Survival and causes of death in patients with alpha and beta-thalassemia in Northern Thailand

Figures & data

Table 1. Demographic and clinical characteristics of the study patients.

Patient characteristics	Total
	(n = 789)
Gender, n (%)
Male	400 (50.7)
Female	389 (49.3)
Thalassemia type, n (%)
Beta-thalassemia major	209 (26.5)
Hb E/beta-thalassemia	279 (35.4)
Hb H disease	301 (38.1)
Transfusion dependency, n (%)
Dependent	395 (50.1)
Non-dependent	394 (49.9)
Splenectomy, n (%)
Yes	233 (29.5)
No	556 (70.5)
Iron chelation, n (%)
Yes	336 (42.6)
No	453 (57.4)
Steady-state or pre-transfusion Hb, n (%)
<7 g/dL	132 (16.7)
≥7 g/dL	657 (83.3)
Mean serum ferritin level, n (%)
≥3000 ng/mL	84 (16.4)
<3000 ng/mL	427 (83.6)
Year of birth median (IQR)	2002 (13)
Follow-up duration in the hospital, years median (IQR)	13.2 (10.6)
Age at the end of follow-up, years median (IQR)	18.8 (11.7)

Table 2. Causes of death as classified by the thalassemia disease type.

Causes	Number (%)	Beta-thalassemia major	Hb E/beta-thalassemia	Hb H disease
Infections-related	24 (36.9)	13 (36.1)	9 (47.4)	2 (20.0)
Cardiac complications	18 (27.7)	11 (30.6)	3 (15.8)	4 (40.0)
Heart failure and dilated cardiomyopathy	15	10	1	4
Coronary artery diseases	2	1	1	0
Severe pulmonary hypertension	1	0	1	0
Thalassemia/anaemia	9 (13.8)	6 (16.6)	3 (15.8)	0
Trauma	4 (6.2)	2 (5.6)	1 (5.2)	1 (10.0)
Others	10 (15.4)	4 (11.1)	3 (15.8)	3 (30.0)
Thrombotic-related complications	2	0	1	1
Diabetes mellitus/diabetic ketoacidosis	2	2	0	0
Relapse ALL	1	1	0	0
Systemic lupus erythematosus	1	0	0	1
Rheumatoid arthritis	1	0	1	0
Hypotension	1	0	1	0
Asthma	1	1	0	0
Kidney failure	1	0	0	1
Total	65 (100)	36 (100)	19 (100)	10 (100)

Table 3. Comparison of clinical parameters and complications according to survival status.

Patient characteristics	Alive	Deceased	p Value
	(n = 724)	(n = 65)
Gender, n (%)
Male	368 (50.8)	32 (49.2)	0.805
Female	356 (49.2)	33 (50.8)
Thalassemia type, n (%)
Beta-thalassemia major	173 (23.9)	36 (55.4)	<0.001*
Hb E/beta-thalassemia	260 (35.9)	19 (29.2)
Hb H disease	291 (40.2)	10 (15.4)
Transfusion dependency, n (%)
Dependent	344 (47.5)	51 (78.5)	<0.001*
Non-dependent	380 (52.5)	14 (21.5)
Iron chelation, n (%)
Yes	303 (41.9)	33 (50.8)	0.164
No	421 (58.1)	32 (49.2)
Steady-state or pre-transfusion Hb, n (%)
<7 g/dL	106 (14.6)	26 (40.0)	<0.001*
≥7 g/dL	618 (85.4)	39 (60.0)
Mean serum ferritin level, n (%)
≥3000 ng/mL	62 (13.2)	22 (52.4)	<0.001*
<3000 ng/mL	407 (86.8)	20 (47.6)
Complications, n (%)
Hepatitis B infection	9 (1.2)	1 (1.5)	0.593
Hepatitis C infection	10 (1.3)	1 (1.5)	0.956
Reduced LVEF <40%	15 (2.0)	12 (18.4)	0.003*
Pulmonary hypertension	23 (3.1)	11 (16.9)	0.042*
Liver cirrhosis	1 (0.1)	1 (1.5)	0.161
Diabetes mellitus	13 (1.8)	5 (7.7)	0.002*
Hypothyroidism	24 (3.3)	4 (6.1)	0.268
Hypoparathyroidism	7 (0.9)	2 (3.0)	0.174
Hypogonadism	22 (3.0)	4 (6.1)	0.071*
Adrenal insufficiency	43 (5.9)	2 (3.0)	0.571
Extramedullary haematopoiesis	23 (3.1)	1 (1.5)	<0.001*
Venous thrombosis	4 (0.6)	0	0.709

LVEF, left ventricular ejection fraction.

* Statistically significant results.

Figure 1. Kaplan–Meier survival curve of thalassemia patients. (A) Kaplan–Meier survival curve of all thalassemia patients. (B) Kaplan–Meier survival curve of thalassemia patients as classified by thalassemia type.

Figure 2. Kaplan–Meier survival curve of thalassemia patients as classified by transfusion status.

Figure 3. Kaplan–Meier survival curve of thalassemia patients as classified by mean serum ferritin levels.

Table 4. Univariable cox regression model results of significant factors (p value <0.1) affecting survivals in thalassemia patients.

Variables	Hazard ratio (95% CI)	p Value
Thalassemia type (beta-thalassemia major vs. Hb H disease)	4.15 (2.06–8.38)	<0.001*
(Hb E/beta-thalassemia vs. Hb H disease)	1.56 (0.72–3.37)	0.251
Transfusion type (TDT vs. NTDT)	3.45 (1.91–6.23)	<0.001*
Hemoglobin level (<7 g/dL vs. ≥7 g/dL)	2.16 (1.31–3.56)	0.002*
Mean serum ferritin level (≥ 3000 ng/mL vs. <3000 ng/mL)	5.93 (3.20–10.99)	<0.001*

NTDT, non-transfusion-dependent thalassemia; TDT, transfusion-dependent thalassemia.

* Statistically significant results.

Table 5. Multivariable cox regression model results of significant factors affecting survivals in thalassemia patients (method: forward likelihood ratio (LR)).

Variables	Adjusted hazard ratio (95% CI)	p Value
Transfusion type (TDT vs. NTDT)	3.68 (1.39–9.72)	0.008*
Mean serum ferritin level (≥3000 ng/mL vs. <3000 ng/mL)	4.18 (2.20–7.92)	<0.001*

LVEF, left ventricular ejection fraction; NTDT, non-transfusion-dependent thalassemia; TDT, transfusion-dependent thalassemia.

* Statistically significant results.

Data availability statement

The medical records of the patients used in this analysis contain identifiable human subject data, which cannot be disseminated under the terms of the IRB and data use agreements with contributing institutions. For analyses of patient-level identifiable data within our trusted research environment, please email the corresponding author.