Material and Methods
This was a retrospective cohort study of pediatric patients with the
diagnosis of primary bone cancer consecutively registered at the
Pediatric Oncology Department of INCA, from January 1 2011 to October 16
2016. This study was approved by the INCA Research Ethics Committee
(CAAE: 67729317.5.0000.5274).
Patients under 19 years old were included, they were registered at
INCA’s Pediatric Oncology Department with primary bone cancer, with
either the diagnosis of OS or bone ES. Patients treated at other
institutions and admitted at INCA for exclusive radiotherapy were
excluded. The diagnosis, OS or ES, was confirmed by INCA Department of
Pathology. Whenever the diagnosis had been carried out in other
institutions, they had a pathology review at INCA. All patients were
registered in Latin American Cooperative Group for Osteosarcoma Protocol
of Treatment (GLATO) or in Latin American Cooperative Group for Ewing
Tumors Family (GALLOP). 12,20–23
At the time of the registration, all patients were initially evaluated
for pain. If they were already using some kind of pain control
medication for this symptom this was modified whenever necessary
according to the patient’s clinical evaluation. Pain management was
performed by the multidisciplinary team according to institutional
clinical protocols established by the pediatric pain clinic service.
In this study, pain measurement was standardized according to Wong and
Baker, who had considered 0 as no pain; 1 to 3 as mild pain, 4 to 6 as
moderate pain, 7 to 9 as severe pain and 10 as excruciating pain24–26.
Data was collected from medical records and registered in a specific
chart. Three moments were considered during this cohort: at the
registration moment, three months after registration and at the last
visit before the end of this study or patients death. Patients were
considered end-of-life when they had an evaluation up to 1 month before
death 27–29.
The variables of this study were: age at diagnosis, sex, race, cancer
type, presence of metastases at diagnosis, progression disease, pain
complaint, pain measurement, pain relieve treatment, modification in
pain relief treatment and pain status at the end-of-life.
Statistical analysis was performed using SPSS for Windows (version 22)
and Stata 13.0 (Stata Corp, LC ). The Kolmogorov-Smirnov Test was
used to verify normality, results are presented as median, interquartile
range (IQR) and 95% confidence intervals (95% CI). The association
between categorical variables was tested by Pearson’s Chi-squared test
or Fisher exact test; Mann-Whitney test was used to compare continuous
variables. Data was analyzed until December 31, 2016. We compared pain
status in the last evaluation between those on treatment or in disease
control and those at the end-of-life.
To identify possible associations between variables and pain status at
the last evaluation, we performed a Poisson regression with robust
estimation, log link function to determine crude prevalence ratios
(CPR); patients were tested for characteristics, presence of metastasis
at registration, disease progression at last evaluation and use of mild
analgesics, weak opioids and strong opioids at last evaluation;
variables associated to pain (CPR with p-value <0.20) were
included in a multivariate model to determine adjusted prevalence ratios
(APR). Considered a p-value of < 0.05.