Radical Prostatectomy: Sources and levels of evidence (LoE) determine the grades of recommendation (GoR)

Sources of evidence in PROSPECT

The
evidence for prospect is derived from three separate sources, and this
evidence is taken into consideration by the prospect Working Group to
determine the prospect recommendations:

Procedure-specific evidence derived from the systematic reviews of the literature
Transferable evidence from comparable procedures, or from other
relevant sources, identified by the members of the prospect Working
Group
Current practice – A commentary on the interventions from the members of the prospect Working Group
Practical prospect recommendations are based on all the information

Study quality assessment

For the Radical Prostatectomy review, the quality of procedure-specific evidence has been assessed according to NICE
methodology, to determine the possibility of selection bias, performance
bias, attrition bias and detection bias (www.nice.org.uk/media/615/64/The_guidelines_manual_2009.pdf).

Any limitations in the reporting of
cited procedure-specific studies are described in the evidence tables
within each
Procedure-Specific Evidence folder.

GoR are assigned according to the overall LoE, which is determined by the quality of studies cited, the
consistency of evidence and the source of evidence (as indicated in the
Table below).

Quality indicators used to determine the LoE of individual studies:

Allocation
concealment: indicates whether there was adequate prevention
of foreknowledge of treatment assignment by those involved in
recruitment (in the table below, A=adequate, B=unclear, C=inadequate,
D=not used). Empirical research has shown that trials with inadequate or
unclear allocation concealment report significantly greater estimates
of treatment effect than those trials in which concealment was adequate (Chalmers 1983, Schulz 1995, Moher 1998).
Allocation concealment was found to be more important for preventing
bias than other aspects of study quality, such as generation of the
allocation sequence and double-blinding (Chalmers 1983, Schulz 1995, Moher 1998, HigginsandGreen 2005: Section 6.3. http://www.cochrane.org/resources/handbook/hbook.htm)
Statistical analyses and patient follow-up:
indicates whether statistical analyses were reported, and whether
patient follow-up was greater or less than 80%.
Numerical scores (total 1–5) for study quality: assigned using the method proposed by Jadad 1996,
to indicate whether a study reports appropriate randomisation,
double-blinding and statements of possible withdrawals. Empirical
research found that low-quality trials were associated with an increased
estimate of treatment benefit than high-quality trials (Moher 1998)

Table: Relationship between quality and source of evidence, levels of evidence and grades of recommendation in PROSPECT

Study quality assessments

Level of Evidence (LoE)

Grade of recommendation
(based on overall LoE, considering balance of clinical practice information
and evidence)

Study type

Statistical analyses and patient
follow-up assessment

Allocation concealment

Jadad scores

Additional assessment of overall
study quality required to judge LoE

Procedure-specific

Transferable

Systematic review with homogeneous
results

N/A

Randomised controlled trial (RCT)

Statistics reported
and >80%
follow-up

AND

(1-5)

N/A

(based on two or more studies or a
single large, well-designed study)

(3-5)

N/A

(1-2)

Yes

RCT

Statistics not reported or
questionable or <80% follow-up

AND/OR

(1-2)

Yes

(or extrapolation from one
procedure-specific
LoE 1 study)

(1-5)

N/A

(1-5)

N/A

Non-systematic review, cohort study,

case study;

(e.g. some adverse effects evidence)

N/A

Clinical practice information
(expert opinion); inconsistent evidence

N/A