Ewan Smith

Background: The paediatric use of ophthalmic chloramphenicol in New Zealand (NZ) is relatively high; however, little more is known about its utilisation, including whether this is equitable. This study aimed to describe chloramphenicol utilisation in NZ children aged five years and under, by patient ethnicity, socioeconomic deprivation, and urban/non-urban domicile. Methods: This analysis included every publicly subsidised chloramphenicol dispensing received from birth to five years of age, for every child born in NZ in 2013. Cumulative proportion of first exposure, dispensing rate per person-year, and seasonality of dispensing were quantified. These were calculated following stratification by ethnicity, socioeconomic deprivation quintile, and urban/non-urban health district. For cumulative proportion of first exposure, odds ratios (OR) were calculated and multivariate logistic regression was performed. For dispensing rate, incidence rate ratios (IRR) were calculated and zero-inflated Poisson regression was performed. Results: Almost one-quarter of NZ children received their first dispensing within the first year of life. By five years of age, 55.2% of children had received their first dispensing. By five years of age, children of Pacific ethnicity, those in the highest deprivation quintile, and in those non-urban health districts had lower odds of receiving chloramphenicol (adjusted OR 0.90, 0.79, and 0.81, respectively, all p < 0.001). In contrast, children of Māori ethnicity had higher odds (adjusted OR 1.99, p < 0.001). Māori and Pacific ethnicity, and residence in non-urban health districts, were associated with fewer dispensings (adjusted IRR 0.88, 0.75 and 0.87, all p < 0.001). In contrast, deprivation quintile was not significantly associated with dispensing rate. Conclusion: Chloramphenicol utilisation is prevalent among NZ children, and utilisation may be lower among children of Pacific ethnicity and those in non-urban areas