Temporal trends in cause-specific mortality in a rural-provincial area of Denmark, Lolland-Falster, 1970-2018

Aim: In Denmark, rural-provincial Lolland-Falster currently has the highest mortality, caused mainly by the high mortality of in-migrating people. To identify possible preventive measures to combat this excess mortality insight into the underlying diseases is needed. Methods: We used data from Danish registers to calculate cause-specific mortality for 1970-1979, 1980-1989, 1990-1999, 2000-2009 and 2010-2018 divided into cancer, cardiovascular diseases, respiratory diseases, external causes and other causes (all remaining causes). We calculated age-standardised mortality rates for Lolland-Falster and the rest of Denmark: mortality rate ratios and excess number of deaths per 100,000 person-years for Lolland-Falster distinguishing between long-term residents (10+ years) and in-migrants. Results: In 1970-1979, the age-standardised mortality rates for Lolland-Falster resembled those for rest of Denmark. Over time, age-standardised mortality rates for cardiovascular diseases decreased but more so for the rest of Denmark than for Lolland-Falster. Age-standardised mortality rates for other diseases increased but more so for Lolland-Falster than for the rest of Denmark. The excess mortality in Lolland-Falster derived in particular from in-migrants: in 2010-2018 the mortality rate ratios for this population reached 2.29 (95% confidence interval 1.96-2.69) for external causes and 2.12 (95% confidence interval 1.97-2.29) for other diseases. In-migrants had in total 411 excess deaths per 100,000 person-years. Of these 27% came from tobacco smoking-related causes of death. However, another 25% came from ill-defined, unspecified and a broad range of other, minor causes of deaths. Conclusions: The excess mortality of in-migrants to Lolland-Falster was attributable to all main causes of deaths, which stresses the complexity in combatting geographical disparities in mortality.