Trends in myeloma incidence, mortality and survival in New Zealand (1985-2016).

Background: Myeloma, one of the most common haematological malignancies worldwide arises in the bone marrow. Incidence rates vary by age and ethnicity but reasons behind these trends are unknown. Treatment of myeloma has changed significantly over recent decades, resulting in longer survival and decreased mortality.

Methods: From data supplied by the Ministry of Health, all new registrations of and deaths from myeloma between 1985 and 2016 were extracted. Trends in age-specific rates were assessed using the method of Armitage. Age-standardised rates were calculated, and trends in age-adjusted rates analysed using the Mantel-Haenszel extension chi-square test. Age-adjusted incidence and mortality rate ratios were calculated. Myeloma-specific survival was visualised using Kaplan-Meier curves and multivariable hazard ratios calculated using Cox regression.

Results: Between 1985 and 2016, 7826 New Zealanders were registered with myeloma. Over this time the age-specific incidence of myeloma increased significantly for men, who had higher rates than women. Myeloma mortality was highest in Maori men. Men had higher mortality rates than women in all time periods. Since 1995-1999, mortality has decreased in women whereas in men it has declined since about 2000-2004. Survival has increased significantly since 1990 but Maori still have a higher risk of death than non-Maori.

Conclusion: The patterns of variation in myeloma incidence, mortality and survival, as well as their trends over time may be used to assist research into the causes and management of myeloma in New Zealand.