Factors associated with the melanoma diagnostic interval in Ontario, Canada: a population-based study

Background Protracted times to diagnosis of cancer can lead to increased patient anxiety, and in some cases, disease progression and worse outcomes. This study assessed the time to diagnosis for melanoma, and its variability, according to patient-, disease-, and system-level factors. Methods This is a descriptive, cross-sectional study in Ontario, Canada from 2007–2019. We used administrative health data to measure the diagnostic interval (DI)–and its two subintervals–the primary care subinterval (PCI) and specialist care subinterval (SCI). Multivariable quantile regression was used. Results There were 33,371 melanoma patients. The median DI was 36 days (interquartile range [IQR]: 8–85 days), median PCI 22 days (IQR: 6–54 days), and median SCI 6 days (IQR: 1–42 days). Increasing comorbidity was associated with increasing DI. Residents in the most deprived neighbourhoods and those in rural areas experienced shorter DIs and PCIs, but no differences in SCI. There was substantial variation in the DI and SCI across health regions, but limited differences in the PCI. Finally, patients with a history of non-melanoma skin cancer, and those previously established with a dermatologist experienced significantly longer DI, PCI, and SCI. Discussion This study found variability in the melanoma DI, notably by system-level factors.