Hodson, T. Cascella, M. Barisella et al.
Notes: Weak for liposarcoma
Systematic review to assess the possibility of return of cerebral and cardiac activity after normothermic regional perfusion for donors after circulatory death. BJS 2019; 106: 174-180.
Authors: I. M. Shapey, A. Summers, T. Augustine, D. van Dellen
Surgical training programmes in the South Pacific, Papua New Guinea and Timor Leste. BJS 2019; 106: e53-e61.
Authors: D. A. Watters, E. McCaig, S. Nagra, I. Kevau
Authors: A. Wladis, N. Roy, J. Löfgren
Prevalence and predictors of surgical‐site infection after caesarean section at a rural district hospital in Rwanda. BJS 2019; 106: e121-e128.
Authors: T. Nkurunziza, F. Kateera, K. Sonderman, M. Gruendl, E. Nihiwacu, B. Ramadhan et al.
Authors: K. R. Iverson, K. Garringer, O. Ahearn, S. Alidina, I. Citron, S. Esseye et al.
Notes: Much to be done still
Evaluation of a surgical training programme for clinical officers in Malawi. BJS 2019; 106: e156-e165.
Authors: J. Gajewski, E. Borgstein, L. Bijlmakers, G. Mwapasa, Z. Aljohani, C. Pittalis et al.