Materials & Methods:
This study is a systematic review of the literature, which involved the
work of two researchers independently evaluating the quality of each
article. The formulation of the research question was based on the PICO
strategy29. The following questions guided the
bibliographic search: Is the action of dipyrone indicated for
pre-emptive or postoperative analgesia in tonsillectomy in children? Are
there any positive or negative influences? The search was carried out in
the databases MEDLINE / PubMed, EMBASE and Virtual Health Library (VHL /
Lilacs), using separate and combined terms, with the Boolean operator OR
and, using the following subject descriptors in health sciences from
BIREME (DeCS): dipyrone OR metamizole AND postoperative pain; dipyrone
OR metamizole AND postoperative pain AND children, dipyrone OR
metamizole AND tonsillectomy, dipyrone OR metamizole AND tonsillectomy
AND children, dipyrone AND metamizole AND pre-emptive analgesia,
dipyrone OR metamizole AND pre-emptive analgesia AND children.
Additionally, the references of the selected articles were reviewed in
the search for other relevant publications. The selection of articles
was carried out in the months of June / 20 and July / 2020.
The inclusion criteria were as follows: studies that addressed the
treatment of pain with dipyrone in a pre-emptive way or after the end of
surgery in children. This was then refined for studies with a randomised
clinical trial design and that dealt exclusively with tonsillectomies,
with dipyrone alone or in combination with another drug in one of the
comparison groups. There was no time limit for publications, and we
included all articles available in full in Portuguese, English, Spanish
and German. As exclusion criteria, the following were adopted:
publications corresponding to theses, dissertations, abstracts of
congresses and annals and all articles that exclusively included
evaluation of chronic pain and studies in adults.
The studies were classified according to the level of evidence,
following the Oxford Centre for Evidence Based Medicine
recommendations30. The studies were also described
according to the GRADE31 classification, which takes
into account the quality of the evidence (high or level A, moderate or
level B, low or level C and very low or level D) and the degree of
recommendation (strong or weak). Finally, the two included studies were
classified according to the Jadad32 scores, which
assess the methodological quality of the study using specific criteria:
poor (scores 0-2), good (3-4) or excellent (score 5 or more). The PRISMA
strategy (Preferred Reporting Items for Systematic Reviews and
Meta-Analysis)33 was used in this review in order to
qualify the work when performing a critical analysis of the selected
studies. Figure 1 shows the flowchart of identification, selection and
inclusion of studies based on the PRISMA recommendation.
(Figure 1: PRISMA flowchart)