Severe combined immunodeficiency in Brazil: management, prognosis, and BCG-associated complications

Severe combined immunodeficiency (SCID) is one of the most severe forms of primary immunodeficiency. The objectives of this study were to analyze the diagnosis, treatment, and prognosis of SCID in Brazil and to document the impact of BCG vaccine.

We actively searched for cases by contacting all Brazilian referral centers.

We contacted 23 centers and 70 patients from 65 families. Patients were born between 1996 and 2011, and 49 (70%) were male. More than half (39) of the diagnoses were made after 2006. Mean age at diagnosis declined from 9.7 to 6.1 months (P = .058) before and after 2000, respectively, and mean delay in diagnosis decreased from 7.9 to 4.2 months (P = .009). Most patients (60/70) were vaccinated with BCG before the diagnosis, 39 of 60 (65%) had complications related to BCG vaccine, and the complication was disseminated in 29 of 39 (74.3%). Less than half of the patients (30, 42.9%) underwent hematopoietic stem cell transplantation (HSCT). Half of the patients died (35, 50%), and 23 of these patients had not undergone HSCT. Disseminated BCG was the cause of death, either alone or in association with other causes, in 9 of 31 cases (29%, no data for 4 cases).

In Brazil, diagnosis of SCID has improved over the last decade, both in terms of the number of cases and age at diagnosis, although a much higher number of cases had been expected. Mortality is higher than in developed countries. Complications of BCG vaccine are an important warning sign for the presence of SCID and account for significant morbidity during disease progression.