Selection criteria and sample size calculation
Our population of interest was all the CPGs, regardless of their scope,
produced by CENETEC and published on their online database called
“Catálogo Maestro – Master Database ” between 2015 and 2017.
(Website citation) The total population of CPGs at the time of this
study design were 224 CPGs (Accessed on el 20/11/2017http://cenetec-difusion.com/gpc-sns/?cat=52).
We considered the GRADE framework as the reference standard to frame the
question, judge the quality of evidence, and move from evidence to
recommendations. (9)Leyva de Los Rios et al. reported the frequency of the GRADE framework
use in the CPGs from CENETEC as 10%.(12) Therefore,
considering an alpha error of 0.05, and a 95% confidence interval, we
determined that we needed to assess 86 CPGs. We chose a random sample
from the total population of 224 CPGs using the software Epidat, version
4.2. (13) The CPGs were
allocated randomly among the assessors (GMV, VAA, PGL, YOE, MTU, SVS,
GML, GTF, LEC). The list of the included CPGs is reported in Table 1S.