Socio-demographic characteristics of participants

In this study a total of 318 hyperthyroid patients were participated, most (90.9%) of them were females. The mean (± standard deviation) age was 44.2 ± 13.6 years. Majority of the participants (68.9%) were married and (71.4%) live in urban area. Regarding educational status, below half (45.9%) of the participants have attained diploma & above and about 36.8% of them were government employed (Table 1).

Table 1 Socio demographic characteristics of the study participants, TASH, Addis Ababa, Ethiopia, 2022 (n = 318)Health related behaviors and clinical conditions of the participants

Almost all (98.1%) of the participants were non-smoker and non-alcoholic. Most of the participants (93.4%) were classified as overt hyperthyroidism and manifesting symptoms of hyperthyroidism for a median time of eight months before the diagnosis. The cause for more than half (57.5%) of hyperthyroid cases were multi-nodular goiter. Regarding the type of medications, more than half (56.3%) of the participants were taking beta blocker and propylthiouracil (PTU). They were taking treatments of hyperthyroidism for a median duration of four months and 83.5% of them had attained the euthyroid state. The maximum time taken to achieve euthyroid state was 48 months (Table 2).

Table 2 Health related behaviors and clinical conditions of the study participants at TASH, Addis Ababa, Ethiopia, 2022Stroke and other comorbidities

Out of 318 hyperthyroid patients, only eight (2.5%) of them had developed stroke (all of them had abnormal Echocardiographic findings). Regarding other comorbidities, more than one third (35.5%) of the study participants had hypertension, 50 (15.7%) had diabetes mellitus, 31(9.7%) had dyslipidemia, 17(5. 3%) had asthma, and 15 (4.7%) had retroviral infection.

Magnitude of cardiac abnormalities

In this study, the overall prevalence of heart failure among hyperthyroid patients was 17.0% (95% CI = 13.0, 21.6). Electrocardiographic examination was done for 264 hyperthyroid patients, out of which 139 (52.7%) of them had abnormal findings. Similarly, out of 271 patients who had Echocardiographic work up, 33.2% of them showed abnormal cardiac findings (Fig. 1).

Fig. 1

Thyrocardiac abnormalities among hyperthyroidism patients on follow up at TASH, Addis Ababa, Ethiopia, 2022

From abnormal Electrocardiographic findings, nearly one third (32.2%) of them were sinus tachycardia. Majority of the study participants had palpitation (81.1%), fatigue (77.4%) and shortness of breath (55.3%). About 44 (13.8%) of the participants had raised jugular vein pressure (JVP) (Table 3).

Table 3 Thyrocardiac abnormalities and presentation of the study participants at TASH, Addis Ababa,  Ethiopia, 2022Factors associated with thyrocardiac abnormality

Bivariable logistic regression was run to identify candidate variables for multivariable analyses. Accordingly, variables with P value ≤ 0.25 were moved to multivariable logistic regression to control the effect of confounders. Variables including marital status (being not married) (COR = 2.21, 95% CI (1.22, 4.03)], age category > 50 years [COR = 1.79, 95% CI (0.99, 3.24)], multi-nodular goiter as a cause of hyperthyroidism [COR = 4.78, 95% CI (1.64, 13.92)], pattern of hyperthyroidism [COR = 16.83, 95% CI (8.34, 33.98)], time taken to achieve euthyroid state [COR = 8.17, 95% CI (3.15, 21.15), having Asthma [COR = 20.61, 95% CI (6.41, 66.28)], having dyslipidemia [COR = 2.20, 95% CI (0.951, 5.09)], duration of hyperthyroidism [COR = 2.51, 95% CI (1.23, 5.13)], type of medication (taking Beta blocker(s) and PTU [COR = 1.62, 95% (0.77, 3.39)], duration of treatment > 6 months [COR = 3.58, 95% CI (1.95, 6.56)], being diabetic [COR = 2.22, 95% CI (1.10, 4.48)], and being hypertensive [COR = 1.89, 95% CI (1.05, 3.42)] were selected to fit the multivariable logistic regression model. After controlling the effect of potential confounding variables, Marital status (not married) [AOR = 2.37, 95% CI (1.03, 5.44)], pattern of hyperthyroidism [AOR = 13.09, 95% CI (4.70, 36.41)], having asthma [AOR = 7.63, 95% CI (1.55, 37.52)], type of medication [AOR = 3.49, 95% CI (1.11, 11.02) and duration of treatment [AOR = 4.95, 95% CI (2.05, 11.99)] were significantly associated with the dependent variable (cardiac abnormality).

In this study, likelihood of developing heart abnormality was more than double among non-married patients than married patients [AOR = 2.37, 95% CI (1.03, 5.44)]. Likewise, patients who have Asthma as a comorbidity were nearly eight times more likely to develop cardiac abnormality than their counterparts [AOR = 7.63, 95% CI (1.55, 37.52)]. Regarding the pattern/degree of hyperthyroidism, patients with hyperthyroid state during the study were 13 times more likely to have heart abnormality as compared with euthyroid state [AOR = 13.09, 95% CI (4.70, 36.41)]. Additionally, participants who stayed on treatment for six months and above were nearly five times more likely to develop cardiac abnormality than those who were taking the treatments for less than six months [AOR = 4.953, 95% CI (2.05, 11.99)]. Moreover, patients who were under Beta blocker(s) and PTU treatment regimen were more than three folds more likely to have cardiac abnormality than those who were taking PTU alone (Table 4).

Table 4 Factors associated with Thyro-cardiac abnormality among hyperthyroidism patients on follow up at TASH, Addis Ababa, Ethiopia, 2022