Objectives The objective of this study was to assess whether National Institute of Health Research (NIHR) Health Technology Assessment (HTA)-funded randomised controlled trials (RCTs) published in the HTA journal were described in sufficient detail to replicate in practice.

Setting RCTs published in the HTA journal.

Participants 98 RCTs published in the HTA journal up to March 2011. Completeness of the intervention description was assessed independently by two researchers using a checklist, which included assessments of participants, intensity, schedule, materials and settings. Disagreements in scoring were discussed in the team; differences were then explored and resolved.

Primary and secondary outcome measures Proportion of trials rated as having a complete description of the intervention (primary outcome measure). The proportion of drug trials versus psychological and non-drug trials rated as having a complete description of the intervention (secondary outcome measures).

Results Components of the intervention description were missing in 68/98 (69.4%) reports. Baseline characteristics and descriptions of settings had the highest levels of completeness with over 90% of reports complete. Reports were less complete on patient information with 58.2% of the journals having an adequate description. When looking at individual intervention types, drug intervention descriptions were more complete than non-drug interventions with 33.3% and 30.6% levels of completeness, respectively, although this was not significant statistically. Only 27.3% of RCTs with psychological interventions were deemed to be complete, although again these differences were not significant statistically.

Conclusions Ensuring the replicability of study interventions is an essential part of adding value in research. All those publishing clinical trial data need to ensure transparency and completeness in the reporting of interventions to ensure that study interventions can be replicated.