Reactivation of retinopathy of prematurity after intravitreal bevacizumab: incidence, risk factors, and retreatment requirements

Abstract

Background

This study aimed to evaluate the incidence and risk factors of reactivation following intravitreal bevacizumab (IVB) treatment for retinopathy of prematurity (ROP) and to determine which cases required additional treatment.

Methods

A retrospective cohort study was conducted including 62 premature infants (119 eyes) diagnosed with type 1 ROP or aggressive ROP (A-ROP) who received IVB monotherapy between September 2021 and July 2024. Demographic and clinical parameters such as gestational age, birth weight, disease zone and stage, duration of oxygen therapy, and timing of IVB administration were analyzed. Reactivation and retreatment rates were compared to identify potential risk factors.

Results

Reactivation occurred in 36 eyes (30.3%), and 31 of these eyes (86.1%) required additional treatment. The mean gestational age and birth weight in reactivated eyes were 24.4 ± 1.2 weeks and 643 ± 149 g, respectively. Reactivation was significantly associated with lower gestational age (p < 0.001), lower birth weight (p < 0.001), longer pre- and post-IVB oxygen therapy (p = 0.006 and p < 0.001), zone 1 disease (p < 0.001), and the presence of A-ROP (p < 0.001). Reactivation developed on average 9.4 weeks after IVB administration. Female infants showed a higher proportion of treatment-requiring reactivation (p = 0.031).

Conclusions

Reactivation following IVB therapy is common among infants with low gestational age, low birth weight, prolonged oxygen exposure, and aggressive or zone 1 disease. Although most reactivations required retreatment, some resolved spontaneously, highlighting the importance of individualized and extended post-treatment monitoring.

Introduction

Retinopathy of prematurity (ROP) is one of the leading causes of preventable blindness in children worldwide [1]. This retinal vascular disease primarily affects premature infants born before 32 weeks of gestation or with a birth weight of less than 1500 g. ROP is characterized by the incomplete development of normal retinal vasculature and the formation of abnormal neovascularization in avascular retinal areas. If left untreated, these pathological blood vessels can progress into the vitreous, leading to traction and retinal detachment, ultimately resulting in permanent vision loss [2].

The BEAT-ROP study, published in 2011, demonstrated that intravitreal bevacizumab (IVB) therapy is particularly effective in stage 3 + posterior ROP cases [3]. Bevacizumab, an anti-VEGF agent that inhibits vascular endothelial growth factor (VEGF), halts neovascularization and prevents the progression of ROP. The BEAT-ROP study reported that IVB injections resulted in better outcomes, especially in posterior ROP cases, with fewer side effects compared to laser treatment. These findings have led to the increasing preference for intravitreal anti-VEGF therapy in the treatment of ROP. However, the long-term safety and recurrence rates of intravitreal bevacizumab remain controversial [4, 5]. It has been reported that anti-VEGF treatment may be associated with variable treatment responses, including incomplete regression and post-treatment reactivation, and that reactivation rates may differ depending on the specific anti-VEGF agent used [6–8]. In addition to recurrence after anti-VEGF treatment, treatment failures may also occur [3]. Given the long-term adverse effects of the disease, early detection of potential treatment failures and recurrences following intravitreal anti-VEGF therapy is critical for appropriate follow-up and management. The use of anti-VEGF agents in ROP treatment requires careful consideration, taking into account not only potential systemic side effects and the risk of recurrence, but also long-term visual outcomes, including the persistence of peripheral avascular retina, the risk of late reactivation, and the need for prolonged follow-up. The objective of this study is to evaluate the incidence of reactivation following IVB injections, to identify the risk factors associated with reactivation, and to determine the necessity for treatment in cases of reactivation.

Methods

Study design and population

This retrospective cohort study was conducted in accordance with the principles set forth in the Declaration of Helsinki and approved by the Çam and Sakura City Hospital Ethics Committee. Written informed consent was obtained from the legal guardians of all participants. The study included infants who were followed up at the Çam and Sakura City Hospital ROP outpatient clinic between September 2021 and July 2024. Eligible infants were those diagnosed with type 1 ROP or aggressive ROP (A-ROP), who received IVB as the initial treatment modality, with no history of prior laser photocoagulation. Infants with severe systemic congenital disorders (e.g., chromosomal abnormalities, metabolic diseases) or other ocular diseases unrelated to ROP were excluded. Patients who died or were lost to follow-up due to transfer to other clinics after IVB treatment were also excluded. A total of 62 patients meeting these criteria were enrolled.

Data collection and ophthalmologic examination

Demographic and clinical data collected included gestational age (GA), birth weight (BW), timing of IVB administration, history of oxygen therapy before and after IVB, ROP zone and stage, occurrence and timing of reactivation, and whether reactivation necessitated treatment. Oxygen therapy encompassed all instances of intubation and incubator-based supplementation. ROP classification was performed according to the International Classification of Retinopathy of Prematurity (ICROP), with flat neovascularizations observed in A-ROP classified as stage 3 ROP [9]. Prior to examination, pharmacological pupil dilation was achieved with topical tropicamide 0.5% and phenylephrine 2.5%. Subsequently, all infants underwent comprehensive ocular examination, including indirect ophthalmoscopy with scleral depression and wide-angle fundus photography using topical proparacaine for anesthesia.

Intravitreal injection procedure

Intravitreal bevacizumab injections were performed under sterile conditions. Topical anesthesia was administered using proparacaine. A 30-gauge needle was used to inject 0.625 mg/0.025 mL bevacizumab at 1.5 mm posterior to the limbus. All injections were performed by a single experienced pediatric retina specialist (CG).

Follow-up and definitions

Following IVB administration, patients were monitored weekly until complete remission of the disease was observed. Thereafter, follow-up examinations were scheduled at two-week intervals until either full retinal vascularization was achieved or signs of reactivation were detected. This two-week interval was maintained until at least postmenstrual week 60. Final follow-up visits were conducted at predetermined intervals throughout the study period. Patients whose last follow-up occurred before the 60th postmenstrual week were excluded from the analysis.

Persistent avascular retina (PAR) was assessed at the 60th postmenstrual week and defined as avascular retinal areas exceeding two disc diameters posterior to the ora serrata. Reactivation was defined in accordance with ICROP criteria as the reappearance of any of the following after initial regression: plus disease, pathological neovascularization, or an elevated ridge [9]. A faint Stage 1 demarcation line without other signs of activity was excluded from reactivation due to its benign and transient nature.

Treatment success was defined as complete regression of plus disease and flattening of the neovascular ridge within one week after IVB administration. Treatment failure was defined as persistence of plus disease or continued elevation of the neovascular ridge beyond one week despite therapy.

Retreatment and patient grouping

Retreatment was indicated in cases of recurrent plus disease, progressive neovascularization, or traction threatening the macula. Mild, non-progressive reactivations without vision-threatening features were managed conservatively under close observation. In selected cases of reactivation, fluorescein angiography (FA) was performed when clinically indicated to assess retinal vascular activity and peripheral vascularization. FA was not routinely performed at the time of reactivation. In cases requiring treatment, FA was obtained during the treatment session under general anesthesia to document vascular findings and guide therapy. In conservatively managed cases, FA was performed at a later stage to evaluate persistent avascular retina following spontaneous regression. Treatment options included repeat IVB injection or laser photocoagulation, depending on the severity and location of the reactivation. Mild, non-progressive reactivations without vision-threatening features were managed conservatively with close observation. No patient required vitrectomy treatment. Patients were categorized according to reactivation status and treatment requirement for subgroup analyses.

Statistical analysis

In this study, statistical analyses were performed with NCSS (Number Cruncher Statistical System) 2007 Statistical Software (Utah, USA) package program. In addition to descriptive statistical methods (mean, standard deviation), the distribution of variables was examined with the Shapiro-Wilk normality test. For the comparison of paired groups of normally distributed variables, an independent t-test was employed. For the comparison of qualitative data, chi-square and Fisher’s exact test were utilized. The results were evaluated at a significance level of p < 0.05.

Results

The study cohort comprised 119 eyes from 62 patients who received IVB treatment. The mean BW and GA of the entire cohort were 910 ± 382 g and 26.5 ± 2.8 postmenstrual weeks, respectively. The mean postmenstrual age at the time of IVB administration was 36.4 ± 2.9 weeks. Treatment failure after IVB was rare, occurring in only 2.5% of eyes (Fig. 1). ROP reactivation was observed in 30.3% of eyes. Demographic and clinical characteristics are summarized in Table 1. Among all eyes, 29 (24.4%) were diagnosed with aggressive ROP (A-ROP), with 93.1% of these cases located in zone 1.

Fig. 1.

a; plus disease combined with stage 3 ROP in zone 2, b; Crunch phenomenon with thickening of the stage line and retinal traction 4 days after IVB treatment, c; After one month of laser treatment

Table 1.

Demographic and clinical characteristics of all eyes and those with reactivation

	All eyes (n = 119)	Eyes with reactivation (n = 36)
Sex, n (%)
Female	51 (42.86)	16 (44.44)
Male	68 (57.14)	20 (55.56)
Disease zone, n (%)
Zone 1	60 (50.42)	32 (88.89)
Zone 2	59 (49.58)	4 (11.11)
Stage of ROP, n (%)
Stage 2	38 (31.93)	12 (33.33)
Stage 3	81 (68.07)	24 (66.67)
Type of ROP, n (%)
Type 1	90 (75.63)	17 (47.22)
A-ROP	29 (24.37)	19 (52.78)
Treatment failure, n (%)
(-)	116 (97.48)	—
(+)	3 (2.52)	—
Birth weight (g)	910 ± 381.98 (370–2180)	643.33 ± 148.76 (370–950)
Gestational age (week)	26.53 ± 2.8 (22–33.42)	24.43 ± 1.24 (22–27)
Age at IVB (postmenstrual, week)	36.37 ± 2.86 (29.71–43.42)	34.65 ± 1.91 (31.71–38.56)
Reactivation time (postmenstrual, week)	—	44.02 ± 3.3 (38.57–51)
Time from IVB to reactivation (week)	—	9.37 ± 2.44 (4.57–15.42)

Data are presented as mean ± SD (range) or n (%). IVB: intravitreal bevacizumab; A-ROP: aggressive retinopathy of prematurity

Infants who developed reactivation had a significantly lower mean GA (24.4 ± 1.2 weeks) and BW (643 ± 149 g). Their mean postmenstrual age at IVB treatment was also lower (34.7 ± 1.9 weeks). Reactivation occurred at a mean postmenstrual age of 44.0 ± 3.3 weeks, approximately 9.4 weeks after IVB administration. In 86.1% of reactivated eyes, additional treatment was required.

No significant difference in sex distribution was observed between patients with and without reactivation (p = 0.818). However, the reactivation group had significantly lower BW and GA (p < 0.001 for both) and a lower postmenstrual age at IVB (p < 0.001). Chronological age at IVB did not differ significantly (p = 0.308). The prevalence of zone 1 disease was significantly higher in the reactivation group (88.9% vs. 33.7%, p < 0.001), while no difference was observed in ROP stage distribution (p = 0.829). A-ROP was significantly more frequent in the reactivation group (52.8% vs. 12.1%, p < 0.001). Detailed comparisons between eyes with and without reactivation are presented in Table 2.

Table 2.

Comparison of patients with and without reactivation

		Reactivation (-)		Reactivation (+)		p
Sex	Female	35	42.17%	16	44.44%	0,818+
	Male	48	57.83%	20	55.56%
Birth Weight (g)		1025.66 ± 394.67		643.33 ± 148.76		0.0001*
Gestational age		27.44 ± 2.8		24.43 ± 1.24		0.0001*
Age at the time of IVB (postmenstrual) (week)		37.12 ± 2.89		34.65 ± 1.91		0.0001*
Age at the time of IVB (chronological) (week)		9.68 ± 2,91		10.22 ± 2,08		0.308*
Disease zone	zone 1	28	33.73%	32	88.89%	0.0001+
	zone 2	55	66.27%	4	11.11%
Stage of ROP	stage 2	26	31.33%	12	33.33%	0.829+
	stage 3	57	68.67%	24	66.67%
Type of ROP	Type 1	73	87.95%	17	47.22%	0.0001+
	A-ROP	10	12.05%	19	52.78%
Duration of pre-IVB oxygen support (week)		8.48 ± 3.47		10.22 ± 2.08		0.006*
Presence of oxygen support post-IVB	(-)	41	49.40%	0	0.00%	0.0001ǂ
	(+)	42	50.60%	36	100.00%
Duration of post-IVB oxygen support (week)		6.1 ± 4.93		12.75 ± 5.45		0.0001*

*Independent t test + Chi-square test ǂFisher’s exact test

Duration of oxygen support prior to IVB was longer in patients who experienced reactivation (10.2 ± 2.1 weeks vs. 8.5 ± 3.5 weeks, p = 0.006). All reactivated patients required post-IVB oxygen support, with a longer duration compared to non-reactivated patients (12.8 ± 5.5 weeks vs. 6.1 ± 4.9 weeks, p < 0.001) cases with reactivation. PAR was present in 95.8% of infants at 60 postmenstrual weeks.

Comparing cases with reactivation requiring treatment versus those not requiring intervention, a significant difference was noted only in sex distribution: females were more frequent in the treatment group (51.6% vs. 0%, p = 0.031). No significant differences were found in BW, GA, age at IVB, disease zone, ROP stage or type, oxygen support duration, or timing of reactivation (Table 3). Among the five untreated cases with reactivation, spontaneous regression occurred without structural sequelae, and these patients were closely followed until full vascularization or clinical stability was confirmed (Fig. 2).

Table 3.

Comparison of reactivation cases with and without treatment

		Reactivation not Requiring Treatment		Reactivation Requiring Treatment		p
Sex	Female	0	0.00%	16	51.61%	0.031ǂ
	Male	5	100.00%	15	48.39%
Birth Weight (g)		654 ± 42.19		641.61 ± 159.87		0.866*
Gestational age (week)		23.68 ± 0.41		24.55 ± 1.29		0.152*
Age at the time of IVB (postmenstrual) (week)		35.54 ± 1.26		34.51 ± 1.97		0.268*
Age at the time of IVB (chronological) (week)		11.86 ± 1,17		9.96 ± 2.08		0.057*
Disease zone	zone 1	5	100.00%	27	87.10%	0.394ǂ
	zone 2	0	0.00%	4	12.90%
Stage of ROP	stage 2	2	40.00%	10	32.26%	0.733+
	stage 3	3	60.00%	21	67.74%
Type of ROP	Type 1	2	40.00%	15	48.39%	0.727+
	A-ROP	3	60.00%	16	51.61%
Duration of pre-IVB oxygen support (week)		11.86 ± 1.17		9.96 ± 2.08		0.057*
Duration of post-IVB oxygen support (week)		9.31 ± 7.35		13.31 ± 5.02		0.130*
Reactivation time (postmenstrual) (week)		45.85 ± 0.78		43.73 ± 3.46		0.186*
Reactivation time (chronological) (week)		22.17 ± 1.1		19.12 ± 3.39		0.057*
Time from IVB to reactivation (week)		10.31 ± 1.2		9.21 ± 2.56		0.358*

*Independent t test + Chi-square test ǂ Fisher’s exact test

Stage and zone data represent findings at the time of initial IVB treatment

Fig. 2.

(a) Stage 2 ROP with plus disease in zone 1 of the temporal retina at 36 weeks + 5 days postmenstrual age in an infant born at 23 weeks + 5 days; (b) Stage 3 ROP with plus disease in zone 1 of the nasal retina of the same eye; (c) Reactivated stage 2 ROP in zone 2, observed 9 weeks and 4 days after IVB treatment; (d) Persistent avascular retina visualized in fluorescein angiography at postmenstrual week 85, following spontaneous regression

Among the five cases with reactivation that did not require retreatment, initial findings were characterized by mild disease activity, typically presenting as limited stage 2 ROP without plus disease or progressive neovascularization. These patients were closely monitored, and no progression to stage 3 disease or development of plus disease was observed during follow-up. All cases demonstrated gradual spontaneous regression without structural complications, ultimately resulting in either complete vascularization or stable peripheral avascular retina. In contrast, in cases with reactivation requiring treatment, either stage 3 disease or definite plus disease was clearly observed (Fig. 3).

Fig. 3.

Fluorescein angiography image of the left eye obtained immediately prior to treatment for reactivation at 50 weeks’ postmenstrual age in an infant born at 25 weeks + 5 days and treated with intravitreal bevacizumab at 37 weeks + 3 days

Discussion

This study demonstrates a notable incidence of ROP reactivation following IVB treatment, with most reactivated cases requiring additional intervention. Key risk factors associated with increased reactivation rates include lower BW and GA, earlier timing of IVB administration, extended oxygen therapy before and after treatment, zone 1 disease involvement, and A-ROP. However, no definitive clinical or demographic predictors were identified to reliably distinguish which cases with reactivation would necessitate additional treatment, highlighting the need for individualized patient monitoring and further investigation.

In this cohort, ROP reactivation occurred in 30.25% of treated eyes, with 86.1% of these cases requiring further intervention. This reactivation rate exceeds that reported in some previous studies, such as a 6.5% rate documented elsewhere, which may be explained by differences in patient populations [10]. Notably, the mean GA of infants with reactivation in our study was 24.43 weeks, compared to a minimum GA of 25 weeks in the referenced study. Additionally, reactivation rates reported in the literature for anti-VEGF treatments, including bevacizumab and ranibizumab, vary widely from 4% to 31% [5, 10–13]. Our findings emphasize the significantly lower GA and BW among infants experiencing reactivation, highlighting prematurity as a critical factor in the pathogenesis and severity of ROP, consistent with prior reports by Darlow et al. [14].

A key finding of our study is the significant association between prolonged oxygen support and ROP reactivation. Infants requiring extended oxygen therapy before and after IVB treatment demonstrated a markedly increased risk of reactivation. Supplemental oxygen administration has long been recognized as a risk factor in ROP pathogenesis [5, 15, 16]. Milani et al. similarly reported that both the need for and duration of oxygen therapy post-IVB correlated with reactivation risk. Likewise, Ling et al. identified oxygen therapy following anti-VEGF treatments as a predictor for ROP recurrence [11, 17]. However, it is critical to interpret this association within the context that infants with lower gestational age and birth weight—who are inherently at greater risk for reactivation—also typically require more oxygen support. These findings emphasize the importance of precise oxygen management and vigilant post-treatment monitoring to reduce the risk of disease progression or recurrence.

Our findings also highlight that while infants with A-ROP and zone 1 disease exhibit a higher prevalence of reactivation, no statistically significant differences in reactivation rates were detected across different ROP stages. This suggests that the anatomical location of the disease is a more critical predictor of reactivation risk than the stage of ROP itself. However, the lack of association between ROP stage and reactivation may be influenced by the limited sample size or study design, warranting further investigation. A-ROP, characterized by rapid progression and severe clinical course, poses a substantial risk for recurrence, aligning with previous research [10, 12]. Several studies have confirmed increased reactivation rates in zone 1 disease and A-ROP cases [3, 10, 12, 18, 19]. Nonetheless, limited data exist on the association between ROP stage and reactivation, underscoring the importance of diligent post-treatment surveillance, especially in high-risk groups such as those with zone 1 involvement and A-ROP.

A prior meta-analysis reported mean reactivation times of 9.29 weeks following ranibizumab, 11.36 weeks following bevacizumab, and 12.96 weeks following aflibercept treatments [8]. Our study found a comparable mean reactivation time of 9.37 weeks after IVB administration. In contrast, the BEAT-ROP trial and Hu et al. reported longer intervals of 16 and 14.4 weeks, respectively [3, 20]. The earlier reactivation observed in our cohort may relate to the lower mean gestational age of infants experiencing reactivation. Notably, our data also demonstrated a higher reactivation incidence in infants treated at an earlier postmenstrual age, corroborating Iwahashi et al.‘s findings that reactivation is more common in those treated before 35 postmenstrual weeks [21]. Similarly, Ling et al. observed increased reactivation rates in infants treated at younger postnatal ages [17]. Lyu et al. recommend follow-up until at least 60 postmenstrual weeks to detect late reactivations [22]. Consistent with this, all cases in our study requiring treatment occurred before 60 postmenstrual weeks. Our results emphasize that earlier treatment initiation may correlate with a more aggressive ROP course, necessitating vigilant long-term monitoring.

The high prevalence of PAR observed in our cohort is consistent with previous reports following anti-VEGF therapy for ROP [22]. Persistent avascular retina may reflect incomplete peripheral retinal vascularization despite regression of active disease and may contribute to the risk of late reactivation, highlighting the importance of prolonged follow-up after IVB treatment [22]. Although PAR was not the primary focus of this study, these findings further support the importance of careful long term surveillance in infants treated with IVB.

In our cohort, treatment failure occurred in three eyes, accounting for 2.52% of the 119 eyes treated with IVB. This rate aligns closely with a multicenter study reporting a 2.5% failure rate among 672 patients [23]. While misdiagnosis was cited as the predominant cause of treatment failure in that study, this factor was not implicated in our cases [23]. Notably, one eye initially unresponsive to IVB showed improvement upon re-treatment nine days later. Additionally, two eyes from the same patient exhibited the crunch phenomenon four days post-treatment and were successfully managed with subsequent laser photocoagulation (Fig. 1).

Management of ROP reactivation remains a critical clinical challenge. In our cohort, most cases with reactivation required additional intervention, primarily repeat IVB injections or laser photocoagulation, selected according to the severity and anatomical location of the recurrence. Interestingly, the likelihood of requiring further treatment was statistically higher among female infants—a finding that diverges from the existing literature and warrants further investigation. Previous meta-analyses have reported male sex as a disadvantage for severe ROP, whereas Iwahashi et al. found that sex was not a significant factor in ROP reactivation [21, 24, 25]. Similarly, in our study, sex was not a significant factor for the occurrence of ROP reactivation itself. However, female sex predominated among infants with reactivation requiring treatment. This phenomenon may be related to the small sample size and should be explored in future studies.

Cases with reactivation requiring treatment are not well defined in the literature. In our practice, reactivation was treated in the presence of stage 3 ROP, plus disease, or abnormal neovascularization. Conversely, in cases of reactivated stage 2 ROP, we adopted a watchful waiting approach, and some patients experienced spontaneous regression. Among those requiring treatment, female sex was more prevalent. Apart from sex, no other demographic or clinical characteristics—including ROP subtype or initial disease location—were significantly associated with the need for retreatment in reactivated cases. Although systemic factors such as weight gain and transfusion status may influence disease course, these parameters were not consistently available in our dataset. These findings suggest that reactivation requiring treatment may represent a clinically distinct subgroup of ROP, warranting further investigation.

This study has several limitations. Its retrospective design and relatively small sample size may restrict the generalizability of the findings. Additionally, certain potential contributors to the pathogenesis and reactivation of ROP—such as maternal health factors, history of blood transfusion, and neonatal sepsis—could not be assessed due to incomplete records. Future research should aim to address these gaps through larger, prospective, multicenter cohorts with standardized data collection, allowing for a more robust evaluation of both established and emerging risk factors. Despite these limitations, a key strength of this study lies in its focus on distinguishing between cases with reactivation that require treatment and those that can be safely monitored. Furthermore, the extremely low GA and BW observed in the reactivation group (mean 24.43 weeks and 643.33 g) closely align with neonatal profiles reported in high-resource settings, making the findings relevant for both developed and developing countries. This underscores the importance of tailoring follow-up strategies to population-specific risk profiles while maintaining vigilance even in settings with advanced neonatal care.

In conclusion, our study highlights the substantial risk of ROP reactivation following IVB treatment, particularly among infants with low gestational age, low birth weight, prolonged oxygen exposure, zone 1 disease, and A-ROP. Early IVB administration at a younger postmenstrual age was also associated with higher reactivation rates, although not all cases with reactivation required intervention. These findings emphasize the necessity for long-term, individualized surveillance protocols—extending at least until the 60th postmenstrual week—to enable prompt detection and treatment in high-risk infants. Beyond clinical vigilance, further prospective, multicenter studies are warranted to refine risk stratification models, optimize retreatment criteria, and develop preventive strategies aimed at preserving visual function and minimizing irreversible vision loss after IVB therapy.

Abbreviations

A-ROP

Aggressive retinopathy of prematurity

BW

Birth weight

FA

Fluorescein angiography

GA

Gestational age

ICROP

International Classification of Retinopathy of Prematurity

IVB

Intravitreal bevacizumab

PAR

Persistent avascular retina

ROP

Retinopathy of prematurity

VEGF

Vascular endothelial growth factor

Author contributions

Conception and design of the study: CG, SE, HB and SAO; acquisition, analysis, and interpretation of data; drafting of the manuscript: CG, MK and EO; critical revision for important intellectual content: CG, SE, MK and SAO; supervision of the study: MK and SAO; and final approval of the version to be published: CG, EO, SE, MK, HB and SAO.

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Data availability

The datasets used and analyzed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The study was conducted in accordance with the principles of the Declaration of Helsinki and approved by the Ethics Committee of Başakşehir Çam and Sakura City Hospital (Approval No: E-96317027-514.10-252621450). Written informed consent was obtained from the legal guardians of all participants.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.