Journal of clinical epidemiology
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Meta Analysis Comparative Study
Adjustment for compliance behavior in trials of epidural analgesia in labor using instrumental variable meta-analysis.
Intention-to-treat (ITT) analysis of randomized controlled trials (RCTs) may cause bias when compliance is poor. Noncompliance describes failure to comply with allocation in the intervention arm, and contamination describes uptake of the intervention in the control arm. Instrumental variable (IV) analysis can be applied in addition to the primary ITT analysis to estimate the causal effect adjusted for noncompliance and contamination, assuming that noncompliers would have had the same treatment benefit as compliers. We aimed to compare ITT and IV meta-analysis of the association between epidural analgesia in labor and cesarean section. ⋯ ITT meta-analysis underestimates the effect of receiving epidural analgesia in labor on cesarean section compared with IV meta-analysis.