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Table 2 Primary outcome analysis methods

From: Analysis and reporting of stepped wedge randomised controlled trials: synthesis and critical appraisal of published studies, 2010 to 2014

Author, year Model fitted Effect estimated Vertical and/or horizontal analysis Method to account for clustering Repeated measures on individuals? Method used Adjustment for confounding? Adjustment for secular trends Risk of lag Accounting for lags Risk of fidelity loss
Bacchieri, 2010 [29] Poisson regression Rate ratio Both Robust standard errors Time-to-event No Fixed effect (no interaction) None None Minor
Bashour, 2013 [22] Linear regression Mean difference Both Random effects No Yes Fixed effect None None Major
(no interaction)
Durovni, 2013 [12] Cox regression Rate ratio Within-step only, plus frailty Random effects Time-to-event Yes Conditional Major None Minor
Fuller, 2012 [23] Logistic regression Odds ratio Both Random effects Yes, not explicitly accounted for Yes Fixed effects Major None (per-protocol analysis using observed lags) Major
(no interaction)
Gruber 2013 [21] Linear regression, Log-Poisson regression Risk difference, risk ratio Both Robust standard errors, GEE Yes, not explicitly accounted for Yes, in secondary analyses Fixed effect Major None Low
(no interaction)
Horner, 2012 [27] Logistic regression Odds ratio Both Random effects Yes, not explicitly accounted for Yes Fixed effect Minor None Minor
(no interaction)
Mhurchu, 2013 [24] Logistic regression Odds ratio Both Random effects Yes, pupil-level summaries and random effect Yes Fixed effect None None Minor
(no interaction)
Roy, 2013 [25] Logistic regression Odds ratio Both Random effects No Yes None None None Minor
Schultz, 2014 [28] Logistic regression Odds ratio Both None: GEE not possible, and RE did not converge No No Fixed effect Minor None None
(no interaction)
Stern, 2014 [26] Linear regression Mean difference Both Random effects Yes, multiple level random effects Yes Fixed effect with interaction Major None Minor