Discussion
Our study evaluated the adjudication processes for the causality
assessment of ADR and the agreement between WHO-UMC. Data suggested
slight interrater agreement for WHO-UMC, according to Lands and Koch
scale.[12] Previous studies have reported interrater agreement
ranging from fair to substantial agreement in the ADR causality
assessment involving inpatients.[3, 13] In hospitalized patients
with high complexity of clinical condition, this classification is
particularly difficult, since many factors are involved in the scenario,
such as polypharmacy, multiple comorbidities, different healthcare teams
with diverse clinical experience involved in patient care.
WHO-UMC system is based on standardized criteria, demanding minimal
expertise in pharmacovigilance process, although clinical practice is an
important requisite for judges. This dependence on the individual
judgement and different judges’ background could also explain the
expected weak reproducibility and slight interrater agreement, as cited
by Khan et al., [4] and demonstrated by our findings.
Nevertheless, from the perspective of patient safety, the evaluation
performed by a multiprofessional team could enrich the assessment of ADR
given the diverse experiences and subjectivity. In the field of
pharmacovigilance, the search for consensus among professionals is
highly desirable to improve the quality of the process instead of
prioritizing their individual view.
In pharmacovigilance, most cases are considered only suspected,
classified as probable or possible, with rarely definite or unlikely
cases.[14] Our study demonstrated this aspect, considering that all
90 cases evaluated by Naranjo algorithm were classified in these
categories and 93% of ADR were categorized similarly by WHO-UMC system.
The assessment using WHO-UMC is not dependent on a score, allowing a
discreet distribution among the categories when compared with Naranjo
algorithm. This method has been shown to be easy to assess the causality
of ADR, however, the influence of confounding variables was not
considered.
Considering preventability, our results revealed about half of cases
were considered definitely preventable or probably preventable, in
consonance with a meta-analysis conducted by Hakkarainen et
al. [15] To our knowledge, there is no previous study designed to
compare the causality assessment and preventability of ADR developed by
multiprofessional teams. We should address some limitations of our
study, including fixed sample size, small number of judges and intrinsic
interrater variability that hindered to obtain homogeneous results in
this investigation. Besides, we did not compare how much better for
clinical practice would be the consensus of three professionals from
different areas than a consensus of three professionals from the same
area.
Finally, to date, a great number of preventable ADR reinforce the need
for improvements in pharmacovigilance strategies in hospital settings.
Variability in the assessment of ADR could result in heterogeneous
decisions in drug safety. Our results suggest that the involvement of
interdisciplinary teams could improve the quality of the monitoring
process of ADR. Further studies focused on standard definitions and
multiprofessional consensual assessment should also be considered as a
strategy to seek for improvements in patient safety.