Equity challenges in bowel cancer screening: A decade of spoilt faecal immunochemical test kit data in New Zealand

Objective To examine spoilt faecal immunochemical test kit data for associations with ethnicity, gender, socioeconomic deprivation and age. Colorectal cancer outcomes in New Zealand remain poor compared with other countries, with diagnostic delays contributing to inequities. A proportion of faecal immunochemical test kits returned to the National Bowel Screening Programme are spoilt due to participant errors, causing further delays. Methods A cross-sectional analysis was conducted on National Bowel Screening Programme data from 2012 to 2022, which includes all participants aged 60–74 years who returned a spoilt faecal immunochemical test kit. Spoilt kit reasons were compared by ethnicity using chi-square tests, and logistic regression assessed associations with demographic factors. Results Of 432,885 returned kits, 32,754 (8.2%) were spoilt. Asians had the highest proportion spoilt (10.7%), followed by Pacific Peoples (9.2%), Europeans (7.2%) and Māori (6.8%). Compared with Europeans, Asians had 53% higher odds and Pacific Peoples 19% higher odds of returning a spoilt kit, while Māori had slightly reduced odds. Men and participants living in higher deprived quintiles also had increased odds of spoiling a kit. While missing collection dates were the primary reason for spoilt kits (53.2%), transit delays emerged as a disproportionate barrier for Māori (25.6%), while Pacific Peoples (17.5%) experienced rates similar to Europeans (18.2%). Conclusions Existing interventions appear to benefit Māori in reducing errors, yet they remain vulnerable to systemic issues like transit delays. The program faces a challenge: addressing the higher rates of participant errors among the Asian and Pacific populations, while simultaneously mitigating the impact of postal infrastructure on Māori.