Analysis of prospective/retrospective registration trends on the Australian New Zealand Clinical Trials Registry (ANZCTR) from 2006-2015

Article type
Year
Authors
Hunter K1, Ko H1, Askie L1
1NHMRC Clinical Trials Centre, University of Sydney, Australia
Abstract
Background: Prospective trial registration is the process whereby key details about a planned clinical trial are made available on a recognised clinical trial registry before enrolment of the first participant. It is now widely recognised as a key strategy to increase research transparency by minimising publication bias and selective outcome reporting bias. The Australian New Zealand Clinical Trials Registry (ANZCTR) was established in mid-2005 and is one of 16 registries recognised by the International Committee of Medical Journal Editors (ICMJE).

Objectives: The key objectives of this study were to:
1. identify the proportion of prospective versus retrospective clinical trial registrations on the ANZCTR from 2006-2015; and
2. analyse prospective registration compliance on the ANZCTR by various key metrics, such as sponsor, funder, intervention type and sample size.

Methods: A descriptive analysis of trial registration data was undertaken. Data from interventional studies registered on the ANZCTR from 1 January 2006 until 31 December 2015 were included.

Results: Compliance with prospective registration of interventional studies increased from 47% in 2006 and plateaued at approximately 60% from 2012-2015 (Fig 1). Patterns of compliance were relatively consistent across sponsor and funder types (industry vs non-industry), type of intervention (drug vs non-drug) and size of trial (n < 100, 100-500, > 500). However, primary sponsors from Australia/New Zealand were approximately twice as likely to register prospectively (67%) as those from other countries with an ICMJE approved registry (34%) or those from countries without a registry (29%) (Table 1).

Conclusions: More stringent enforcement of prospective registration by journal editors, ethics committees and other regulatory bodies is needed to increase rates of trials registered prospectively. Differences in prospective registration rates by primary sponsor country may be due to priority given to Australian and New Zealand trials on ANZCTR and/or non-acceptance of retrospective registrations by some ICJME-recognised registries.