Sickle cell anemia (SCA) is one of the major hemoglobin disorders worldwide. SCA has a high degree of disease-associated mortality and morbidity that can be prevented by early identification of affected individuals and implementation of comprehensive care measures. Newborn screening (NBS) has been shown to be an effective measure for early diagnosis and to help decrease disease related complications.
Alberta has not implemented a routine newborn screening program for hemoglobin disorders. For this reason, we hypothesize that a significant portion of the SCA patients followed at Alberta Children's Hospital (ACH) are diagnosed at a later age (> 1 year of age) due to a presentation with sickle cell complications or from targeted screening at medical visits.
The primary objective of the study is to identify the age of diagnosis of SCA patients followed at the Alberta Children's Hospital when a universal newborn screening program was not available.
In this retrospective cohort study, we reviewed 100 charts for patients with hemoglobin (Hb) disorders who had attended Alberta Children's Hospital (ACH) hematology clinic during the period from January 2003 to January 2014. Only patients with SCA (HbSS, Hb SB0, Hb SB+, Hb SC, S-HPFH) were included in the study. Data collected included demographic variables, SCA diagnosis related information such as the age of diagnosis, the reason for screening, and characteristics of the first SCA presentation. Late diagnosis was defined as a diagnosis after 12 months of age. The clinical course of SCA as complications, the age of penicillin prophylaxis initiation and the age of first transcranial Doppler testing (TCD) were obtained as secondary measures.
A total of 77 patients with SCA (40.3% male, 59.7% Female) that attended sickle cell clinic at ACH met our inclusion criteria. Thirty-four percent (N=26) of patients were born in Alberta, 26.5% (N=19) in other Canadian provinces and the United States and 41% (N=32) in other parts of the world. The majority (94.8 %) were African, and 5.2% were of other ethnic backgrounds including Arab/Latin American and South Asian.
More than half of the patients who were born in Alberta (58 %) were diagnosed after the age of 12 months. The mean (M) age of diagnosis for the patients born in Alberta was 21.4 ± 21 months (median 19, range 0-84). None of the patients were diagnosed because of newborn screening whereas 39% were identified due to family history, 50% due to disease related complication and 8% due to abnormal lab low Hb/abnormal smear. Fifteen percent of those patients never started on penicillin prophylaxis due to old age at the time of diagnosis, otherwise, the mean age of penicillin initiation was 15 ± 10.8 months (median 14, range 2-36). Only 65% of the patients had TCD testing with mean age of the first TCD was 44 ± 24 months (median 36, range 24-96).
The mean age of diagnosis was 8 ± 18 months (median 0, range 0-72) for children who were born in other Canadian provinces/US where newborn screening is available. There was a significant difference in the mean age of diagnosis in children with SCA who were born in Alberta (M = 21.4, SD = 21) where newborn screening is not available and sickle cell patients who were born in the United States and elsewhere in Canada (M = 8, SD = 18); t (43) = 2.08, p = 0.043, 95% CI [0.4,25], using an independent samples t-test to compare the mean age.
The number of SCA patients attending the ACH Hematology clinic has almost tripled since the time of data collection due to upward trends in immigration. Patients who were born in our province had a significant late diagnosis compared to other jurisdictions and frequently present initially with severe disease complications. Our findings provide strong evidence to support the implementation of a provincial universal screening program so prophylactic treatment, and comprehensive care is provided before the development of clinical complications. Also, positive screening results could provide an additional opportunity to provide timely genetic counseling to at-risk individuals and families in Alberta.
No relevant conflicts of interest to declare.
Asterisk with author names denotes non-ASH members.