Hambleton, Ian R.

Loureiro, Monique M.

Rozenfeld, Suely

Wierenga, Klaas J. J.

English

Cadernos Espinosanos (E-Journal)

Rev Saúde Pública 2006;40(1):65-70Comment on: Loureiro &Rozenfeld “Epidemiology ofsickle cell disease hospitaladmissions in Brazil”Comentário sobre: “Epidemiologiadas internações por doençafalciforme no Brasil”, de Loureiro &Rozenfeld4 740-1 Carta ao Editor | Letters to the EditorMiami, May 8, 2006Dear Editor,We read with interest the report by Loureiro &Rozenfeld on the epidemiology of sickle cell diseasehospital admissions in Brazil.2 In this article, the au-thors reported median age at death in three Brazilianregions of 26.5 years, 30 years, and 31.5 years. Theythen compared these summaries with Jamaican me-dian survival rates of 53 years for men and 58.5 yearsfor women,4 and reported ”an early lethality” reflect-ing ”social inequalities that exist between Brazil andother countries”.In assuming the equivalence of median survival andmedian age at death, -the authors have made a simpleerror that is common in the epidemiological literature.Median survival is defined as the age at which 50% ofthe study population has died, and must additionallyinclude participants that do not die. These living par-ticipants are accounted for using statistical techniquesthat remove or ”censor” the live participant at theirlast known contact date within a study window.In the Jamaican report, homozygous sickle cell (SS)disease was studied over a 10-year period, duringwhich 290 out of 3,301 (8.8%) patients died. In thesame paper, median age at death was reported as 24.9years for men, and 25.7 years for women. These fig-ures for Jamaicans with SS disease are directly com-parable with, and broadly similar to the reported me-dian ages at death in Bahia, Rio de Janeiro, and SãoPaulo. The dataset reported by Loureiro and Rozenfelddoes not allow the calculation of median survival. Itremains possible that median survival is similar tothose identified in Jamaica and the USA.3In a later paper from the Jamaican group it is shownthat, in the absence of newborn screening for sicklecell disease, almost 65% of children affected by SSdisease and not identified at birth will not benefitfrom important early-life clinical intervention.1 It istherefore likely that early deaths, even if they oc-curred in hospital, are not ascribed to SS disease, andthis possibly leads to an optimistic median age atdeath when relying on hospital-based data.In the coming decades more accurate information onmedian survival in homozygous sickle-cell diseasewill become available from patient groups such asthe Jamaican Cohort Study, in which patients are iden-tified at birth and prospectively followed. Until then,survival estimates will depend on the appropriate-ness of techniques used and assumptions made.Klaas J. J. WierengaDr. John T. Macdonald Foundation Center for Medical GeneticsUniversity of Miami, Miami, USAIan R. HambletonChronic Disease Research Centre, Tropical Medicine Research Institute,University of the West Indies, Bridgetown, Barbados, West Indies741Rev Saúde Pública 2006;40(4):740-1 Carta ao EditorREFERENCES1. Hambleton IR, Wierenga KJ. Identifying homozygoussickle cell disease when neonatal screening is notavailable: a clinic-based observational study. J MedScreen. 2004;11:175-9.2. Loureiro MM, Rozenfeld S. Epidemiology of sicklecell disease hospital admissions in Brazil. Rev SaúdePública. 2005:39:943-9.Rio de Janeiro, June 17, 2006Dear Editor,In reference to the letter from Dr Wierenga and DrHambleton, we agree with them in respect to theirstatement that median survival cannot be straightlycompared to median age at death, as we have writtenin our article. However, as we estimated a very lowage at death in these patients, we improperly con-cluded that there were differences in survival betweencountries, explaining the differences by social in-equalities. Our data did not allow this comparison.The median survival in Brazilian sickle disease may3. Platt OS, Brambilla DJ, Rosse WF, Milner PF, CastroO, Steinberg MH, et aI. Mortality in sickle celldisease. Life expectancy and risk factors for earlydeath. N Engl J Med. 1994;330:1639-44.4. Wierenga KJ, Hambleton IR, Lewis NA. Survivalestimates for patients with homozygous sickle-celldisease in Jamaica: a clinic-based population study.Lancet. 2001;357:680-3.be similar to other countries estimates but unfortu-nately we have no awareness of any cohort study inBrazil on this subject. In fact, the age at death be-tween Jamaica and Brazil can be comparable.We thank the authors for their remarks and we expectto give notice on Brazilian sickle disease epidemiol-ogy soon.Monique M. LoureiroSuely RozenfeldEscola Nacional de Saúde Pública,Fundação Oswaldo CruzThis article has received corrections in agreement with the ERRATUM published in Volume 40 Number 5.

Comment on: Loureiro & Rozenfeld "Epidemiology of sickle cell disease hospital admissions in Brazil"

https://www.revistas.usp.br/rsp/article/download/32125/34204

Comentário sobre: "Epidemiologia das internações por doença falciforme no Brasil", de Loureiro & Rozenfeld

Abstract

Similar works

Full text

Available Versions

Cadernos Espinosanos (E-Journal)