Assessment of the prevalence and associated risk factors of QT prolongation, with a focus on medication use, among patients with cardiovascular disease referred to Shahid Chamran Heart Hospital

Abstract

Background

Given the importance of LQTS and its association with potentially fatal ventricular arrhythmias, assessing its prevalence across diverse populations is crucial. This study aims to determine the prevalence of LQTS and its associated risk factors among patients with cardiovascular disease admitted to a heart hospital in Iran, particularly focusing on medication use.

Method

Upon arrival at the emergency department, all patients were evaluated, and relevant data, including medication use, past medical history, and laboratory test results, were extracted from their medical records. Additionally, a 12-lead ECG was obtained from each patient at admission. In this study, the QT interval was reported using the Hodges formulas. QTc thresholds were defined according to both the 2009 AHA/ACCF/HRS guideline and the 99th percentile reference values.

Result

A total of 371 individuals presenting to the emergency department of Shahid Chamran Heart Hospital were included in this study. According to the 2009 guideline, 64 (17.25%) patients were diagnosed with LQTS, and, using the Hodges formula and considering the 99th percentile cutoff, 31 (8.35%) had QT intervals above the 99th percentile. Out of 64 patients diagnosed with LQTS, 27 (42.18%) were using QT-prolonging medications. Furthermore, a significant correlation was observed between medication use and the incidence of LQTS.

Conclusion

The prevalence of LQTS observed in the present study was slightly higher than in other studies, which may be attributed to the selection of a cardiac patient population. A significant correlation was observed between medication use and the incidence of LQTS.

Background

Long QT Syndrome (LQTS) is a disorder of ventricular repolarization characterized by a prolonged QT interval on the electrocardiogram (ECG). This condition can predispose individuals to life-threatening polymorphic ventricular arrhythmias, such as Torsades de Pointes (TdP). While TdP often results in syncope, it can also cause sudden cardiac death. The etiology of LQTS can be classified as either acquired (because of medications, underlying medical conditions, or metabolic disorders) or genetic [1]. These categories often overlap significantly. Among the identified causes, medication use is particularly significant and is the most common reason for prolonged QT intervals. Studies reveal that over half of patients with prolonged QT have used QT-prolonging drugs [1].

Furthermore, approximately 60% of TdP arrhythmias are associated with drugs that induce this condition [2]. The underlying mechanism of drug-induced arrhythmias linked to LQTS involves early afterdepolarizations and triggers activity resulting from prolonged repolarization. Nearly all drugs that cause LQTS do so by blocking the KCNH2 channel and the IKr current, prolonging action potentials [3].

As many affected individuals exhibit no symptoms, the true prevalence of LQTS remains difficult to ascertain accurately. In some cases, sudden death may be the initial indication, often occurring outside hospital settings and often remaining undocumented [4]. A study by the US Food and Drug Administration Adverse Event Reporting System, analyzing data from 2004 to 2008, identified 374 reports of drug-induced LQTS/TdP, of which 62% were related to antimicrobials [2]. Numerous case reports and series further emphasize that drug-induced LQTS/TdP is a considerable health concern, not a condition to be overlooked [3].

Given the significance of LQTS and its association with potentially fatal ventricular arrhythmias, assessing its prevalence across diverse populations is crucial. Such evaluations can enhance healthcare providers’ awareness of risk factors and help identify high-risk patients. This study aims to determine the prevalence of LQTS and its associated risk factors among patients with cardiovascular disease admitted to Chamran Heart Hospital in Isfahan, with particular focus on medication use.

Method

Study design and patient selection

This research is a cross-sectional, observational study with a fundamental-applied approach. The primary objective was to investigate the prevalence of LQTS and its associated risk factors among patients with cardiovascular disease presenting to Shahid Chamran Heart Hospital in Isfahan. The study received approval from the Ethics Committee of Isfahan University of Medical Sciences, under the ethical code IR.MUI.RESEARCH.REC.1400.404.

All patients aged 18 or older who visited the emergency department of Shahid Chamran Heart Hospital during the second half of 2022 were included. Patients were excluded if an ECG could not be obtained for any reason or if their initial ECG was unsuitable for QT interval measurement due to abnormal rhythms, such as ventricular tachycardia.

Data collection

Upon arrival at the emergency department, all patients were evaluated, and relevant data were extracted from their medical records. The collected information included demographic details (such as gender and age), medical history (including cardiovascular conditions such as heart failure and ischemic heart disease), diagnoses, medication use, and laboratory test results (serum magnesium and potassium levels). Moreover, echocardiogram data (such as ejection fraction) were recorded. A 12-lead ECG was obtained from each patient at admission using the Cardiovit ECG recorder (speed: 25 mm/sec; amplification: 10 mm/mV; Cardiovit ECG recorder 25, Schiller AG, Baar, Switzerland). Heart rates were noted, and the QT interval was measured using leads V2 or V3. In cases where overlap occurred between the T wave and the U wave, complicating the identification of the T-wave endpoint, other leads, such as aVR and aVL, were utilized. The measurement of the QT interval began from the initial point of the QRS complex and extended to the final point of the T wave, in accordance with the AHA/ACCF/HRS 2009 guideline. This method involved counting small squares, starting at the beginning of the QRS wave and ceasing at the end of the T wave. The T-wave endpoint was determined using the tangent method, which involved tracing the end of the T wave by drawing a tangent line at the steepest point where the T wave connected with the isoelectric line. In cases of irregular heart rhythms (such as atrial fibrillation), the average of the shortest and longest R-R intervals was calculated. This involved identifying the shortest and longest R-R intervals, measuring the QT interval for each, and reporting the average of the two. In cases of wide QRS complexes (e.g., bundle branch block or pacing rhythms), the Bogossian formula was applied.

Accurate measurement of the QT interval remains a challenge for electrophysiologists. Since heart rate is a crucial factor influencing the QT interval duration, various methods have been developed to adjust for it. One of the most widely used techniques is the Bazett formula (Eq. 1); however, researchers have increasingly recognized its limitations in terms of precision. Specifically, the QT interval estimated using the Bazett method tends to be overestimated at higher heart rates and underestimated at lower heart rates. To mitigate these inaccuracies, the 2009 AHA/ACCF/HRS guideline recommends measuring the QT interval using linear adjustment methods, including the Hodge method (Eq. 2). In this study, the QT interval was primarily determined using the Linear Hodge formula, in accordance with the 2009 AHA/ACCF/HRS guidelines. Since most studies—particularly earlier research—commonly used the Bazett formula to calculate the QT interval, the overall prevalence was reported using both the Bazett and Hodges formulas, facilitating comparison with the existing literature. However, because the Hodges method is more reliable, this method was used for calculations beyond overall prevalence.

Bazzet formula

1

Hodges formula

2

The QT interval was independently determined by two researchers using data entered into the QT calculator available at qtcalculator.org. When there was disagreement between the two researchers, the specific case was discussed in the presence of a third researcher, leading to a consensus before the final result was reported.

In this study, QTc thresholds were defined according to both the 2009 AHA/ACCF/HRS guideline and the 99th percentile reference values. A QTc duration exceeding 450 milliseconds in men and 460 milliseconds in women was considered prolonged based on the definition of the 2009 AHA/ACCF/HRS guideline. Furthermore, the 99th percentile cutoffs for the QT interval were at 470 milliseconds in men and 480 milliseconds in women.

To identify medications associated with QT interval prolongation, the AZCERT reference was used (available at crediblemeds.org).

All electrolyte abnormalities associated with QT prolongation, such as hypokalemia and hypomagnesemia, were corrected in accordance with standard hospital protocols. However, the baseline ECG was obtained immediately upon admission, prior to correcting these electrolyte imbalances. Patients were then followed until discharge to identify any arrhythmias related to LQTS, such as Torsades de Pointes.

Data analysis and statistics

Qualitative nominal variables were reported as counts and percentages, while quantitative variables were expressed as mean ± standard deviation. An independent t-test was used to compare the means of quantitative variables, and the Chi-square test was employed for qualitative variables. To investigate the independent association between potential risk factors and LQTS, multiple logistic regression models were used. Variables entered into the adjusted model were those considered clinically relevant based on prior literature. Before model fitting, multicollinearity was assessed using VIF and tolerance values for the independent variables. A VIF > 5 was considered indicative of multicollinearity. For this study, version 20 of the Statistical Package for the Social Sciences (SPSS) was employed, and a p-value of less than 0.05 was considered statistically significant.

Results

In this study, 371 individuals presented to the emergency department of Shahid Chamran Heart Hospital. Among them, 244 (65.76%) were men and 127 (34.23%) were women. The mean age of the male participants was 62.88 years, while the mean age of the female participants was 63.57 years. (Table 1)

Table 1.

Demographic characteristics of the studied patients

Total number of patients	371
Male	244(%65.76)
Female	127(%34.23)
Average age of males	62.88 ± 11.31
Average age of females	63.57 ± 9.47

Table 2 presents the prevalence of LQTS among patients, assessed using two measurement methods (Hodges, a more reliable method, and Bazett) and two definitions (the 99th percentile and the AHA/ACCF/HRS 2009 guideline). According to the 2009 guideline, 64 (17.25%) patients were diagnosed with LQTS using the Hodges method, compared with 135 (36.4%) using the Bazett method. When considering the 99th percentile cutoff, 67 (18.05%) patients had QT intervals above the 99th percentile using the Bazett formula and 31 (8.35%) using the Hodges formula. Ten patients exhibited QT intervals exceeding 500 milliseconds according to the Hodges formula. Among the patients with LQTS, three experienced Torsades de Pointes (TdP) during hospitalization, and one patient died shortly after admission.

Table 2.

Frequency of LQTS in the studied patients

Patients		Bazzet method	Hodges method
According to The 99th percentile	Males with QT longer than 470 ms	44 (%18.03)	20 (%8.19)
	Females with QT longer than 480 ms	23 (%18.11)	11 (%8.66)
	Total patients	67 (%18.05)	31 (%8.35)
According to the AHA/ACCF/HRS 2009	Males with QT longer than 450 ms	95 (%38.93)	42 (%17.21)
	Females with QT longer than 460 ms	40 (%31.49)	22 (%17.32)
	Total patients	135 (%36.38)	64 (%17.25)

Table 3 presents the frequency of QT-prolonging medications among all patients in this study, categorized by specific drugs. Among the 371 patients analyzed, 74 (19.9%) were prescribed QT-prolonging medications, with amiodarone being the most frequently used, accounting for 10 patients. Furthermore, 16 out of the 371 patients studied were taking multiple QT-prolonging medications. Among all patients, there was a single case of a patient concurrently using three QT-prolonging medications: citalopram, quetiapine, and nortriptyline.

Table 3.

The frequency of QT-prolonging medication use among the studied patients

Dru Classes	Number of Patients (%)
Total patients receiving QT prolonging drugs	74 (19.94%)
Cardiovascular medications Amiodarone 10, Mexiletine 9, Ranolazine 6, Flecainide 1	26 (7%)
Psychologic and neurologic medications Citalopram 8, Quetiapine 7, Sertraline 5, Risperidone 4, Escitalopram 3, Amitriptyline 3, Nortriptyline 2, Haloperidol 2, Donepezil 1	35 (9.43%)
Antimicrobial medications Ciprofloxacin 6, Levofloxacin 1	7 (1.88%)
Gastrointestinal medications Ondansetron 9, Domperidone 2	11 (2.96%))
Others Methadone 7, Hydroxychloroquine 2, Tacrolimus 2, Hydroxyzine 1	12 (3.23%)
Patients taking two QT-prolonging drugs concurrently	15(4.04%)
Patients taking three QT-prolonging drugs concurrently	1(0.27%)

Table 4 displays the frequency of QT-prolonging medication use among patients diagnosed with LQTS. Out of the 64 patients diagnosed according to the AHA/ACCF/HRS 2009 guideline, 27 (42.18%) were found to be using QT-prolonging medications. The most commonly prescribed drugs in this group were cardiovascular medications (16 patients). Among these 64 patients, 11 (17.2%) were taking more than one QT-prolonging medication simultaneously. Furthermore, among the 31 patients with QT intervals above the 99th percentile, 14 (45.16%) were using QT-prolonging medications. A significant difference was observed between the two groups (patients with LQTS and those without) regarding the frequency of QT-prolonging drug use.

Table 4.

Frequency of QT-prolonging drug use among patients with LQTS

Drugs	Patients with LQTS based on the AHA/ACCF/HRS 2009a	Patients with QT interval above the 99th percentilea
Total patients with LQTS Receiving QT prolonging drugs	27 (42.18%)	14 (45.16%)
Cardiovascular medications Amiodarone, Mexiletine, Ranolazine	16 (25%)	8 (25.8%)
Psychologic and neurologic medications Citalopram, Quetiapine, Sertraline, Risperidone, Escitalopram, Amitriptyline, Nortriptyline, Donepezil	13 (20.31%)	4 (12.9%)
Antimicrobial medications Levofloxacin, Ciprofloxacin	5 (7.81%)	3 (9.67%)
Gastrointestinal medications Ondansetron, Domperidone	5 (7.81%)	1 (3.22%)
Patients taking two QT-prolonging drugs concurrently	10 (15.62%)	4 (12.9%)
Patients taking three QT-prolonging drugs concurrently	1 (1.56%)	0 (0%)

^aBased on the Hodges method

Table 5 presents the prevalence of LQTS among patients prescribed QT-prolonging medications, evaluated according to the 2009 AHA/ACCF/HRS LQTS guideline and the 99th percentile definition. Of the 74 patients identified as using QT-prolonging drugs, 27 (36.5%) met AHA/ACCF/HRS guideline criteria, and 14 (18.91%) had QT intervals above the 99th percentile. As demonstrated in the table, among the 15 patients taking more than one QT-prolonging medication, 10 were diagnosed with LQTS according to the 2009 guideline.

Table 5.

Frequency of LQTS in the patients taking QT-prolonging drugs

Drugs	Patients with LQTS based on the AHA/ACCF/HRS 2009a	Patients with QT interval above the 99th percentilea
Total patients with LQTS Receiving QT prolonging drugs Number of patients with LQTS receiving drug/Total number of patients receiving drug	27/74 (36.48%)	14/74 (18.91%)
Cardiovascular medications	16/25 (64%)	10/25 (40%)
Amiodarone	6/10 (60%)	4/10 (40%)
Mexiletine	8/9 (88.88%)	4/9 (44.44%)
Ranolazine	2/6 (33.33%)	2/6 (33.33%)
Psychologic and neurologic medications	13/33 (39.39%)	4/33 (12.12%)
Citalopram	2/8 (25%)	0/8 (0%)
Quetiapine	4/7 (57.14%)	1/7 (14.28%)
Sertraline	1/5 (20%)	0/5 (0%)
Escitalopram	1/3 (33.33%)	1/3 (33.33%)
Risperidone	1/4 (25%)	1/4 (25%)
Amitriptyline	2/3 (66.66%)	0/3 (0%)
Nortriptyline	1/2 (50%)	0/2 (0%)
Donepezil	1/1 (100%)	1/1 (100%)
Antimicrobial medications	5/7 (71.42%)	3/7(42.85%)
Ciprofloxacin	4/6 (66.66%)	2/6 (33.33%)
Levofloxacin	1/1 (100%)	1/1 (100%)
Gastrointestinal medications	5/11 (45.45%)	1/11 (9.09%)
Ondansetron	3/9 (33.33%)	0/9 (0%)
Domperidone	2/2 (100%)	1/2(50%)
Patients taking two QT-prolonging drugs concurrently	10/15 (66.66%)	4/15 (26.66%)
Patients taking three QT-prolonging drugs concurrently	1/1 (100%)	0/1 (0%)

^aBased on the Hodges method

Table 6 demonstrates the relationship between patient risk factors and LQTS. No significant multicollinearity was observed among independent variables (all VIF values < 5.0). Interaction terms were tested, but did not achieve statistical significance. Notably, after data adjustment, a significant association was found between heart failure (P-value 0.02) and the use of QT-prolonging medications (P-value < 0.001), with the incidence of LQTS based on AHA/ACCF/HRS guideline criteria. However, no significant associations were observed with the other risk factors.

Table 6.

The relationship between the risk factors and the incidence of LQTS (Based on the hodges method)

Parameters	Full Adjusted (AHA/ACCF/HRS 2009)		Full Adjusted The 99th percentile))
	Confidence Level of 95%	P Value	Confidence Level of 95%	P Value
Age	1.01 (0.99–1.03)	0.195	1.485 (0.63–3.47)	0.362
Sex	1.28 (0.68–2.4)	0.44	1.00 (0.97–1.03)	0.599
Hypomagnesemia	0.91 (0.37–2.20)	0.84	0.51 (0.13–1.94)	0.32
Hypokalemia	1.51 (0.60–3.81)	0.37	1.35 (0.39–4.65)	0.62
IHD	0.65 (0.33–1.27)	0.21	0.425 (0.166–1.08)	0.074
HFrEF	2.25 (1.13–4.49)	0.02	3.2 (1.13–9.01)	0.027
Use of QT prolonging medication	3.31 (1.77–6.19)	< 0.001	2.77 (1.17–6.19)	0.019

IHD Ischemic heart disease, HFrEF Heart failure with reduced ejection fraction

Discussion

LQTS is a disorder of ventricular myocardial repolarization characterized by a prolonged QT interval on the ECG. This condition can lead to life-threatening ventricular arrhythmias and an increased risk of sudden cardiac death [5, 6]. Although LQTS is relatively rare, its potential for fatal outcomes and the presence of various modifiable risk factors highlight the importance of understanding its prevalence and associated risk factors to effectively reduce mortality related to this syndrome. This study aimed to assess the frequency of LQTS and its associated risk factors, with a particular focus on medication use, among cardiac patients referred to Chamran Heart Hospital emergency department, who are likely among the most sensitive and high-risk individuals for this condition.

The findings revealed that 17.25% and 36.38% of the patients studied were diagnosed with LQTS using the Hodges and the Bazett methods, respectively, as defined in AHA/ACCF/HRS 2009 guidelines. Among these patients, three experienced Torsades de Pointes (TdP) during hospitalization, and one patient died.

A noteworthy point in this study is the significant discrepancy in LQTS prevalence between the Bazett and Hodges formulas. As demonstrated in the results (Table 2), the Bazett formula tends to overestimate the QT interval length, particularly at higher heart rates. To mitigate these inaccuracies, the 2009 AHA/ACCF/HRS guideline recommends measuring the QT interval using linear adjustment methods, including the Hodge method (Eq. 2). In this study, the QT interval was primarily determined using the Linear Hodge formula, in accordance with the 2009 AHA/ACCF/HRS guidelines. Since most studies—particularly prior research—used the Bazett formula to calculate the QT interval, the overall prevalence was reported using both the Bazett and Hodges formulas, facilitating comparison with the existing literature. However, because the Hodges method is more reliable, this method was used for calculations beyond overall prevalence.

A retrospective study conducted in the United States in 2009, involving 1,558 adults admitted to a general emergency department, found that 35% of the patients had LQTS, with 8% exhibiting a QT interval exceeding 500 ms [7]. Another study conducted in 2019 on the general population in China estimated the overall prevalence of prolonged QT intervals to be 31.6% [8]. Research focusing on the Iranian population with stroke and atherosclerotic disorders reported the prevalence of LQTS to range from 15% to 25%, based on the Bazett method used in all three studies [9].

The prevalence of LQTS observed in the present study was slightly higher than in other studies, likely due to the specific cardiac patient population selected for this study. This demographic is predisposed to developing LQTS due to multiple risk factors, including medication use, ischemic heart disease, and structural heart abnormalities. Notably, 75% of patients with LQTS in our study had at least one established risk factor for the syndrome. Consequently, the results may not apply to the general population.

The prevalence of QT-prolonging medication use in this study was reported at 19.94%, with 21.6% of these patients concurrently taking more than one QT-prolonging drug. According to the AHA/ACCF/HRS 2009 definition of LQTS, 42% of the patients diagnosed with LQTS were receiving at least one medication known to contribute to this condition. Moreover, 36.48% of those prescribed QT-prolonging medications were also diagnosed with LQTS. The most commonly associated drug was amiodarone, with 60% of patients on this medication developing QT prolongation. Additionally, 88% of those receiving mexilitin experienced LQTS. These results indicated a significant correlation between medication use and the LQTS. Furthermore, a significant difference was observed between the two groups (patients with LQTS and those without) regarding the frequency of QT-prolonging drug use.

A study involving 172 patients with LQTS admitted to a university hospital in Canada identified the primary cause of LQTS as the use of QT-prolonging medications, with 48% developing the syndrome due to medication use. Furthermore, 25% of patients using QT-prolonging drugs were found to be taking more than one medication implicated in LQTS [10]. In another study conducted between 2010 and 2011 in the emergency department at Rochester Hospital, New York, 16% of patients (including outpatients, inpatients, and emergency cases) experienced QT prolongation solely due to medication [11]. In another study involving elderly patients admitted to a hospital in Switzerland over six months, 33 (21.7%) out of 152 patients were diagnosed with LQTS, comprising 14 women and 19 men. Among these 33 patients, 8 had not taken any medications, 15 were on one drug, and 10 were taking multiple medications associated with LQTS [12].

Medication-induced QT prolongation is the most common environmental and modifiable factor influencing this condition. The significance of this finding is underscored by the fact that, in some cases, simply altering or discontinuing a medication can markedly reduce the risk of developing LQTS and its severe complications. Additionally, it is important to recognize that pharmacokinetic interactions or inappropriate dosing—particularly in patients with liver or kidney dysfunction—can lead to increased serum drug concentrations, thereby further elevating the risk of LQTS [13, 14].

This study also identified significant associations between heart failure and LQTS, which is a recognized risk factor for this condition. The relationship between heart failure and QT prolongation was corroborated by findings from other researchers [14–16].

In this study, only three patients experienced TdP during hospitalization, and despite appropriate medical intervention, one patient died. However, it is worth noting that most patients presenting to the cardiac hospital’s emergency department underwent continuous cardiac monitoring after initial evaluation and were closely monitored for the development of cardiac arrhythmias. This enabled prompt intervention in cases of arrhythmias. Moreover, risk factors for LQTS, such as hypomagnesemia and hypokalemia, were rapidly addressed upon identification in the hospital setting. Consequently, the incidence of life-threatening arrhythmias and related mortality observed in this study cannot be generalized to other populations or non-admitted patients. Nonetheless, the potential danger posed by this syndrome should still be kept in mind and warrants continued vigilance.

The actual prevalence of TdP and its associated mortality rate are inherently difficult to determine with precision, primarily because most cases occur in the community setting rather than hospitals, which complicates systematic identification and documentation. As a result, there is insufficient data in the existing literature to directly compare our findings.

Given that LQTS is often asymptomatic and can occasionally present with sudden cardiac death due to life-threatening arrhythmias, recognizing the risk factors and identifying susceptible patients is crucial for reducing modifiable risks (such as electrolyte disturbances and inappropriate medication use). Therefore, it is imperative to identify high-risk patients and exercise caution when prescribing medications. Furthermore, since ECG monitoring is a simple, cost-effective, and readily available method for detecting and tracking individuals with LQTS, it is recommended that patients receiving LQTS medications undergo regular ECG assessments throughout their treatment.

It is noteworthy that many drugs have the potential to prolong the QT interval; however, this effect does not occur in all individuals, and not all patients with LQTS develop TdP or die from it. Consequently, in some situations, denying patients access to appropriate medications solely to prevent this adverse effect may not be justifiable. This is where remote monitoring of QT interval strategies, such as implantable cardiac monitors (ICM), can play a crucial role. ICMs could enable ongoing QT monitoring in high-risk patients prescribed QT-prolonging medications [17–19].

Limitations

This study was conducted in the emergency department at a single center and enrolled only patients with cardiac disease who appeared to be at increased risk of LQTS due to identified risk factors. Consequently, the results may not be generalizable to the general population or to out-of-hospital cases. Additionally, most patients presenting to the cardiac hospital’s emergency department underwent continuous cardiac monitoring after initial evaluation and were closely monitored for the development of cardiac arrhythmias. This enabled prompt intervention in cases of arrhythmias. Furthermore, risk factors for LQTS, such as hypomagnesemia and hypokalemia, were rapidly addressed upon identification in the hospital setting. Consequently, the incidence of life-threatening arrhythmias and related mortality observed in this study cannot be generalized to other populations or non-admitted patients.

Conclusion

The results of this study revealed that the frequency of long QT syndrome in the population of heart patients referred to a referral heart hospital is approximately 17% and its risk factors include heart failure, metabolic disorders such as hypokalemia and hypomagnesemia, and the use of drugs that prolong the QT interval.

Abbreviations

LQTS

Long QT Syndrome

TdP

Torsades de Pointes

ECG

Electrocardiogram

IHD

Ischemic Heart Disease

HFrEF

Heart Failure with Reduced Ejection Fraction

AHA/ACCF/HRS guideline

American Heart Association/American College of Cardiology / and Heart Rhythm Society guideline

Authors’ contributions

“M.M. and M.D. and A.A. wrote the main manuscript text and E.SH. verified the analytical methods. Z.T. and S.B. helped supervise the project All authors reviewed the manuscript.”

Funding

not applicable.

Data availability

The datasets generated and/or analyzed during the current study are available in the • The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The study received approval from the Ethics Committee of Isfahan University of Medical Sciences, under the ethical code IR.MUI.RESEARCH.REC.1400.404.

The study was conducted in accordance with the principles of the declaration of Helsinki.

Informed consent was obtained from all participants.

Consent for publication

No individual patient data/images included.

Competing interests

The authors declare no competing interests.