Men had higher mortality rates than women in all
Men had higher mortality rates than women in all time periods with male to female rate ratios for each NPS-2143 ranging from 1.38 to 1.98 and all statistically significantly above 1.0. There was no significant heterogeneity in the age-specific trends of myeloma mortality in the population overall so age-standardised mortality rates could be used as a summary measure of mortality trends. Men showed a non-significant linear decrease in mortality of 11% and women a significant (p = 0.029) linear decrease of 23% (Fig. 3). However, a linear trend did not fit the data for either men or women very well. Men appeared to have a decrease in mortality rate from about 2000–2004, and women showed the highest mortality in 1995–1999 and decreased thereafter.
When the trends in mortality rates were examined by ethnic group (Fig. 4), there was only a statistically significant linear decrease, of 31%, in non-Maori women. The point estimates of mortality rates in Maori women and non-Maori men also decreased slightly from 1996 to 2000 to 2011–2015 but the decreases were not statistically significant (p = 0.847 for Maori women; p = 0.067 for non-Maori men).
Myeloma-specific survival probability curves by year of diagnosis are shown in Fig. 5. From 1990–1994 to 2010–2015 survival from myeloma significantly increased (p < 0.001). Over this time, the median survival time increased from 23.7 months in 1990–1994, to 56.4 months in 2005–2009. The median survival time has not yet been reached for patients diagnosed in 2010–2015.
In univariable Cox regression (Table 4), only age at diagnosis and year of diagnosis were significant predictors of risk of myeloma death, with the risk increasing with age but decreasing with more recent diagnosis. However, after adjustment for age at diagnosis, sex and year of diagnosis, ethnicity was also a significant predictor of myeloma death: Maori had a 36% higher risk of death from myeloma compared to non-Maori.
Discussion Although myeloma is a rare disease, New Zealand was one of the 20 countries with the highest myeloma incidence and mortality in the world in 2012 , and the higher incidence and mortality in men, compared to women, is similar in many other countries . Similar to what has occurred in Great Britain , but unlike some other countries [, , ], New Zealand’s incidence rates have significantly increased since 1985. Treatment of myeloma has changed markedly over the time covered in Frameshift mutations study. In the late 1990s some new therapies were introduced for myeloma: autologous stem cell transplantation was the first major breakthrough followed more recently by immunomodulatory drugs and proteasome inhibitors. These have resulted in better prognosis and improved survival, particularly in younger patients [2,24]. We have also shown improving survival since 1990, and some decrease in mortality since about 2000–2004. Mortality rates have also decreased in the USA [2,15] and some other countries  over a similar timeframe. We found higher incidence rates in Maori compared to non-Maori (34% higher in men and 87% higher in women in 2015–2016). The incidence rates for Maori males and females (8.81 and 6.81 per 100,000 person-years, respectively) were comparable to but lower than those reported for African Americans (9.5 and 7.2 for men and women, respectively, in 2008–2012) . Multiple myeloma has been shown to be more than twice as common in African Americans than European Americans , and in Blacks compared to Whites in England . The reasons for these ethnic differences remain unclear but some work has suggested there are underlying biological differences between myeloma in African Americans and European Americans . Whether these explain ethnic differences in New Zealand is unknown. There is no evidence of variation in treatment response between Blacks and Whites with myeloma in clinical trials [28,29] but there is evidence of differential access to effective treatment by ethnicity in the USA . Future work is needed to examine detailed patterns of survival in New Zealand and identify any ethnic disparities in outcome, particularly in the light of changing treatment and management options. Further exploration of potential variation in the biology of myeloma among ethnic and other subgroups may also provide valuable information about the causes of this disease.