Demographic, socioeconomic, and audiological outcomes in children undergoing surgery for severe chronic suppurative otitis media: a retrospective cohort study from New Zealand

Introduction

Chronic suppurative otitis media (CSOM) is defined by the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS, 2000) as any persistent or recurrent tympanic membrane perforation with inflammation or a history of recurrent and/or persistent ear discharge unrelated to cholesteatoma (1,2). Although rare in high-income countries, its prevalence correlates strongly with socioeconomic disadvantage, driven by factors such as overcrowding, limited healthcare access, and inadequate sanitation (1,3). The exact prevalence of CSOM in New Zealand remains undocumented; however, disproportionate burdens of related ear diseases among Māori and Pacific populations are well-documented (4,5).

CSOM can manifest as safe perforations, amenable to conservative management or myringoplasty, or as recalcitrant infections necessitating surgical intervention. Refractory cases often involve underlying cholesteatoma or unexplained persistent otorrhea, requiring tympanomastoid procedures to achieve a safe, dry ear and, secondarily, to preserve or restore hearing (2).

While most CSOM cases, including dry perforations, are uncomplicated and may be safely managed by observation, untreated refractory or severe infections can lead to debilitating complications ranging from hearing impairment to intracranial infections (6). Hearing loss (HL) associated with CSOM significantly impacts speech-language development, educational attainment, and psychosocial well-being. Furthermore, the economic burden of managing CSOM, including surgical interventions, hearing aids, and special educational needs, is substantial (3,6).

This study aims to elucidate the demographic, socioeconomic, and ethnic factors influencing severe CSOM in children, specifically those requiring mastoid surgery for cholesteatoma or unsafe disease, at a tertiary centre in Auckland. Additionally, we evaluate surgical outcomes, with a focus on audiological changes, to identify potential disparities and inform public health strategies.

Methods

Patient selection

A retrospective review of electronic medical records was conducted at Starship Children’s Hospital, Auckland, New Zealand. Children aged 15 years and younger who underwent primary mastoid surgery for CSOM between January 2012 and December 2021 were identified. Both CSOM cases with and without cholesteatoma were included to represent the full spectrum of disease severity. We specifically included children undergoing mastoid surgery (mastoidectomy with or without tympanoplasty) to focus on advanced CSOM cases requiring mastoid intervention beyond myringoplasty alone. Inclusion criteria encompassed cases of CSOM confirmed through surgical intervention. Exclusion criteria included revision procedures and incomplete data. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. Ethical approval was granted by the Auckland Health Research Ethics Committee (AHREC) (AH 24570). Because of the retrospective nature of the research, the requirement for informed consent was waived. This study adheres to the STROBE reporting guidelines (available at https://www.theajo.com/article/view/10.21037/ajo-25-28/rc).

Data collection

Demographic information, including ethnicity (categorized as European, Māori, Pacific, Asian, and other), gender, and age at surgery, was recorded. Ethnicity distribution was compared against the 2018 New Zealand Census data (7). Socioeconomic status was assessed using the New Zealand Index of Deprivation (NZDep), with deciles ranging from 1 (least deprived) to 10 (most deprived) (7). NZDep2018 deciles were assigned by linking each patient’s residential postcode at admission to meshblock-level deprivation scores provided by the Ministry of Health.

Surgical details, including the type of procedure and disease severity, were documented. The European Academy of Otology and Neurotology/Japan Otological Society (EAONO/JOS) staging system was employed to classify cholesteatoma severity: Stage I (limited to one site), Stage II (involving multiple sites), Stage III (with extracranial complications), and Stage IV (intracranial complications) (8).

Audiological assessments included preoperative and postoperative pure-tone audiometry, measured at 0.5, 1, 2, and 4 kHz. Results were analysed for the operated and contralateral ears, with significant changes defined as a 10-dB deterioration or a 5-dB improvement, in accordance with the Occupational Safety and Health Administration (OSHA) criteria, which are widely used in audiological research to denote clinically meaningful changes even in paediatric populations (9).

Statistical analysis

Statistical analyses were conducted using Microsoft Excel, R (version 4.1.2), and GraphPad Prism (v9.0.2). Descriptive statistics summarized patient demographics and clinical characteristics. The Kruskal-Wallis test evaluated group differences, while pairwise comparisons employed the Wilcoxon test with Benjamini-Hochberg adjustments for multiple comparisons. Statistical significance was set at P<0.05.

Hearing outcomes were visualized using benefit plots adapted from the Glasgow benefit plot (10), illustrating pre- and postoperative changes in hearing thresholds.

Results

Demographics

A total of 160 children underwent primary mastoid surgery during the study period. After excluding 35 cases due to incomplete data, revision procedures, or coding errors, 125 cases were analysed. The cohort consisted of 87 males (69%) and 38 females (31%). The mean age at surgery was 8.7±2.5 years [n=38, 95% confidence interval (CI): 7.9–9.5] for European children, 9.9±2.8 years (n=32, 95% CI: 8.9–10.9) for Māori children, and 9.0±2.6 years (n=45, 95% CI: 8.2–9.8) for Pacific children. Asian children (n=10) had a mean age of 6.6±1.8 years (95% CI: 5.4–7.8), which was significantly lower compared with all other ethnicities combined (P=0.01, between-group comparison; Figure 1).

Figure 1 Age distribution of different ethnic groups of New Zealand children undergoing primary mastoid surgery (n=125). Box plots display median, interquartile range, and full range by ethnic group. Statistical comparison was performed using Kruskal-Wallis test.

Ethnic representation revealed an overrepresentation of Māori (26%) and Pacific (36%) children compared to their proportions in the general Auckland paediatric population (16.9% and 23.5%, respectively, P=0.02) (11). European children comprised 30% of the cohort, and Asian children represented 9%, both lower than their census-based population proportions (Figure 2).

Figure 2 The distribution of ethnicity. Study population of children with CSOM undergoing mastoid surgery over 10 years in the Auckland area compared to population census 2018. CSOM, chronic suppurative otitis media.

Socioeconomic status

Most children (n=87/125, 70%) were from areas with high deprivation scores (NZDep deciles 7–10). The median NZDep score was 8 [interquartile range (IQR), 7–10] in Pacific children (n=45) and 7 (IQR, 6–9) in Māori children (n=32), compared with 6 (IQR, 5–8) in European (n=38) and 5 (IQR, 4–6) in Asian children (n=10), with differences between groups significant (P<0.001, Kruskal-Wallis test; Figure 3). The mean NZDep score was highest among Pacific (8.7) and Māori (7.4) children, significantly exceeding those of European (5.7) and Asian (5.2) counterparts (P<0.001, Figure 3).

Figure 3 NZDep of children at the time of surgery, grouped by ethnicity. Box plots display median, interquartile range, and full range. Overall comparison was performed using Kruskal-Wallis test; between-group comparisons used Wilcoxon test with BH adjustment. P values reported as P<0.001 where appropriate. BH, Benjamini-Hochberg; NZDep, New Zealand Index of Deprivation.

Surgical intervention

Unless otherwise specified, denominators are the total cohort (n=125). Cholesteatoma removal was performed in 107/125 (85.6%) children. Using the total cohort as the denominator, the distribution of cholesteatoma stage was: Stage II: 79/125 (63.2%), Stage I: 15/125 (12.0%), Stage III: 3/125 (2.4%), and Stage IV: 10/125 (8.0%). Of the 10 Stage IV cases, 3/10 (30.0%) were in Māori (n=2) and Pacific (n=1) children. Surgical techniques were canal wall up 65/125 (52.0%), canal wall down 58/125 (46.4%), and other 2/125 (1.6%); distribution did not differ by ethnicity (P=0.52; Table 1).

Hearing outcomes

Audiological data were available for 98 children. Preoperatively, children exhibited a wide range of hearing thresholds. Postoperative outcomes varied: 35 children showed improved hearing (≥7.5 dB gain), 29 experienced no significant change, and 34 exhibited deteriorations (≥6.25 dB loss). Children with preoperative HL ≥35 dB HL (n=52) demonstrated a mean postoperative improvement of 18±6 dB HL (95% CI: 15–21; P<0.001, within-group comparison), while those with baseline hearing ≤35 dB HL (n=46) had a mean deterioration of −5±4 dB HL (95% CI: −8 to −2; P=0.03, within-group comparison; Figure 4). The overall distribution of postoperative hearing improvement, stability, or deterioration across the cohort is illustrated in Figure 5.

Figure 4 Population distribution grouped by ethnicity. (A) Stage of disease. (B) NZDep. Statistical tests as described in “Methods” section. P values reported as P<0.001 where appropriate. chol, cholesteatoma; NZDep, New Zealand Index of Deprivation.

Figure 5 Glasgow benefit plot of New Zealand children undergoing primary mastoid surgery for CSOM (n=98). CSOM, chronic suppurative otitis media; HL, hearing loss; POST-OP, post-operative; PRE-OP, pre-operative.

Ethnic disparities in hearing outcomes were minimal, with slight improvements noted in Asian children. Socioeconomic status did not significantly correlate with postoperative hearing outcomes. However, a subset of children (n=16) experienced bilateral HL postoperatively, predominantly affecting Pacific and Māori children.

Discussion

This study highlights significant pre- and postoperative challenges faced by children with CSOM undergoing mastoid surgery, emphasizing the complex interplay of socioeconomic and ethnic factors influencing disease prevalence and outcomes. Our findings reveal a disproportionate burden of CSOM among Māori and Pacific children, consistent with prior reports on health disparities in New Zealand (4,5,11,12).

Socioeconomic and ethnic disparities

The association between low socioeconomic status and CSOM was evident, with 70% of the cohort residing in high-deprivation areas. Contributing factors include overcrowded living conditions, limited healthcare access, and barriers to early intervention (11). Māori and Pacific children, overrepresented in our cohort, experienced higher deprivation indices and more advanced disease stages, reflecting entrenched health inequities (5,12-14).

While ethnicity did not influence surgical management or hearing outcomes directly, systemic factors likely contributed to delayed presentations and advanced disease severity among minority groups. Cultural, structural, and institutional barriers within the healthcare system may exacerbate these disparities (4,15,16). These findings apply specifically to children with severe CSOM requiring mastoid surgery and should not be generalised to patients with mild or ’safe’ CSOM presentations.

Hearing outcomes

Postoperative hearing outcomes varied. Children with severe preoperative HL (≥35 dB HL) showed significant improvements, whereas those with milder losses were more susceptible to deterioration. This trend may reflect the complexity of surgical intervention, where disease clearance and ossicular chain disruption influence audiological outcomes (17,18).

The incidence of bilateral HL postoperatively underscores the need for robust follow-up and early intervention programs, particularly for vulnerable populations. Early detection through screening programs and improved access to audiological services could mitigate long-term impacts on language development and educational attainment (16,19).

Public health implications

Addressing the root causes of CSOM-related disparities requires multi-faceted public health strategies. Initiatives such as culturally responsive healthcare delivery, community-based outreach programs, and targeted screening for at-risk populations could improve early detection and management (12,15,17,20).

The establishment of Te Aka Whai Ora (Māori Health Authority) offers a promising framework to address systemic inequities and promote equitable health outcomes through partnership models and culturally tailored interventions (12).

Limitations

This study has several limitations. First, the retrospective design carries inherent risks of missing or incomplete data. Second, as this was conducted at a tertiary referral centre, referral bias may have contributed to the high proportion of advanced cases, limiting generalisability to community or primary care populations. Third, potential confounding variables such as comorbidities, environmental exposures, and healthcare access were not fully controlled for, which may have influenced both disease severity and outcomes. Fourth, surgical decision-making criteria evolved over the 10-year study period as practice patterns changed; although broad principles were consistent, variability in individual surgeon preference may have influenced case selection. Finally, the overrepresentation of Māori and Pacific children may reflect both true disease burden and possible selection bias, as these groups are more likely to be referred with advanced disease. These factors should be considered when interpreting our findings.

Conclusions

CSOM imposes a substantial health burden on children, particularly among Māori and Pacific populations, reflecting broader socioeconomic and ethnic inequities. While surgical management yields variable audiological outcomes, addressing upstream determinants including early access to care and culturally competent health services is critical. Systemic changes, alongside targeted public health initiatives, are essential to achieve sustainable equity in CSOM outcomes.

Acknowledgments

Our abstract has been accepted for presentation at the New Zealand and Australian Society of Paediatric Otolaryngology meeting, Queenstown, New Zealand 2022.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://www.theajo.com/article/view/10.21037/ajo-25-28/rc

Data Sharing Statement: Available at https://www.theajo.com/article/view/10.21037/ajo-25-28/dss

Peer Review File: Available at https://www.theajo.com/article/view/10.21037/ajo-25-28/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://www.theajo.com/article/view/10.21037/ajo-25-28/coif). J.J. serves as an unpaid editorial board member of Australian Journal of Otolaryngology from July 2024 to December 2026. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. Ethical approval was granted by the Auckland Health Research Ethics Committee (AHREC) (AH 24570). Because of the retrospective nature of the research, the requirement for informed consent was waived.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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