The PACE trial was the first randomized controlled trial (RCT) investigating the efficacy of paracetamol in acute low back pain. Non-compliance to study medication was considered to be a limitation of this RCT. In contrast to conventional statistical methods, complier average causal effects (CACE) analysis may provide unbiased estimates of the effects for participants compliant to paracetamol. Intention to treat (ITT), as-treated, propensity weighted CACE and joint modeling CACE estimates were calculated for pain intensity, disability, global perceived effect and function at two weeks of follow up with compliance defined as an average of at least four tablets per day during the first two weeks of the trial. For pain intensity, exploratory analyses were conducted using additional time points and definitions of compliance.Introduction
Methods
Measurement inconsistency across clinical trials is tackled by the development of a core outcome measurement set. Four core outcome domains were recommended for clinical trials in patients with non-specific LBP (nsLBP): physical functioning, pain intensity, health-related quality of life (HRQoL), and number of deaths. This study aimed to reach consensus on core instruments to measure the first three domains. The Steering Committee overseeing this project selected 17 potential core instruments for physical functioning, three for pain intensity, and five for HRQoL. Evidence on their measurement properties in nsLBP was synthesized in three systematic reviews using COSMIN methodology. Researchers, clinicians, and patients (n = 208) were invited in a Delphi survey to seek consensus on which instruments to endorse as core. Consensus was Background & purpose
Methods & Results
