MATERIAL AND METHODS
All patients under 15 years of age, hospitalized between 2010 and 2018
in the two study hospitals, with a primary or secondary diagnosis of
pleural effusion or empyema were eligible. Exclusion criteria were:
non-infectious cause of the effusion; tuberculosis; nosocomial
pneumonia; unknown date of admission; patients transferred to finish
their treatment in a center other than HA or HB; and patients with
previous or concomitant severe comorbidities that could markedly
interfere with the course, treatment or LOS, specifically patients with
oncological diseases, immunodeficiencies, severe encephalopathies and
myopathies, significant heart or lung diseases, or Down’s syndrome.
Medical records of the included patients were reviewed to register the
date of admission and discharge, age, sex, previous diseases, days of
fever, analytical and microbiological results in blood and pleural
fluid, radiological characteristics of the effusion, and treatments
used. The size of the effusion was considered a surrogate of severity
and was classified according to the maximum thickness observed on
imaging tests, as less than 10 mm (PPE/PE−) or 10 mm or more (PPE/PE+).
Patients with PPE/PE+ were further divided into two groups according to
the thickness of the effusion: 10 mm to 20 mm (PPE/PE+1) or greater than
20 mm (PPE/PE+2). The primary outcome measures were the proportion of
patients undergoing pleural drainage and LOS. Total LOS was defined as
the days between the patient’s first admission to a hospital with a
diagnosis of PPE/PE until final discharge from the tertiary hospital.
LOS in the tertiary reference hospital was defined as the days between
admission to the reference hospital (from the emergency department or
transferred from another center) and definitive discharge for this
condition. In the case of patients who had been discharged from hospital
but required a new admission for the same process, LOS included the days
that the patient remained at home between the two hospitalizations.
Other secondary variables were duration of fever and duration of
intravenous antibiotic treatment.
The data collected were entered into a database for statistical analysis
using the SPSS v.22 program. Statistical analyses were carried out using
R software, version 4.0.2 (R Foundation for Statistical Computing,
Vienna, Austria; http://www.R-project.org). Bilateral statistical tests
were applied with a significance level set at 0.05. Normal distribution
of the continuous variables was checked using the Kolmogorov-Smirnov
test. Qualitative variables were described using frequencies and
percentages, and quantitative variables using median and interquartile
range, given that they were not normally distributed. To evaluate
differences in the characteristics between two hospitals, we applied the
Chi-square test or Fisher’s exact test (categorical variables) or the
Mann-Whitney U test (continuous variables).
The study was approved by the
research ethics committees at HA and HB.