Survival of Medically Treated Thalassemia Patients in Cyprus. Trends and Risk Factors Over the Period 1980-2004

Authors
Telfer, P., Coen, P.G., Christou, S., Hadjigavriel, M., Kolnakou, A., Pangalou, E., Pavlides, N., Psiloines, M., Simamonian, S., Skordos, G., Sitarou, M., Angastiniotis, M.

Journal
Haematologica, 2006; 91(9) 1187-1192.

Background
Cyprus has a high carrier rate for thalassaemia major, and most patients are born and treated exclusively on the island. This makes Cypriot thalassaemia patients an excellent population to study for trends and changes relating to survival. Evidence of an increasing trend in cardiac deaths in Cyprus, occurring despite intensive intravenous treatment with deferoxamine, prompted a protocol of combination therapy with deferiprone in addition to deferoxamine to be introduced in 1999.
The current study applied multi-variate survival analysis in the Cypriot thalassemia cohort to test the hypothesis that survival has improved post introduction of combination therapy.


Methods
Patients with thalassaemia major who were born and treated exclusively on the island of Cyprus were eligible for the study. The follow up period of these patients was from 1980-2004. Survival analysis was carried out via Cox proportional hazards on left- and right-censored data (multiple-record and multiple-event data). Univariate comparison of mortality was carried out by means of Poisson regression (cardiac and non-cardiac deaths). Multivariate Cox proportional hazards analysis was used to establish risk/protective factors against mortality.


Results
Data on 539 patients born after 1960 and followed over the period of 1980 to the end of 2004 were analyzed. There were 58 deaths during the review period, 53.4% of which were due to cardiac disease. There was no overall trend in non-cardiac deaths (p=0.57) over the entire period but there was an increasing trend in cardiac deaths between 1980 and 2000 (p<0.001), and a decrease of cardiac deaths of borderline significance after 2000 (p=0.06). This coincides with the introduction of combination therapy with deferiprone and deferoxamine. There were no cardiac deaths in the patients who switched to combination therapy. Due to the small number of patient years of follow-up on combination therapy compared to follow-up on deferoxamine, there is currently insufficient statistical power for a direct assessment of the independent protective effect of combination therapy compared to deferoxamine.

Conclusions
There has been a marked improvement in survival for patients of all ages since 2000 and this may be due to the introduction of a combination chelation regime with deferoxamine and deferiprone.

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