Patient-reported diagnostic intervals to colorectal cancer diagnosis in the Midland region of New Zealand: a prospective cohort study

Lay Summary New Zealand has high rates of colorectal cancer but low rates of early detection. We interviewed newly diagnosed patients about their diagnostic experience to identify factors influencing time to diagnosis. More than half of patients experienced a long diagnostic interval. Young patients, Maori, females, and patients experiencing changes of bowel habit may be at particular risk for long intervals. With the diagnostic difficulty of colorectal cancer (CRC), we need to increase CRC symptom awareness for patients and general practitioners. Background and objectives New Zealand (NZ) has high rates of colorectal cancer (CRC) but low rates of early detection. The majority of CRC is diagnosed through general practice, where lengthy diagnostic intervals are common. We investigated factors contributing to diagnostic delay in a cohort of patients newly diagnosed with CRC. Methods Patients were recruited from the Midland region and interviewed about their diagnostic experience using a questionnaire based on a modified Model of Pathways to Treatment framework and SYMPTOM questionnaire. Descriptive statistics were used to describe the population characteristics. Chi-square analysis and logistic regression were used to analyse factors influencing diagnostic intervals. Results Data from 176 patients were analysed, of which 65 (36.9%) experienced a general practitioner (GP) diagnostic interval of >120 days and 96 (54.5%) experienced a total diagnostic interval (TDI) > 120 days. Patients reporting rectal bleeding were less likely to experience a long TDI (odds ratio [OR] 0.34, 95% confidence interval [CI]: 0.14-0.78) and appraisal/help-seeking interval (OR, 0.19, 95% CI: 0.06-0.59). Patients <60 were more likely to report a longer appraisal/help-seeking interval (OR, 3.32, 95% CI: 1.17-9.46). Female (OR, 2.19, 95% CI: 1.08-4.44) and Maori patients (OR, 3.18, 95% CI: 1.04-9.78) were more likely to experience a long GP diagnostic interval. Conclusion NZ patients with CRC can experience long diagnostic intervals, attributed to patient and health system factors. Young patients, Maori, females, and patients experiencing change of bowel habit may be at particular risk. We need to increase symptom awareness of CRC for patients and GPs. Concentrated efforts are needed to ensure equity for Maori in access to screening, diagnostics, and treatment.