Beta-thalassemia is an inherited hemoglobin disorder in the beta-globin chain that results in chronic hemolytic anemia. Two major forms of beta-thalassemia have been identified according to their clinical severity [1,2]. Thalassemia major (TM) manifests with severe anemia in the first year of life in newborns, while thalassemia intermedia (TI) involves clinically asymptomatic mild anemia [3]. In developing and underdeveloped countries, patients with TM die in childhood and adolescence due to the lack of public access to blood transfusions tested for viruses and timely iron removal from the body [4]. The underlying causes of death in patients with TM include iron overload and excess serum ferritin [5], which lead to cardiac disease, liver and endocrine disorders, infection, thrombosis, anemia, malignancy, and eventually death [6-9].

In the long term, untreated TI causes gallstones, pulmonary hypertension, thrombophilia, osteoporosis, and foot ulcers [10-12]. These symptoms are rare in patients with TM. Untreated TI causes cardiac problems in the fourth decade of life through hypoxia and increased pulmonary resistance, potentially leading to death [1,11,13-15].

Beta-thalassemia is widely prevalent across the Mediterranean region, Africa, and the Middle East (including Iran), and the prevalence of the mutation reaches 3 to 10% in some of these regions [2]. In Iran, beta-thalassemia is the most common form [16]; the disorder is most common along the coast of the Persian Gulf and the Caspian Sea, with a prevalence of more than 10% [17,18].

Although the prognosis and survival of thalassemia patients are improving across the world [19] and in Iran (based on results of some local studies), the prevalence of complications remains high in those affected [20-22], and cardiac disease remains the main cause of death in patients with high ferritin levels [23]. Variations in the prognosis of thalassemia patients may be due to the development of new treatments, such as bone marrow transplant or splenectomy in TI patients [7,10,24,25], or due to certain new causes of death, such as human immunodeficiency virus and hepatitis C [7].

Given the variations in the prognosis of the disease, obtaining adequate reliable information about common complications that affect the trend and prognosis of the disease in patients treated with conventional or modern methods in different regions of Iran is essential for planning and making decisions about genetic consultations and bone marrow transplantations in affected children [26].

The present study was conducted to determine the survival rate of patients with TM, TI, and sickle-thalassemia in highly endemic regions of Iran and to examine the effects of the main factors associated with survival in patients with TM and TI.

The present historical cohort study was conducted to determine the survival rate of patients with thalassemia born before 1971 and those born from 1971 to 2015 in Sistan and Baluchestan (Zahedan and Iranshahr), Hormozgan (Center for Special Diseases of Shahid Mohammadi Hospital), Tehran, and Mazandaran (Sari) Provinces. In Iran, the northern and southern provinces have highest frequency of thalassemia, and there are referral hospitals in the selected provinces that accept all patients from around the areas of the referral hospitals. Therefore, based on the prevalence of thalassemia and the existence of referral hospitals/centers, we selected 2 high-prevalence provinces from the north (Tehran and Mazandaran) and 2 provinces (Sistan and Baluchestan [Zahedan and Iranshahr] and Hormozgan) from the south of Iran. People with symptoms of anemia are screened for thalassemia at health provider centers, and patients suffering from thalassemia are referred to centers that provide medical services for thalassemia patients. The study population consisted of patients with TM, TI, and sickle beta-thalassemia that had medical records at the thalassemia units and were receiving medical services from them. Patients who had not presented to these medical centers in the 2 years preceding the study or who had incomplete or no records were excluded from the study.

Data about the form of thalassemia, the date of diagnosis, the initiation of iron removal from the body, and age were extracted from the patients’ records, along with some other required information. Trained investigators who were familiar with medical records visited the referral centers for thalassemia in each province, selected the records of all patients admitted from the inauguration of the center until 2015, and extracted the patients’ demographic details, such as age, gender, family history of thalassemia, date of diagnosis, and date of initiation of treatment. Certain outcomes, such as the date of death after the diagnosis of thalassemia, were determined by referring to the patients’ health records or the hospital archivists, or by asking their physicians. Subjects without valid and secure evidence of their death were considered to still be alive.

The present study examined the health records of a total of 5,491 patients from Tehran (n=2,717), Sari (n=739), Bandar-e-Abbas (Hormozgan) (n=815), Iranshahr (n=599), and Zahedan (n=621) using the consensus method (Figure 1).

Thalassemia is prevalent in the southern and northern regions of Iran. Due to the high frequency of thalassemia and the distances between cities, thalassemia patients are referred to a central hospital in each province. In the present study, all medical records from the selected provinces in the south of Iran (Hormozgan, Zahedan, and Iranshahr) and the north of Iran (Tehran and Mazandaran) were assessed to analyze the survival rate. It should be noted that Iranshahr and Zahedan are the 2 major cities in Sistan and Baluchestan Province; Iranshahr is located in the south and Zahedan in the north of the province.

The present study examined 5,491 health records (2,647 [48.2%] from men and 2,634 [48.0%] from women, and 210 (3.8%) cases did not have available medical records). The mean age of the thalassemia patients was estimated as 23.81±11.32 years; it was very similar in Tehran and Sari (28.53 vs. 28.12 years), but was lower in Bandar-e-Abbas (Hormozgan) and Zahedan (18.92 and 15.88 years). Iranshahr had the youngest population of thalassemia patients, with a mean age of 11.39, which was lower than in the other cities.

The plurality of medical records (n=2,717, 49.5%) were obtained from Tehran, the capital of Iran. Additionally, 739 (13.5%) records were obtained from Sari, 815 (14.8%) from Bandar-e-Abbas (Hormozgan), 621 (11.3%) from Zahedan, and 599 (10.9%) from Iranshahr. By type of thalassemia, 3,936 (71.7%) belonged to patients with TM, 999 (2.2%) to patients with TI, and 89 (1.6%) to patients with sickle beta-thalassemia. The form of thalassemia could not be determined in 467 (8.5%) cases due to illegible, outdated, or incomplete records. In terms of the level of education, more than 60% of the TM patients, 50% of those with TI, and 70% of those with sickle beta-thalassemia had less than a high school education. Overall, 1,091 (22.5%) patients were illiterate, 1,947 (40.0%) had less than a high school education, 995 (20.5%) had a high school diploma, and 826 (17.0%) had above a high school education. Iranshahr, among the poorest cities in Iran, had the highest percentage of illiterate patients (54.5%), followed by Zahedan (19.6%) and Tehran (14.8%). Sari had the lowest number of illiterate patients (0.1%), followed by Bandar-e-Abbas (Hormozgan) (0.1%). Overall, 79.4% of the thalassemia patients were single and 20.2% were married. According to the health records, 85.2% of the TM patients, 66.0% of the TI patients, and 73.1% of the sickle beta-thalassemia patients were single.

Our findings showed that 1,666 (30.3%) patients were blood relatives of their spouse, while 1,519 (27.7%) had no such relationship to their spouse. The ratio of patients who were related by blood to their spouse was similar for all the different forms of thalassemia; however, this ratio differed by city. In Zahedan, most thalassemia patients (72.1 vs. 27.9%) reported a blood relationship to their spouse; in Bandar-e-Abbas (Hormozgan), this ratio (56.7%) was lower than in Zahedan, but higher than in all the other cities examined; in Sari, it was 32.5% (vs. the 67.5% who were not related by blood to their spouse); in Tehran, it was 50.7% (vs. 49.2%) (Table 1).

The present study examined 5,491 records of thalassemia patients. The overall mean and median survival of the patients were calculated as 52.42 and 58.00 years, respectively, which seem to be higher than the mean survival of patients reported in a study conducted only in Tehran (41.97 years) [27]. The higher overall survival in the present study may have been because of differences in survival across cities and according to the type of thalassemia. A significant difference was observed in the mean survival between men (51.47 years) and women (53.49 years), suggesting a longer survival in women, which is consistent with the results obtained in other studies; however, the mean survival reported for men and women in the present study is longer than has been reported in other studies [28]. The differences in the survival rates reported in various studies may be attributed to the smaller sample size used in the studies and calculating survival rate only in beta-thalassemia or intermedia thalassemia patients. The present study showed that 99% of the patients lived until 10, 97% until 15, 95% until 20, and 92% until 25 years old. The survival rates reported for these age intervals are higher than those reported in studies conducted in other parts of Iran (Shiraz, Hamadan, and Sistan and Baluchestan) [28-30]. In studies conducted by Zamani et al. [28] and Rajaeefard et al. [29], 88 and 85% of the patients lived until age 20, compared to the 95% rate reported in the present study. The improved patient survival in the present study may be explained by timely iron removal from the body and better patient care [31,32]. The survival rate to the age of 30 was estimated as roughly 41% in Ahvaz (a province in southwest Iran), which is lower than our estimation (88%), but this discrepancy may be explained by differences in patients’ place of residence [33]. Studies conducted in other countries over the last few years reported that the survival rate for thalassemia patients was 89% until the age of 20 and 82% until the age of 25 [26], which is similar to the results obtained in studies previously conducted in Iran; however, the rates may have gradually improved in recent years. Nonetheless, as shown in the survival curves, the patients born after 1971 showed a lower survival at older ages than those born before 1971; for instance, the survival rate was 99% until 40 years in patients born before 1971, compared to 85% in patients born after 1971. The reason for the lower survival of patients born in recent years is that we estimated the overall survival rate without adjusting for the place of residence. Since inhabitants of the south of Iran (Iranshahr and Zahedan) do not have enough access to health care and medical surveillance, their low survival rate affected the overall estimation of survival. In addition, our findings may have been affected by selection bias, in which patients with severe forms of disease may have died before being diagnosed and having medical records made; therefore, patients with better survival remained in the cohort born before 1971, whereas improvements in diagnostic tools might have led to diagnosis of the severe forms of thalassemia in patients born after 1971, resulting in a lower estimated survival. Furthermore, the level of access to health services and health literacy of patients may have contributed to differences in the survival rate. Before 1971, the disease registry in Iran was not as complete as after 1971. In that period of time, there was limited access to health services. Therefore, selected patients with good knowledge and perceptions of the disease, as well as relatively high socioeconomic conditions, may have been more likely to seek care in the health system.

The mean survival was 50.07 years for patients with TM and 56.59 and 53.10 years for patients with TI and sickle beta-thalassemia, respectively. TM patients appear to be at a greater risk of complications and death due to the severity of the disease and their higher need for transfusion and the subsequent iron overload in their body [11]. The mean survival of patients differed across cities, and the highest survival was observed in Tehran and the lowest in Iranshahr (54.10 vs. 30.23 years). It appears that patients residing in Tehran were in a better condition due to the early diagnosis of their disease, the earlier iron removal from their body, and the better care they received in the course of illness, while only 7 out of 590 patients and 27 out of 530 patients remained alive until 30 years old in Iranshahr and Zahedan, respectively. This suggests that patients in these cities receive later diagnoses and poorer care.

The survival of thalassemia patients is affected by various factors, including gender, which was examined in the present study. Although some studies have shown that the survival of patients was not affected by gender [33], others have confirmed the effect of gender on patient survival [26]. According to the present findings, the chances of death were 45% higher in men than in women, which is consistent with the results obtained in a study conducted in Hamadan [28]. The survival calculated in the life table and the Cox regression test showed that, in addition to men gender, having TM was associated with a higher risk of death compared to all other forms of the disease (HR, 4.22 for TM and 0.77 for TI). Patients with TM are at a higher risk of death due to their more critical condition, greater need for transfusion and the subsequent iron overload in their body, and various other complications. Another factor that indirectly affects the survival of thalassemia patients is their place of residence. In the present study, the risk of death in thalassemia patients was 5 and 6 times higher in Iranshahr and Zahedan than in Tehran (p<0.001). The risk of death was also 3.30 and 4.00 times higher in Sari and Bandar-e-Abbas (Hormozgan) than in Tehran (p<0.001). The differences in the survival rate across cities may have been due to differences in the available health care services, timeliness of diagnoses, regular and accurate treatment measures, and regular monitoring and follow-up by medical teams.

In the present study, age at diagnosis was found to be inversely related to the risk of death. In other words, the earlier the disease is

diagnosed, the longer patients will survive [20]. The improved survival of patients may be caused by early care procedures. Another protective factor with an inverse relationship with the risk of death was found to be the initiation of deferoxamine therapy. The early initiation of deferoxamine therapy reduces damage to the body organs and thereby prolongs survival [34].

The substantial sample size of 5,491, the nationwide coverage, and the investigation of all the existing records in the examined cities are strengths of this study. The main limitations were incomplete records (especially in Iranshahr), which caused missing data, difficulty accessing the records of deceased patients, and the geographical dispersion of the selected areas of study. Another point that should be considered in the interpretation and application of our results is that some patients with health records in Tehran appeared to have been residents of other cities, such as Sari and Bandar-e-Abbas (Hormozgan), which may have caused repeated entry and analysis of certain individuals’ details. Furthermore, regarding the study of medical records from hospitals, the possibility of selection bias must be considered when interpreting the results. According to the results obtained, the survival rate was 50% by age 55. The overall mean survival of patients was 52.42 years, and the mean survival of patients with TM was 50.07 years. Patients living in Tehran survived longer than those in other cities, and the patients Iranshahr and Zahedan had an unfavorable lifespan. Gender was found to affect the risk of death, with men having a 45% higher risk of death than women. The risk of death was also 4.22 times higher in patients with TM than in those with the sickle form of the disease. A higher level of education, women gender, being married as opposed to being single, and living in metropolises (due to the better healthcare services) increased patient survival.