Admission due to Malignant Neoplasm of Eye and Adnexa in Australia: A Time-Trend Analysis

Many malignant tumors affect the eye and its adnexa [1], with Burkitt’s lymphoma, retinoblastoma and conjunctival carcinoma being the most common [2]. Unlike other disorders that affect the eye [3], the diversity and rarity of malignant eye tumors pose significant challenges in their diagnosis and management [3]. Besides, eye cancers are associated with threats to the lives and vision of affected persons and with a substantial economic burden on society [3-5]. The primary cause of cancer-related economic burden is healthcare utilization [6]. In recent decades, cancer treatments have advanced significantly, increasing the demand for healthcare and improving cancer survival rates [7,8]. With these advances in treatment and diagnosis, the number of reported eye and adnexal cancer cases has increased [1]. All these factors have increased costs and economic burdens on healthcare systems more and more [9].

Eye cancer development is influenced by genetic and environmental factors [10]. Additionally, the nature and incidence of eye cancer vary across population groups, with incidence rates being higher in Western countries than in Asia [11]. A previous study by Naser et al. showed that during the past two decades over 464,000 hospital admissions were recorded due to malignant neoplasms of eye, brain and other parts of central nervous system in the United Kingdom [12]. According to the latest available statistics, there are over 13 million Australian who have one or more chronic eye conditions [13]. Eye disorders are common and are associated with multiple complications that require hospital admissions [13]. However, studies on epidemiological trends of eye cancer are limited due to the rarity of eye cancer cases [14,15]. Therefore, this study aimed to investigate trends in hospital admissions for eye cancer in Australia. Examining hospital admission profile for eye cancer can by used as a proxy for disease burden as it reflects healthcare utilization pattern (capturing severe cases that required medical intervention and hospitalization); which enable population level comparison over time. This study provided a longitudinal analysis of the epidemiology of hospital admissions for eye cancer stratified by cancer type, age and gender. Different types of eye cancer (retina vs choroid vs orbit) differ in their associated risk factors including age, genetics. This study hypothesized that patients’ age and gender will affect admission rate due to eye cancer.

Study Design and Data Sources

This is a time trend analysis study used data from Australian electronic health databases, including information from the Australian Statistical Agency (the Australian Bureau of Statistics (ABS)), which was utilized to collect population data, as this data is reliable and independent [16,17]. Hospital admission data were gathered from the National Hospital Disease Database (NHMD), which includes data from Australian private and public hospitals managed by the Australian Institute of Health and Welfare (AIHW) for the duration between 1998 and 2023 [18,19]. Admissions related to malignant neoplasm of eye and adnexa were identified using relevant ICD codes (C69). The codes were checked and confirmed by expert ophthalmologist. The validity and reliability concerning the quality of data entry in this medical databased were previously mentioned in previous literature. Diagnostic codes were harmonized to ensure consistency. Admission rates were estimated by dividing the number of admissions in a specific year by the number of populations in the same year. The AIHW perform regular validations for patients’ data. Data are checked for valid values, consistency and historical consistency.

Statistical Analysis

Data were analysed using the Statistical Package for Social Science Software, version 29. Categorical variables were presented as frequencies and percentage. The significance on the difference in the admission rate between 1998 and 2023 was examined using Chi-Square test. The statistical significance level was assigned as p-value less than 0.05.