Poor Reliability between Cochrane Reviewers & Blinded External Reviewers When Applying the Cochrane Risk of Bias Tool in Physical Therapy Trials,2014

Sly Saint

Sly Saint

Senior Member (Voting Rights)
Abstract
Objectives
To test the inter-rater reliability of the RoB tool applied to Physical Therapy (PT) trials by comparing ratings from Cochrane review authors with those of blinded external reviewers.

Methods
Randomized controlled trials (RCTs) in PT were identified by searching the Cochrane Database of Systematic Reviews for meta-analysis of PT interventions. RoB assessments were conducted independently by 2 reviewers blinded to the RoB ratings reported in the Cochrane reviews. Data on RoB assessments from Cochrane reviews and other characteristics of reviews and trials were extracted. Consensus assessments between the two reviewers were then compared with the RoB ratings from the Cochrane reviews. Agreement between Cochrane and blinded external reviewers was assessed using weighted kappa (κ).

Results
In total, 109 trials included in 17 Cochrane reviews were assessed. Inter-rater reliability on the overall RoB assessment between Cochrane review authors and blinded external reviewers was poor (κ  =  0.02, 95%CI: −0.06, 0.06]). Inter-rater reliability on individual domains of the RoB tool was poor (median κ  = 0.19), ranging from κ  =  −0.04 (“Other bias”) to κ  =  0.62 (“Sequence generation”). There was also no agreement (κ  =  −0.29, 95%CI: −0.81, 0.35]) in the overall RoB assessment at the meta-analysis level.

Conclusions
Risk of bias assessments of RCTs using the RoB tool are not consistent across different research groups. Poor agreement was not only demonstrated at the trial level but also at the meta-analysis level. Results have implications for decision making since different recommendations can be reached depending on the group analyzing the evidence. Improved guidelines to consistently apply the RoB tool and revisions to the tool for different health areas are needed.

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0096920
 
Not surprising. Ultimately the biggest flaw with evidence-based medicine is that more often than not, if you change the people you change the outcome. And it applies at every single step, from design, approval, funding, oversight, review, meta-review and so on. Every single one of those steps has arbitrary elements, all of which compound.

Properly controlled trials are a very useful tool, ones that achieve near perfect control anyway. Almost all trials are poorly controlled, making everything else as arbitrary as what an average legislative committee does. No other discipline makes use of such tools precisely for those reasons. If you don't know what you're measuring, hell if you don't know what to measure, you're not doing science. And only science works, the rest is too biased to be trusted.

But this was published 9 years ago, and if anything things have gotten worse, including at Cochrane. The trolley keeps on ramming into people simply because no one can decide to end its disastrous run.
 
Unfortunately for the relevance of this 2014 study, there is now RoB2
Version 2 of the Cochrane risk-of-bias tool for randomized trials (RoB 2) is the recommended tool to assess the risk of bias in randomized trials included in Cochrane Reviews. RoB 2 is structured into a fixed set of domains of bias, focussing on different aspects of trial design, conduct, and reporting.
....
Version 2 of the tool replaces the first version, originally published in Version 5 of the Cochrane Handbook in 2008, and updated in 2011 (see here). Research in the field has progression and RoB 2 reflects current understanding of how the causes of bias can influence study results, and the most appropriate ways to assess this risk. The tool can be used now but will only be implemented in the online version of Review Manager software 2020. Authors of updates will not be required to switch to the new tool.
Click to expand...

https://methods.cochrane.org/bias/r...f the Cochrane,design, conduct, and reporting.

So, it's really easy for a Cochrane person to say, yes, we know the RoB tool wasn't perfect, that's why we made RoB2.
 
Hutan said:
Unfortunately for the relevance of this 2014 study, there is now RoB2


https://methods.cochrane.org/bias/resources/rob-2-revised-cochrane-risk-bias-tool-randomized-trials#:~:text=Version 2 of the Cochrane,design, conduct, and reporting.

So, it's really easy for a Cochrane person to say, yes, we know the RoB tool wasn't perfect, that's why we made RoB2.
Click to expand...
depends on the relevance of this line
"Authors of updates will not be required to switch to the new tool."
so I'm guessing for a lot of the 'current'/'live' reviews it (ROB2) hasn't been used.

Really they should repeat the process in this paper to see if it holds up tho.
 
It does sound as though you are right:
What can we learn from results of the RoB 2 comparison study?
The biggest divergence between the tools was with subjective outcomes in open-label studies, where RoB 1 was more likely to penalize than RoB 2. RoB 1 also tended to lead to harsher risk of bias judgements as a result of the options available (high/low/unclear), whereas the ratings, algorithm, signalling questions and guidance built into the RoB 2 tool made it easier to work through complexity and context.
Click to expand...
 
whereas the ratings, algorithm, signalling questions and guidance built into the RoB 2 tool made it easier to work through complexity and context.

So, more wriggle and less rigour?

(EDIT: Not suggesting that complexity and context don't matter.)
 
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