Original Research

Hearing loss among children with sickle cell disease at a tertiary hospital in Tanzania

Innocent Kimaro, Desderius C. Chussi, Elifaraja E. Naman, Ummykulthum A. Kipanga, Denis R. Katundu, Peter S. Shija

Received: 07 Nov. 2025; Accepted: 26 June 2026; Published: 07 Aug. 2026

Copyright: © 2026. The Authors. Licensee: AOSIS.
This work is licensed under the Creative Commons Attribution 4.0 International (CC BY 4.0) license (https://creativecommons.org/licenses/by/4.0/).

Abstract

Background: Sickle cell disease (SCD) is documented to cause sensorineural hearing loss. Although no major international guideline formally mandates routine audiological screening for all patients with SCD, multiple studies and meta-analyses have highlighted the value of early audiological assessment and the integration of rehabilitation services to mitigate the impact of SCD. This study aimed to determine the magnitude, pattern, and associated factors of hearing loss among paediatric patients with sickle cell disease in northern Tanzania.

Methods: This was a hospital-based analytical cross-sectional study conducted between October 2024 and May 2025 at a tertiary hospital in Northern Tanzania. The study sought to document and review the prevalence, patterns, and factors associated with hearing loss in children aged between 4 years and 17 years of age with confirmed sickle cell disease.

Results: A total of 90 patients with SCD were included in the final analysis. Hearing loss was identified in 31.1% of patients, with the most common type being sensorineural hearing loss (53.6%). The majority of these patients experienced bilateral hearing loss of mild to severe degree. The hearing loss was associated with the presence of vaso-occlusive episodes in the past year.

Conclusion: Mild to severe sensorineural hearing loss is commonly observed among paediatric patients with SCD. The presence of vaso-occlusive crises in the past year was associated with hearing loss.

Contribution: This study delivers the first systematic evidence on the burden, audiological patterns, and associated factors of hearing loss in paediatric SCD in an East African tertiary setting. The findings expose a neglected morbidity, strengthen context-specific clinical surveillance, and advance JCMSA’s mandate to support equitable, evidence-driven child health across African health systems.

Keywords: magnitude; pattern; associated factors; hearing loss; sickle cell disease.

Introduction

Hearing loss is defined as a hearing threshold greater than 20 decibels (dB) in the better-hearing ear, measured across standard audiometric frequencies.¹ Hearing loss can be classified as conductive, sensorineural or mixed and is a significant public health problem affecting around 1.5 billion people worldwide. Around 466 million people (5.5% of the population) have disabling hearing loss, and nearly 34 million of these are children. In all, 80% of people with disabling hearing loss live in the world’s middle-income and lower-middle-income countries. It is estimated that by 2050, over 700 million people will live with disabling hearing loss. In sub-Saharan countries, the prevalence of hearing loss among children is estimated to be 1.9% compared to 0.4% in developed countries.²

In Tanzania, the prevalence of hearing loss among children is estimated to range from 7.1% to 16.7%,³ and it is estimated that 20 000 children are deaf.⁴ In children, hearing loss can significantly impact their communication abilities. Hearing loss in children can significantly impair language acquisition and subsequent cognitive, social and emotional development. Unaddressed hearing loss costs over $980 billion in relation to healthcare, education, productivity costs and society costs.^1,5,6

Globally, the prevalence of hearing loss among patients with sickle cell disease (SCD) was found to be 19.3%.⁷ A study done in the United States showed a high prevalence of 50.8% among children with homozygous SCD.⁸ A Ugandan study found the prevalence of hearing loss among children with SCD to be 17%.⁹

Hearing loss in SCD may involve various pathophysiological mechanisms. In sensorineural hearing loss, the precise mechanism is not fully comprehended, but it appears to result from the cochlea’s heightened sensitivity to blood vessel occlusion, a hallmark of this condition. Specifically, sickle cells impede blood flow to the cochlear epithelium, leading to ischaemia in the stria vascularis.¹⁰ The labyrinthine artery serves as the sole arterial blood supply to the cochlea, rendering the inner ear susceptible to circulatory fluctuations.⁹

Conductive hearing loss stemming from middle ear disorders can be triggered by upper airway infections.¹¹ Adenoid hypertrophy may contribute to otitis media with effusion either mechanically by obstructing the Eustachian tube or by serving as a reservoir for bacteria that cause otitis media. Children with SCD are prone to adenoid hypertrophy due to their functional asplenia, which increases susceptibility to infections caused by Streptococcus pneumoniae and Haemophilus influenza.¹² Studies have reported a prevalence of adenotonsillar hypertrophy in children with SCD as 55.3%, compared to 30% – 37.6% in children without the disease.¹³

Several studies have recommended routine audiological screening and the integration of rehabilitation services into SCD management guidelines to reduce the burden of hearing loss in patients with SCD.^7,14 In resource-limited developing countries like Tanzania, where audiological services are scarce, understanding the prevalence, pattern (types, laterality and severity) and associated factors among sickle cell paediatric patients will assist in the formulation of targeted hearing screening programmes as well as a preventative approach in this vulnerable group.

Research methods and design

Study design

This was a hospital-based cross-sectional study conducted over 8 months from October 2024 to May 2025.

Study area

The study was conducted at the paediatric sickle cell clinic of the Kilimanjaro Christian Medical Centre (KCMC), which is a zonal referral hospital. Kilimanjaro Christian Medical Centre is situated in the Northern Zone of Tanzania with a bed capacity of over 800, serving approximately 13 million people and 400 patients with SCD. It also serves as a teaching hospital for the KCMC University.

Study population

All available paediatric patients with SCD eligible for the study were enrolled.

Sampling technique

A consecutive sampling technique was used, whereby all patients who met the inclusion criteria during the study period were recruited.

Inclusion criteria

Patients with SCD, confirmed by Hb electrophoresis, aged 4 years to 17 years old, whose caretakers consented.

Exclusion criteria

Patients with SCD with altered mental status, congenital anomalies of the external ear, such as canal atresia (limits audiology assessment), and patients with a history of ear surgery.

Variables

Independent variables were age, sex, frequency of painful vaso-occlusive crises (documented crises requiring hospital visit or admission), number of blood transfusions, use of medications (ototoxic drugs, hydroxyurea), number of admissions, presence of other SCD complications (stroke, anaemia, acute chest syndrome and asplenia), presence of comorbidities (diabetes mellitus and hypertension), family history of hearing loss, age of initiation of treatment and recurrent upper respiratory tract infections. The dependent variable was hearing loss.

Outcome definition

The primary outcome was hearing loss, assessed using pure-tone audiometry and defined as a pure-tone average greater than 20 dB across frequencies of 0.25 kHz to 8 kHz in accordance with the updated World Health Organization criteria. The pattern of hearing loss was characterised in terms of type, severity and laterality; type was classified as conductive hearing loss (CHL), sensorineural hearing loss (SNHL) or mixed hearing loss (MHL), severity was categorised as mild (20 dB – 34 dB), moderate (35 dB – 49 dB), moderate severe (50 dB – 64 dB), severe (65 dB – 79 dB), profound (80 dB – 94 dB) and deafness (≥ 95 dB), and laterality was defined as unilateral or bilateral involvement. Variables assessed as associated factors include demographic and clinical characteristics such as age, sex, duration of disease and other relevant patient-related factors.

Data collection tools

A structured electronic data collection sheet was developed and administered using Kobo Toolbox to record patients’ demographic information, clinical characteristics, otological examination findings and audiogram results.

Study procedure

All sickle cell patients attending the sickle cell clinic at KCMC were evaluated before the audiometric test. Patients who met the inclusion criteria were asked for assent. Demographic data were collected, and an otoscopic examination was performed using an otomicroscope to examine the ear canal and tympanic membrane at otorhinolaryngology clinic. Impacted cerumen and foreign bodies were removed before the audiometric test.

Pure-tone audiometry was performed in a sound-treated room that met background noise levels according to the International Organisation for Standardisation (ISO) 8253-1 standards by an audiologist using a pure-tone audiometer, a calibrated diagnostic audiometer (with both air and bone conduction transducers) that complied with ISO 389 standards to ensure accuracy. During a pure-tone audiometric test, patients respond to auditory stimuli delivered via air conduction (through headphones) and bone conduction (vibrating the skull directly). The typical frequency range tested is 0.25 kHz to 8 kHz, which covers critical speech frequencies. Testing was carried out using the modified Hughson-Westlake method in which tone intensity was decreased by 5 dB until the hearing threshold level was determined. Both air and bone conduction thresholds were recorded, and results were plotted on a standard audiogram to classify the type, degree (severity), laterality and frequencies affected. High-frequency hearing thresholds (HFHTs) were defined as the average hearing threshold at 4, 5, 6 and 8 kHz. Low-frequency hearing thresholds (LFHTs) were defined as the average hearing threshold at 0.25, 0.5, 1, 2 and 3 kHz in both ears.

Data analysis plan

Data were entered and analysed using Statistical Package for the Social Sciences (SPSS) version 20. The mean and standard deviation (s.d.) were calculated for continuous variables, whereas proportion and frequency were used to summarise categorical variables. Cross-tabulations with Chi-square tests were used to explore associations between variables. Univariable logistic regression was first used to assess the crude association between independent variables and hearing loss; variables with a p-value of less than 0.05 were included in multivariable logistic regression to identify independent factors. The strength of association was expressed using adjusted odds ratios (AORs) with 95% confidence intervals (CI), and a p-value of less than 0.05 was considered statistically significant.

Ethical considerations

Ethical clearance to conduct this study was obtained from the KCMC University College Research Ethics Committee (No. PG 156/2024).

Results

Socio-demographic characteristics of the patients

A total of 90 patients with SCD were included in the final analysis (Table 1). The age ranged from 4 years to 17 years old, with a mean age of 10.67 ± 4.22 years. The male to female ratio was 60:40. In all, 70% (n = 63) patients resided in urban areas, with more than half were attending primary school (56.7%, n = 51 patients).

Clinical characteristics of the study patients

In all, 31% (28) of patients had hearing loss (Figure 1); 86% of patients were diagnosed with SCD at or before the age of 5 years, with a mean age at diagnosis of 3.15 ± 2.16 years. A total of 91% had a normal body mass index (BMI) of 20.41 ± 1.66 kg/m². Of the 90 patients, 93.3% were on hydroxyurea and folic acid treatments, while 6.7% used folic acid alone. Approximately 26.7% of the study patients had experienced SCD-related complications, while 27% had a history of blood transfusion. Additionally, only 2.2% reported prior exposure to ototoxic drugs (Table 2).

FIGURE 1: Magnitude of hearing loss in relation to patients’ characteristics (N = 90).

Patterns of hearing loss among patients with sickle cell disease

In this study, 28/90 patients were found to have hearing loss. Among affected patients, 57% (16) had bilateral hearing loss, and 43% (12) had unilateral hearing loss. With regard to severity, moderate hearing loss was the most common presentation, affecting 35.7% (10/28) of patients, followed by mild hearing loss in 32.1% (9/28), moderate-to-severe hearing loss in 25.0% (7/28) and severe hearing loss in 7.1% (2/28). Sensorineural hearing loss was the most common type of hearing loss, accounting for 53.6% (15/28) of cases, followed by CHL in 35.7% (10/28) and MHL in 10.7% (3/28) (Figure 2).

FIGURE 2: Pattern of hearing loss in paediatric patients with hearing loss (N = 28).

Among patients with SNHL, high-frequency hearing loss was the predominant pattern, occurring in 58.8% (10/17) of patients, while 29.4% (5/17) had low-frequency hearing loss and 11.8% (2/17) had hearing loss affecting all frequencies (Figure 3).

FIGURE 3: Frequencies affected in patients with sensorineural hearing loss.

Factors associated with hearing loss among patients with sickle cell disease

In assessing factors associated with hearing loss among paediatric patients with SCD, only the presence of painful vaso-occlusive crises within the past year was found to be significantly associated with hearing loss in both univariate and multivariate analyses (Table 3). In the univariate analysis, patients who had experienced painful vaso-occlusive crises within the past year had approximately 15 times higher odds of developing hearing loss compared to those without such episodes (Crude odds ratio [COR]= 15.88; 95% CI: 4.8–12.55; p < 0.001). In the multivariate analysis, the association remained significant, with affected patients showing six times higher odds of hearing loss compared to those without painful crises (Adjusted odds ratio (AOR) = 6.3; 95% CI: 1.61–9.69; p < 0.008).

Discussion

The study evaluated the prevalence, patterns and factors associated with hearing loss in children with SCD. The prevalence of hearing loss in this cohort was 31.1%, which is higher than estimates reported in the general paediatric population in Tanzania (7.1% – 16.7%).³ These findings suggest that hearing impairment represents an important comorbidity among children with SCD, affecting approximately one-third of patients in this study population.

The prevalence observed in this study is comparable to findings reported from studies conducted in Brazil and Nigeria.^15,16 This may reflect similarities in study populations, age distribution and audiological assessment methods. In contrast, a lower prevalence was reported in a Ugandan study.⁹ One possible explanation for this discrepancy is the difference in diagnostic thresholds used to define hearing loss, as the Ugandan study used a hearing threshold of 25 dB compared with 20 dB in the present study.

Our study showed that SNHL is the most common type of hearing loss among paediatric patients with SCD, with high-frequency hearing loss being the most predominant pattern. This type of hearing loss is attributed to inner-ear pathologies and vaso-occlusive crises occurring in SCD. This finding is biologically plausible, as the cochlea is supplied by terminal blood vessels and is therefore particularly vulnerable to ischaemic injury during vaso-occlusion.¹⁷ In SNHL, the most commonly affected frequencies are high frequencies. The basal turn of the cochlea, which is responsible for high-frequency sound transmission, has a high metabolic demand and may be especially susceptible to microvascular compromise. Recurrent vaso-occlusive events may therefore contribute to cochlear ischaemia and subsequent damage to the outer hair cells, resulting in high-frequency SNHL.¹⁵ Exposure to ototoxic medications may further contribute to cochlear injury in some patients. These findings are consistent with previous studies reporting a predominance of SNHL, particularly at high frequencies, among paediatric patients with SCD.^9,18,19

Conductive hearing loss accounted for 35.7% among patients in our study, representing a substantial and potentially preventable proportion. In children with SCD, CHL is frequently linked to middle ear pathology, particularly otitis media with effusion or recurrent acute otitis media. Interestingly, only 4.4% of patients in our study reported a history of ear infections. This low rate suggests possible under-reporting by caregivers or the presence of subclinical or chronic middle ear disease that was not captured in the clinical history. This finding aligns with a Nigerian study, which reported a high prevalence of otitis media with effusion (27.5%) among children with sickle cell anaemia, many of whom had minimal or no symptoms reported in their history.¹¹ The absence of tympanometric assessment may also have limited the detection of occult middle ear pathology.

Bilateral hearing loss was more common than unilateral hearing loss in our study population. This finding is consistent with the pathophysiology of SCD that includes chronic hypoxia, microvascular occlusion and recurrent vaso-occlusive crisis that may affect bilateral inner ear function. Recurrent hospitalisations associated with severe SCD may also increase exposure to potentially ototoxic medications, which could contribute to hearing impairment in some patients. Similar findings have been reported in previous studies, supporting the hypothesis that systemic inner ear ischaemia plays an important role in the development of hearing loss in patients with SCD.^9,16

In the present study, the presence of a vaso-occlusive crisis within 1 year was independently associated with hearing loss among paediatric patients with SCD. This implies that vaso-occlusive crisis may be an important contributing factor in the etiopathogenesis of hearing loss by causing ischaemia in the inner ear, resulting in SNHL. Thus, those who experience vaso-occlusive crises are more likely to develop hearing loss compared to those who do not experience vaso-occlusive crises. Similar findings were reported in the Brazilian study, which demonstrated that vaso-occlusive crisis in the preceding year played a significant role in developing SNHL among paediatric patients with SCD.¹⁵

Strength of the study

This study focused on a vulnerable population of children with SCD, who are predisposed to multiple systemic complications, including hearing impairment. By examining this group, the study draws attention to an often overlooked yet clinically significant problem. Furthermore, conducting the research in a low-resource setting where audiological services are limited provides valuable insights that may inform the development of targeted interventions for individuals with SCD.

Limitations of the study

This study has several limitations. Firstly, the relatively small sample size and single-centre design limit the generalisability of the findings to other regions and populations. Secondly, the use of a hospital-based sample may introduce selection bias, as children attending the clinic may differ from those in the wider community with SCD, which may further affect representativeness. Thirdly, the absence of a control group restricts direct comparison with children without SCD, limiting broader interpretation of the findings. Although multivariable analysis was performed to adjust for potential confounders, residual confounding from unmeasured variables cannot be excluded. In addition, the study did not account for some potential confounding factors, including genetic predispositions, which may also influence the development of hearing loss.

Recommendations

This study recommends integrating targeted hearing screening into SCD management at both national and institutional levels. Routine hearing assessments should be prioritised for all patients, and in particular for patients with recurrent vaso-occlusive crisis. Prevention of SCD crisis by optimising use of hydroxyurea and rapid intervention to manage vaso-occlusive events would further prevent associated sensorineural damage. Conductive hearing loss associated with OM, especially in the context of an impaired immune system in SCD, requires more aggressive identification and treatment. Further multicentre and longitudinal studies are needed to enhance generalisability and clarify causal relationships between SCD and hearing loss. Future research should employ objective audiological assessments and include broader age groups.

Conclusion

Hearing loss is a common complication in paediatric patients with SCD, with both unilateral and bilateral impairment observed. Sensorineural hearing loss was the predominant subtype, with severity ranging from mild to severe. A history of vaso-occlusive crisis was independently associated with hearing loss in this population and may represent an important contributing factor. Conductive hearing loss is a significant contributor; early identification and aggressive management of OM would decrease the associated hearing loss and should also be prioritised.

Acknowledgement

The authors would like to express their gratitude to the respondents for their co-operation and willingness to contribute. They sincerely appreciate the support and significant contributions of the staff and residents of the ENT department at KCMC. This article is partially based on Innocent Kimaro master’s dissertation titled ‘Hearing loss among children with sickle cell disease at tertiary hospital in Tanzania’ towards the degree of Masters of Medicine in Otorhinolaryngology, KCMC University, in 2025. The dissertation is currently unpublished and not publicly available. The thesis was supervised by Peter S. Shija. The dissertation was reworked, revised, and adapted into a journal article for publication.

Dr Peter S. Shija served as the academic supervisor, providing continuous guidance, methodological oversight and critical review of the manuscript.

The authors declare that they have no financial or personal relationships that may have inappropriately influenced them in writing this article.

Innocent Kimaro: Conceptualisation, Data curation, Writing – original draft. Desderius C. Chussi: Supervision, Visualisation. Elifaraja E. Naman: Data curation, Formal analysis, Visualisation. Ummykulthum A. Kipanga: Data curation, Project administration. Denis R. Katundu: Data curation, Resources, Writing – review & editing. Peter S. Shija: Methodology, Supervision, Writing – review & editing. All authors reviewed the article, contributed to the discussion of results, approved the final version for submission and publication and take responsibility for the integrity of its findings.

The authors received no financial support for the research, authorship and/or publication of this article.

The authors declare that all data that support this research article and its findings are available in the article and its references.

The views and opinions expressed in this article are those of the authors and are the product of professional research. They do not necessarily reflect the official policy or position of any affiliated institution, funder, agency, or that of the publisher. The authors are responsible for this article’s results, findings, and content.

References