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. Author manuscript; available in PMC: 2018 Nov 13.
Published in final edited form as: Curr Rheumatol Rep. 2018 Oct 18;20(12):75. doi: 10.1007/s11926-018-0787-4

Table 5.

Risk of bias criteria

Type of bias Criteria
Low High Unclear
Selection bias:
random
sequence
Generation
Random-numbers table or a computer software
program
Tossing a coin, throwing dice or
basing randomization on a date,
name, etc.
Methods not described
Selection bias:
allocation
concealment
Concealment of allocation means strict implementation
of a randomized sequence without foreknowledge of
the next assignment. Strategies that include central
randomization by computer or phone and
sequentially numbered envelopes that are both
sealed and opaque are low risk.
Strategies with a reasonable
chance of being anticipated.
Inadequate description of the envelope
process, which is often the case,
should be marked as “unclear risk of
bias.”
Performance
bias
If methods to mask participants and physicians were
described and these methods had a reasonable
chance of being effective.
If treatment assignment known by
patient/physician.
If the study did not discuss methods of
masking the participant or physician.
Detection bias Methods to mask the outcome assessor were described. The outcome assessor was
not-masked.
Methods to mask the outcome assessor
were not described.
Incomplete
outcome
data/attrition
bias
Losses to follow-up are similar in number and in
reason between intervention and control. An
intention to treat analysis is performed.
Losses to follow-up are more than
10% different between the
intervention and control
groups.
If attrition is not reported or reasons for
loss of attrition are not reported.
Reporting bias If the primary outcome(s) in the methods section is
identical to those reported in the results section of
the manuscript. If a protocol is available, we will
also review for discrepancies between targeted
outcomes and results.
If the primary outcomes differ
between the methods section or
protocol and manuscript.
If there is no reported primary outcome
in a trial registry, the outcome will be
considered “unclear.”