Background: Increasing patient-reported outcome measures in the 1980s and 1990s led to the development of recommendations at the turn of the millennium for standardising outcome measures in non-specific low back pain (LBP) trials. Whether these recommendations impacted use is unclear. Previous work has examined citation counts, but actual use and change over time, has not been explored. Since 2011, there has been some consensus on the optimal methods for reporting back pain trial outcomes. We explored reporting practice, outcome measure use, and publications over time. Methods: We performed a systematic review of LBP trials, searching the European Guidelines for the management of LBP, extending the search to 2012. We abstracted data on publications by year, outcome measure use, analytical approach, and approaches taken to reporting trials outcomes. Data were analysed using descriptive statistics and regression analyses. Results: We included 401 trials. The number of published trials per year has increased by a factor of 4.5 from 5.4 (1980-1999) to 24.4 (2000-2012). The most commonly used outcome measures have been the Visual Analogue Scale for pain intensity, which has slowly increased in use since 1980/81 from 20% to 60% of trials by 2012, and the Roland-Morris Disability Questionnaire, which rose to 55% in 2002/2003, and then fell back to 28% by 2012. Most trialists (85%) report between-group mean differences. Few (8%) report individual improvements, and some (4%) report only within-group analyses. Student's t test, ANOVA, and ANCOVA regression, or mixed models, were the most common approaches to analysis. Conclusions: Recommendations for standardising outcomes may have had a limited or inconsistent effect on practice. Since the research community is again considering outcome measures and modifying recommendations, groups offering recommendations should be cognisant that better ways of generating trialist buy-in may be required in order for their recommendations to have impact.