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.